2166 lines
86 KiB
Rust
2166 lines
86 KiB
Rust
use super::{ImplTraitContext, LoweringContext, ParamMode, ParenthesizedGenericArgs};
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use rustc_ast::attr;
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use rustc_ast::ptr::P as AstP;
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use rustc_ast::*;
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use rustc_data_structures::fx::FxHashMap;
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use rustc_data_structures::stack::ensure_sufficient_stack;
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use rustc_data_structures::thin_vec::ThinVec;
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use rustc_errors::struct_span_err;
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use rustc_hir as hir;
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use rustc_hir::def::Res;
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use rustc_hir::definitions::DefPathData;
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use rustc_session::parse::feature_err;
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use rustc_span::hygiene::ExpnId;
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use rustc_span::source_map::{respan, DesugaringKind, Span, Spanned};
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use rustc_span::symbol::{sym, Ident, Symbol};
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use rustc_span::{hygiene::ForLoopLoc, DUMMY_SP};
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use rustc_target::asm;
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use std::collections::hash_map::Entry;
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use std::fmt::Write;
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impl<'hir> LoweringContext<'_, 'hir> {
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fn lower_exprs(&mut self, exprs: &[AstP<Expr>]) -> &'hir [hir::Expr<'hir>] {
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self.arena.alloc_from_iter(exprs.iter().map(|x| self.lower_expr_mut(x)))
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}
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pub(super) fn lower_expr(&mut self, e: &Expr) -> &'hir hir::Expr<'hir> {
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self.arena.alloc(self.lower_expr_mut(e))
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}
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pub(super) fn lower_expr_mut(&mut self, e: &Expr) -> hir::Expr<'hir> {
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ensure_sufficient_stack(|| {
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let kind = match e.kind {
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ExprKind::Box(ref inner) => hir::ExprKind::Box(self.lower_expr(inner)),
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ExprKind::Array(ref exprs) => hir::ExprKind::Array(self.lower_exprs(exprs)),
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ExprKind::ConstBlock(ref anon_const) => {
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let anon_const = self.lower_anon_const(anon_const);
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hir::ExprKind::ConstBlock(anon_const)
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}
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ExprKind::Repeat(ref expr, ref count) => {
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let expr = self.lower_expr(expr);
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let count = self.lower_anon_const(count);
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hir::ExprKind::Repeat(expr, count)
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}
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ExprKind::Tup(ref elts) => hir::ExprKind::Tup(self.lower_exprs(elts)),
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ExprKind::Call(ref f, ref args) => {
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if let Some(legacy_args) = self.resolver.legacy_const_generic_args(f) {
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self.lower_legacy_const_generics((**f).clone(), args.clone(), &legacy_args)
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} else {
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let f = self.lower_expr(f);
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hir::ExprKind::Call(f, self.lower_exprs(args))
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}
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}
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ExprKind::MethodCall(ref seg, ref args, span) => {
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let hir_seg = self.arena.alloc(self.lower_path_segment(
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e.span,
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seg,
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ParamMode::Optional,
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0,
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ParenthesizedGenericArgs::Err,
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ImplTraitContext::disallowed(),
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None,
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));
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let args = self.lower_exprs(args);
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hir::ExprKind::MethodCall(hir_seg, seg.ident.span, args, span)
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}
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ExprKind::Binary(binop, ref lhs, ref rhs) => {
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let binop = self.lower_binop(binop);
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let lhs = self.lower_expr(lhs);
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let rhs = self.lower_expr(rhs);
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hir::ExprKind::Binary(binop, lhs, rhs)
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}
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ExprKind::Unary(op, ref ohs) => {
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let op = self.lower_unop(op);
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let ohs = self.lower_expr(ohs);
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hir::ExprKind::Unary(op, ohs)
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}
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ExprKind::Lit(ref l) => hir::ExprKind::Lit(respan(l.span, l.kind.clone())),
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ExprKind::Cast(ref expr, ref ty) => {
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let expr = self.lower_expr(expr);
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let ty = self.lower_ty(ty, ImplTraitContext::disallowed());
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hir::ExprKind::Cast(expr, ty)
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}
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ExprKind::Type(ref expr, ref ty) => {
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let expr = self.lower_expr(expr);
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let ty = self.lower_ty(ty, ImplTraitContext::disallowed());
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hir::ExprKind::Type(expr, ty)
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}
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ExprKind::AddrOf(k, m, ref ohs) => {
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let ohs = self.lower_expr(ohs);
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hir::ExprKind::AddrOf(k, m, ohs)
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}
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ExprKind::Let(ref pat, ref scrutinee) => {
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self.lower_expr_let(e.span, pat, scrutinee)
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}
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ExprKind::If(ref cond, ref then, ref else_opt) => match cond.kind {
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ExprKind::Let(ref pat, ref scrutinee) => {
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self.lower_expr_if_let(e.span, pat, scrutinee, then, else_opt.as_deref())
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}
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ExprKind::Paren(ref paren) => match paren.peel_parens().kind {
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ExprKind::Let(ref pat, ref scrutinee) => {
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// A user has written `if (let Some(x) = foo) {`, we want to avoid
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// confusing them with mentions of nightly features.
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// If this logic is changed, you will also likely need to touch
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// `unused::UnusedParens::check_expr`.
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self.if_let_expr_with_parens(cond, &paren.peel_parens());
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self.lower_expr_if_let(
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e.span,
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pat,
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scrutinee,
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then,
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else_opt.as_deref(),
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)
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}
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_ => self.lower_expr_if(cond, then, else_opt.as_deref()),
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},
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_ => self.lower_expr_if(cond, then, else_opt.as_deref()),
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},
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ExprKind::While(ref cond, ref body, opt_label) => self
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.with_loop_scope(e.id, |this| {
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this.lower_expr_while_in_loop_scope(e.span, cond, body, opt_label)
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}),
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ExprKind::Loop(ref body, opt_label) => self.with_loop_scope(e.id, |this| {
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hir::ExprKind::Loop(
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this.lower_block(body, false),
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opt_label,
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hir::LoopSource::Loop,
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DUMMY_SP,
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)
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}),
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ExprKind::TryBlock(ref body) => self.lower_expr_try_block(body),
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ExprKind::Match(ref expr, ref arms) => hir::ExprKind::Match(
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self.lower_expr(expr),
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self.arena.alloc_from_iter(arms.iter().map(|x| self.lower_arm(x))),
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hir::MatchSource::Normal,
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),
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ExprKind::Async(capture_clause, closure_node_id, ref block) => self
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.make_async_expr(
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capture_clause,
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closure_node_id,
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None,
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block.span,
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hir::AsyncGeneratorKind::Block,
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|this| this.with_new_scopes(|this| this.lower_block_expr(block)),
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),
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ExprKind::Await(ref expr) => self.lower_expr_await(e.span, expr),
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ExprKind::Closure(
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capture_clause,
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asyncness,
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movability,
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ref decl,
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ref body,
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fn_decl_span,
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) => {
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if let Async::Yes { closure_id, .. } = asyncness {
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self.lower_expr_async_closure(
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capture_clause,
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closure_id,
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decl,
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body,
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fn_decl_span,
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)
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} else {
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self.lower_expr_closure(
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capture_clause,
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movability,
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decl,
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body,
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fn_decl_span,
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)
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}
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}
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ExprKind::Block(ref blk, opt_label) => {
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hir::ExprKind::Block(self.lower_block(blk, opt_label.is_some()), opt_label)
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}
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ExprKind::Assign(ref el, ref er, span) => {
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self.lower_expr_assign(el, er, span, e.span)
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}
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ExprKind::AssignOp(op, ref el, ref er) => hir::ExprKind::AssignOp(
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self.lower_binop(op),
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self.lower_expr(el),
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self.lower_expr(er),
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),
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ExprKind::Field(ref el, ident) => hir::ExprKind::Field(self.lower_expr(el), ident),
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ExprKind::Index(ref el, ref er) => {
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hir::ExprKind::Index(self.lower_expr(el), self.lower_expr(er))
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}
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ExprKind::Range(Some(ref e1), Some(ref e2), RangeLimits::Closed) => {
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self.lower_expr_range_closed(e.span, e1, e2)
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}
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ExprKind::Range(ref e1, ref e2, lims) => {
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self.lower_expr_range(e.span, e1.as_deref(), e2.as_deref(), lims)
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}
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ExprKind::Underscore => {
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self.sess
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.struct_span_err(
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e.span,
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"in expressions, `_` can only be used on the left-hand side of an assignment",
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)
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.span_label(e.span, "`_` not allowed here")
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.emit();
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hir::ExprKind::Err
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}
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ExprKind::Path(ref qself, ref path) => {
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let qpath = self.lower_qpath(
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e.id,
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qself,
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path,
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ParamMode::Optional,
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ImplTraitContext::disallowed(),
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);
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hir::ExprKind::Path(qpath)
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}
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ExprKind::Break(opt_label, ref opt_expr) => {
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let opt_expr = opt_expr.as_ref().map(|x| self.lower_expr(x));
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hir::ExprKind::Break(self.lower_jump_destination(e.id, opt_label), opt_expr)
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}
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ExprKind::Continue(opt_label) => {
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hir::ExprKind::Continue(self.lower_jump_destination(e.id, opt_label))
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}
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ExprKind::Ret(ref e) => {
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let e = e.as_ref().map(|x| self.lower_expr(x));
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hir::ExprKind::Ret(e)
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}
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ExprKind::InlineAsm(ref asm) => self.lower_expr_asm(e.span, asm),
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ExprKind::LlvmInlineAsm(ref asm) => self.lower_expr_llvm_asm(asm),
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ExprKind::Struct(ref path, ref fields, ref rest) => {
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let rest = match rest {
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StructRest::Base(e) => Some(self.lower_expr(e)),
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StructRest::Rest(sp) => {
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self.sess
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.struct_span_err(*sp, "base expression required after `..`")
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.span_label(*sp, "add a base expression here")
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.emit();
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Some(&*self.arena.alloc(self.expr_err(*sp)))
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}
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StructRest::None => None,
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};
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hir::ExprKind::Struct(
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self.arena.alloc(self.lower_qpath(
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e.id,
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&None,
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path,
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ParamMode::Optional,
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ImplTraitContext::disallowed(),
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)),
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self.arena.alloc_from_iter(fields.iter().map(|x| self.lower_field(x))),
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rest,
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)
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}
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ExprKind::Yield(ref opt_expr) => self.lower_expr_yield(e.span, opt_expr.as_deref()),
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ExprKind::Err => hir::ExprKind::Err,
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ExprKind::Try(ref sub_expr) => self.lower_expr_try(e.span, sub_expr),
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ExprKind::Paren(ref ex) => {
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let mut ex = self.lower_expr_mut(ex);
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// Include parens in span, but only if it is a super-span.
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if e.span.contains(ex.span) {
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ex.span = e.span;
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}
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// Merge attributes into the inner expression.
