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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6
compiler/rustc_ast_lowering/src/expr.rs
View file

@ -152,13 +152,14 @@ impl<'hir> LoweringContext<'_, 'hir> {
let ohs = self.lower_expr(ohs);
hir::ExprKind::AddrOf(*k, *m, ohs)
}
ExprKind::Let(pat, scrutinee, span) => {
ExprKind::Let(pat, scrutinee, span, is_recovered) => {
hir::ExprKind::Let(self.arena.alloc(hir::Let {
hir_id: self.next_id(),
span: self.lower_span(*span),
pat: self.lower_pat(pat),
ty: None,
init: self.lower_expr(scrutinee),
is_recovered: *is_recovered,
}))
}
ExprKind::If(cond, then, else_opt) => {
@ -558,13 +559,14 @@ impl<'hir> LoweringContext<'_, 'hir> {
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(pat, scrutinee, span) = &cond.kind {
if let ExprKind::Let(pat, scrutinee, span, is_recovered) = &cond.kind {
hir::Guard::IfLet(self.arena.alloc(hir::Let {
hir_id: self.next_id(),
span: self.lower_span(*span),
pat: self.lower_pat(pat),
ty: None,
init: self.lower_expr(scrutinee),
is_recovered: *is_recovered,
}))
} else {
hir::Guard::If(self.lower_expr(cond))