Fix spurious rebuilds for phony targets with validations#2729
Open
codesuki wants to merge 4 commits intoninja-build:masterfrom
Open
Fix spurious rebuilds for phony targets with validations#2729codesuki wants to merge 4 commits intoninja-build:masterfrom
codesuki wants to merge 4 commits intoninja-build:masterfrom
Conversation
Phony targets with no inputs are considered dirty if their output is missing. However, phony targets used as anchors for validation dependencies (e.g. from GN groups) often have no regular inputs but should not force a rebuild if the validations are clean. This change updates RecomputeOutputDirty to check if a phony target has validation dependencies. If so, it is treated similarly to a target with inputs: it is only dirty if its dependencies are dirty, not automatically dirty because the output file is missing. This fixes an issue where targets depending on a phony validation anchor would rebuild on every run.
digit-google
approved these changes
Feb 15, 2026
Contributor
digit-google
left a comment
digit-google
left a comment
There was a problem hiding this comment.
Thank you, this looks fine, @jhasse please take a look.
src/graph.cc
Outdated
| @@ -285,7 +285,8 @@ bool DependencyScan::RecomputeOutputDirty(const Edge* edge, | |||
| if (edge->is_phony()) { | |||
| // Phony edges don't write any output. Outputs are only dirty if | |||
| // there are no inputs and we're missing the output. | |||
Contributor
There was a problem hiding this comment.
nit: Can you add a segment in the comment that explains why validations_ is checked too.
Author
There was a problem hiding this comment.
I added a small comment. Please let me know if that clarifies it.
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
3 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.
Phony targets with no inputs are considered dirty if their output is missing. However, phony targets used as anchors for validation dependencies (e.g. from GN groups) often have no regular inputs but should not force a rebuild if the validations are clean.
This change updates RecomputeOutputDirty to check if a phony target has validation dependencies. If so, it is treated similarly to a target with inputs: it is only dirty if its dependencies are dirty, not automatically dirty because the output file is missing.
This fixes an issue where targets depending on a phony validation anchor would rebuild on every run.