rust/compiler/rustc_mir_build/src/thir/cx/expr.rs

1147 lines
51 KiB
Rust

use crate::thir::cx::Cx;
use crate::thir::util::UserAnnotatedTyHelpers;
use crate::thir::*;
use rustc_data_structures::stack::ensure_sufficient_stack;
use rustc_hir as hir;
use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
use rustc_index::vec::Idx;
use rustc_middle::hir::place::PlaceBase as HirPlaceBase;
use rustc_middle::hir::place::ProjectionKind as HirProjectionKind;
use rustc_middle::mir::interpret::Scalar;
use rustc_middle::mir::BorrowKind;
use rustc_middle::ty::adjustment::{
Adjust, Adjustment, AutoBorrow, AutoBorrowMutability, PointerCast,
};
use rustc_middle::ty::subst::{InternalSubsts, SubstsRef};
use rustc_middle::ty::{self, AdtKind, Ty};
use rustc_span::Span;
use std::iter;
impl<'thir, 'tcx> Cx<'thir, 'tcx> {
/// Mirrors and allocates a single [`hir::Expr`]. If you need to mirror a whole slice
/// of expressions, prefer using [`mirror_exprs`].
///
/// [`mirror_exprs`]: Self::mirror_exprs
crate fn mirror_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) -> &'thir Expr<'thir, 'tcx> {
// `mirror_expr` is recursing very deep. Make sure the stack doesn't overflow.
ensure_sufficient_stack(|| self.arena.alloc(self.mirror_expr_inner(expr)))
}
/// Mirrors and allocates a slice of [`hir::Expr`]s. They will be allocated as a
/// contiguous sequence in memory.
crate fn mirror_exprs(&mut self, exprs: &'tcx [hir::Expr<'tcx>]) -> &'thir [Expr<'thir, 'tcx>] {
self.arena.alloc_from_iter(exprs.iter().map(|expr| self.mirror_expr_inner(expr)))
}
/// Mirrors a [`hir::Expr`] without allocating it into the arena.
/// This is a separate, private function so that [`mirror_expr`] and [`mirror_exprs`] can
/// decide how to allocate this expression (alone or within a slice).
///
/// [`mirror_expr`]: Self::mirror_expr
/// [`mirror_exprs`]: Self::mirror_exprs
pub(super) fn mirror_expr_inner(
&mut self,
hir_expr: &'tcx hir::Expr<'tcx>,
) -> Expr<'thir, 'tcx> {
let temp_lifetime = self.region_scope_tree.temporary_scope(hir_expr.hir_id.local_id);
let expr_scope =
region::Scope { id: hir_expr.hir_id.local_id, data: region::ScopeData::Node };
debug!("Expr::make_mirror(): id={}, span={:?}", hir_expr.hir_id, hir_expr.span);
let mut expr = self.make_mirror_unadjusted(hir_expr);
// Now apply adjustments, if any.
for adjustment in self.typeck_results.expr_adjustments(hir_expr) {
debug!("make_mirror: expr={:?} applying adjustment={:?}", expr, adjustment);
expr = self.apply_adjustment(hir_expr, expr, adjustment);
}
// Next, wrap this up in the expr's scope.
expr = Expr {
temp_lifetime,
ty: expr.ty,
span: hir_expr.span,
kind: ExprKind::Scope {
region_scope: expr_scope,
value: self.arena.alloc(expr),
lint_level: LintLevel::Explicit(hir_expr.hir_id),
},
};
// Finally, create a destruction scope, if any.
if let Some(region_scope) =
self.region_scope_tree.opt_destruction_scope(hir_expr.hir_id.local_id)
{
expr = Expr {
temp_lifetime,
ty: expr.ty,
span: hir_expr.span,
kind: ExprKind::Scope {
region_scope,
value: self.arena.alloc(expr),
lint_level: LintLevel::Inherited,
},
};
}
// OK, all done!
expr
}
fn apply_adjustment(
&mut self,
hir_expr: &'tcx hir::Expr<'tcx>,
mut expr: Expr<'thir, 'tcx>,
adjustment: &Adjustment<'tcx>,
) -> Expr<'thir, 'tcx> {
let Expr { temp_lifetime, mut span, .. } = expr;
// Adjust the span from the block, to the last expression of the
// block. This is a better span when returning a mutable reference
// with too short a lifetime. The error message will use the span
// from the assignment to the return place, which should only point
// at the returned value, not the entire function body.
//
// fn return_short_lived<'a>(x: &'a mut i32) -> &'static mut i32 {
// x
// // ^ error message points at this expression.
