Avoid inconsistent implicit toString on potential string subtypes#21318
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Avoid inconsistent implicit toString on potential string subtypes#21318
toString on potential string subtypes#21318Conversation
Fix cases where the compiler cannot prove types don't extend string: 1. FileSystem.qll: Add toString() to ContainerBase signature. The instantiation sites already provide toString(), so no changes needed there. Container.toString() now delegates to super.toString(). No behaviour change. 2. DataFlowImplCommon.qll: Content.toString() now delegates to super.toString() instead of returning the literal "Content". This is a behaviour change: Content now displays its actual description (e.g. field names) rather than the generic "Content".
hvitved
reviewed
Feb 18, 2026
| * This is the absolute path of the container. | ||
| */ | ||
| string toString() { result = this.getAbsolutePath() } | ||
| string toString() { result = super.toString() } |
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This adds the possibility for languages to use different toStrings, which I think we'll want to avoid. Does it make a difference if we change class Container instanceof Input::ContainerBase to class Container extends ContainerBaseFinal where private final class ContainerBaseFinal = Input::ContainerBase?
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Pull request overview
This PR fixes inconsistent implicit toString behavior on types that might extend string by ensuring explicit toString() definitions are provided in signatures and properly delegated.
Changes:
- Added
toString()method to theContainerBasesignature in FileSystem.qll - Changed Container.toString() to delegate to super.toString() instead of directly calling getAbsolutePath()
- Changed Content.toString() in DataFlowImplCommon.qll to delegate to super.toString() instead of returning the literal "Content"
Reviewed changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| shared/util/codeql/util/FileSystem.qll | Adds toString() to ContainerBase signature and updates Container class to delegate to super.toString() |
| shared/dataflow/codeql/dataflow/internal/DataFlowImplCommon.qll | Updates Content class to delegate toString() to super instead of returning literal "Content" |
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Fix cases where the compiler cannot prove types don't extend string:
FileSystem.qll: Add
toString()to ContainerBase signature. The instantiation sites already provide toString(), so no changes needed there.Container.toString()now delegates tosuper.toString(). No behaviour change.DataFlowImplCommon.qll:
Content.toString()now delegates tosuper.toString()instead of returning the literal"Content". This is a behaviour change: Content now displays its actual description (e.g. field names) rather than the generic"Content".See also #21306.