[cfe-dev] retrieving anonymous struct decl name

[David Rector via cfe-dev]

You cannot get the VarDecl name from the TagDecl; the anonymous struct is placed as its own node and the VarDecls placed subsequently (which is a bit unfortunate, it would be nice if the syntax were more directly represented, but that might present its own problems); but you might benefit from looking at how DeclPrinter handles this tricky case:

https://github.com/llvm-mirror/clang/blob/master/lib/AST/DeclPrinter.cpp#L394 

Basically, while iterating over decls(), you would look for TagDecls for which `isFreeStanding()` returns false, then accumulate the subsequent VarDecls whose “base” type (after removing pointers etc.) is the TagDecl, and when those are exhausted you handle the Tag + VarDecls together as a whole.

Not 100% sure what you ultimately want to do but hope that helps.

> On Dec 20, 2020, at 10:11 PM, John Leidel via cfe-dev <cfe-dev at lists.llvm.org> wrote:
> 
> I'm still working on the same issue associated with translating
> anonymous struct decl's to non-anonymous structs.  With the same
> original example, I have the TagDecl for the nested struct definition.
> Is there a way to retrieve the declaration name "first" from the
> TagDecl?
> 
> typedef struct test_case_t {
>  struct {
>     int value;
>  } first[1];
>  int second;
>  int third[1];
> } test_case_t;
> 
> As an example below, I grab the RecordDecl for the top-level struct,
> then traverse each member using the decl_iterator.  I have other code
> to examine each FieldDecl, but I'm specifically interested in the
> following.  If I can dyn_cast to a TagDecl, then I'm looking at the
> struct declaration.  I'm trying to retrieve the anonymous
> DeclarationName and use it to reset the declaration of the nested
> struct and its variable definition. Thoughts?
> 
> for(RecordDecl::decl_iterator iter = RD->decls_begin(), end =
> RD->decls_end(); iter != end; ++iter) {
>  if(TagDecl *TD = dyn_cast<TagDecl>(*iter)){
>     if(TD->isThisDeclarationADefinition()){
>        // This sets the struct definition and instance name to test_case_t
>        // how do I retrieve "first"?
>        // this should induce struct first { }; struct first first[1];
>        TD->setDeclName( ??? );
>     }
>  }
> }
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