// }
let mut adjust_span = |expr: &mut Expr<'thir, 'tcx>| {
if let ExprKind::Block { body } = &expr.kind {
if let Some(ref last_expr) = body.expr {
span = last_expr.span;
expr.span = span;
}
}
};
let kind = match adjustment.kind {
Adjust::Pointer(PointerCast::Unsize) => {
adjust_span(&mut expr);
ExprKind::Pointer { cast: PointerCast::Unsize, source: self.arena.alloc(expr) }
}
Adjust::Pointer(cast) => ExprKind::Pointer { cast, source: self.arena.alloc(expr) },
Adjust::NeverToAny => ExprKind::NeverToAny { source: self.arena.alloc(expr) },
Adjust::Deref(None) => {
adjust_span(&mut expr);
ExprKind::Deref { arg: self.arena.alloc(expr) }
}
Adjust::Deref(Some(deref)) => {
// We don't need to do call adjust_span here since
// deref coercions always start with a built-in deref.
let call = deref.method_call(self.tcx(), expr.ty);
expr = Expr {
temp_lifetime,
ty: self
.tcx
.mk_ref(deref.region, ty::TypeAndMut { ty: expr.ty, mutbl: deref.mutbl }),
span,
kind: ExprKind::Borrow {
borrow_kind: deref.mutbl.to_borrow_kind(),
arg: self.arena.alloc(expr),
},
};
self.overloaded_place(
hir_expr,
adjustment.target,
Some(call),
self.arena.alloc_from_iter(iter::once(expr)),
deref.span,
)
}
Adjust::Borrow(AutoBorrow::Ref(_, m)) => {
ExprKind::Borrow { borrow_kind: m.to_borrow_kind(), arg: self.arena.alloc(expr) }
}
Adjust::Borrow(AutoBorrow::RawPtr(mutability)) => {
ExprKind::AddressOf { mutability, arg: self.arena.alloc(expr) }
}
};
Expr { temp_lifetime, ty: adjustment.target, span, kind }
}
fn make_mirror_unadjusted(&mut self, expr: &'tcx hir::Expr<'tcx>) -> Expr<'thir, 'tcx> {
let expr_ty = self.typeck_results().expr_ty(expr);
let temp_lifetime = self.region_scope_tree.temporary_scope(expr.hir_id.local_id);
let kind = match expr.kind {
// Here comes the interesting stuff:
hir::ExprKind::MethodCall(_, method_span, ref args, fn_span) => {
// Rewrite a.b(c) into UFCS form like Trait::b(a, c)
let expr = self.method_callee(expr, method_span, None);
let args = self.mirror_exprs(args);
ExprKind::Call {
ty: expr.ty,
fun: self.arena.alloc(expr),
args,
from_hir_call: true,
fn_span,
}
}
hir::ExprKind::Call(ref fun, ref args) => {
if self.typeck_results().is_method_call(expr) {
// The callee is something implementing Fn, FnMut, or FnOnce.
// Find the actual method implementation being called and
// build the appropriate UFCS call expression with the
// callee-object as expr parameter.
// rewrite f(u, v) into FnOnce::call_once(f, (u, v))
let method = self.method_callee(expr, fun.span, None);
let arg_tys = args.iter().map(|e| self.typeck_results().expr_ty_adjusted(e));
let tupled_args = Expr {
ty: self.tcx.mk_tup(arg_tys),
temp_lifetime,
span: expr.span,
kind: ExprKind::Tuple { fields: self.mirror_exprs(args) },
};
ExprKind::Call {
ty: method.ty,
fun: self.arena.alloc(method),
args: self
.arena
.alloc_from_iter(vec![self.mirror_expr_inner(fun), tupled_args]),
from_hir_call: true,
fn_span: expr.span,
}
} else {
let adt_data =
if let hir::ExprKind::Path(hir::QPath::Resolved(_, ref path)) = fun.kind {
// Tuple-like ADTs are represented as ExprKind::Call. We convert them here.
expr_ty.ty_adt_def().and_then(|adt_def| match path.res {
Res::Def(DefKind::Ctor(_, CtorKind::Fn), ctor_id) => {
Some((adt_def, adt_def.variant_index_with_ctor_id(ctor_id)))
}
Res::SelfCtor(..) => Some((adt_def, VariantIdx::new(0))),
_ => None,
})
} else {
None
};
if let Some((adt_def, index)) = adt_data {
let substs = self.typeck_results().node_substs(fun.hir_id);
let user_provided_types = self.typeck_results().user_provided_types();
let user_ty =
user_provided_types.get(fun.hir_id).copied().map(|mut u_ty| {
if let UserType::TypeOf(ref mut did, _) = &mut u_ty.value {
*did = adt_def.did;
}
u_ty
});
debug!("make_mirror_unadjusted: (call) user_ty={:?}", user_ty);
let field_refs =
self.arena.alloc_from_iter(args.iter().enumerate().map(|(idx, e)| {
FieldExpr { name: Field::new(idx), expr: self.mirror_expr(e) }
}));
ExprKind::Adt {
adt_def,
substs,
variant_index: index,
fields: field_refs,
user_ty,
base: None,
}
} else {
ExprKind::Call {
ty: self.typeck_results().node_type(fun.hir_id),
fun: self.mirror_expr(fun),
args: self.mirror_exprs(args),
from_hir_call: true,
fn_span: expr.span,
}
}
}
}
