Warn about useless assignments of variables/fields to themselves#87129
Merged
bors merged 1 commit intorust-lang:masterfrom Jul 18, 2021
Merged
Warn about useless assignments of variables/fields to themselves#87129bors merged 1 commit intorust-lang:masterfrom
bors merged 1 commit intorust-lang:masterfrom
Conversation
rust-highfive
added
the
S-waiting-on-review
This comment has been minimized.
This comment has been minimized.
Contributor
|
Thanks, this looks good! @bors r+ |
Collaborator
|
📌 Commit dc639c9 has been approved by |
bors
added
S-waiting-on-bors
Collaborator
Collaborator
|
☀️ Test successful - checks-actions |
fmease
added a commit
to fmease/rust
that referenced
this pull request
Aug 11, 2025
…, r=petrochenkov fix: re-enable self-assignment ## Description Re-enables the self-assignment detection that was previously disabled due to unrelated regressions. The fix detects useless assignments like `x = x` and `foo.field = foo.field`. ## History The original regressions (rust-lang#81626, rust-lang#81658) were specifically about false positives in write-only field detection, not self-assignment detection. Belows are brief history for the rule that I understand. - Self-assignment detection was originally implemented in rust-lang#87129 to address rust-lang#75356 - The implementation was disabled alongside the revert of rust-lang#81473's "write-only fields" detection - rust-lang#81473 was reverted via rust-lang#86212 and rust-lang#83171 due to false positives in write-only field detection (rust-lang#81626, rust-lang#81658) - The self-assignment detection feature got removed, even though it wasn't the reason for the problems This PR only re-enables the self-assignment checks, which are orthogonal to the problematic write-only field analysis. ## Changes - Removed `#[allow(dead_code)]` from `compiler/rustc_passes/src/dead.rs` file - `handle_assign` and - `check_for_self_assign` - Added `ExprKind::Assign` handling in `visit_expr` to call both methods - Updated test expectations in `tests/ui/lint/dead-code/self-assign.rs`
fmease
added a commit
to fmease/rust
that referenced
this pull request
Aug 12, 2025
…, r=petrochenkov fix: re-enable self-assignment ## Description Re-enables the self-assignment detection that was previously disabled due to unrelated regressions. The fix detects useless assignments like `x = x` and `foo.field = foo.field`. ## History The original regressions (rust-lang#81626, rust-lang#81658) were specifically about false positives in write-only field detection, not self-assignment detection. Belows are brief history for the rule that I understand. - Self-assignment detection was originally implemented in rust-lang#87129 to address rust-lang#75356 - The implementation was disabled alongside the revert of rust-lang#81473's "write-only fields" detection - rust-lang#81473 was reverted via rust-lang#86212 and rust-lang#83171 due to false positives in write-only field detection (rust-lang#81626, rust-lang#81658) - The self-assignment detection feature got removed, even though it wasn't the reason for the problems This PR only re-enables the self-assignment checks, which are orthogonal to the problematic write-only field analysis. ## Changes - Removed `#[allow(dead_code)]` from `compiler/rustc_passes/src/dead.rs` file - `handle_assign` and - `check_for_self_assign` - Added `ExprKind::Assign` handling in `visit_expr` to call both methods - Updated test expectations in `tests/ui/lint/dead-code/self-assign.rs`
fmease
added a commit
to fmease/rust
that referenced
this pull request
Aug 12, 2025
…, r=petrochenkov fix: re-enable self-assignment ## Description Re-enables the self-assignment detection that was previously disabled due to unrelated regressions. The fix detects useless assignments like `x = x` and `foo.field = foo.field`. ## History The original regressions (rust-lang#81626, rust-lang#81658) were specifically about false positives in write-only field detection, not self-assignment detection. Belows are brief history for the rule that I understand. - Self-assignment detection was originally implemented in rust-lang#87129 to address rust-lang#75356 - The implementation was disabled alongside the revert of rust-lang#81473's "write-only fields" detection - rust-lang#81473 was reverted via rust-lang#86212 and rust-lang#83171 due to false positives in write-only field detection (rust-lang#81626, rust-lang#81658) - The self-assignment detection feature got removed, even though it wasn't the reason for the problems This PR only re-enables the self-assignment checks, which are orthogonal to the problematic write-only field analysis. ## Changes - Removed `#[allow(dead_code)]` from `compiler/rustc_passes/src/dead.rs` file - `handle_assign` and - `check_for_self_assign` - Added `ExprKind::Assign` handling in `visit_expr` to call both methods - Updated test expectations in `tests/ui/lint/dead-code/self-assign.rs`
fmease
added a commit
to fmease/rust
that referenced
this pull request
Aug 12, 2025
…, r=petrochenkov fix: re-enable self-assignment ## Description Re-enables the self-assignment detection that was previously disabled due to unrelated regressions. The fix detects useless assignments like `x = x` and `foo.field = foo.field`. ## History The original regressions (rust-lang#81626, rust-lang#81658) were specifically about false positives in write-only field detection, not self-assignment detection. Belows are brief history for the rule that I understand. - Self-assignment detection was originally implemented in rust-lang#87129 to address rust-lang#75356 - The implementation was disabled alongside the revert of rust-lang#81473's "write-only fields" detection - rust-lang#81473 was reverted via rust-lang#86212 and rust-lang#83171 due to false positives in write-only field detection (rust-lang#81626, rust-lang#81658) - The self-assignment detection feature got removed, even though it wasn't the reason for the problems This PR only re-enables the self-assignment checks, which are orthogonal to the problematic write-only field analysis. ## Changes - Removed `#[allow(dead_code)]` from `compiler/rustc_passes/src/dead.rs` file - `handle_assign` and - `check_for_self_assign` - Added `ExprKind::Assign` handling in `visit_expr` to call both methods - Updated test expectations in `tests/ui/lint/dead-code/self-assign.rs`
