This is the mail archive of the gcc-patches@gcc.gnu.org mailing list for the GCC project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: [PATCH][C++] Fix PR61004


On Wed, 30 Apr 2014, Richard Biener wrote:

> 
> With no longer recording alias subsets using BINFOs we now emit
> bogus alias warnings for accessing empty bases.  The following
> avoids this, accessing those with an incompatible alias-set is
> harmless.
> 
> Bootstrapped and tested on x86_64-unknown-linux-gnu, ok?

Ping.

> Thanks,
> Richard.
> 
> 2014-04-30  Richard Biener  <rguenther@suse.de>
> 
> 	PR c++/61004
> 	* typeck.c (cp_build_indirect_ref): Do not emit strict-aliasing
> 	warnings for accessing empty classes.
> 
> 	* g++.dg/diagnostic/pr61004.C: New testcase.
> 
> Index: gcc/cp/typeck.c
> ===================================================================
> --- gcc/cp/typeck.c	(revision 209928)
> +++ gcc/cp/typeck.c	(working copy)
> @@ -2921,8 +2921,9 @@ cp_build_indirect_ref (tree ptr, ref_ope
>  	 of  the  result  is  "T."  */
>        tree t = TREE_TYPE (type);
>  
> -      if (CONVERT_EXPR_P (ptr)
> -          || TREE_CODE (ptr) == VIEW_CONVERT_EXPR)
> +      if ((CONVERT_EXPR_P (ptr)
> +	   || TREE_CODE (ptr) == VIEW_CONVERT_EXPR)
> +	  && (!CLASS_TYPE_P (t) || !CLASSTYPE_EMPTY_P (t)))
>  	{
>  	  /* If a warning is issued, mark it to avoid duplicates from
>  	     the backend.  This only needs to be done at
> Index: gcc/testsuite/g++.dg/diagnostic/pr61004.C
> ===================================================================
> --- gcc/testsuite/g++.dg/diagnostic/pr61004.C	(revision 0)
> +++ gcc/testsuite/g++.dg/diagnostic/pr61004.C	(working copy)
> @@ -0,0 +1,11 @@
> +// { dg-do compile }
> +// { dg-options "-O2 -Wall" }
> +
> +struct A{ };
> +struct B:A{};
> +void f(A const&);
> +int main()
> +{
> +  B b;
> +  f(b); // { dg-bogus "strict-aliasing" }
> +}
> 


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]