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Borrow checker added

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This commit is contained in:
jrqc 2020-08-13 15:14:08 +03:00
parent 85f4ef0fbd
commit 65d10c7abf
4 changed files with 80 additions and 46 deletions
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101
clippy_lints/src/needless_return.rs
View File

@ -1,13 +1,13 @@
use rustc_lint::{LateLintPass, LateContext};
use rustc_ast::ast::Attribute;
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_errors::Applicability;
use rustc_hir::intravisit::{FnKind, walk_expr, NestedVisitorMap, Visitor};
use rustc_span::source_map::Span;
use rustc_middle::lint::in_external_macro;
use rustc_middle::hir::map::Map;
use rustc_middle::ty::subst::GenericArgKind;
use rustc_hir::intravisit::{walk_expr, FnKind, NestedVisitorMap, Visitor};
use rustc_hir::{Block, Body, Expr, ExprKind, FnDecl, HirId, MatchSource, StmtKind};
use rustc_lint::{LateContext, LateLintPass};
use rustc_middle::hir::map::Map;
use rustc_middle::lint::in_external_macro;
use rustc_middle::ty::subst::GenericArgKind;
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::source_map::Span;
use crate::utils::{fn_def_id, snippet_opt, span_lint_and_sugg, span_lint_and_then};
@ -46,16 +46,39 @@ enum RetReplacement {
declare_lint_pass!(NeedlessReturn => [NEEDLESS_RETURN]);
impl<'tcx> LateLintPass<'tcx> for NeedlessReturn {
fn check_fn(&mut self, cx: &LateContext<'tcx>, kind: FnKind<'tcx>, _: &'tcx FnDecl<'tcx>, body: &'tcx Body<'tcx>, _: Span, _: HirId) {
fn check_fn(
&mut self,
cx: &LateContext<'tcx>,
kind: FnKind<'tcx>,
_: &'tcx FnDecl<'tcx>,
body: &'tcx Body<'tcx>,
_: Span,
_: HirId,
) {
match kind {
FnKind::Closure(_) => {
check_final_expr(cx, &body.value, Some(body.value.span), RetReplacement::Empty)
}
if !last_statement_borrows(cx, &body.value) {
check_final_expr(cx, &body.value, Some(body.value.span), RetReplacement::Empty)
}
},
FnKind::ItemFn(..) | FnKind::Method(..) => {
if let ExprKind::Block(ref block, _) = body.value.kind {
check_block_return(cx, block)
if let Some(expr) = block.expr {
if !last_statement_borrows(cx, expr) {
check_final_expr(cx, expr, Some(expr.span), RetReplacement::Empty);
}
} else if let Some(stmt) = block.stmts.iter().last() {
match stmt.kind {
StmtKind::Expr(ref expr) | StmtKind::Semi(ref expr) => {
if !last_statement_borrows(cx, expr) {
check_final_expr(cx, expr, Some(stmt.span), RetReplacement::Empty);
}
},
_ => (),
}
}
}
}
},
}
}
}
@ -71,23 +94,16 @@ fn check_block_return(cx: &LateContext<'_>, block: &Block<'_>) {
match stmt.kind {
StmtKind::Expr(ref expr) | StmtKind::Semi(ref expr) => {
check_final_expr(cx, expr, Some(stmt.span), RetReplacement::Empty);
}
},
_ => (),
}
}
}
fn check_final_expr(
cx: &LateContext<'_>,
expr: &Expr<'_>,
span: Option<Span>,
replacement: RetReplacement,
) {
fn check_final_expr(cx: &LateContext<'_>, expr: &Expr<'_>, span: Option<Span>, replacement: RetReplacement) {
match expr.kind {
// simple return is always "bad"
ExprKind::Ret(ref inner) => {
// allow `#[cfg(a)] return a; #[cfg(b)] return b;`
if !expr.attrs.iter().any(attr_is_cfg) {
emit_return_lint(
@ -97,32 +113,34 @@ fn check_final_expr(
replacement,
);
}
}
},
// a whole block? check it!
ExprKind::Block(ref block, _) => {
check_block_return(cx, block);
}
},
// a match expr, check all arms
// an if/if let expr, check both exprs
// note, if without else is going to be a type checking error anyways
// (except for unit type functions) so we don't match it
ExprKind::Match(_, ref arms, source) => {
match source {
MatchSource::Normal => {
for arm in arms.iter() {
check_final_expr(cx, &arm.body, Some(arm.body.span), RetReplacement::Block);
}
ExprKind::Match(_, ref arms, source) => match source {
MatchSource::Normal => {
for arm in arms.iter() {
check_final_expr(cx, &arm.body, Some(arm.body.span), RetReplacement::Block);
}
MatchSource::IfDesugar { contains_else_clause: true } | MatchSource::IfLetDesugar { contains_else_clause: true } => {
if let ExprKind::Block(ref ifblock, _) = arms[0].body.kind {
check_block_return(cx, ifblock);
}
check_final_expr(cx, arms[1].body, None, RetReplacement::Empty);
}
_ => ()
},
MatchSource::IfDesugar {
contains_else_clause: true,
}
}
| MatchSource::IfLetDesugar {
contains_else_clause: true,
} => {
if let ExprKind::Block(ref ifblock, _) = arms[0].body.kind {
check_block_return(cx, ifblock);
}
check_final_expr(cx, arms[1].body, None, RetReplacement::Empty);
},
_ => (),
},
_ => (),
}
}
@ -139,7 +157,7 @@ fn emit_return_lint(cx: &LateContext<'_>, ret_span: Span, inner_span: Option<Spa
diag.span_suggestion(ret_span, "remove `return`", snippet, Applicability::MachineApplicable);
}
})
}
},
None => match replacement {
RetReplacement::Empty => {
span_lint_and_sugg(
@ -151,7 +169,7 @@ fn emit_return_lint(cx: &LateContext<'_>, ret_span: Span, inner_span: Option<Spa
String::new(),
Applicability::MachineApplicable,
);
}
},
RetReplacement::Block => {
span_lint_and_sugg(
cx,
@ -162,7 +180,7 @@ fn emit_return_lint(cx: &LateContext<'_>, ret_span: Span, inner_span: Option<Spa
"{}".to_string(),
Applicability::MachineApplicable,
);
}
},
},
}
}
@ -204,4 +222,3 @@ impl<'tcx> Visitor<'tcx> for BorrowVisitor<'_, 'tcx> {
NestedVisitorMap::None
}
}