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if !e.attrs.is_empty() {
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let old_attrs = self.attrs.get(&ex.hir_id).map(|la| *la).unwrap_or(&[]);
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self.attrs.insert(
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ex.hir_id,
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&*self.arena.alloc_from_iter(
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e.attrs
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.iter()
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.map(|a| self.lower_attr(a))
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.chain(old_attrs.iter().cloned()),
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),
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);
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}
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return ex;
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}
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// Desugar `ExprForLoop`
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// from: `[opt_ident]: for <pat> in <head> <body>`
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ExprKind::ForLoop(ref pat, ref head, ref body, opt_label) => {
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return self.lower_expr_for(e, pat, head, body, opt_label);
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}
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ExprKind::MacCall(_) => panic!("{:?} shouldn't exist here", e.span),
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};
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let hir_id = self.lower_node_id(e.id);
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self.lower_attrs(hir_id, &e.attrs);
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hir::Expr { hir_id, kind, span: e.span }
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})
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}
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fn lower_unop(&mut self, u: UnOp) -> hir::UnOp {
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match u {
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UnOp::Deref => hir::UnOp::Deref,
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UnOp::Not => hir::UnOp::Not,
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UnOp::Neg => hir::UnOp::Neg,
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}
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}
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fn lower_binop(&mut self, b: BinOp) -> hir::BinOp {
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Spanned {
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node: match b.node {
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BinOpKind::Add => hir::BinOpKind::Add,
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BinOpKind::Sub => hir::BinOpKind::Sub,
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BinOpKind::Mul => hir::BinOpKind::Mul,
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BinOpKind::Div => hir::BinOpKind::Div,
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BinOpKind::Rem => hir::BinOpKind::Rem,
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BinOpKind::And => hir::BinOpKind::And,
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BinOpKind::Or => hir::BinOpKind::Or,
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BinOpKind::BitXor => hir::BinOpKind::BitXor,
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BinOpKind::BitAnd => hir::BinOpKind::BitAnd,
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BinOpKind::BitOr => hir::BinOpKind::BitOr,
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BinOpKind::Shl => hir::BinOpKind::Shl,
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BinOpKind::Shr => hir::BinOpKind::Shr,
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BinOpKind::Eq => hir::BinOpKind::Eq,
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BinOpKind::Lt => hir::BinOpKind::Lt,
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BinOpKind::Le => hir::BinOpKind::Le,
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BinOpKind::Ne => hir::BinOpKind::Ne,
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BinOpKind::Ge => hir::BinOpKind::Ge,
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BinOpKind::Gt => hir::BinOpKind::Gt,
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},
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span: b.span,
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}
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}
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fn lower_legacy_const_generics(
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&mut self,
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mut f: Expr,
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args: Vec<AstP<Expr>>,
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legacy_args_idx: &[usize],
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) -> hir::ExprKind<'hir> {
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let path = match f.kind {
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ExprKind::Path(None, ref mut path) => path,
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_ => unreachable!(),
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};
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// Split the arguments into const generics and normal arguments
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let mut real_args = vec![];
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let mut generic_args = vec![];
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for (idx, arg) in args.into_iter().enumerate() {
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if legacy_args_idx.contains(&idx) {
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let parent_def_id = self.current_hir_id_owner.last().unwrap().0;
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let node_id = self.resolver.next_node_id();
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// Add a definition for the in-band const def.
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self.resolver.create_def(
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parent_def_id,
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node_id,
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DefPathData::AnonConst,
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ExpnId::root(),
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arg.span,
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);
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let anon_const = AnonConst { id: node_id, value: arg };
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generic_args.push(AngleBracketedArg::Arg(GenericArg::Const(anon_const)));
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} else {
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real_args.push(arg);
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}
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}
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// Add generic args to the last element of the path.
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let last_segment = path.segments.last_mut().unwrap();
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assert!(last_segment.args.is_none());
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last_segment.args = Some(AstP(GenericArgs::AngleBracketed(AngleBracketedArgs {
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span: DUMMY_SP,
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args: generic_args,
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})));
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// Now lower everything as normal.
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let f = self.lower_expr(&f);
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hir::ExprKind::Call(f, self.lower_exprs(&real_args))
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}
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fn if_let_expr_with_parens(&mut self, cond: &Expr, paren: &Expr) {
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let start = cond.span.until(paren.span);
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let end = paren.span.shrink_to_hi().until(cond.span.shrink_to_hi());
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self.sess
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.struct_span_err(
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vec![start, end],
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"invalid parentheses around `let` expression in `if let`",
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)
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.multipart_suggestion(
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"`if let` needs to be written without parentheses",
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vec![(start, String::new()), (end, String::new())],
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rustc_errors::Applicability::MachineApplicable,
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)
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.emit();
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// Ideally, we'd remove the feature gating of a `let` expression since we are already
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// complaining about it here, but `feature_gate::check_crate` has already run by now:
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// self.sess.parse_sess.gated_spans.ungate_last(sym::let_chains, paren.span);
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}
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|
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|
/// Emit an error and lower `ast::ExprKind::Let(pat, scrutinee)` into:
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/// ```rust
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/// match scrutinee { pats => true, _ => false }
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/// ```
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|
fn lower_expr_let(&mut self, span: Span, pat: &Pat, scrutinee: &Expr) -> hir::ExprKind<'hir> {
|
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// If we got here, the `let` expression is not allowed.
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|
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if self.sess.opts.unstable_features.is_nightly_build() {
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self.sess
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.struct_span_err(span, "`let` expressions are not supported here")
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.note(
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|
"only supported directly without parentheses in conditions of `if`- and \
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`while`-expressions, as well as in `let` chains within parentheses",
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)
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.emit();
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} else {
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self.sess
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.struct_span_err(span, "expected expression, found statement (`let`)")
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.note("variable declaration using `let` is a statement")
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.emit();
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}
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// For better recovery, we emit:
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// ```
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// match scrutinee { pat => true, _ => false }
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// ```
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|
// While this doesn't fully match the user's intent, it has key advantages:
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// 1. We can avoid using `abort_if_errors`.
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// 2. We can typeck both `pat` and `scrutinee`.
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// 3. `pat` is allowed to be refutable.
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// 4. The return type of the block is `bool` which seems like what the user wanted.
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let scrutinee = self.lower_expr(scrutinee);
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|
let then_arm = {
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let pat = self.lower_pat(pat);
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let expr = self.expr_bool(span, true);
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|
self.arm(pat, expr)
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|
};
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|
let else_arm = {
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let pat = self.pat_wild(span);
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let expr = self.expr_bool(span, false);
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self.arm(pat, expr)
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};
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|
hir::ExprKind::Match(
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scrutinee,
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arena_vec![self; then_arm, else_arm],
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hir::MatchSource::Normal,
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)
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}
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|
|
|
fn lower_expr_if(
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&mut self,
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cond: &Expr,
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then: &Block,
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else_opt: Option<&Expr>,
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) -> hir::ExprKind<'hir> {
|
|
macro_rules! make_if {
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|
($opt:expr) => {{
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|
let cond = self.lower_expr(cond);
|
|
let then_expr = self.lower_block_expr(then);
|
|
hir::ExprKind::If(cond, self.arena.alloc(then_expr), $opt)
|
|
}};
|
|
}
|
|
if let Some(rslt) = else_opt {
|
|
make_if!(Some(self.lower_expr(rslt)))
|
|
} else {
|
|
make_if!(None)
|
|
}
|
|
}
|
|
|
|
fn lower_expr_if_let(
|
|
&mut self,
|
|
span: Span,
|
|
pat: &Pat,
|
|
scrutinee: &Expr,
|
|
then: &Block,
|
|
else_opt: Option<&Expr>,
|
|
) -> hir::ExprKind<'hir> {
|
|
// FIXME(#53667): handle lowering of && and parens.
|
|
|
|
// `_ => else_block` where `else_block` is `{}` if there's `None`:
|
|
let else_pat = self.pat_wild(span);
|
|
let (else_expr, contains_else_clause) = match else_opt {
|
|
None => (self.expr_block_empty(span.shrink_to_hi()), false),
|
|
Some(els) => (self.lower_expr(els), true),
|
|
};
|
|
let else_arm = self.arm(else_pat, else_expr);
|
|
|
|
// Handle then + scrutinee:
|
|
let scrutinee = self.lower_expr(scrutinee);
|
|
let then_pat = self.lower_pat(pat);
|
|
|
|
let then_expr = self.lower_block_expr(then);
|
|
let then_arm = self.arm(then_pat, self.arena.alloc(then_expr));
|
|
|
|
let desugar = hir::MatchSource::IfLetDesugar { contains_else_clause };
|
|
hir::ExprKind::Match(scrutinee, arena_vec![self; then_arm, else_arm], desugar)
|
|
}
|
|
|
|
fn lower_expr_while_in_loop_scope(
|
|
&mut self,
|
|
span: Span,
|
|
cond: &Expr,
|
|
body: &Block,
|
|
opt_label: Option<Label>,
|
|
) -> hir::ExprKind<'hir> {
|
|
// FIXME(#53667): handle lowering of && and parens.
|
|
|
|
// Note that the block AND the condition are evaluated in the loop scope.
|
|
// This is done to allow `break` from inside the condition of the loop.
|
|
|
|
// `_ => break`:
|
|
let else_arm = {
|
|
let else_pat = self.pat_wild(span);
|
|
let else_expr = self.expr_break(span, ThinVec::new());
|
|
self.arm(else_pat, else_expr)
|
|
};
|
|
|
|
// Handle then + scrutinee:
|
|
let (then_pat, scrutinee, desugar, source) = match cond.kind {
|
|
ExprKind::Let(ref pat, ref scrutinee) => {
|
|
// to:
|
|
//
|
|
// [opt_ident]: loop {
|
|
// match <sub_expr> {
|
|
// <pat> => <body>,
|
|
// _ => break
|
|
// }
|
|
// }
|
|
let scrutinee = self.with_loop_condition_scope(|t| t.lower_expr(scrutinee));
|
|
let pat = self.lower_pat(pat);
|
|
(pat, scrutinee, hir::MatchSource::WhileLetDesugar, hir::LoopSource::WhileLet)
|
|
}
|
|
_ => {
|
|
// We desugar: `'label: while $cond $body` into:
|
|
//
|
|
// ```
|
|
// 'label: loop {
|
|
// match drop-temps { $cond } {
|
|
// true => $body,
|
|
// _ => break,
|
|
// }
|
|
// }
|
|
// ```
|
|
|
|
// Lower condition:
|
|
let cond = self.with_loop_condition_scope(|this| this.lower_expr(cond));
|
|
let span_block =
|
|
self.mark_span_with_reason(DesugaringKind::CondTemporary, cond.span, None);
|
|
// Wrap in a construct equivalent to `{ let _t = $cond; _t }`
|
|
// to preserve drop semantics since `while cond { ... }` does not
|
|
// let temporaries live outside of `cond`.
|
|
let cond = self.expr_drop_temps(span_block, cond, ThinVec::new());
|
|
// `true => <then>`:
|
|
let pat = self.pat_bool(span, true);
|
|
(pat, cond, hir::MatchSource::WhileDesugar, hir::LoopSource::While)
|
|
}
|
|
};
|
|
let then_expr = self.lower_block_expr(body);
|
|
let then_arm = self.arm(then_pat, self.arena.alloc(then_expr));
|
|
|
|
// `match <scrutinee> { ... }`
|
|
let match_expr =
|
|
self.expr_match(span, scrutinee, arena_vec![self; then_arm, else_arm], desugar);
|
|
|
|
// `[opt_ident]: loop { ... }`
|
|
hir::ExprKind::Loop(
|
|
self.block_expr(self.arena.alloc(match_expr)),
|
|
opt_label,
|
|
source,
|
|
span.with_hi(cond.span.hi()),
|
|
)
|
|
}
|
|
|
|
/// Desugar `try { <stmts>; <expr> }` into `{ <stmts>; ::std::ops::Try::from_ok(<expr>) }`,
|
|
/// `try { <stmts>; }` into `{ <stmts>; ::std::ops::Try::from_ok(()) }`
|
|
/// and save the block id to use it as a break target for desugaring of the `?` operator.