hir::ExprKind::AddrOf(hir::BorrowKind::Ref, mutbl, ref arg) => {
ExprKind::Borrow { borrow_kind: mutbl.to_borrow_kind(), arg: self.mirror_expr(arg) }
}
hir::ExprKind::AddrOf(hir::BorrowKind::Raw, mutability, ref arg) => {
ExprKind::AddressOf { mutability, arg: self.mirror_expr(arg) }
}
hir::ExprKind::Block(ref blk, _) => ExprKind::Block { body: self.mirror_block(blk) },
hir::ExprKind::Assign(ref lhs, ref rhs, _) => {
ExprKind::Assign { lhs: self.mirror_expr(lhs), rhs: self.mirror_expr(rhs) }
}
hir::ExprKind::AssignOp(op, ref lhs, ref rhs) => {
if self.typeck_results().is_method_call(expr) {
let lhs = self.mirror_expr_inner(lhs);
let rhs = self.mirror_expr_inner(rhs);
self.overloaded_operator(expr, self.arena.alloc_from_iter(vec![lhs, rhs]))
} else {
ExprKind::AssignOp {
op: bin_op(op.node),
lhs: self.mirror_expr(lhs),
rhs: self.mirror_expr(rhs),
}
}
}
hir::ExprKind::Lit(ref lit) => ExprKind::Literal {
literal: self.const_eval_literal(&lit.node, expr_ty, lit.span, false),
user_ty: None,
const_id: None,
},
hir::ExprKind::Binary(op, ref lhs, ref rhs) => {
if self.typeck_results().is_method_call(expr) {
let lhs = self.mirror_expr_inner(lhs);
let rhs = self.mirror_expr_inner(rhs);
self.overloaded_operator(expr, self.arena.alloc_from_iter(vec![lhs, rhs]))
} else {
// FIXME overflow
match op.node {
hir::BinOpKind::And => ExprKind::LogicalOp {
op: LogicalOp::And,
lhs: self.mirror_expr(lhs),
rhs: self.mirror_expr(rhs),
},
hir::BinOpKind::Or => ExprKind::LogicalOp {
op: LogicalOp::Or,
lhs: self.mirror_expr(lhs),
rhs: self.mirror_expr(rhs),
},
_ => {
let op = bin_op(op.node);
ExprKind::Binary {
op,
lhs: self.mirror_expr(lhs),
rhs: self.mirror_expr(rhs),
}
}
}
}
}
hir::ExprKind::Index(ref lhs, ref index) => {
if self.typeck_results().is_method_call(expr) {
let lhs = self.mirror_expr_inner(lhs);
let index = self.mirror_expr_inner(index);
self.overloaded_place(
expr,
expr_ty,
None,
self.arena.alloc_from_iter(vec![lhs, index]),
expr.span,
)
} else {
ExprKind::Index { lhs: self.mirror_expr(lhs), index: self.mirror_expr(index) }
}
}
hir::ExprKind::Unary(hir::UnOp::Deref, ref arg) => {
if self.typeck_results().is_method_call(expr) {
let arg = self.mirror_expr_inner(arg);
self.overloaded_place(
expr,
expr_ty,
None,
self.arena.alloc_from_iter(iter::once(arg)),
expr.span,
)
} else {
ExprKind::Deref { arg: self.mirror_expr(arg) }
}
}
hir::ExprKind::Unary(hir::UnOp::Not, ref arg) => {
if self.typeck_results().is_method_call(expr) {
let arg = self.mirror_expr_inner(arg);
self.overloaded_operator(expr, self.arena.alloc_from_iter(iter::once(arg)))
} else {
ExprKind::Unary { op: UnOp::Not, arg: self.mirror_expr(arg) }
}
}
hir::ExprKind::Unary(hir::UnOp::Neg, ref arg) => {
if self.typeck_results().is_method_call(expr) {
let arg = self.mirror_expr_inner(arg);
self.overloaded_operator(expr, self.arena.alloc_from_iter(iter::once(arg)))
} else if let hir::ExprKind::Lit(ref lit) = arg.kind {
ExprKind::Literal {
literal: self.const_eval_literal(&lit.node, expr_ty, lit.span, true),
user_ty: None,
const_id: None,
}
} else {
ExprKind::Unary { op: UnOp::Neg, arg: self.mirror_expr(arg) }
}
}
hir::ExprKind::Struct(ref qpath, ref fields, ref base) => match expr_ty.kind() {
ty::Adt(adt, substs) => match adt.adt_kind() {
AdtKind::Struct | AdtKind::Union => {
let user_provided_types = self.typeck_results().user_provided_types();
let user_ty = user_provided_types.get(expr.hir_id).copied();
debug!("make_mirror_unadjusted: (struct/union) user_ty={:?}", user_ty);
ExprKind::Adt {
adt_def: adt,
variant_index: VariantIdx::new(0),
substs,
user_ty,
fields: self.field_refs(fields),
base: base.as_ref().map(|base| FruInfo {
base: self.mirror_expr(base),
field_types: self.arena.alloc_from_iter(
self.typeck_results().fru_field_types()[expr.hir_id]
.iter()
.cloned(),
),
}),
}
}
AdtKind::Enum => {
let res = self.typeck_results().qpath_res(qpath, expr.hir_id);
match res {
Res::Def(DefKind::Variant, variant_id) => {
assert!(base.is_none());
let index = adt.variant_index_with_id(variant_id);
let user_provided_types =
self.typeck_results().user_provided_types();
let user_ty = user_provided_types.get(expr.hir_id).copied();
debug!("make_mirror_unadjusted: (variant) user_ty={:?}", user_ty);
ExprKind::Adt {
adt_def: adt,
variant_index: index,
