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Rollup merge of #104147 - WaffleLapkin:don't-compare-ptr-addresses-in-parser-, r=compiler-errors

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Remove an address comparison from the parser

Originally this check was added in #68985, as suggested by https://github.com/rust-lang/rust/pull/68985/commits/940f65782cc5df7fecad27b38cc25b6d1eeaf2e8#r376850175. I don't think that this address check is a robust way of making parser more robust.

This code is also extensively tested by [`ui/parser/issues/issue-35813-postfix-after-cast.rs`](57d3c58ed6/src/test/ui/parser/issues/issue-35813-postfix-after-cast.rs).

_Replaces #103700_

r? `@compiler-errors`
This commit is contained in:
Guillaume Gomez 2022-11-08 20:40:53 +01:00 • committed by GitHub
commit e3c98a88bf
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9
compiler/rustc_parse/src/parser/expr.rs
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@ -833,16 +833,11 @@ impl<'a> Parser<'a> {
("cast", None)
};
// Save the memory location of expr before parsing any following postfix operators.
// This will be compared with the memory location of the output expression.
// If they different we can assume we parsed another expression because the existing expression is not reallocated.
let addr_before = &*cast_expr as *const _ as usize;
let with_postfix = self.parse_dot_or_call_expr_with_(cast_expr, span)?;
let changed = addr_before != &*with_postfix as *const _ as usize;
// Check if an illegal postfix operator has been added after the cast.
// If the resulting expression is not a cast, or has a different memory location, it is an illegal postfix operator.
if !matches!(with_postfix.kind, ExprKind::Cast(_, _) | ExprKind::Type(_, _)) || changed {
// If the resulting expression is not a cast, it is an illegal postfix operator.
if !matches!(with_postfix.kind, ExprKind::Cast(_, _) | ExprKind::Type(_, _)) {
let msg = format!(
"{cast_kind} cannot be followed by {}",
match with_postfix.kind {