Improve diagnostics for pointer arithmetic += and -= (fixes #137391) #140094
+122
−1
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
r? @nnethercote rustbot has assigned @nnethercote. Use |
rustbot
added
S-waiting-on-review
This comment has been minimized.
This comment has been minimized.
rustbot
added
has-merge-commits
|
Oh wait, I did something very wrong with brances... |
Kivooeo
force-pushed
the
raw-pointer-assignment-suggestion
branch
from
7f207ae to
5fcf14a
Compare
rustbot
removed
has-merge-commits
Kivooeo
force-pushed
the
raw-pointer-assignment-suggestion
branch
from
5fcf14a to
023fab8
Compare
compiler/rustc_hir_typeck/src/op.rs
Outdated
Comment on lines
700
to
701
| // If there any better way to get lhs name variable please tell me :) | ||
| // I really wanna know |
There was a problem hiding this comment.
Please don't leave comments like this in the codebase. If you have questions for the reviewer, leave them as review comments on the github PR.
There was a problem hiding this comment.
oh, I see, I thought is a good way to ask something related to code, comments will anyway be removed before merge, but it's a good remark I'll keep that in mind thanks
compiler/rustc_hir_typeck/src/op.rs
Outdated
| if lhs_ty.is_raw_ptr() && rhs_ty.is_integral() => | ||
| { | ||
| err.multipart_suggestion( | ||
| "consider replacing `ptr += offset` with `ptr = ptr.wrapping_add(offset)` or `ptr.add(offset)`", |
There was a problem hiding this comment.
The suggestion is already responsible for showing what should be replaced. I think this can be made a lot shorter -- something like "consider using add or wrapping_add to do pointer arithmetic"
|
r? compiler-errors |
|
Some changes occurred in src/tools/cargo cc @ehuss |
This comment has been minimized.
This comment has been minimized.
Kivooeo
force-pushed
the
raw-pointer-assignment-suggestion
branch
from
bc620e4 to
9d69c35
Compare
Kivooeo
force-pushed
the
raw-pointer-assignment-suggestion
branch
from
9d69c35 to
834e476
Compare
compiler-errors
approved these changes
Apr 22, 2025
|
@bors r+ rollup |
bors
added
S-waiting-on-bors
bors
added a commit
to rust-lang-ci/rust
that referenced
this pull request
Apr 22, 2025
…enton Rollup of 5 pull requests Successful merges: - rust-lang#139981 (Don't compute name of associated item if it's an RPITIT) - rust-lang#140077 (Construct OutputType using macro and print [=FILENAME] help info) - rust-lang#140081 (Update `libc` to 0.2.172) - rust-lang#140094 (Improve diagnostics for pointer arithmetic += and -= (fixes rust-lang#137391)) - rust-lang#140128 (Use correct annotation for CSS pseudo elements) r? `@ghost` `@rustbot` modify labels: rollup
rust-timer
added a commit
to rust-lang-ci/rust
that referenced
this pull request
Apr 22, 2025
Rollup merge of rust-lang#140094 - Kivooeo:raw-pointer-assignment-suggestion, r=compiler-errors Improve diagnostics for pointer arithmetic += and -= (fixes rust-lang#137391) **Description**: This PR improves the diagnostic message for cases where a binary assignment operation like `ptr += offset` or `ptr -= offset` is attempted on `*mut T`. These operations are not allowed, and the compiler previously suggested calling `.add()` or `.wrapping_add()`, which is misleading if not assigned. This PR updates the diagnostics to suggest assigning the result of `.wrapping_add()` or `.wrapping_sub()` back to the pointer, e.g.: **Examples** For this code ```rust let mut arr = [0u8; 10]; let mut ptr = arr.as_mut_ptr(); ptr += 2; ``` it will say: ```rust 10 | ptr += 2; | ---^^^^^ | | | cannot use `+=` on type `*mut u8` | help: consider replacing `ptr += offset` with `ptr = ptr.wrapping_add(offset)` or `ptr.add(offset)` | 10 - ptr += 2; 10 + ptr = ptr.wrapping_add(2); ``` **Related issue**: rust-lang#137391 cc `@nabijaczleweli` for context (issue author)
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Description:
This PR improves the diagnostic message for cases where a binary assignment operation like
ptr += offsetorptr -= offsetis attempted on*mut T. These operations are not allowed, and the compiler previously suggested calling.add()or.wrapping_add(), which is misleading if not assigned.This PR updates the diagnostics to suggest assigning the result of
.wrapping_add()or.wrapping_sub()back to the pointer, e.g.:Examples
For this code
it will say:
Related issue: #137391
cc @nabijaczleweli for context (issue author)