substs,
user_ty,
fields: self.field_refs(fields),
base: None,
}
}
_ => {
span_bug!(expr.span, "unexpected res: {:?}", res);
}
}
}
},
_ => {
span_bug!(expr.span, "unexpected type for struct literal: {:?}", expr_ty);
}
},
hir::ExprKind::Closure(..) => {
let closure_ty = self.typeck_results().expr_ty(expr);
let (def_id, substs, movability) = match *closure_ty.kind() {
ty::Closure(def_id, substs) => (def_id, UpvarSubsts::Closure(substs), None),
ty::Generator(def_id, substs, movability) => {
(def_id, UpvarSubsts::Generator(substs), Some(movability))
}
_ => {
span_bug!(expr.span, "closure expr w/o closure type: {:?}", closure_ty);
}
};
let upvars = self.arena.alloc_from_iter(
self.typeck_results
.closure_min_captures_flattened(def_id)
.zip(substs.upvar_tys())
.map(|(captured_place, ty)| self.capture_upvar(expr, captured_place, ty)),
);
ExprKind::Closure { closure_id: def_id, substs, upvars, movability }
}
hir::ExprKind::Path(ref qpath) => {
let res = self.typeck_results().qpath_res(qpath, expr.hir_id);
self.convert_path_expr(expr, res)
}
hir::ExprKind::InlineAsm(ref asm) => ExprKind::InlineAsm {
template: asm.template,
operands: self.arena.alloc_from_iter(asm.operands.iter().map(|(op, _op_sp)| {
match *op {
hir::InlineAsmOperand::In { reg, ref expr } => {
InlineAsmOperand::In { reg, expr: self.mirror_expr(expr) }
}
hir::InlineAsmOperand::Out { reg, late, ref expr } => {
InlineAsmOperand::Out {
reg,
late,
expr: expr.as_ref().map(|expr| self.mirror_expr(expr)),
}
}
hir::InlineAsmOperand::InOut { reg, late, ref expr } => {
InlineAsmOperand::InOut { reg, late, expr: self.mirror_expr(expr) }
}
hir::InlineAsmOperand::SplitInOut {
reg,
late,
ref in_expr,
ref out_expr,
} => InlineAsmOperand::SplitInOut {
reg,
late,
in_expr: self.mirror_expr(in_expr),
out_expr: out_expr.as_ref().map(|expr| self.mirror_expr(expr)),
},
hir::InlineAsmOperand::Const { ref expr } => {
InlineAsmOperand::Const { expr: self.mirror_expr(expr) }
}
hir::InlineAsmOperand::Sym { ref expr } => {
let qpath = match expr.kind {
hir::ExprKind::Path(ref qpath) => qpath,
_ => span_bug!(
expr.span,
"asm `sym` operand should be a path, found {:?}",
expr.kind
),
};
let temp_lifetime =
self.region_scope_tree.temporary_scope(expr.hir_id.local_id);
let res = self.typeck_results().qpath_res(qpath, expr.hir_id);
let ty;
match res {
Res::Def(DefKind::Fn, _) | Res::Def(DefKind::AssocFn, _) => {
ty = self.typeck_results().node_type(expr.hir_id);
let user_ty = self.user_substs_applied_to_res(expr.hir_id, res);
InlineAsmOperand::SymFn {
expr: self.arena.alloc(Expr {
ty,
temp_lifetime,
span: expr.span,
kind: ExprKind::Literal {
literal: ty::Const::zero_sized(self.tcx, ty),
user_ty,
const_id: None,
},
}),
}
}
Res::Def(DefKind::Static, def_id) => {
InlineAsmOperand::SymStatic { def_id }
}
_ => {
self.tcx.sess.span_err(
expr.span,
"asm `sym` operand must point to a fn or static",
);
// Not a real fn, but we're not reaching codegen anyways...
ty = self.tcx.ty_error();
InlineAsmOperand::SymFn {
expr: self.arena.alloc(Expr {
ty,
temp_lifetime,
span: expr.span,
kind: ExprKind::Literal {
literal: ty::Const::zero_sized(self.tcx, ty),
user_ty: None,
const_id: None,
},
}),
}
}
}
}
}
})),
options: asm.options,
line_spans: asm.line_spans,
},
hir::ExprKind::LlvmInlineAsm(ref asm) => ExprKind::LlvmInlineAsm {
asm: &asm.inner,
outputs: self.mirror_exprs(asm.outputs_exprs),
inputs: self.mirror_exprs(asm.inputs_exprs),
},
hir::ExprKind::ConstBlock(ref anon_const) => {
let anon_const_def_id = self.tcx.hir().local_def_id(anon_const.hir_id);
let value = ty::Const::from_anon_const(self.tcx, anon_const_def_id);
ExprKind::ConstBlock { value }
}
// Now comes the rote stuff:
hir::ExprKind::Repeat(ref v, ref count) => {
let count_def_id = self.tcx.hir().local_def_id(count.hir_id);
let count = ty::Const::from_anon_const(self.tcx, count_def_id);
ExprKind::Repeat { value: self.mirror_expr(v), count }
}
hir::ExprKind::Ret(ref v) => {
ExprKind::Return { value: v.as_ref().map(|v| self.mirror_expr(v)) }
}
hir::ExprKind::Break(dest, ref value) => match dest.target_id {
Ok(target_id) => ExprKind::Break {
label: region::Scope { id: target_id.local_id, data: region::ScopeData::Node },
value: value.as_ref().map(|value| self.mirror_expr(value)),
},