|
|
fn lower_expr_try_block(&mut self, body: &Block) -> hir::ExprKind<'hir> {
|
|
self.with_catch_scope(body.id, |this| {
|
|
let mut block = this.lower_block_noalloc(body, true);
|
|
|
|
// Final expression of the block (if present) or `()` with span at the end of block
|
|
let (try_span, tail_expr) = if let Some(expr) = block.expr.take() {
|
|
(
|
|
this.mark_span_with_reason(
|
|
DesugaringKind::TryBlock,
|
|
expr.span,
|
|
this.allow_try_trait.clone(),
|
|
),
|
|
expr,
|
|
)
|
|
} else {
|
|
let try_span = this.mark_span_with_reason(
|
|
DesugaringKind::TryBlock,
|
|
this.sess.source_map().end_point(body.span),
|
|
this.allow_try_trait.clone(),
|
|
);
|
|
|
|
(try_span, this.expr_unit(try_span))
|
|
};
|
|
|
|
let ok_wrapped_span =
|
|
this.mark_span_with_reason(DesugaringKind::TryBlock, tail_expr.span, None);
|
|
|
|
// `::std::ops::Try::from_ok($tail_expr)`
|
|
block.expr = Some(this.wrap_in_try_constructor(
|
|
hir::LangItem::TryFromOk,
|
|
try_span,
|
|
tail_expr,
|
|
ok_wrapped_span,
|
|
));
|
|
|
|
hir::ExprKind::Block(this.arena.alloc(block), None)
|
|
})
|
|
}
|
|
|
|
fn wrap_in_try_constructor(
|
|
&mut self,
|
|
lang_item: hir::LangItem,
|
|
method_span: Span,
|
|
expr: &'hir hir::Expr<'hir>,
|
|
overall_span: Span,
|
|
) -> &'hir hir::Expr<'hir> {
|
|
let constructor =
|
|
self.arena.alloc(self.expr_lang_item_path(method_span, lang_item, ThinVec::new()));
|
|
self.expr_call(overall_span, constructor, std::slice::from_ref(expr))
|
|
}
|
|
|
|
fn lower_arm(&mut self, arm: &Arm) -> hir::Arm<'hir> {
|
|
let pat = self.lower_pat(&arm.pat);
|
|
let guard = arm.guard.as_ref().map(|cond| {
|
|
if let ExprKind::Let(ref pat, ref scrutinee) = cond.kind {
|
|
hir::Guard::IfLet(self.lower_pat(pat), self.lower_expr(scrutinee))
|
|
} else {
|
|
hir::Guard::If(self.lower_expr(cond))
|
|
}
|
|
});
|
|
let hir_id = self.next_id();
|
|
self.lower_attrs(hir_id, &arm.attrs);
|
|
hir::Arm { hir_id, pat, guard, body: self.lower_expr(&arm.body), span: arm.span }
|
|
}
|
|
|
|
/// Lower an `async` construct to a generator that is then wrapped so it implements `Future`.
|
|
///
|
|
/// This results in:
|
|
///
|
|
/// ```text
|
|
/// std::future::from_generator(static move? |_task_context| -> <ret_ty> {
|
|
/// <body>
|
|
/// })
|
|
/// ```
|
|
pub(super) fn make_async_expr(
|
|
&mut self,
|
|
capture_clause: CaptureBy,
|
|
closure_node_id: NodeId,
|
|
ret_ty: Option<AstP<Ty>>,
|
|
span: Span,
|
|
async_gen_kind: hir::AsyncGeneratorKind,
|
|
body: impl FnOnce(&mut Self) -> hir::Expr<'hir>,
|
|
) -> hir::ExprKind<'hir> {
|
|
let output = match ret_ty {
|
|
Some(ty) => hir::FnRetTy::Return(self.lower_ty(&ty, ImplTraitContext::disallowed())),
|
|
None => hir::FnRetTy::DefaultReturn(span),
|
|
};
|
|
|
|
// Resume argument type. We let the compiler infer this to simplify the lowering. It is
|
|
// fully constrained by `future::from_generator`.
|
|
let input_ty = hir::Ty { hir_id: self.next_id(), kind: hir::TyKind::Infer, span };
|
|
|
|
// The closure/generator `FnDecl` takes a single (resume) argument of type `input_ty`.
|
|
let decl = self.arena.alloc(hir::FnDecl {
|
|
inputs: arena_vec![self; input_ty],
|
|
output,
|
|
c_variadic: false,
|
|
implicit_self: hir::ImplicitSelfKind::None,
|
|
});
|
|
|
|
// Lower the argument pattern/ident. The ident is used again in the `.await` lowering.
|
|
let (pat, task_context_hid) = self.pat_ident_binding_mode(
|
|
span,
|
|
Ident::with_dummy_span(sym::_task_context),
|
|
hir::BindingAnnotation::Mutable,
|
|
);
|
|
let param = hir::Param { hir_id: self.next_id(), pat, ty_span: span, span };
|
|
let params = arena_vec![self; param];
|
|
|
|
let body_id = self.lower_body(move |this| {
|
|
this.generator_kind = Some(hir::GeneratorKind::Async(async_gen_kind));
|
|
|
|
let old_ctx = this.task_context;
|
|
this.task_context = Some(task_context_hid);
|
|
let res = body(this);
|
|
this.task_context = old_ctx;
|
|
(params, res)
|
|
});
|
|
|
|
// `static |_task_context| -> <ret_ty> { body }`:
|
|
let generator_kind = hir::ExprKind::Closure(
|
|
capture_clause,
|
|
decl,
|
|
body_id,
|
|
span,
|
|
Some(hir::Movability::Static),
|
|
);
|
|
let generator =
|
|
hir::Expr { hir_id: self.lower_node_id(closure_node_id), kind: generator_kind, span };
|
|
|
|
// `future::from_generator`:
|
|
let unstable_span =
|
|
self.mark_span_with_reason(DesugaringKind::Async, span, self.allow_gen_future.clone());
|
|
let gen_future =
|
|
self.expr_lang_item_path(unstable_span, hir::LangItem::FromGenerator, ThinVec::new());
|
|
|
|
// `future::from_generator(generator)`:
|
|
hir::ExprKind::Call(self.arena.alloc(gen_future), arena_vec![self; generator])
|
|
}
|
|
|
|
/// Desugar `<expr>.await` into:
|
|
/// ```rust
|
|
/// match <expr> {
|
|
/// mut pinned => loop {
|
|
/// match unsafe { ::std::future::Future::poll(
|
|
/// <::std::pin::Pin>::new_unchecked(&mut pinned),
|
|
/// ::std::future::get_context(task_context),
|
|
/// ) } {
|
|
/// ::std::task::Poll::Ready(result) => break result,
|
|
/// ::std::task::Poll::Pending => {}
|
|
/// }
|
|
/// task_context = yield ();
|
|
/// }
|
|
/// }
|
|
/// ```
|
|
fn lower_expr_await(&mut self, await_span: Span, expr: &Expr) -> hir::ExprKind<'hir> {
|
|
match self.generator_kind {
|
|
Some(hir::GeneratorKind::Async(_)) => {}
|
|
Some(hir::GeneratorKind::Gen) | None => {
|
|
let mut err = struct_span_err!(
|
|
self.sess,
|
|
await_span,
|
|
E0728,
|
|
"`await` is only allowed inside `async` functions and blocks"
|
|
);
|
|
err.span_label(await_span, "only allowed inside `async` functions and blocks");
|
|
if let Some(item_sp) = self.current_item {
|
|
err.span_label(item_sp, "this is not `async`");
|
|
}
|
|
err.emit();
|
|
}
|
|
}
|
|
let span = self.mark_span_with_reason(DesugaringKind::Await, await_span, None);
|
|
let gen_future_span = self.mark_span_with_reason(
|
|
DesugaringKind::Await,
|
|
await_span,
|
|
self.allow_gen_future.clone(),
|
|
);
|
|
let expr = self.lower_expr(expr);
|
|
|
|
let pinned_ident = Ident::with_dummy_span(sym::pinned);
|
|
let (pinned_pat, pinned_pat_hid) =
|
|
self.pat_ident_binding_mode(span, pinned_ident, hir::BindingAnnotation::Mutable);
|
|
|
|
let task_context_ident = Ident::with_dummy_span(sym::_task_context);
|
|
|
|
// unsafe {
|
|
// ::std::future::Future::poll(
|
|
// ::std::pin::Pin::new_unchecked(&mut pinned),
|
|
// ::std::future::get_context(task_context),
|
|
// )
|
|
// }
|
|
let poll_expr = {
|
|
let pinned = self.expr_ident(span, pinned_ident, pinned_pat_hid);
|
|
let ref_mut_pinned = self.expr_mut_addr_of(span, pinned);
|
|
let task_context = if let Some(task_context_hid) = self.task_context {
|
|
self.expr_ident_mut(span, task_context_ident, task_context_hid)
|
|
} else {
|
|
// Use of `await` outside of an async context, we cannot use `task_context` here.
|
|
self.expr_err(span)
|
|
};
|
|
let new_unchecked = self.expr_call_lang_item_fn_mut(
|
|
span,
|
|
hir::LangItem::PinNewUnchecked,
|
|
arena_vec![self; ref_mut_pinned],
|
|
);
|
|
let get_context = self.expr_call_lang_item_fn_mut(
|
|
gen_future_span,
|
|
hir::LangItem::GetContext,
|
|
arena_vec![self; task_context],
|
|
);
|
|
let call = self.expr_call_lang_item_fn(
|
|
span,
|
|
hir::LangItem::FuturePoll,
|
|
arena_vec![self; new_unchecked, get_context],
|
|
);
|
|
self.arena.alloc(self.expr_unsafe(call))
|
|
};
|
|
|
|
// `::std::task::Poll::Ready(result) => break result`
|
|
let loop_node_id = self.resolver.next_node_id();
|
|
let loop_hir_id = self.lower_node_id(loop_node_id);
|
|
let ready_arm = {
|
|
let x_ident = Ident::with_dummy_span(sym::result);
|
|
let (x_pat, x_pat_hid) = self.pat_ident(span, x_ident);
|
|
let x_expr = self.expr_ident(span, x_ident, x_pat_hid);
|
|
let ready_field = self.single_pat_field(span, x_pat);
|
|
let ready_pat = self.pat_lang_item_variant(span, hir::LangItem::PollReady, ready_field);
|
|
let break_x = self.with_loop_scope(loop_node_id, move |this| {
|
|
let expr_break =
|
|
hir::ExprKind::Break(this.lower_loop_destination(None), Some(x_expr));
|
|
this.arena.alloc(this.expr(await_span, expr_break, ThinVec::new()))
|
|
});
|
|
self.arm(ready_pat, break_x)
|
|
};
|
|
|
|
// `::std::task::Poll::Pending => {}`
|
|
let pending_arm = {
|
|
let pending_pat = self.pat_lang_item_variant(span, hir::LangItem::PollPending, &[]);
|
|
let empty_block = self.expr_block_empty(span);
|
|
self.arm(pending_pat, empty_block)
|
|
};
|
|
|
|
let inner_match_stmt = {
|
|
let match_expr = self.expr_match(
|
|
span,
|
|
poll_expr,
|
|
arena_vec![self; ready_arm, pending_arm],
|
|
hir::MatchSource::AwaitDesugar,
|
|
);
|
|
self.stmt_expr(span, match_expr)
|
|
};
|
|
|
|
// task_context = yield ();
|
|
let yield_stmt = {
|
|
let unit = self.expr_unit(span);
|
|
let yield_expr = self.expr(
|
|
span,
|
|
hir::ExprKind::Yield(unit, hir::YieldSource::Await { expr: Some(expr.hir_id) }),
|
|
ThinVec::new(),
|
|
);
|
|
let yield_expr = self.arena.alloc(yield_expr);
|
|
|
|
if let Some(task_context_hid) = self.task_context {
|
|
let lhs = self.expr_ident(span, task_context_ident, task_context_hid);
|
|
let assign =
|
|
self.expr(span, hir::ExprKind::Assign(lhs, yield_expr, span), AttrVec::new());
|
|
self.stmt_expr(span, assign)
|
|
} else {
|
|
// Use of `await` outside of an async context. Return `yield_expr` so that we can
|
|
// proceed with type checking.
