bjoernager/rust
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Move let expression checking to parsing

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There was an incomplete version of the check in parsing and a second
version in AST validation. This meant that some, but not all, invalid
uses were allowed inside macros/disabled cfgs. It also means that later
passes have a hard time knowing when the let expression is in a valid
location, sometimes causing ICEs.

- Add a field to ExprKind::Let in AST/HIR to mark whether it's in a
  valid location.
- Suppress later errors and MIR construction for invalid let
  expressions.
This commit is contained in:
Matthew Jasper 2023-09-08 10:14:36 +00:00
parent 7b61f7f002
commit 333388fd3c
40 changed files with 915 additions and 2246 deletions
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12
compiler/rustc_lint/src/unused.rs
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@ -816,8 +816,7 @@ trait UnusedDelimLint {
let (value, ctx, followed_by_block, left_pos, right_pos, is_kw) = match e.kind {
// Do not lint `unused_braces` in `if let` expressions.
If(ref cond, ref block, _)
if !matches!(cond.kind, Let(_, _, _))
|| Self::LINT_EXPR_IN_PATTERN_MATCHING_CTX =>
if !matches!(cond.kind, Let(..)) || Self::LINT_EXPR_IN_PATTERN_MATCHING_CTX =>
{
let left = e.span.lo() + rustc_span::BytePos(2);
let right = block.span.lo();
@ -826,8 +825,7 @@ trait UnusedDelimLint {
// Do not lint `unused_braces` in `while let` expressions.
While(ref cond, ref block, ..)
if !matches!(cond.kind, Let(_, _, _))
|| Self::LINT_EXPR_IN_PATTERN_MATCHING_CTX =>
if !matches!(cond.kind, Let(..)) || Self::LINT_EXPR_IN_PATTERN_MATCHING_CTX =>
{
let left = e.span.lo() + rustc_span::BytePos(5);
let right = block.span.lo();
@ -1003,7 +1001,7 @@ impl UnusedDelimLint for UnusedParens {
self.emit_unused_delims_expr(cx, value, ctx, left_pos, right_pos, is_kw)
}
}
ast::ExprKind::Let(_, ref expr, _) => {
ast::ExprKind::Let(_, ref expr, _, _) => {
self.check_unused_delims_expr(
cx,
expr,
@ -1067,7 +1065,7 @@ impl EarlyLintPass for UnusedParens {
}
match e.kind {
ExprKind::Let(ref pat, _, _) | ExprKind::ForLoop(ref pat, ..) => {
ExprKind::Let(ref pat, _, _, _) | ExprKind::ForLoop(ref pat, ..) => {
self.check_unused_parens_pat(cx, pat, false, false, (true, true));
}
// We ignore parens in cases like `if (((let Some(0) = Some(1))))` because we already
@ -1311,7 +1309,7 @@ impl UnusedDelimLint for UnusedBraces {
}
}
}
ast::ExprKind::Let(_, ref expr, _) => {
ast::ExprKind::Let(_, ref expr, _, _) => {
self.check_unused_delims_expr(
cx,
expr,