Err(err) => bug!("invalid loop id for break: {}", err),
},
hir::ExprKind::Continue(dest) => match dest.target_id {
Ok(loop_id) => ExprKind::Continue {
label: region::Scope { id: loop_id.local_id, data: region::ScopeData::Node },
},
Err(err) => bug!("invalid loop id for continue: {}", err),
},
hir::ExprKind::If(cond, then, else_opt) => ExprKind::If {
cond: self.mirror_expr(cond),
then: self.mirror_expr(then),
else_opt: else_opt.map(|el| self.mirror_expr(el)),
},
hir::ExprKind::Match(ref discr, ref arms, _) => ExprKind::Match {
scrutinee: self.mirror_expr(discr),
arms: self.arena.alloc_from_iter(arms.iter().map(|a| self.convert_arm(a))),
},
hir::ExprKind::Loop(ref body, ..) => {
let block_ty = self.typeck_results().node_type(body.hir_id);
let temp_lifetime = self.region_scope_tree.temporary_scope(body.hir_id.local_id);
let block = self.mirror_block(body);
let body = self.arena.alloc(Expr {
ty: block_ty,
temp_lifetime,
span: block.span,
kind: ExprKind::Block { body: block },
});
ExprKind::Loop { body }
}
hir::ExprKind::Field(ref source, ..) => ExprKind::Field {
lhs: self.mirror_expr(source),
name: Field::new(self.tcx.field_index(expr.hir_id, self.typeck_results)),
},
hir::ExprKind::Cast(ref source, ref cast_ty) => {
// Check for a user-given type annotation on this `cast`
let user_provided_types = self.typeck_results.user_provided_types();
let user_ty = user_provided_types.get(cast_ty.hir_id);
debug!(
"cast({:?}) has ty w/ hir_id {:?} and user provided ty {:?}",
expr, cast_ty.hir_id, user_ty,
);
// Check to see if this cast is a "coercion cast", where the cast is actually done
// using a coercion (or is a no-op).
let cast = if self.typeck_results().is_coercion_cast(source.hir_id) {
// Convert the lexpr to a vexpr.
ExprKind::Use { source: self.mirror_expr(source) }
} else if self.typeck_results().expr_ty(source).is_region_ptr() {
// Special cased so that we can type check that the element
// type of the source matches the pointed to type of the
// destination.
ExprKind::Pointer {
source: self.mirror_expr(source),
cast: PointerCast::ArrayToPointer,
}
} else {
// check whether this is casting an enum variant discriminant
// to prevent cycles, we refer to the discriminant initializer
// which is always an integer and thus doesn't need to know the
// enum's layout (or its tag type) to compute it during const eval
// Example:
// enum Foo {
// A,
// B = A as isize + 4,
// }
// The correct solution would be to add symbolic computations to miri,
// so we wouldn't have to compute and store the actual value
let var = if let hir::ExprKind::Path(ref qpath) = source.kind {
let res = self.typeck_results().qpath_res(qpath, source.hir_id);
self.typeck_results().node_type(source.hir_id).ty_adt_def().and_then(
|adt_def| match res {
Res::Def(
DefKind::Ctor(CtorOf::Variant, CtorKind::Const),
variant_ctor_id,
) => {
let idx = adt_def.variant_index_with_ctor_id(variant_ctor_id);
let (d, o) = adt_def.discriminant_def_for_variant(idx);
use rustc_middle::ty::util::IntTypeExt;
let ty = adt_def.repr.discr_type();
let ty = ty.to_ty(self.tcx());
Some((d, o, ty))
}
_ => None,
},
)
} else {
None
};
let source = if let Some((did, offset, var_ty)) = var {
let mk_const = |literal| {
self.arena.alloc(Expr {
temp_lifetime,
ty: var_ty,
span: expr.span,
kind: ExprKind::Literal { literal, user_ty: None, const_id: None },
})
};
let offset = mk_const(ty::Const::from_bits(
self.tcx,
offset as u128,
self.param_env.and(var_ty),
));
match did {
Some(did) => {
// in case we are offsetting from a computed discriminant
// and not the beginning of discriminants (which is always `0`)
let substs = InternalSubsts::identity_for_item(self.tcx(), did);
let lhs = mk_const(self.tcx().mk_const(ty::Const {
val: ty::ConstKind::Unevaluated(
ty::WithOptConstParam::unknown(did),
substs,
None,
),
ty: var_ty,
}));
let bin =
ExprKind::Binary { op: BinOp::Add, lhs: lhs, rhs: offset };
self.arena.alloc(Expr {
temp_lifetime,
ty: var_ty,
span: expr.span,
kind: bin,
})
}
None => offset,
}
} else {
self.mirror_expr(source)
};
ExprKind::Cast { source: source }
};
if let Some(user_ty) = user_ty {
// NOTE: Creating a new Expr and wrapping a Cast inside of it may be
// inefficient, revisit this when performance becomes an issue.