|
|
self.stmt(span, hir::StmtKind::Semi(yield_expr))
|
|
}
|
|
};
|
|
|
|
let loop_block = self.block_all(span, arena_vec![self; inner_match_stmt, yield_stmt], None);
|
|
|
|
// loop { .. }
|
|
let loop_expr = self.arena.alloc(hir::Expr {
|
|
hir_id: loop_hir_id,
|
|
kind: hir::ExprKind::Loop(loop_block, None, hir::LoopSource::Loop, span),
|
|
span,
|
|
});
|
|
|
|
// mut pinned => loop { ... }
|
|
let pinned_arm = self.arm(pinned_pat, loop_expr);
|
|
|
|
// match <expr> {
|
|
// mut pinned => loop { .. }
|
|
// }
|
|
hir::ExprKind::Match(expr, arena_vec![self; pinned_arm], hir::MatchSource::AwaitDesugar)
|
|
}
|
|
|
|
fn lower_expr_closure(
|
|
&mut self,
|
|
capture_clause: CaptureBy,
|
|
movability: Movability,
|
|
decl: &FnDecl,
|
|
body: &Expr,
|
|
fn_decl_span: Span,
|
|
) -> hir::ExprKind<'hir> {
|
|
let (body_id, generator_option) = self.with_new_scopes(move |this| {
|
|
let prev = this.current_item;
|
|
this.current_item = Some(fn_decl_span);
|
|
let mut generator_kind = None;
|
|
let body_id = this.lower_fn_body(decl, |this| {
|
|
let e = this.lower_expr_mut(body);
|
|
generator_kind = this.generator_kind;
|
|
e
|
|
});
|
|
let generator_option =
|
|
this.generator_movability_for_fn(&decl, fn_decl_span, generator_kind, movability);
|
|
this.current_item = prev;
|
|
(body_id, generator_option)
|
|
});
|
|
|
|
// Lower outside new scope to preserve `is_in_loop_condition`.
|
|
let fn_decl = self.lower_fn_decl(decl, None, false, None);
|
|
|
|
hir::ExprKind::Closure(capture_clause, fn_decl, body_id, fn_decl_span, generator_option)
|
|
}
|
|
|
|
fn generator_movability_for_fn(
|
|
&mut self,
|
|
decl: &FnDecl,
|
|
fn_decl_span: Span,
|
|
generator_kind: Option<hir::GeneratorKind>,
|
|
movability: Movability,
|
|
) -> Option<hir::Movability> {
|
|
match generator_kind {
|
|
Some(hir::GeneratorKind::Gen) => {
|
|
if decl.inputs.len() > 1 {
|
|
struct_span_err!(
|
|
self.sess,
|
|
fn_decl_span,
|
|
E0628,
|
|
"too many parameters for a generator (expected 0 or 1 parameters)"
|
|
)
|
|
.emit();
|
|
}
|
|
Some(movability)
|
|
}
|
|
Some(hir::GeneratorKind::Async(_)) => {
|
|
panic!("non-`async` closure body turned `async` during lowering");
|
|
}
|
|
None => {
|
|
if movability == Movability::Static {
|
|
struct_span_err!(self.sess, fn_decl_span, E0697, "closures cannot be static")
|
|
.emit();
|
|
}
|
|
None
|
|
}
|
|
}
|
|
}
|
|
|
|
fn lower_expr_async_closure(
|
|
&mut self,
|
|
capture_clause: CaptureBy,
|
|
closure_id: NodeId,
|
|
decl: &FnDecl,
|
|
body: &Expr,
|
|
fn_decl_span: Span,
|
|
) -> hir::ExprKind<'hir> {
|
|
let outer_decl =
|
|
FnDecl { inputs: decl.inputs.clone(), output: FnRetTy::Default(fn_decl_span) };
|
|
|
|
let body_id = self.with_new_scopes(|this| {
|
|
// FIXME(cramertj): allow `async` non-`move` closures with arguments.
|
|
if capture_clause == CaptureBy::Ref && !decl.inputs.is_empty() {
|
|
struct_span_err!(
|
|
this.sess,
|
|
fn_decl_span,
|
|
E0708,
|
|
"`async` non-`move` closures with parameters are not currently supported",
|
|
)
|
|
.help(
|
|
"consider using `let` statements to manually capture \
|
|
variables by reference before entering an `async move` closure",
|
|
)
|
|
.emit();
|
|
}
|
|
|
|
// Transform `async |x: u8| -> X { ... }` into
|
|
// `|x: u8| future_from_generator(|| -> X { ... })`.
|
|
let body_id = this.lower_fn_body(&outer_decl, |this| {
|
|
let async_ret_ty =
|
|
if let FnRetTy::Ty(ty) = &decl.output { Some(ty.clone()) } else { None };
|
|
let async_body = this.make_async_expr(
|
|
capture_clause,
|
|
closure_id,
|
|
async_ret_ty,
|
|
body.span,
|
|
hir::AsyncGeneratorKind::Closure,
|
|
|this| this.with_new_scopes(|this| this.lower_expr_mut(body)),
|
|
);
|
|
this.expr(fn_decl_span, async_body, ThinVec::new())
|
|
});
|
|
body_id
|
|
});
|
|
|
|
// We need to lower the declaration outside the new scope, because we
|
|
// have to conserve the state of being inside a loop condition for the
|
|
// closure argument types.
|
|
let fn_decl = self.lower_fn_decl(&outer_decl, None, false, None);
|
|
|
|
hir::ExprKind::Closure(capture_clause, fn_decl, body_id, fn_decl_span, None)
|
|
}
|
|
|
|
/// Destructure the LHS of complex assignments.
|
|
/// For instance, lower `(a, b) = t` to `{ let (lhs1, lhs2) = t; a = lhs1; b = lhs2; }`.
|
|
fn lower_expr_assign(
|
|
&mut self,
|
|
lhs: &Expr,
|
|
rhs: &Expr,
|
|
eq_sign_span: Span,
|
|
whole_span: Span,
|
|
) -> hir::ExprKind<'hir> {
|
|
// Return early in case of an ordinary assignment.
|
|
fn is_ordinary(lower_ctx: &mut LoweringContext<'_, '_>, lhs: &Expr) -> bool {
|
|
match &lhs.kind {
|
|
ExprKind::Array(..)
|
|
| ExprKind::Struct(..)
|
|
| ExprKind::Tup(..)
|
|
| ExprKind::Underscore => false,
|
|
// Check for tuple struct constructor.
|
|
ExprKind::Call(callee, ..) => lower_ctx.extract_tuple_struct_path(callee).is_none(),
|
|
ExprKind::Paren(e) => {
|
|
match e.kind {
|
|
// We special-case `(..)` for consistency with patterns.
|
|
ExprKind::Range(None, None, RangeLimits::HalfOpen) => false,
|
|
_ => is_ordinary(lower_ctx, e),
|
|
}
|
|
}
|
|
_ => true,
|
|
}
|
|
}
|
|
if is_ordinary(self, lhs) {
|
|
return hir::ExprKind::Assign(self.lower_expr(lhs), self.lower_expr(rhs), eq_sign_span);
|
|
}
|
|
if !self.sess.features_untracked().destructuring_assignment {
|
|
feature_err(
|
|
&self.sess.parse_sess,
|
|
sym::destructuring_assignment,
|
|
eq_sign_span,
|
|
"destructuring assignments are unstable",
|
|
)
|
|
.span_label(lhs.span, "cannot assign to this expression")
|
|
.emit();
|
|
}
|
|
|
|
let mut assignments = vec![];
|
|
|
|
// The LHS becomes a pattern: `(lhs1, lhs2)`.
|
|
let pat = self.destructure_assign(lhs, eq_sign_span, &mut assignments);
|
|
let rhs = self.lower_expr(rhs);
|
|
|
|
// Introduce a `let` for destructuring: `let (lhs1, lhs2) = t`.
|
|
let destructure_let = self.stmt_let_pat(
|
|
None,
|
|
whole_span,
|
|
Some(rhs),
|
|
pat,
|
|
hir::LocalSource::AssignDesugar(eq_sign_span),
|
|
);
|
|
|
|
// `a = lhs1; b = lhs2;`.
|
|
let stmts = self
|
|
.arena
|
|
.alloc_from_iter(std::iter::once(destructure_let).chain(assignments.into_iter()));
|
|
|
|
// Wrap everything in a block.
|
|
hir::ExprKind::Block(&self.block_all(whole_span, stmts, None), None)
|
|
}
|
|
|
|
/// If the given expression is a path to a tuple struct, returns that path.
|
|
/// It is not a complete check, but just tries to reject most paths early
|
|
/// if they are not tuple structs.
|
|
/// Type checking will take care of the full validation later.
|
|
fn extract_tuple_struct_path<'a>(&mut self, expr: &'a Expr) -> Option<&'a Path> {
|
|
// For tuple struct destructuring, it must be a non-qualified path (like in patterns).
|
|
if let ExprKind::Path(None, path) = &expr.kind {
|
|
// Does the path resolves to something disallowed in a tuple struct/variant pattern?
|
|
if let Some(partial_res) = self.resolver.get_partial_res(expr.id) {
|
|
if partial_res.unresolved_segments() == 0
|
|
&& !partial_res.base_res().expected_in_tuple_struct_pat()
|
|
{
|
|
return None;
|
|
}
|
|
}
|
|
return Some(path);
|
|
}
|
|
None
|
|
}
|
|
|
|
/// Convert the LHS of a destructuring assignment to a pattern.
|
|
/// Each sub-assignment is recorded in `assignments`.
|
|
fn destructure_assign(
|
|
&mut self,
|
|
lhs: &Expr,
|
|
eq_sign_span: Span,
|
|
assignments: &mut Vec<hir::Stmt<'hir>>,
|
|
) -> &'hir hir::Pat<'hir> {
|
|
match &lhs.kind {
|
|
// Underscore pattern.
|
|
ExprKind::Underscore => {
|
|
return self.pat_without_dbm(lhs.span, hir::PatKind::Wild);
|
|
}
|
|
// Slice patterns.
|
|
ExprKind::Array(elements) => {
|
|
let (pats, rest) =
|
|
self.destructure_sequence(elements, "slice", eq_sign_span, assignments);
|
|
let slice_pat = if let Some((i, span)) = rest {
|
|
let (before, after) = pats.split_at(i);
|
|
hir::PatKind::Slice(
|
|
before,
|
|
Some(self.pat_without_dbm(span, hir::PatKind::Wild)),
|
|
after,
|
|
)
|
|
} else {
|
|
hir::PatKind::Slice(pats, None, &[])
|
|
};
|
|
return self.pat_without_dbm(lhs.span, slice_pat);
|
|
}
|
|
// Tuple structs.
