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Rollup merge of #125049 - dtolnay:castbrace, r=compiler-errors

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Disallow cast with trailing braced macro in let-else

This fixes an edge case I noticed while porting #118880 and #119062 to syn.

Previously, rustc incorrectly accepted code such as:

```rust
let foo = &std::ptr::null as &'static dyn std::ops::Fn() -> *const primitive! {
    8
} else {
    return;
};
```

even though a right curl brace `}` directly before `else` in a `let...else` statement is not supposed to be valid syntax.
This commit is contained in:
León Orell Valerian Liehr 2024-05-22 19:04:44 +02:00 • committed by GitHub
commit 5b485f04de
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4 changed files with 210 additions and 298 deletions
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28
compiler/rustc_parse/src/parser/stmt.rs
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@ -15,7 +15,7 @@ use ast::Label;
use rustc_ast as ast;
use rustc_ast::ptr::P;
use rustc_ast::token::{self, Delimiter, TokenKind};
use rustc_ast::util::classify;
use rustc_ast::util::classify::{self, TrailingBrace};
use rustc_ast::{AttrStyle, AttrVec, LocalKind, MacCall, MacCallStmt, MacStmtStyle};
use rustc_ast::{Block, BlockCheckMode, Expr, ExprKind, HasAttrs, Local, Recovered, Stmt};
use rustc_ast::{StmtKind, DUMMY_NODE_ID};
@ -407,18 +407,24 @@ impl<'a> Parser<'a> {
fn check_let_else_init_trailing_brace(&self, init: &ast::Expr) {
if let Some(trailing) = classify::expr_trailing_brace(init) {
let sugg = match &trailing.kind {
ExprKind::MacCall(mac) => errors::WrapInParentheses::MacroArgs {
left: mac.args.dspan.open,
right: mac.args.dspan.close,
},
_ => errors::WrapInParentheses::Expression {
left: trailing.span.shrink_to_lo(),
right: trailing.span.shrink_to_hi(),
},
let (span, sugg) = match trailing {
TrailingBrace::MacCall(mac) => (
mac.span(),
errors::WrapInParentheses::MacroArgs {
left: mac.args.dspan.open,
right: mac.args.dspan.close,
},
),
TrailingBrace::Expr(expr) => (
expr.span,
errors::WrapInParentheses::Expression {
left: expr.span.shrink_to_lo(),
right: expr.span.shrink_to_hi(),
},
),
};
self.dcx().emit_err(errors::InvalidCurlyInLetElse {
span: trailing.span.with_lo(trailing.span.hi() - BytePos(1)),
span: span.with_lo(span.hi() - BytePos(1)),
sugg,
});
}