let cast_expr = self.arena.alloc(Expr {
temp_lifetime,
ty: expr_ty,
span: expr.span,
kind: cast,
});
debug!("make_mirror_unadjusted: (cast) user_ty={:?}", user_ty);
ExprKind::ValueTypeAscription { source: cast_expr, user_ty: Some(*user_ty) }
} else {
cast
}
}
hir::ExprKind::Type(ref source, ref ty) => {
let user_provided_types = self.typeck_results.user_provided_types();
let user_ty = user_provided_types.get(ty.hir_id).copied();
debug!("make_mirror_unadjusted: (type) user_ty={:?}", user_ty);
let mirrored = self.mirror_expr(source);
if source.is_syntactic_place_expr() {
ExprKind::PlaceTypeAscription { source: mirrored, user_ty }
} else {
ExprKind::ValueTypeAscription { source: mirrored, user_ty }
}
}
hir::ExprKind::DropTemps(ref source) => {
ExprKind::Use { source: self.mirror_expr(source) }
}
hir::ExprKind::Box(ref value) => ExprKind::Box { value: self.mirror_expr(value) },
hir::ExprKind::Array(ref fields) => {
ExprKind::Array { fields: self.mirror_exprs(fields) }
}
hir::ExprKind::Tup(ref fields) => ExprKind::Tuple { fields: self.mirror_exprs(fields) },
hir::ExprKind::Yield(ref v, _) => ExprKind::Yield { value: self.mirror_expr(v) },
hir::ExprKind::Err => unreachable!(),
};
Expr { temp_lifetime, ty: expr_ty, span: expr.span, kind }
}
fn user_substs_applied_to_res(
&mut self,
hir_id: hir::HirId,
res: Res,
) -> Option<ty::CanonicalUserType<'tcx>> {
debug!("user_substs_applied_to_res: res={:?}", res);
let user_provided_type = match res {
// A reference to something callable -- e.g., a fn, method, or
// a tuple-struct or tuple-variant. This has the type of a
// `Fn` but with the user-given substitutions.
Res::Def(DefKind::Fn, _)
| Res::Def(DefKind::AssocFn, _)
| Res::Def(DefKind::Ctor(_, CtorKind::Fn), _)
| Res::Def(DefKind::Const, _)
| Res::Def(DefKind::AssocConst, _) => {
self.typeck_results().user_provided_types().get(hir_id).copied()
}
// A unit struct/variant which is used as a value (e.g.,
// `None`). This has the type of the enum/struct that defines
// this variant -- but with the substitutions given by the
// user.
Res::Def(DefKind::Ctor(_, CtorKind::Const), _) => {
self.user_substs_applied_to_ty_of_hir_id(hir_id)
}
// `Self` is used in expression as a tuple struct constructor or an unit struct constructor
Res::SelfCtor(_) => self.user_substs_applied_to_ty_of_hir_id(hir_id),
_ => bug!("user_substs_applied_to_res: unexpected res {:?} at {:?}", res, hir_id),
};
debug!("user_substs_applied_to_res: user_provided_type={:?}", user_provided_type);
user_provided_type
}
fn method_callee(
&mut self,
expr: &hir::Expr<'_>,
span: Span,
overloaded_callee: Option<(DefId, SubstsRef<'tcx>)>,
) -> Expr<'thir, 'tcx> {
let temp_lifetime = self.region_scope_tree.temporary_scope(expr.hir_id.local_id);
let (def_id, substs, user_ty) = match overloaded_callee {
Some((def_id, substs)) => (def_id, substs, None),
None => {
let (kind, def_id) =
self.typeck_results().type_dependent_def(expr.hir_id).unwrap_or_else(|| {
span_bug!(expr.span, "no type-dependent def for method callee")
});
let user_ty = self.user_substs_applied_to_res(expr.hir_id, Res::Def(kind, def_id));
debug!("method_callee: user_ty={:?}", user_ty);
(def_id, self.typeck_results().node_substs(expr.hir_id), user_ty)
}
};
let ty = self.tcx().mk_fn_def(def_id, substs);
Expr {
temp_lifetime,
ty,
span,
kind: ExprKind::Literal {
literal: ty::Const::zero_sized(self.tcx(), ty),
user_ty,
const_id: None,
},
}
}
fn convert_arm(&mut self, arm: &'tcx hir::Arm<'tcx>) -> Arm<'thir, 'tcx> {
Arm {
pattern: self.pattern_from_hir(&arm.pat),
guard: arm.guard.as_ref().map(|g| match g {
hir::Guard::If(ref e) => Guard::If(self.mirror_expr(e)),
hir::Guard::IfLet(ref pat, ref e) => {
Guard::IfLet(self.pattern_from_hir(pat), self.mirror_expr(e))
}
}),
body: self.mirror_expr(arm.body),
lint_level: LintLevel::Explicit(arm.hir_id),
scope: region::Scope { id: arm.hir_id.local_id, data: region::ScopeData::Node },
span: arm.span,
}
}
fn convert_path_expr(
&mut self,
expr: &'tcx hir::Expr<'tcx>,
res: Res,
) -> ExprKind<'thir, 'tcx> {
let substs = self.typeck_results().node_substs(expr.hir_id);
match res {
// A regular function, constructor function or a constant.
