C++: Tests for variables with ambiguous types#2970
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MathiasVP merged 1 commit intogithub:masterfrom Mar 11, 2020
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nickrolfe
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| // BUG: types of members depend on extraction order. | ||
| // Only one copy of this struct is extracted, and the types of its members refer | ||
| // to the typedefs in file1.c. Had file2.c been extracted first instead, the | ||
| // types of its members would be different. |
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That sounds right, and is similar to the way that the existing variables/global test would produce different output if a.c and b.c got extracted in a different order.
nickrolfe
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Mar 3, 2020
| // The type of `structMember` is ambiguous, and the two possible types are not | ||
| // unifiable, meaning in this context that they don't share an unspecified type. | ||
| // The types are nevertheless _compatible_, so it's valid C (not C++) to use | ||
| // these two definitions interchangably in the same program. |
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Right. The content hashes for NotUnifiableTwice include the name emptyStruct1 or emptyStruct2, which is how they end up differing.
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The comments you've added look right to me, and correspond with my understanding of the extractor and QL library's behaviour.
MathiasVP
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It sounds like it "Looks Good To Nick"
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We've worked around several issues with malformed IR due to malformed databases (#2821, #2844, #2835), and some of these workarounds should be replaced with fixes at a deeper level.
This PR is an attempt to understand why variables (and therefore expressions) can get multiple types. Hopefully that will get us closer to proposing and implementing a fix, either at the extractor level or the QL level.