fmease
added a commit
to fmease/rust
that referenced
this pull request
Aug 12, 2025
…, r=petrochenkov fix: re-enable self-assignment ## Description Re-enables the self-assignment detection that was previously disabled due to unrelated regressions. The fix detects useless assignments like `x = x` and `foo.field = foo.field`. ## History The original regressions (rust-lang#81626, rust-lang#81658) were specifically about false positives in write-only field detection, not self-assignment detection. Belows are brief history for the rule that I understand. - Self-assignment detection was originally implemented in rust-lang#87129 to address rust-lang#75356 - The implementation was disabled alongside the revert of rust-lang#81473's "write-only fields" detection - rust-lang#81473 was reverted via rust-lang#86212 and rust-lang#83171 due to false positives in write-only field detection (rust-lang#81626, rust-lang#81658) - The self-assignment detection feature got removed, even though it wasn't the reason for the problems This PR only re-enables the self-assignment checks, which are orthogonal to the problematic write-only field analysis. ## Changes - Removed `#[allow(dead_code)]` from `compiler/rustc_passes/src/dead.rs` file - `handle_assign` and - `check_for_self_assign` - Added `ExprKind::Assign` handling in `visit_expr` to call both methods - Updated test expectations in `tests/ui/lint/dead-code/self-assign.rs`
Zalathar
added a commit
to Zalathar/rust
that referenced
this pull request
Aug 12, 2025
…, r=petrochenkov fix: re-enable self-assignment ## Description Re-enables the self-assignment detection that was previously disabled due to unrelated regressions. The fix detects useless assignments like `x = x` and `foo.field = foo.field`. ## History The original regressions (rust-lang#81626, rust-lang#81658) were specifically about false positives in write-only field detection, not self-assignment detection. Belows are brief history for the rule that I understand. - Self-assignment detection was originally implemented in rust-lang#87129 to address rust-lang#75356 - The implementation was disabled alongside the revert of rust-lang#81473's "write-only fields" detection - rust-lang#81473 was reverted via rust-lang#86212 and rust-lang#83171 due to false positives in write-only field detection (rust-lang#81626, rust-lang#81658) - The self-assignment detection feature got removed, even though it wasn't the reason for the problems This PR only re-enables the self-assignment checks, which are orthogonal to the problematic write-only field analysis. ## Changes - Removed `#[allow(dead_code)]` from `compiler/rustc_passes/src/dead.rs` file - `handle_assign` and - `check_for_self_assign` - Added `ExprKind::Assign` handling in `visit_expr` to call both methods - Updated test expectations in `tests/ui/lint/dead-code/self-assign.rs`
Zalathar
added a commit
to Zalathar/rust
that referenced
this pull request
Aug 12, 2025
…, r=petrochenkov fix: re-enable self-assignment ## Description Re-enables the self-assignment detection that was previously disabled due to unrelated regressions. The fix detects useless assignments like `x = x` and `foo.field = foo.field`. ## History The original regressions (rust-lang#81626, rust-lang#81658) were specifically about false positives in write-only field detection, not self-assignment detection. Belows are brief history for the rule that I understand. - Self-assignment detection was originally implemented in rust-lang#87129 to address rust-lang#75356 - The implementation was disabled alongside the revert of rust-lang#81473's "write-only fields" detection - rust-lang#81473 was reverted via rust-lang#86212 and rust-lang#83171 due to false positives in write-only field detection (rust-lang#81626, rust-lang#81658) - The self-assignment detection feature got removed, even though it wasn't the reason for the problems This PR only re-enables the self-assignment checks, which are orthogonal to the problematic write-only field analysis. ## Changes - Removed `#[allow(dead_code)]` from `compiler/rustc_passes/src/dead.rs` file - `handle_assign` and - `check_for_self_assign` - Added `ExprKind::Assign` handling in `visit_expr` to call both methods - Updated test expectations in `tests/ui/lint/dead-code/self-assign.rs`
rust-timer
added a commit
that referenced
this pull request
Aug 12, 2025
Rollup merge of #145214 - notJoon:fix/enable-self-assignment, r=petrochenkov fix: re-enable self-assignment ## Description Re-enables the self-assignment detection that was previously disabled due to unrelated regressions. The fix detects useless assignments like `x = x` and `foo.field = foo.field`. ## History The original regressions (#81626, #81658) were specifically about false positives in write-only field detection, not self-assignment detection. Belows are brief history for the rule that I understand. - Self-assignment detection was originally implemented in #87129 to address #75356 - The implementation was disabled alongside the revert of #81473's "write-only fields" detection - #81473 was reverted via #86212 and #83171 due to false positives in write-only field detection (#81626, #81658) - The self-assignment detection feature got removed, even though it wasn't the reason for the problems This PR only re-enables the self-assignment checks, which are orthogonal to the problematic write-only field analysis. ## Changes - Removed `#[allow(dead_code)]` from `compiler/rustc_passes/src/dead.rs` file - `handle_assign` and - `check_for_self_assign` - Added `ExprKind::Assign` handling in `visit_expr` to call both methods - Updated test expectations in `tests/ui/lint/dead-code/self-assign.rs`
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
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
6 participants
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.
This PR fixes #75356. Following @varkor's suggestion in #75356 (comment), I have implemented this warning as part of the
dead_codelint. Unlike the-Wself-assignimplementation in Clang, my implementation also warns about self-assignments of struct fields (s.x = s.x).r? @varkor