Res::Def(DefKind::Fn, _)
| Res::Def(DefKind::AssocFn, _)
| Res::Def(DefKind::Ctor(_, CtorKind::Fn), _)
| Res::SelfCtor(..) => {
let user_ty = self.user_substs_applied_to_res(expr.hir_id, res);
debug!("convert_path_expr: user_ty={:?}", user_ty);
ExprKind::Literal {
literal: ty::Const::zero_sized(
self.tcx,
self.typeck_results().node_type(expr.hir_id),
),
user_ty,
const_id: None,
}
}
Res::Def(DefKind::ConstParam, def_id) => {
let hir_id = self.tcx.hir().local_def_id_to_hir_id(def_id.expect_local());
let item_id = self.tcx.hir().get_parent_node(hir_id);
let item_def_id = self.tcx.hir().local_def_id(item_id);
let generics = self.tcx.generics_of(item_def_id);
let index = generics.param_def_id_to_index[&def_id];
let name = self.tcx.hir().name(hir_id);
let val = ty::ConstKind::Param(ty::ParamConst::new(index, name));
ExprKind::Literal {
literal: self.tcx.mk_const(ty::Const {
val,
ty: self.typeck_results().node_type(expr.hir_id),
}),
user_ty: None,
const_id: Some(def_id),
}
}
Res::Def(DefKind::Const, def_id) | Res::Def(DefKind::AssocConst, def_id) => {
let user_ty = self.user_substs_applied_to_res(expr.hir_id, res);
debug!("convert_path_expr: (const) user_ty={:?}", user_ty);
ExprKind::Literal {
literal: self.tcx.mk_const(ty::Const {
val: ty::ConstKind::Unevaluated(
ty::WithOptConstParam::unknown(def_id),
substs,
None,
),
ty: self.typeck_results().node_type(expr.hir_id),
}),
user_ty,
const_id: Some(def_id),
}
}
Res::Def(DefKind::Ctor(_, CtorKind::Const), def_id) => {
let user_provided_types = self.typeck_results.user_provided_types();
let user_provided_type = user_provided_types.get(expr.hir_id).copied();
debug!("convert_path_expr: user_provided_type={:?}", user_provided_type);
let ty = self.typeck_results().node_type(expr.hir_id);
match ty.kind() {
// A unit struct/variant which is used as a value.
// We return a completely different ExprKind here to account for this special case.
ty::Adt(adt_def, substs) => ExprKind::Adt {
adt_def,
variant_index: adt_def.variant_index_with_ctor_id(def_id),
substs,
user_ty: user_provided_type,
fields: self.arena.alloc_from_iter(iter::empty()),
base: None,
},
_ => bug!("unexpected ty: {:?}", ty),
}
}
// We encode uses of statics as a `*&STATIC` where the `&STATIC` part is
// a constant reference (or constant raw pointer for `static mut`) in MIR
Res::Def(DefKind::Static, id) => {
let ty = self.tcx.static_ptr_ty(id);
let temp_lifetime = self.region_scope_tree.temporary_scope(expr.hir_id.local_id);
let kind = if self.tcx.is_thread_local_static(id) {
ExprKind::ThreadLocalRef(id)
} else {
let ptr = self.tcx.create_static_alloc(id);
ExprKind::StaticRef {
literal: ty::Const::from_scalar(self.tcx, Scalar::Ptr(ptr.into()), ty),
def_id: id,
}
};
ExprKind::Deref {
arg: self.arena.alloc(Expr { ty, temp_lifetime, span: expr.span, kind }),
}
}
Res::Local(var_hir_id) => self.convert_var(var_hir_id),
_ => span_bug!(expr.span, "res `{:?}` not yet implemented", res),
}
}
fn convert_var(&mut self, var_hir_id: hir::HirId) -> ExprKind<'thir, 'tcx> {
// We want upvars here not captures.
// Captures will be handled in MIR.
let is_upvar = self
.tcx
.upvars_mentioned(self.body_owner)
.map_or(false, |upvars| upvars.contains_key(&var_hir_id));
debug!(
"convert_var({:?}): is_upvar={}, body_owner={:?}",
var_hir_id, is_upvar, self.body_owner
);
if is_upvar {
ExprKind::UpvarRef { closure_def_id: self.body_owner, var_hir_id }
} else {
ExprKind::VarRef { id: var_hir_id }
}
}
fn overloaded_operator(
&mut self,
expr: &'tcx hir::Expr<'tcx>,
args: &'thir [Expr<'thir, 'tcx>],
) -> ExprKind<'thir, 'tcx> {
let fun = self.arena.alloc(self.method_callee(expr, expr.span, None));
ExprKind::Call { ty: fun.ty, fun, args, from_hir_call: false, fn_span: expr.span }
}
fn overloaded_place(
&mut self,
expr: &'tcx hir::Expr<'tcx>,
place_ty: Ty<'tcx>,
overloaded_callee: Option<(DefId, SubstsRef<'tcx>)>,
args: &'thir [Expr<'thir, 'tcx>],
span: Span,
) -> ExprKind<'thir, 'tcx> {
// For an overloaded *x or x[y] expression of type T, the method
// call returns an &T and we must add the deref so that the types
// line up (this is because `*x` and `x[y]` represent places):
// Reconstruct the output assuming it's a reference with the
// same region and mutability as the receiver. This holds for
// `Deref(Mut)::Deref(_mut)` and `Index(Mut)::index(_mut)`.