|
|
ExprKind::Call(callee, args) => {
|
|
if let Some(path) = self.extract_tuple_struct_path(callee) {
|
|
let (pats, rest) = self.destructure_sequence(
|
|
args,
|
|
"tuple struct or variant",
|
|
eq_sign_span,
|
|
assignments,
|
|
);
|
|
let qpath = self.lower_qpath(
|
|
callee.id,
|
|
&None,
|
|
path,
|
|
ParamMode::Optional,
|
|
ImplTraitContext::disallowed(),
|
|
);
|
|
// Destructure like a tuple struct.
|
|
let tuple_struct_pat =
|
|
hir::PatKind::TupleStruct(qpath, pats, rest.map(|r| r.0));
|
|
return self.pat_without_dbm(lhs.span, tuple_struct_pat);
|
|
}
|
|
}
|
|
// Structs.
|
|
ExprKind::Struct(path, fields, rest) => {
|
|
let field_pats = self.arena.alloc_from_iter(fields.iter().map(|f| {
|
|
let pat = self.destructure_assign(&f.expr, eq_sign_span, assignments);
|
|
hir::FieldPat {
|
|
hir_id: self.next_id(),
|
|
ident: f.ident,
|
|
pat,
|
|
is_shorthand: f.is_shorthand,
|
|
span: f.span,
|
|
}
|
|
}));
|
|
let qpath = self.lower_qpath(
|
|
lhs.id,
|
|
&None,
|
|
path,
|
|
ParamMode::Optional,
|
|
ImplTraitContext::disallowed(),
|
|
);
|
|
let fields_omitted = match rest {
|
|
StructRest::Base(e) => {
|
|
self.sess
|
|
.struct_span_err(
|
|
e.span,
|
|
"functional record updates are not allowed in destructuring \
|
|
assignments",
|
|
)
|
|
.span_suggestion(
|
|
e.span,
|
|
"consider removing the trailing pattern",
|
|
String::new(),
|
|
rustc_errors::Applicability::MachineApplicable,
|
|
)
|
|
.emit();
|
|
true
|
|
}
|
|
StructRest::Rest(_) => true,
|
|
StructRest::None => false,
|
|
};
|
|
let struct_pat = hir::PatKind::Struct(qpath, field_pats, fields_omitted);
|
|
return self.pat_without_dbm(lhs.span, struct_pat);
|
|
}
|
|
// Tuples.
|
|
ExprKind::Tup(elements) => {
|
|
let (pats, rest) =
|
|
self.destructure_sequence(elements, "tuple", eq_sign_span, assignments);
|
|
let tuple_pat = hir::PatKind::Tuple(pats, rest.map(|r| r.0));
|
|
return self.pat_without_dbm(lhs.span, tuple_pat);
|
|
}
|
|
ExprKind::Paren(e) => {
|
|
// We special-case `(..)` for consistency with patterns.
|
|
if let ExprKind::Range(None, None, RangeLimits::HalfOpen) = e.kind {
|
|
let tuple_pat = hir::PatKind::Tuple(&[], Some(0));
|
|
return self.pat_without_dbm(lhs.span, tuple_pat);
|
|
} else {
|
|
return self.destructure_assign(e, eq_sign_span, assignments);
|
|
}
|
|
}
|
|
_ => {}
|
|
}
|
|
// Treat all other cases as normal lvalue.
|
|
let ident = Ident::new(sym::lhs, lhs.span);
|
|
let (pat, binding) = self.pat_ident(lhs.span, ident);
|
|
let ident = self.expr_ident(lhs.span, ident, binding);
|
|
let assign = hir::ExprKind::Assign(self.lower_expr(lhs), ident, eq_sign_span);
|
|
let expr = self.expr(lhs.span, assign, ThinVec::new());
|
|
assignments.push(self.stmt_expr(lhs.span, expr));
|
|
pat
|
|
}
|
|
|
|
/// Destructure a sequence of expressions occurring on the LHS of an assignment.
|
|
/// Such a sequence occurs in a tuple (struct)/slice.
|
|
/// Return a sequence of corresponding patterns, and the index and the span of `..` if it
|
|
/// exists.
|
|
/// Each sub-assignment is recorded in `assignments`.
|
|
fn destructure_sequence(
|
|
&mut self,
|
|
elements: &[AstP<Expr>],
|
|
ctx: &str,
|
|
eq_sign_span: Span,
|
|
assignments: &mut Vec<hir::Stmt<'hir>>,
|
|
) -> (&'hir [&'hir hir::Pat<'hir>], Option<(usize, Span)>) {
|
|
let mut rest = None;
|
|
let elements =
|
|
self.arena.alloc_from_iter(elements.iter().enumerate().filter_map(|(i, e)| {
|
|
// Check for `..` pattern.
|
|
if let ExprKind::Range(None, None, RangeLimits::HalfOpen) = e.kind {
|
|
if let Some((_, prev_span)) = rest {
|
|
self.ban_extra_rest_pat(e.span, prev_span, ctx);
|
|
} else {
|
|
rest = Some((i, e.span));
|
|
}
|
|
None
|
|
} else {
|
|
Some(self.destructure_assign(e, eq_sign_span, assignments))
|
|
}
|
|
}));
|
|
(elements, rest)
|
|
}
|
|
|
|
/// Desugar `<start>..=<end>` into `std::ops::RangeInclusive::new(<start>, <end>)`.
|
|
fn lower_expr_range_closed(&mut self, span: Span, e1: &Expr, e2: &Expr) -> hir::ExprKind<'hir> {
|
|
let e1 = self.lower_expr_mut(e1);
|
|
let e2 = self.lower_expr_mut(e2);
|
|
let fn_path = hir::QPath::LangItem(hir::LangItem::RangeInclusiveNew, span);
|
|
let fn_expr =
|
|
self.arena.alloc(self.expr(span, hir::ExprKind::Path(fn_path), ThinVec::new()));
|
|
hir::ExprKind::Call(fn_expr, arena_vec![self; e1, e2])
|
|
}
|
|
|
|
fn lower_expr_range(
|
|
&mut self,
|
|
span: Span,
|
|
e1: Option<&Expr>,
|
|
e2: Option<&Expr>,
|
|
lims: RangeLimits,
|
|
) -> hir::ExprKind<'hir> {
|
|
use rustc_ast::RangeLimits::*;
|
|
|
|
let lang_item = match (e1, e2, lims) {
|
|
(None, None, HalfOpen) => hir::LangItem::RangeFull,
|
|
(Some(..), None, HalfOpen) => hir::LangItem::RangeFrom,
|
|
(None, Some(..), HalfOpen) => hir::LangItem::RangeTo,
|
|
(Some(..), Some(..), HalfOpen) => hir::LangItem::Range,
|
|
(None, Some(..), Closed) => hir::LangItem::RangeToInclusive,
|
|
(Some(..), Some(..), Closed) => unreachable!(),
|
|
(_, None, Closed) => {
|
|
self.diagnostic().span_fatal(span, "inclusive range with no end").raise()
|
|
}
|
|
};
|
|
|
|
let fields = self.arena.alloc_from_iter(
|
|
e1.iter().map(|e| ("start", e)).chain(e2.iter().map(|e| ("end", e))).map(|(s, e)| {
|
|
let expr = self.lower_expr(&e);
|
|
let ident = Ident::new(Symbol::intern(s), e.span);
|
|
self.field(ident, expr, e.span)
|
|
}),
|
|
);
|
|
|
|
hir::ExprKind::Struct(self.arena.alloc(hir::QPath::LangItem(lang_item, span)), fields, None)
|
|
}
|
|
|
|
fn lower_loop_destination(&mut self, destination: Option<(NodeId, Label)>) -> hir::Destination {
|
|
let target_id = match destination {
|
|
Some((id, _)) => {
|
|
if let Some(loop_id) = self.resolver.get_label_res(id) {
|
|
Ok(self.lower_node_id(loop_id))
|
|
} else {
|
|
Err(hir::LoopIdError::UnresolvedLabel)
|
|
}
|
|
}
|
|
None => self
|
|
.loop_scopes
|
|
.last()
|
|
.cloned()
|
|
.map(|id| Ok(self.lower_node_id(id)))
|
|
.unwrap_or(Err(hir::LoopIdError::OutsideLoopScope)),
|
|
};
|
|
hir::Destination { label: destination.map(|(_, label)| label), target_id }
|
|
}
|
|
|
|
fn lower_jump_destination(&mut self, id: NodeId, opt_label: Option<Label>) -> hir::Destination {
|
|
if self.is_in_loop_condition && opt_label.is_none() {
|
|
hir::Destination {
|
|
label: None,
|
|
target_id: Err(hir::LoopIdError::UnlabeledCfInWhileCondition),
|
|
}
|
|
} else {
|
|
self.lower_loop_destination(opt_label.map(|label| (id, label)))
|
|
}
|
|
}
|
|
|
|
fn with_catch_scope<T>(&mut self, catch_id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
|
|
let len = self.catch_scopes.len();
|
|
self.catch_scopes.push(catch_id);
|
|
|
|
let result = f(self);
|
|
assert_eq!(
|
|
len + 1,
|
|
self.catch_scopes.len(),
|
|
"catch scopes should be added and removed in stack order"
|
|
);
|
|
|
|
self.catch_scopes.pop().unwrap();
|
|
|
|
result
|
|
}
|
|
|
|
fn with_loop_scope<T>(&mut self, loop_id: NodeId, f: impl FnOnce(&mut Self) -> T) -> T {
|
|
// We're no longer in the base loop's condition; we're in another loop.
|
|
let was_in_loop_condition = self.is_in_loop_condition;
|
|
self.is_in_loop_condition = false;
|
|
|
|
let len = self.loop_scopes.len();
|
|
self.loop_scopes.push(loop_id);
|
|
|
|
let result = f(self);
|
|
assert_eq!(
|
|
len + 1,
|
|
self.loop_scopes.len(),
|
|
"loop scopes should be added and removed in stack order"
|
|
);
|
|
|
|
self.loop_scopes.pop().unwrap();
|
|
|
|
self.is_in_loop_condition = was_in_loop_condition;
|
|
|
|
result
|
|
}
|
|
|
|
fn with_loop_condition_scope<T>(&mut self, f: impl FnOnce(&mut Self) -> T) -> T {
|
|
let was_in_loop_condition = self.is_in_loop_condition;
|
|
self.is_in_loop_condition = true;
|
|
|
|
let result = f(self);
|
|
|
|
self.is_in_loop_condition = was_in_loop_condition;
|
|
|
|
result
|
|
}
|
|
|
|
fn lower_expr_asm(&mut self, sp: Span, asm: &InlineAsm) -> hir::ExprKind<'hir> {
|
|
// Rustdoc needs to support asm! from foriegn architectures: don't try
|
|
// lowering the register contraints in this case.
|
|
let asm_arch = if self.sess.opts.actually_rustdoc { None } else { self.sess.asm_arch };
|
|
if asm_arch.is_none() && !self.sess.opts.actually_rustdoc {
|
|
struct_span_err!(self.sess, sp, E0472, "asm! is unsupported on this target").emit();
|
|
}
|
|
if asm.options.contains(InlineAsmOptions::ATT_SYNTAX)
|
|
&& !matches!(asm_arch, Some(asm::InlineAsmArch::X86 | asm::InlineAsmArch::X86_64))
|
|
&& !self.sess.opts.actually_rustdoc
|
|
{
|
|
self.sess
|
|
.struct_span_err(sp, "the `att_syntax` option is only supported on x86")
|
|
.emit();
|
|
}
|
|
|
|
// Lower operands to HIR. We use dummy register classes if an error
|
|
// occurs during lowering because we still need to be able to produce a
|
|
// valid HIR.
