[PATCH] D153003: [ODRHash] Fix ODR hashing of template names

[Richard Smith - zygoloid via Phabricator via cfe-commits]

rsmith added a comment.

I think the behavior change for the testcase here is correct, though I'm not sure that the patch is getting that behaviour change in the right way. Per [temp.type]/1.4 (http://eel.is/c++draft/temp.type#1.4),

> Two template-ids are the same if [...] their corresponding template template-arguments refer to the same template.

so `B<A>` and `B<NS::A>` are the same type. The stricter "same sequence of tokens" rule doesn't apply here, because using-declarations are not definitions.

But that also suggests that ODR hashing should not be visiting these template arguments in using-declarations at all, because the ODR does not apply to the types specified in a namespace-scope using-declaration. How to we even get into the ODR hasher here? I thought we only applied it to function and class definitions (to which the ODR does apply).


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https://reviews.llvm.org/D153003