improve diagnostic for raw pointer field access with -> #139921

Kivooeo · 2025-04-16T13:39:46Z

This PR enhances the error messages emitted by the Rust compiler when users attempt to use the -> operator for field access on raw pointers or when dereferencing is needed. The changes aim to provide clearer guidance, by suggesting the correct use of the . operator and explicit dereferencing.

Before:

help: `xs` is a raw pointer; try dereferencing it
   |
LL |         (*xs)->count += 1;
   |         ++  +

Now:

help: use `.` on a dereferenced raw pointer instead
   |
LL -         xs->count += 1;
LL +         (*xs).count += 1;
   |

rustbot · 2025-04-16T13:39:52Z

r? @estebank

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compiler/rustc_hir_typeck/src/expr.rs

compiler-errors · 2025-04-16T17:01:07Z

Please squash the last commit into the first

compiler/rustc_parse/messages.ftl

compiler/rustc_hir_typeck/src/expr.rs

tests/ui/parser/issues/issue-118530-ice.stderr

WaffleLapkin · 2025-04-20T14:34:20Z

@Kivooeo as errs said, a few days of inactivity is very common, reviewing PRs takes time and energy and people have lifes besides rustc :)

The sponsor page talks more about being on review rotation, doing PR review as a big part of the work. I still occasionally review PRs if I feel like it. I wouldn't assign myself to the PR if I wouldn't want to review it.

Kivooeo · 2025-04-20T22:36:31Z

@WaffleLapkin check this changes, tldr I reverted sugesstion attribute for Rarrow span in parser, removed rustfix in my testfile, updated error messages. I actually little bit ruined commits, starting this in master was awful idea, I will try to fix it tomorrow if could, if no I will close this and open new PR in separate branch
upd: fixed branch

WaffleLapkin

Looks good to me, modulo 1 nit

tests/ui/parser/expr-rarrow-call.rs

WaffleLapkin

Thanks!

WaffleLapkin · 2025-04-22T13:04:06Z

bors · 2025-04-22T13:04:09Z

📌 Commit b5e8f1f has been approved by WaffleLapkin

It is now in the queue for this repository.

…enton Rollup of 8 pull requests Successful merges: - rust-lang#139617 (Use posix_spawn on cygwin) - rust-lang#139921 (improve diagnostic for raw pointer field access with ->) - rust-lang#140031 (compiletest: Fix deadline bugs in new executor) - rust-lang#140072 (handle function alignment in miri) - rust-lang#140104 (Fix auto diff failing on inherent impl blocks) - rust-lang#140124 (Update books) - rust-lang#140144 (Handle another negated literal in `eat_token_lit`.) - rust-lang#140149 (test_nan: ensure the NAN contant is quiet) r? `@ghost` `@rustbot` modify labels: rollup

Rollup merge of rust-lang#139921 - Kivooeo:master, r=WaffleLapkin improve diagnostic for raw pointer field access with -> This PR enhances the error messages emitted by the Rust compiler when users attempt to use the `->` operator for field access on raw pointers or when dereferencing is needed. The changes aim to provide clearer guidance, by suggesting the correct use of the `.` operator and explicit dereferencing. **Before:** ``` help: `xs` is a raw pointer; try dereferencing it | LL | (*xs)->count += 1; | ++ + ``` **Now:** ``` help: use `.` on a dereferenced raw pointer instead | LL - xs->count += 1; LL + (*xs).count += 1; | ``` I added extra clarification in the message. Since this error occurs in the parser, we can't be certain that the type is a raw pointer. That's why the message includes only a small note in brackets. (In contrast, the message above is emitted in HIR, where we *can* check whether it's a raw pointer.) **Before:** ``` --> main.rs:11:11 | 11 | xs->count += 1; | ^^ | = help: the . operator will dereference the value if needed ``` **After:** ``` --> main.rs:11:11 | 11 | xs->count += 1; | ^^ | = help: the `.` operator will automatically dereference the value, except if the value is a raw pointer ```

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Urgau mentioned this pull request Apr 17, 2025

Fix new-line at the start in no_merges handler rust-lang/triagebot#1941

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improve diagnostic for raw pointer field access using ->

b5e8f1f

Kivooeo force-pushed the master branch from 0f82d47 to b5e8f1f Compare April 21, 2025 19:53

WaffleLapkin approved these changes Apr 22, 2025

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ChrisDenton mentioned this pull request Apr 22, 2025

Rollup of 8 pull requests #140165

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bors merged commit 8089e31 into rust-lang:master Apr 23, 2025
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improve diagnostic for raw pointer field access with -> #139921

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