|
|
let sess = self.sess;
|
|
let operands: Vec<_> = asm
|
|
.operands
|
|
.iter()
|
|
.map(|(op, op_sp)| {
|
|
let lower_reg = |reg| match reg {
|
|
InlineAsmRegOrRegClass::Reg(s) => {
|
|
asm::InlineAsmRegOrRegClass::Reg(if let Some(asm_arch) = asm_arch {
|
|
asm::InlineAsmReg::parse(
|
|
asm_arch,
|
|
|feature| sess.target_features.contains(&Symbol::intern(feature)),
|
|
&sess.target,
|
|
s,
|
|
)
|
|
.unwrap_or_else(|e| {
|
|
let msg = format!("invalid register `{}`: {}", s.as_str(), e);
|
|
sess.struct_span_err(*op_sp, &msg).emit();
|
|
asm::InlineAsmReg::Err
|
|
})
|
|
} else {
|
|
asm::InlineAsmReg::Err
|
|
})
|
|
}
|
|
InlineAsmRegOrRegClass::RegClass(s) => {
|
|
asm::InlineAsmRegOrRegClass::RegClass(if let Some(asm_arch) = asm_arch {
|
|
asm::InlineAsmRegClass::parse(asm_arch, s).unwrap_or_else(|e| {
|
|
let msg = format!("invalid register class `{}`: {}", s.as_str(), e);
|
|
sess.struct_span_err(*op_sp, &msg).emit();
|
|
asm::InlineAsmRegClass::Err
|
|
})
|
|
} else {
|
|
asm::InlineAsmRegClass::Err
|
|
})
|
|
}
|
|
};
|
|
|
|
let op = match *op {
|
|
InlineAsmOperand::In { reg, ref expr } => hir::InlineAsmOperand::In {
|
|
reg: lower_reg(reg),
|
|
expr: self.lower_expr_mut(expr),
|
|
},
|
|
InlineAsmOperand::Out { reg, late, ref expr } => hir::InlineAsmOperand::Out {
|
|
reg: lower_reg(reg),
|
|
late,
|
|
expr: expr.as_ref().map(|expr| self.lower_expr_mut(expr)),
|
|
},
|
|
InlineAsmOperand::InOut { reg, late, ref expr } => {
|
|
hir::InlineAsmOperand::InOut {
|
|
reg: lower_reg(reg),
|
|
late,
|
|
expr: self.lower_expr_mut(expr),
|
|
}
|
|
}
|
|
InlineAsmOperand::SplitInOut { reg, late, ref in_expr, ref out_expr } => {
|
|
hir::InlineAsmOperand::SplitInOut {
|
|
reg: lower_reg(reg),
|
|
late,
|
|
in_expr: self.lower_expr_mut(in_expr),
|
|
out_expr: out_expr.as_ref().map(|expr| self.lower_expr_mut(expr)),
|
|
}
|
|
}
|
|
InlineAsmOperand::Const { ref expr } => {
|
|
hir::InlineAsmOperand::Const { expr: self.lower_expr_mut(expr) }
|
|
}
|
|
InlineAsmOperand::Sym { ref expr } => {
|
|
hir::InlineAsmOperand::Sym { expr: self.lower_expr_mut(expr) }
|
|
}
|
|
};
|
|
(op, *op_sp)
|
|
})
|
|
.collect();
|
|
|
|
// Validate template modifiers against the register classes for the operands
|
|
for p in &asm.template {
|
|
if let InlineAsmTemplatePiece::Placeholder {
|
|
operand_idx,
|
|
modifier: Some(modifier),
|
|
span: placeholder_span,
|
|
} = *p
|
|
{
|
|
let op_sp = asm.operands[operand_idx].1;
|
|
match &operands[operand_idx].0 {
|
|
hir::InlineAsmOperand::In { reg, .. }
|
|
| hir::InlineAsmOperand::Out { reg, .. }
|
|
| hir::InlineAsmOperand::InOut { reg, .. }
|
|
| hir::InlineAsmOperand::SplitInOut { reg, .. } => {
|
|
let class = reg.reg_class();
|
|
if class == asm::InlineAsmRegClass::Err {
|
|
continue;
|
|
}
|
|
let valid_modifiers = class.valid_modifiers(asm_arch.unwrap());
|
|
if !valid_modifiers.contains(&modifier) {
|
|
let mut err = sess.struct_span_err(
|
|
placeholder_span,
|
|
"invalid asm template modifier for this register class",
|
|
);
|
|
err.span_label(placeholder_span, "template modifier");
|
|
err.span_label(op_sp, "argument");
|
|
if !valid_modifiers.is_empty() {
|
|
let mut mods = format!("`{}`", valid_modifiers[0]);
|
|
for m in &valid_modifiers[1..] {
|
|
let _ = write!(mods, ", `{}`", m);
|
|
}
|
|
err.note(&format!(
|
|
"the `{}` register class supports \
|
|
the following template modifiers: {}",
|
|
class.name(),
|
|
mods
|
|
));
|
|
} else {
|
|
err.note(&format!(
|
|
"the `{}` register class does not support template modifiers",
|
|
class.name()
|
|
));
|
|
}
|
|
err.emit();
|
|
}
|
|
}
|
|
hir::InlineAsmOperand::Const { .. } => {
|
|
let mut err = sess.struct_span_err(
|
|
placeholder_span,
|
|
"asm template modifiers are not allowed for `const` arguments",
|
|
);
|
|
err.span_label(placeholder_span, "template modifier");
|
|
err.span_label(op_sp, "argument");
|
|
err.emit();
|
|
}
|
|
hir::InlineAsmOperand::Sym { .. } => {
|
|
let mut err = sess.struct_span_err(
|
|
placeholder_span,
|
|
"asm template modifiers are not allowed for `sym` arguments",
|
|
);
|
|
err.span_label(placeholder_span, "template modifier");
|
|
err.span_label(op_sp, "argument");
|
|
err.emit();
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
let mut used_input_regs = FxHashMap::default();
|
|
let mut used_output_regs = FxHashMap::default();
|
|
let mut required_features: Vec<&str> = vec![];
|
|
for (idx, &(ref op, op_sp)) in operands.iter().enumerate() {
|
|
if let Some(reg) = op.reg() {
|
|
// Make sure we don't accidentally carry features from the
|
|
// previous iteration.
|
|
required_features.clear();
|
|
|
|
// Validate register classes against currently enabled target
|
|
// features. We check that at least one type is available for
|
|
// the current target.
|
|
let reg_class = reg.reg_class();
|
|
if reg_class == asm::InlineAsmRegClass::Err {
|
|
continue;
|
|
}
|
|
for &(_, feature) in reg_class.supported_types(asm_arch.unwrap()) {
|
|
if let Some(feature) = feature {
|
|
if self.sess.target_features.contains(&Symbol::intern(feature)) {
|
|
required_features.clear();
|
|
break;
|
|
} else {
|
|
required_features.push(feature);
|
|
}
|
|
} else {
|
|
required_features.clear();
|
|
break;
|
|
}
|
|
}
|
|
// We are sorting primitive strs here and can use unstable sort here
|
|
required_features.sort_unstable();
|
|
required_features.dedup();
|
|
match &required_features[..] {
|
|
[] => {}
|
|
[feature] => {
|
|
let msg = format!(
|
|
"register class `{}` requires the `{}` target feature",
|
|
reg_class.name(),
|
|
feature
|
|
);
|
|
sess.struct_span_err(op_sp, &msg).emit();
|
|
}
|
|
features => {
|
|
let msg = format!(
|
|
"register class `{}` requires at least one target feature: {}",
|
|
reg_class.name(),
|
|
features.join(", ")
|
|
);
|
|
sess.struct_span_err(op_sp, &msg).emit();
|
|
}
|
|
}
|
|
|
|
// Check for conflicts between explicit register operands.
