[PATCH] D154774: [Sema] Respect instantiated-from template's VisibilityAttr for two implicit/explicit instantiation cases

[Fangrui Song via Phabricator via cfe-commits]

MaskRay added inline comments.


================
Comment at: clang/lib/AST/Decl.cpp:380
+                                                ->getTemplatedDecl()
+                                                ->hasAttr<VisibilityAttr>();
 }
----------------
rjmccall wrote:
> Okay, this change seems wrong.  A visibility attribute on an explicit specialization or instantiation should definitely override everything else.  A visibility attribute on a template pattern should only override other visibility information that we would derive from that pattern, like the visibility of the template parameters; it should not override visibility from the template arguments.  You probably need this function to return an enum with three cases: (1) factor in both template arguments and template parameters, (2) factor in only template arguments, and (3) factor in nothing.
> 
> Also, the bug here doesn't seem to be specific to function templates, and you should fix the code for all three paths (function templates, class templates, and variable templates).  Basically we're universally mishandling visibility attributes on template patterns for templates with non-type template parameters with hidden visibility.
I have added test coverage to `test51` in `visibility.cpp` and studied GCC's behavior.

Sent https://github.com/llvm/llvm-project/pull/72092 to ignore visibility effects from template parameters. It will bring our behavior closer to GCC.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D154774/new/

https://reviews.llvm.org/D154774