GCC 4.5.0 Reports invalid warning

[Dave Korn]

On 16/07/2010 00:59, J Decker wrote:

> ------------------------------
> 
> #define PointerA struct a *
> 
> void f( PointerA );
> 
> typedef struct a * PA;
> struct a { int x; };
> 
> void f( PA a )
> {
> }
> 
> ---------------------------------
> 
> This is the output
> 
>  warning: 'struct a' declared inside parameter list
>  warning: its scope is only this definition or declaration, which is
> probably not what you want
> error: conflicting types for 'f'
>  note: previous declaration of 'f' was here
> 
> 
> --------------------------------
> 
> This is valid C code by every other compiler.

  Not so, as far as I can tell.  Comeau online says:

> Comeau C/C++ 4.3.10.1 (Oct  6 2008 11:28:09) for ONLINE_EVALUATION_BETA2
> Copyright 1988-2008 Comeau Computing.  All rights reserved.
> MODE:strict errors C99 
> 
> "ComeauTest.c", line 3: warning: declaration is not visible outside of function
>   void f( PointerA );
>           ^
> 
> "ComeauTest.c", line 8: error: declaration is incompatible with "void f(struct a *)"
>           (declared at line 3)
>   void f( PA a )
>        ^
> 
> 1 error detected in the compilation of "ComeauTest.c".

  As long as "struct a" hasn't been (forward-)declared at the time the
declaration of f() is found, it is a different one from the "struct a" in the
global namespace that the formal parameter on the definition of f() then
subsequently refers to.

    cheers,
      DaveK