[PATCH] D63954: Add lifetime categories attributes

[Gábor Horváth via Phabricator via cfe-commits]

xazax.hun added inline comments.


================
Comment at: clang/lib/Sema/SemaDeclAttr.cpp:4553
+  // we always add (and check) the attribute to the cannonical decl.
+  D = D->getCanonicalDecl();
+  if(AL.getKind() ==  ParsedAttr::AT_Owner) {
----------------
aaron.ballman wrote:
> xazax.hun wrote:
> > aaron.ballman wrote:
> > > Will this work? What happens if we see a forward declaration with this attribute first and then see the canonical declaration later? I suspect this work needs to be done when merging declaration attributes instead.
> > For `TagDecl`s the canonical decl is the first declaration:
> > ```
> > TagDecl *TagDecl::getCanonicalDecl() { return getFirstDecl(); }
> > ```
> > 
> > So I suspect we can never see a non-canonical declaration first. And once we see the canonical declaration it remains the same no matter how many new declaration do we see.
> This is the scenario I am worried about:
> ```
> struct [[whatever]] Foo;
> struct Foo {};
> ```
This works well as the forward declaration is the canonical declaration since it is the first declaration in the redecl chain. A declaration being canonical or being a definition are two independent properties.

The only caveat here is that the users of these attributes always need to query the attribute of the canonical decl.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D63954/new/

https://reviews.llvm.org/D63954