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Rollup merge of #103223 - compiler-errors:deref-sugg-slow, r=wesleywiser

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Use already checked RHS ty for LHS deref suggestions

There's no reason to do the `check_lhs_assignable` and RHS `check_expr_with_hint` in that order, so invert them and use the typeck results to avoid exponential blowup on error.

Fixes #103219
This commit is contained in:
Matthias Krüger 2022-10-19 21:38:40 +02:00 • committed by GitHub
commit e500dcb8cb
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3 changed files with 219 additions and 5 deletions
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11
compiler/rustc_hir_analysis/src/check/expr.rs
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@ -1130,11 +1130,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
}
};
self.check_lhs_assignable(lhs, "E0070", span, |err| {
let rhs_ty = self.check_expr(&rhs);
suggest_deref_binop(err, rhs_ty);
});
// This is (basically) inlined `check_expr_coercable_to_type`, but we want
// to suggest an additional fixup here in `suggest_deref_binop`.
let rhs_ty = self.check_expr_with_hint(&rhs, lhs_ty);
@ -1145,6 +1140,12 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
diag.emit();
}
self.check_lhs_assignable(lhs, "E0070", span, |err| {
if let Some(rhs_ty) = self.typeck_results.borrow().expr_ty_opt(rhs) {
suggest_deref_binop(err, rhs_ty);
}
});
self.require_type_is_sized(lhs_ty, lhs.span, traits::AssignmentLhsSized);
if lhs_ty.references_error() || rhs_ty.references_error() {