|
|
if let asm::InlineAsmRegOrRegClass::Reg(reg) = reg {
|
|
let (input, output) = match op {
|
|
hir::InlineAsmOperand::In { .. } => (true, false),
|
|
// Late output do not conflict with inputs, but normal outputs do
|
|
hir::InlineAsmOperand::Out { late, .. } => (!late, true),
|
|
hir::InlineAsmOperand::InOut { .. }
|
|
| hir::InlineAsmOperand::SplitInOut { .. } => (true, true),
|
|
hir::InlineAsmOperand::Const { .. } | hir::InlineAsmOperand::Sym { .. } => {
|
|
unreachable!()
|
|
}
|
|
};
|
|
|
|
// Flag to output the error only once per operand
|
|
let mut skip = false;
|
|
reg.overlapping_regs(|r| {
|
|
let mut check = |used_regs: &mut FxHashMap<asm::InlineAsmReg, usize>,
|
|
input| {
|
|
match used_regs.entry(r) {
|
|
Entry::Occupied(o) => {
|
|
if skip {
|
|
return;
|
|
}
|
|
skip = true;
|
|
|
|
let idx2 = *o.get();
|
|
let &(ref op2, op_sp2) = &operands[idx2];
|
|
let reg2 = match op2.reg() {
|
|
Some(asm::InlineAsmRegOrRegClass::Reg(r)) => r,
|
|
_ => unreachable!(),
|
|
};
|
|
|
|
let msg = format!(
|
|
"register `{}` conflicts with register `{}`",
|
|
reg.name(),
|
|
reg2.name()
|
|
);
|
|
let mut err = sess.struct_span_err(op_sp, &msg);
|
|
err.span_label(op_sp, &format!("register `{}`", reg.name()));
|
|
err.span_label(op_sp2, &format!("register `{}`", reg2.name()));
|
|
|
|
match (op, op2) {
|
|
(
|
|
hir::InlineAsmOperand::In { .. },
|
|
hir::InlineAsmOperand::Out { late, .. },
|
|
)
|
|
| (
|
|
hir::InlineAsmOperand::Out { late, .. },
|
|
hir::InlineAsmOperand::In { .. },
|
|
) => {
|
|
assert!(!*late);
|
|
let out_op_sp = if input { op_sp2 } else { op_sp };
|
|
let msg = "use `lateout` instead of \
|
|
`out` to avoid conflict";
|
|
err.span_help(out_op_sp, msg);
|
|
}
|
|
_ => {}
|
|
}
|
|
|
|
err.emit();
|
|
}
|
|
Entry::Vacant(v) => {
|
|
v.insert(idx);
|
|
}
|
|
}
|
|
};
|
|
if input {
|
|
check(&mut used_input_regs, true);
|
|
}
|
|
if output {
|
|
check(&mut used_output_regs, false);
|
|
}
|
|
});
|
|
}
|
|
}
|
|
}
|
|
|
|
let operands = self.arena.alloc_from_iter(operands);
|
|
let template = self.arena.alloc_from_iter(asm.template.iter().cloned());
|
|
let line_spans = self.arena.alloc_slice(&asm.line_spans[..]);
|
|
let hir_asm = hir::InlineAsm { template, operands, options: asm.options, line_spans };
|
|
hir::ExprKind::InlineAsm(self.arena.alloc(hir_asm))
|
|
}
|
|
|
|
fn lower_expr_llvm_asm(&mut self, asm: &LlvmInlineAsm) -> hir::ExprKind<'hir> {
|
|
let inner = hir::LlvmInlineAsmInner {
|
|
inputs: asm.inputs.iter().map(|&(c, _)| c).collect(),
|
|
outputs: asm
|
|
.outputs
|
|
.iter()
|
|
.map(|out| hir::LlvmInlineAsmOutput {
|
|
constraint: out.constraint,
|
|
is_rw: out.is_rw,
|
|
is_indirect: out.is_indirect,
|
|
span: out.expr.span,
|
|
})
|
|
.collect(),
|
|
asm: asm.asm,
|
|
asm_str_style: asm.asm_str_style,
|
|
clobbers: asm.clobbers.clone(),
|
|
volatile: asm.volatile,
|
|
alignstack: asm.alignstack,
|
|
dialect: asm.dialect,
|
|
};
|
|
let hir_asm = hir::LlvmInlineAsm {
|
|
inner,
|
|
inputs_exprs: self.arena.alloc_from_iter(
|
|
asm.inputs.iter().map(|&(_, ref input)| self.lower_expr_mut(input)),
|
|
),
|
|
outputs_exprs: self
|
|
.arena
|
|
.alloc_from_iter(asm.outputs.iter().map(|out| self.lower_expr_mut(&out.expr))),
|
|
};
|
|
hir::ExprKind::LlvmInlineAsm(self.arena.alloc(hir_asm))
|
|
}
|
|
|
|
fn lower_field(&mut self, f: &Field) -> hir::Field<'hir> {
|
|
hir::Field {
|
|
hir_id: self.next_id(),
|
|
ident: f.ident,
|
|
expr: self.lower_expr(&f.expr),
|
|
span: f.span,
|
|
is_shorthand: f.is_shorthand,
|
|
}
|
|
}
|
|
|
|
fn lower_expr_yield(&mut self, span: Span, opt_expr: Option<&Expr>) -> hir::ExprKind<'hir> {
|
|
match self.generator_kind {
|
|
Some(hir::GeneratorKind::Gen) => {}
|
|
Some(hir::GeneratorKind::Async(_)) => {
|
|
struct_span_err!(
|
|
self.sess,
|
|
span,
|
|
E0727,
|
|
"`async` generators are not yet supported"
|
|
)
|
|
.emit();
|
|
}
|
|
None => self.generator_kind = Some(hir::GeneratorKind::Gen),
|
|
}
|
|
|
|
let expr =
|
|
opt_expr.as_ref().map(|x| self.lower_expr(x)).unwrap_or_else(|| self.expr_unit(span));
|
|
|
|
hir::ExprKind::Yield(expr, hir::YieldSource::Yield)
|
|
}
|
|
|
|
/// Desugar `ExprForLoop` from: `[opt_ident]: for <pat> in <head> <body>` into:
|
|
/// ```rust
|
|
/// {
|
|
/// let result = match ::std::iter::IntoIterator::into_iter(<head>) {
|
|
/// mut iter => {
|
|
/// [opt_ident]: loop {
|
|
/// let mut __next;
|
|
/// match ::std::iter::Iterator::next(&mut iter) {
|
|
/// ::std::option::Option::Some(val) => __next = val,
|
|
/// ::std::option::Option::None => break
|
|
/// };
|
|
/// let <pat> = __next;
|
|
/// StmtKind::Expr(<body>);
|
|
/// }
|
|
/// }
|
|
/// };
|
|
/// result
|
|
/// }
|
|
/// ```
|
|
fn lower_expr_for(
|
|
&mut self,
|
|
e: &Expr,
|
|
pat: &Pat,
|
|
head: &Expr,
|
|
body: &Block,
|
|
opt_label: Option<Label>,
|
|
) -> hir::Expr<'hir> {
|
|
let orig_head_span = head.span;
|
|
// expand <head>
|
|
let mut head = self.lower_expr_mut(head);
|
|
let desugared_span = self.mark_span_with_reason(
|
|
DesugaringKind::ForLoop(ForLoopLoc::Head),
|
|
orig_head_span,
|
|
None,
|
|
);
|
|
head.span = desugared_span;
|
|
|
|
let iter = Ident::with_dummy_span(sym::iter);
|
|
|
|
let next_ident = Ident::with_dummy_span(sym::__next);
|
|
let (next_pat, next_pat_hid) = self.pat_ident_binding_mode(
|
|
desugared_span,
|
|
next_ident,
|
|
hir::BindingAnnotation::Mutable,
|
|
);
|
|
|
|
// `::std::option::Option::Some(val) => __next = val`
|
|
let pat_arm = {
|
|
let val_ident = Ident::with_dummy_span(sym::val);
|
|
let (val_pat, val_pat_hid) = self.pat_ident(pat.span, val_ident);
|
|
let val_expr = self.expr_ident(pat.span, val_ident, val_pat_hid);
|
|
let next_expr = self.expr_ident(pat.span, next_ident, next_pat_hid);
|
|
let assign = self.arena.alloc(self.expr(
|
|
pat.span,
|
|
hir::ExprKind::Assign(next_expr, val_expr, pat.span),
|
|
ThinVec::new(),
|
|
));
|
|
let some_pat = self.pat_some(pat.span, val_pat);
|
|
self.arm(some_pat, assign)
|
|
};
|
|
|
|
// `::std::option::Option::None => break`
|
|
let break_arm = {
|
|
let break_expr =
|
|
self.with_loop_scope(e.id, |this| this.expr_break(e.span, ThinVec::new()));
|
|
let pat = self.pat_none(e.span);
|
|
self.arm(pat, break_expr)
|
|
};
|
|
|
|
// `mut iter`
|
|
let (iter_pat, iter_pat_nid) =
|
|
self.pat_ident_binding_mode(desugared_span, iter, hir::BindingAnnotation::Mutable);
|
|
|
|
// `match ::std::iter::Iterator::next(&mut iter) { ... }`
|
|
let match_expr = {
|
|
let iter = self.expr_ident(desugared_span, iter, iter_pat_nid);
|
|
let ref_mut_iter = self.expr_mut_addr_of(desugared_span, iter);
|
|
let next_expr = self.expr_call_lang_item_fn(
|
|
desugared_span,
|
|
hir::LangItem::IteratorNext,
|
|
arena_vec![self; ref_mut_iter],
|
|
);
|
|
let arms = arena_vec![self; pat_arm, break_arm];
|
|
|
|
self.expr_match(desugared_span, next_expr, arms, hir::MatchSource::ForLoopDesugar)
|
|
};
|
|
let match_stmt = self.stmt_expr(desugared_span, match_expr);
|
|
|
|
let next_expr = self.expr_ident(desugared_span, next_ident, next_pat_hid);
|
|
|
|
// `let mut __next`
|
|
let next_let = self.stmt_let_pat(
|
|
None,
|
|
desugared_span,
|
|
None,
|
|
next_pat,
|
|
hir::LocalSource::ForLoopDesugar,
|
|
);
|
|
|
|
// `let <pat> = __next`
|
|
let pat = self.lower_pat(pat);
|
|
let pat_let = self.stmt_let_pat(
|
|
None,
|
|
desugared_span,
|
|
Some(next_expr),
|
|
pat,
|
|
hir::LocalSource::ForLoopDesugar,
|
|
);
|
|
|
|
let body_block = self.with_loop_scope(e.id, |this| this.lower_block(body, false));
|
|
let body_expr = self.expr_block(body_block, ThinVec::new());
|
|
let body_stmt = self.stmt_expr(body.span, body_expr);
|
|
|
|
let loop_block = self.block_all(
|
|
e.span,
|
|
arena_vec![self; next_let, match_stmt, pat_let, body_stmt],
|
|
None,
|
|
);
|
|
|
|
// `[opt_ident]: loop { ... }`
|
|
let kind = hir::ExprKind::Loop(
|
|
loop_block,
|
|
opt_label,
|
|
hir::LoopSource::ForLoop,
|
|
e.span.with_hi(orig_head_span.hi()),
|
|
);
|
|
let loop_expr =
|
|
self.arena.alloc(hir::Expr { hir_id: self.lower_node_id(e.id), kind, span: e.span });
|
|
|
|
// `mut iter => { ... }`
|
|
let iter_arm = self.arm(iter_pat, loop_expr);
|
|
|
|
let into_iter_span = self.mark_span_with_reason(
|
|
DesugaringKind::ForLoop(ForLoopLoc::IntoIter),
|
|
orig_head_span,
|
|
None,
|
|
);
|
|
|
|
// `match ::std::iter::IntoIterator::into_iter(<head>) { ... }`
|
|
let into_iter_expr = {
|
|
self.expr_call_lang_item_fn(
|
|
into_iter_span,
|
|
hir::LangItem::IntoIterIntoIter,
|
|
arena_vec![self; head],
|
|
)
|
|
};
|
|
|
|
let match_expr = self.arena.alloc(self.expr_match(
|
|
desugared_span,
|
|
into_iter_expr,
|
|
arena_vec![self; iter_arm],
|
|
hir::MatchSource::ForLoopDesugar,
|
|
));
|
|
|
|
let attrs: Vec<_> = e.attrs.iter().map(|a| self.lower_attr(a)).collect();
|
|
|
|
// This is effectively `{ let _result = ...; _result }`.
|
|
// The construct was introduced in #21984 and is necessary to make sure that
|
|
// temporaries in the `head` expression are dropped and do not leak to the
|
|
// surrounding scope of the `match` since the `match` is not a terminating scope.
|
|
//
|
|
// Also, add the attributes to the outer returned expr node.
