Re: C identifier lookup speedups, 2/2

[Neil Booth <neil at daikokuya dot co dot uk>]

Zack Weinberg wrote:-

> > 	I do not know if any of the follow-up patches fixes it.
> 
> This program is ill-formed - the static decl 'v' at file scope refers
> to the same object as the extern decl 'v' at block scope, which
> induces undefined behavior.  Having said that, I do not know why it
> compiles and executes successfully on Linux but not on AIX.
> 
> My inclination is to "fix" this by causing the compiler to reject the
> program, and move the test case to c-torture/noncompile.  However,
> this situation was specifically allowed in the old code:
> 
> #if 0
>           /* This case is probably sometimes the right thing to do.  */
>           /* If we have a local external declaration,
>              then any file-scope declaration should not
>              have been static.  */
>           if (oldlocal == 0 && oldglobal != 0
>               && !TREE_PUBLIC (oldglobal)
>               && DECL_EXTERNAL (x) && TREE_PUBLIC (x))
>             warning ("`%s' locally external but globally static",
>                      IDENTIFIER_POINTER (name));
> #endif
> 
> so I would like to get reactions from other people about what GCC
> *should* do with this program before changing anything.

I agree with your inclination.

Neil.