[Lldb-commits] [clang] [lldb] [clang][AST] fix ast-print of extern <lang> with >=2 declarators, fixed (PR #93913)

[Artem Yurchenko via lldb-commits]

================
@@ -2380,7 +2380,7 @@ FunctionDecl *Sema::CreateBuiltin(IdentifierInfo *II, QualType Type,
   }
 
   FunctionDecl *New = FunctionDecl::Create(Context, Parent, Loc, Loc, II, Type,
-                                           /*TInfo=*/nullptr, SC_Extern,
+                                           /*TInfo=*/nullptr, SC_None,
----------------
temyurchenko wrote:

> > That's not actually correct -- the declaration of a function at block scope should definitely _not_ be extern, it should have no linkage: https://godbolt.org/z/81fMaPaTq
> 
> I may be wrong to rely on cppreference, but the following page tells that indeed a function at a block scope has implicit `extern`, which could also be made explicit: https://en.cppreference.com/w/c/language/storage_duration.
> 
> I also checked your example locally by compiling (via clang) `main.c` with an additional `defs.c`: main.c:
> 
> ```c
> int main(void) {
>   void f();
>   extern void g();
> 
>   f();
>   g();
> 
>   return 0;
> }
> ```
> 
> defs.c:
> 
> ```c
> #include <stdio.h>
> 
> void f() {
>   printf("f\n");
> }
> 
> void g() {
>   printf("g\n");
> }
> ```
> 
> The executable works as expected.
> 
> I will also take a look at the C99 standard draft.

Paragraph 6.2.2.5 says: 

> If the declaration of an identifier for a function has no storage-class specifier, its linkage
is determined exactly as if it were declared with the storage-class specifier extern. If
the declaration of an identifier for an object has file scope and no storage-class specifier,
its linkage is external.

Thus, seemingly confirming that a function declared at the block scope is declared with an implicit `extern`.

https://github.com/llvm/llvm-project/pull/93913