5
clippy_lints/src/returns.rs
View File

@ -7,7 +7,7 @@ use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::source_map::Span;
use rustc_span::BytePos;
use crate::utils::{span_lint_and_sugg};
use crate::utils::span_lint_and_sugg;
declare_clippy_lint! {
/// **What it does:** Checks for unit (`()`) expressions that can be removed.
@ -30,12 +30,10 @@ declare_clippy_lint! {
"needless unit expression"
}
declare_lint_pass!(Return => [UNUSED_UNIT]);
impl EarlyLintPass for Return {
fn check_fn(&mut self, cx: &EarlyContext<'_>, kind: FnKind<'_>, span: Span, _: ast::NodeId) {
if_chain! {
if let ast::FnRetTy::Ty(ref ty) = kind.decl().output;
if let ast::TyKind::Tup(ref vals) = ty.kind;
@ -102,7 +100,6 @@ impl EarlyLintPass for Return {
}
}
// get the def site
#[must_use]
fn get_def(span: Span) -> Option<Span> {

10
tests/ui/needless_return.fixed
View File

@ -69,6 +69,16 @@ fn test_void_match(x: u32) {
}
}
mod no_lint_if_stmt_borrows {
mod issue_5858 {
fn read_line() -> String {
use std::io::BufRead;
let stdin = ::std::io::stdin();
return stdin.lock().lines().next().unwrap().unwrap();
}
}
}
fn main() {
let _ = test_end_of_fn();
let _ = test_no_semicolon();

10
tests/ui/needless_return.rs
View File

@ -69,6 +69,16 @@ fn test_void_match(x: u32) {
}
}
mod no_lint_if_stmt_borrows {
mod issue_5858 {
fn read_line() -> String {
use std::io::BufRead;
let stdin = ::std::io::stdin();
return stdin.lock().lines().next().unwrap().unwrap();
}
}
}
fn main() {
let _ = test_end_of_fn();
let _ = test_no_semicolon();