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UsedNamespaceOrType comparing type argument incorrectly #7015

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jaredpar opened this issue Nov 24, 2015 · 0 comments · Fixed by #7019
Closed

UsedNamespaceOrType comparing type argument incorrectly #7015

jaredpar opened this issue Nov 24, 2015 · 0 comments · Fixed by #7019
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@jaredpar
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Area-Compilers Concept-Determinism The issue involves our ability to support determinism in binaries and PDBs created at build time.
Milestone
1.2

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@jaredpar
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Consider the contents of the Equals method

return AliasOpt == other.AliasOpt
    && TargetAssemblyOpt == other.TargetAssemblyOpt
    && TargetNamespaceOpt == other.TargetNamespaceOpt
    && TargetTypeOpt == other.TargetTypeOpt
    && TargetXmlNamespaceOpt == other.TargetXmlNamespaceOpt;

This is comparing ITypeReference values by reference instead of using their Equals method. In the case of generic types the ITypeReference values can be different objects for equivalent symbols and this comparison will incorrectly return false.

This is actually breaking determinism on compilations that have a using alias where the target type is a bound generic. It causes the result of ShouldForwardNamespaceScopes to be non-deterministic and hence changes the PDB output and content id hash.
@jaredpar jaredpar added Bug Concept-Determinism The issue involves our ability to support determinism in binaries and PDBs created at build time. labels Nov 24, 2015
@jaredpar jaredpar self-assigned this Nov 24, 2015
@jaredpar jaredpar added this to the 1.2 milestone Nov 24, 2015
@jaredpar jaredpar mentioned this issue Nov 25, 2015
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jaredpar added a commit to jaredpar/roslyn that referenced this issue Nov 26, 2015
@jaredpar
Fix UsedNamespaceOrType::Equals
b40e1bb 
The Equals method was using reference equality to compare ITypeReference instances.  Correct comparison of that type must use .Equals as equivalent generic values can be different objects.

This surfaced as a bug in determinism.  In the case we had an alias'd using where the target type was generic this Equals method came into play.  Based on whether we got a generic cache hit or not ended up changing the PDB output and as an effect the determinism id of the resulting assembly.

closes dotnet#7015
@gafter gafter removed the Bug label Nov 28, 2015
@AlekseyTs AlekseyTs mentioned this issue Oct 18, 2023
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Area-Compilers Concept-Determinism The issue involves our ability to support determinism in binaries and PDBs created at build time.
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1.2
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Fix UsedNamespaceOrType::Equals jaredpar/roslyn
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@jaredpar @gafter