let (region, mutbl) = match *args[0].ty.kind() {
ty::Ref(region, _, mutbl) => (region, mutbl),
_ => span_bug!(span, "overloaded_place: receiver is not a reference"),
};
let ref_ty = self.tcx.mk_ref(region, ty::TypeAndMut { ty: place_ty, mutbl });
// construct the complete expression `foo()` for the overloaded call,
// which will yield the &T type
let temp_lifetime = self.region_scope_tree.temporary_scope(expr.hir_id.local_id);
let fun = self.arena.alloc(self.method_callee(expr, span, overloaded_callee));
let ref_expr = self.arena.alloc(Expr {
temp_lifetime,
ty: ref_ty,
span,
kind: ExprKind::Call { ty: fun.ty, fun, args, from_hir_call: false, fn_span: span },
});
// construct and return a deref wrapper `*foo()`
ExprKind::Deref { arg: ref_expr }
}
fn capture_upvar(
&mut self,
closure_expr: &'tcx hir::Expr<'tcx>,
captured_place: &'tcx ty::CapturedPlace<'tcx>,
upvar_ty: Ty<'tcx>,
) -> Expr<'thir, 'tcx> {
let upvar_capture = captured_place.info.capture_kind;
let temp_lifetime = self.region_scope_tree.temporary_scope(closure_expr.hir_id.local_id);
let var_ty = captured_place.place.base_ty;
// The result of capture analysis in `rustc_typeck/check/upvar.rs`represents a captured path
// as it's seen for use within the closure and not at the time of closure creation.
//
// That is we see expect to see it start from a captured upvar and not something that is local
// to the closure's parent.
let var_hir_id = match captured_place.place.base {
HirPlaceBase::Upvar(upvar_id) => upvar_id.var_path.hir_id,
base => bug!("Expected an upvar, found {:?}", base),
};
let mut captured_place_expr = Expr {
temp_lifetime,
ty: var_ty,
span: closure_expr.span,
kind: self.convert_var(var_hir_id),
};
for proj in captured_place.place.projections.iter() {
let kind = match proj.kind {
HirProjectionKind::Deref => {
ExprKind::Deref { arg: self.arena.alloc(captured_place_expr) }
}
HirProjectionKind::Field(field, ..) => {
// Variant index will always be 0, because for multi-variant
// enums, we capture the enum entirely.
ExprKind::Field {
lhs: self.arena.alloc(captured_place_expr),
name: Field::new(field as usize),
}
}
HirProjectionKind::Index | HirProjectionKind::Subslice => {
// We don't capture these projections, so we can ignore them here
continue;
}
};
captured_place_expr =
Expr { temp_lifetime, ty: proj.ty, span: closure_expr.span, kind };
}
match upvar_capture {
ty::UpvarCapture::ByValue(_) => captured_place_expr,
ty::UpvarCapture::ByRef(upvar_borrow) => {
let borrow_kind = match upvar_borrow.kind {
ty::BorrowKind::ImmBorrow => BorrowKind::Shared,
ty::BorrowKind::UniqueImmBorrow => BorrowKind::Unique,
ty::BorrowKind::MutBorrow => BorrowKind::Mut { allow_two_phase_borrow: false },
};
Expr {
temp_lifetime,
ty: upvar_ty,
span: closure_expr.span,
kind: ExprKind::Borrow {
borrow_kind,
arg: self.arena.alloc(captured_place_expr),
},
}
}
}
}
/// Converts a list of named fields (i.e., for struct-like struct/enum ADTs) into FieldExpr.
fn field_refs(
&mut self,
fields: &'tcx [hir::ExprField<'tcx>],
) -> &'thir [FieldExpr<'thir, 'tcx>] {
self.arena.alloc_from_iter(fields.iter().map(|field| FieldExpr {
name: Field::new(self.tcx.field_index(field.hir_id, self.typeck_results)),
expr: self.mirror_expr(field.expr),
}))
}
}
trait ToBorrowKind {
fn to_borrow_kind(&self) -> BorrowKind;
}
impl ToBorrowKind for AutoBorrowMutability {
fn to_borrow_kind(&self) -> BorrowKind {
use rustc_middle::ty::adjustment::AllowTwoPhase;
match *self {
AutoBorrowMutability::Mut { allow_two_phase_borrow } => BorrowKind::Mut {
allow_two_phase_borrow: match allow_two_phase_borrow {
AllowTwoPhase::Yes => true,
AllowTwoPhase::No => false,
},
},
AutoBorrowMutability::Not => BorrowKind::Shared,
}
}
}
impl ToBorrowKind for hir::Mutability {
fn to_borrow_kind(&self) -> BorrowKind {
match *self {
hir::Mutability::Mut => BorrowKind::Mut { allow_two_phase_borrow: false },
hir::Mutability::Not => BorrowKind::Shared,
}
}
}
fn bin_op(op: hir::BinOpKind) -> BinOp {
match op {
hir::BinOpKind::Add => BinOp::Add,
hir::BinOpKind::Sub => BinOp::Sub,
hir::BinOpKind::Mul => BinOp::Mul,
hir::BinOpKind::Div => BinOp::Div,
hir::BinOpKind::Rem => BinOp::Rem,
hir::BinOpKind::BitXor => BinOp::BitXor,
hir::BinOpKind::BitAnd => BinOp::BitAnd,
hir::BinOpKind::BitOr => BinOp::BitOr,
hir::BinOpKind::Shl => BinOp::Shl,
hir::BinOpKind::Shr => BinOp::Shr,
hir::BinOpKind::Eq => BinOp::Eq,
hir::BinOpKind::Lt => BinOp::Lt,
hir::BinOpKind::Le => BinOp::Le,
hir::BinOpKind::Ne => BinOp::Ne,
hir::BinOpKind::Ge => BinOp::Ge,
hir::BinOpKind::Gt => BinOp::Gt,
_ => bug!("no equivalent for ast binop {:?}", op),
}
}