|
|
self.expr_drop_temps_mut(desugared_span, match_expr, attrs.into())
|
|
}
|
|
|
|
/// Desugar `ExprKind::Try` from: `<expr>?` into:
|
|
/// ```rust
|
|
/// match Try::into_result(<expr>) {
|
|
/// Ok(val) => #[allow(unreachable_code)] val,
|
|
/// Err(err) => #[allow(unreachable_code)]
|
|
/// // If there is an enclosing `try {...}`:
|
|
/// break 'catch_target Try::from_error(From::from(err)),
|
|
/// // Otherwise:
|
|
/// return Try::from_error(From::from(err)),
|
|
/// }
|
|
/// ```
|
|
fn lower_expr_try(&mut self, span: Span, sub_expr: &Expr) -> hir::ExprKind<'hir> {
|
|
let unstable_span = self.mark_span_with_reason(
|
|
DesugaringKind::QuestionMark,
|
|
span,
|
|
self.allow_try_trait.clone(),
|
|
);
|
|
let try_span = self.sess.source_map().end_point(span);
|
|
let try_span = self.mark_span_with_reason(
|
|
DesugaringKind::QuestionMark,
|
|
try_span,
|
|
self.allow_try_trait.clone(),
|
|
);
|
|
|
|
// `Try::into_result(<expr>)`
|
|
let scrutinee = {
|
|
// expand <expr>
|
|
let sub_expr = self.lower_expr_mut(sub_expr);
|
|
|
|
self.expr_call_lang_item_fn(
|
|
unstable_span,
|
|
hir::LangItem::TryIntoResult,
|
|
arena_vec![self; sub_expr],
|
|
)
|
|
};
|
|
|
|
// `#[allow(unreachable_code)]`
|
|
let attr = {
|
|
// `allow(unreachable_code)`
|
|
let allow = {
|
|
let allow_ident = Ident::new(sym::allow, span);
|
|
let uc_ident = Ident::new(sym::unreachable_code, span);
|
|
let uc_nested = attr::mk_nested_word_item(uc_ident);
|
|
attr::mk_list_item(allow_ident, vec![uc_nested])
|
|
};
|
|
attr::mk_attr_outer(allow)
|
|
};
|
|
let attrs = vec![attr];
|
|
|
|
// `Ok(val) => #[allow(unreachable_code)] val,`
|
|
let ok_arm = {
|
|
let val_ident = Ident::with_dummy_span(sym::val);
|
|
let (val_pat, val_pat_nid) = self.pat_ident(span, val_ident);
|
|
let val_expr = self.arena.alloc(self.expr_ident_with_attrs(
|
|
span,
|
|
val_ident,
|
|
val_pat_nid,
|
|
ThinVec::from(attrs.clone()),
|
|
));
|
|
let ok_pat = self.pat_ok(span, val_pat);
|
|
self.arm(ok_pat, val_expr)
|
|
};
|
|
|
|
// `Err(err) => #[allow(unreachable_code)]
|
|
// return Try::from_error(From::from(err)),`
|
|
let err_arm = {
|
|
let err_ident = Ident::with_dummy_span(sym::err);
|
|
let (err_local, err_local_nid) = self.pat_ident(try_span, err_ident);
|
|
let from_expr = {
|
|
let err_expr = self.expr_ident_mut(try_span, err_ident, err_local_nid);
|
|
self.expr_call_lang_item_fn(
|
|
try_span,
|
|
hir::LangItem::FromFrom,
|
|
arena_vec![self; err_expr],
|
|
)
|
|
};
|
|
let from_err_expr = self.wrap_in_try_constructor(
|
|
hir::LangItem::TryFromError,
|
|
unstable_span,
|
|
from_expr,
|
|
unstable_span,
|
|
);
|
|
let thin_attrs = ThinVec::from(attrs);
|
|
let catch_scope = self.catch_scopes.last().copied();
|
|
let ret_expr = if let Some(catch_node) = catch_scope {
|
|
let target_id = Ok(self.lower_node_id(catch_node));
|
|
self.arena.alloc(self.expr(
|
|
try_span,
|
|
hir::ExprKind::Break(
|
|
hir::Destination { label: None, target_id },
|
|
Some(from_err_expr),
|
|
),
|
|
thin_attrs,
|
|
))
|
|
} else {
|
|
self.arena.alloc(self.expr(
|
|
try_span,
|
|
hir::ExprKind::Ret(Some(from_err_expr)),
|
|
thin_attrs,
|
|
))
|
|
};
|
|
|
|
let err_pat = self.pat_err(try_span, err_local);
|
|
self.arm(err_pat, ret_expr)
|
|
};
|
|
|
|
hir::ExprKind::Match(
|
|
scrutinee,
|
|
arena_vec![self; err_arm, ok_arm],
|
|
hir::MatchSource::TryDesugar,
|
|
)
|
|
}
|
|
|
|
// =========================================================================
|
|
// Helper methods for building HIR.
|
|
// =========================================================================
|
|
|
|
/// Constructs a `true` or `false` literal expression.
|
|
pub(super) fn expr_bool(&mut self, span: Span, val: bool) -> &'hir hir::Expr<'hir> {
|
|
let lit = Spanned { span, node: LitKind::Bool(val) };
|
|
self.arena.alloc(self.expr(span, hir::ExprKind::Lit(lit), ThinVec::new()))
|
|
}
|
|
|
|
/// Wrap the given `expr` in a terminating scope using `hir::ExprKind::DropTemps`.
|
|
///
|
|
/// In terms of drop order, it has the same effect as wrapping `expr` in
|
|
/// `{ let _t = $expr; _t }` but should provide better compile-time performance.
|
|
///
|
|
/// The drop order can be important in e.g. `if expr { .. }`.
|
|
pub(super) fn expr_drop_temps(
|
|
&mut self,
|
|
span: Span,
|
|
expr: &'hir hir::Expr<'hir>,
|
|
attrs: AttrVec,
|
|
) -> &'hir hir::Expr<'hir> {
|
|
self.arena.alloc(self.expr_drop_temps_mut(span, expr, attrs))
|
|
}
|
|
|
|
pub(super) fn expr_drop_temps_mut(
|
|
&mut self,
|
|
span: Span,
|
|
expr: &'hir hir::Expr<'hir>,
|
|
attrs: AttrVec,
|
|
) -> hir::Expr<'hir> {
|
|
self.expr(span, hir::ExprKind::DropTemps(expr), attrs)
|
|
}
|
|
|
|
fn expr_match(
|
|
&mut self,
|
|
span: Span,
|
|
arg: &'hir hir::Expr<'hir>,
|
|
arms: &'hir [hir::Arm<'hir>],
|
|
source: hir::MatchSource,
|
|
) -> hir::Expr<'hir> {
|
|
self.expr(span, hir::ExprKind::Match(arg, arms, source), ThinVec::new())
|
|
}
|
|
|
|
fn expr_break(&mut self, span: Span, attrs: AttrVec) -> &'hir hir::Expr<'hir> {
|
|
let expr_break = hir::ExprKind::Break(self.lower_loop_destination(None), None);
|
|
self.arena.alloc(self.expr(span, expr_break, attrs))
|
|
}
|
|
|
|
fn expr_mut_addr_of(&mut self, span: Span, e: &'hir hir::Expr<'hir>) -> hir::Expr<'hir> {
|
|
self.expr(
|
|
span,
|
|
hir::ExprKind::AddrOf(hir::BorrowKind::Ref, hir::Mutability::Mut, e),
|
|
ThinVec::new(),
|
|
)
|
|
}
|
|
|
|
fn expr_unit(&mut self, sp: Span) -> &'hir hir::Expr<'hir> {
|
|
self.arena.alloc(self.expr(sp, hir::ExprKind::Tup(&[]), ThinVec::new()))
|
|
}
|
|
|
|
fn expr_call_mut(
|
|
&mut self,
|
|
span: Span,
|
|
e: &'hir hir::Expr<'hir>,
|
|
args: &'hir [hir::Expr<'hir>],
|
|
) -> hir::Expr<'hir> {
|
|
self.expr(span, hir::ExprKind::Call(e, args), ThinVec::new())
|
|
}
|
|
|
|
fn expr_call(
|
|
&mut self,
|
|
span: Span,
|
|
e: &'hir hir::Expr<'hir>,
|
|
args: &'hir [hir::Expr<'hir>],
|
|
) -> &'hir hir::Expr<'hir> {
|
|
self.arena.alloc(self.expr_call_mut(span, e, args))
|
|
}
|
|
|
|
fn expr_call_lang_item_fn_mut(
|
|
&mut self,
|
|
span: Span,
|
|
lang_item: hir::LangItem,
|
|
args: &'hir [hir::Expr<'hir>],
|
|
) -> hir::Expr<'hir> {
|
|
let path = self.arena.alloc(self.expr_lang_item_path(span, lang_item, ThinVec::new()));
|
|
self.expr_call_mut(span, path, args)
|
|
}
|
|
|
|
fn expr_call_lang_item_fn(
|
|
&mut self,
|
|
span: Span,
|
|
lang_item: hir::LangItem,
|
|
args: &'hir [hir::Expr<'hir>],
|
|
) -> &'hir hir::Expr<'hir> {
|
|
self.arena.alloc(self.expr_call_lang_item_fn_mut(span, lang_item, args))
|
|
}
|
|
|
|
fn expr_lang_item_path(
|
|
&mut self,
|
|
span: Span,
|
|
lang_item: hir::LangItem,
|
|
attrs: AttrVec,
|
|
) -> hir::Expr<'hir> {
|
|
self.expr(span, hir::ExprKind::Path(hir::QPath::LangItem(lang_item, span)), attrs)
|
|
}
|
|
|
|
pub(super) fn expr_ident(
|
|
&mut self,
|
|
sp: Span,
|
|
ident: Ident,
|
|
binding: hir::HirId,
|
|
) -> &'hir hir::Expr<'hir> {
|
|
self.arena.alloc(self.expr_ident_mut(sp, ident, binding))
|
|
}
|
|
|
|
pub(super) fn expr_ident_mut(
|
|
&mut self,
|
|
sp: Span,
|
|
ident: Ident,
|
|
binding: hir::HirId,
|
|
) -> hir::Expr<'hir> {
|
|
self.expr_ident_with_attrs(sp, ident, binding, ThinVec::new())
|
|
}
|
|
|
|
fn expr_ident_with_attrs(
|
|
&mut self,
|
|
span: Span,
|
|
ident: Ident,
|
|
binding: hir::HirId,
|
|
attrs: AttrVec,
|
|
) -> hir::Expr<'hir> {
|
|
let expr_path = hir::ExprKind::Path(hir::QPath::Resolved(
|
|
None,
|
|
self.arena.alloc(hir::Path {
|
|
span,
|
|
res: Res::Local(binding),
|
|
segments: arena_vec![self; hir::PathSegment::from_ident(ident)],
|
|
}),
|
|
));
|
|
|
|
self.expr(span, expr_path, attrs)
|
|
}
|
|
|
|
fn expr_unsafe(&mut self, expr: &'hir hir::Expr<'hir>) -> hir::Expr<'hir> {
|
|
let hir_id = self.next_id();
|
|
let span = expr.span;
|
|
self.expr(
|
|
span,
|
|
hir::ExprKind::Block(
|
|
self.arena.alloc(hir::Block {
|
|
stmts: &[],
|
|
expr: Some(expr),
|
|
hir_id,
|
|
rules: hir::BlockCheckMode::UnsafeBlock(hir::UnsafeSource::CompilerGenerated),
|
|
span,
|
|
targeted_by_break: false,
|
|
}),
|
|
None,
|
|
),
|
|
ThinVec::new(),
|
|
)
|
|
}
|
|
|
|
fn expr_block_empty(&mut self, span: Span) -> &'hir hir::Expr<'hir> {
|
|
let blk = self.block_all(span, &[], None);
|
|
let expr = self.expr_block(blk, ThinVec::new());
|
|
self.arena.alloc(expr)
|
|
}
|
|
|
|
pub(super) fn expr_block(
|
|
&mut self,
|
|
b: &'hir hir::Block<'hir>,
|
|
attrs: AttrVec,
|
|
) -> hir::Expr<'hir> {
|
|
self.expr(b.span, hir::ExprKind::Block(b, None), attrs)
|
|
}
|
|
|
|
pub(super) fn expr(
|
|
&mut self,
|
|
span: Span,
|
|
kind: hir::ExprKind<'hir>,
|
|
attrs: AttrVec,
|
|
) -> hir::Expr<'hir> {
|
|
let hir_id = self.next_id();
|
|
self.lower_attrs(hir_id, &attrs);
|
|
hir::Expr { hir_id, kind, span }
|
|
}
|
|
|
|
fn field(&mut self, ident: Ident, expr: &'hir hir::Expr<'hir>, span: Span) -> hir::Field<'hir> {
|
|
hir::Field { hir_id: self.next_id(), ident, span, expr, is_shorthand: false }
|
|
}
|
|
|
|
fn arm(&mut self, pat: &'hir hir::Pat<'hir>, expr: &'hir hir::Expr<'hir>) -> hir::Arm<'hir> {
|
|
hir::Arm { hir_id: self.next_id(), pat, guard: None, span: expr.span, body: expr }
|
|
}
|
|
}
|