C#: Handle non-unique type arguments when computing generics strings #19782
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Pull Request Overview
This PR updates QL utilities to use monotonic aggregates and strictconcat when computing generic type argument strings, aiming to prevent combinatorial explosion for non-unique arguments.
- Enabled
language[monotonicAggregates]for two helper functions - Replaced direct
getFullName/getNamecalls withstrictconcataggregators
Reviewed Changes
Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.
| File | Description |
|---|---|
| csharp/ql/lib/semmle/code/csharp/commons/QualifiedName.qll | Added language[monotonicAggregates] and switched to strictconcat in getTypeArgumentsQualifiedName |
| csharp/ql/lib/semmle/code/csharp/Generics.qll | Added language[monotonicAggregates] and switched to strictconcat in getTypeArgumentName |
Comments suppressed due to low confidence (2)
csharp/ql/lib/semmle/code/csharp/commons/QualifiedName.qll:54
- Using a
strictconcatover a single-element generator tied toidoesn’t aggregate across all type arguments, so it won’t prevent combinatorial explosion. Consider removing theiparameter and aggregating overcg.getTypeArgument(*)in one call or moving the aggregation into the caller.
result = strictconcat(Type t | t = cg.getTypeArgument(i) | getFullName(t), "/")
csharp/ql/lib/semmle/code/csharp/Generics.qll:116
- This
strictconcatis also scoped to a singlei, so you’re effectively concatenating only one element. To handle non-unique arguments correctly, aggregate over all arguments at once rather than indexing per call.
result = strictconcat(Type t | t = cg.getTypeArgument(i) | t.getName(), "/")
aschackmull
reviewed
Jun 17, 2025
| @@ -110,9 +110,10 @@ private string getTypeArgumentsToString(ConstructedGeneric cg) { | |||
| strictconcat(Type t, int i | t = cg.getTypeArgument(i) | t.toStringWithTypes(), ", " order by i) | |||
| } | |||
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| language[monotonicAggregates] | |||
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Could we add comments stating that this is merely a precaution and that we expect he concat to only concat a single name.
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aschackmull
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Jun 17, 2025
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Avoids a combinatorial explosion when type arguments are not unique.