[C++ PATCH] PR c++/90590 Suppress warning for enumeration value not handled in switch warning

[Marek Polacek]

On Mon, Jul 15, 2019 at 09:47:26AM -0400, Matthew Beliveau wrote:
> Okay I kept the TYPE_MAIN_VARIANT and dropped the accidental new line!
> Hopefully this should be fine!

CCing Joseph as this is c-family/ stuff.

> Bootstrapped/regtested on x86_64-linux, ok for trunk?
> 
> 2019-07-12  Matthew Beliveau  <mbelivea@redhat.com>
> 
> 	PR c++/90590
> 	* c-warn.c (c_do_switch_warnings): Suppress warning for enumerators
> 	with reserved names that are in a system header.
> 
> 	* c-c++-common/pr90590-1.c: New test.
> 	* c-c++-common/pr90590-1.h: New test.
> 	* c-c++-common/pr90590-2.c: New test.
> 	* c-c++-common/pr90590-2.h: New test.
> 
> diff --git gcc/c-family/c-warn.c gcc/c-family/c-warn.c
> index b5d09e761d7..51c54a283e5 100644
> --- gcc/c-family/c-warn.c
> +++ gcc/c-family/c-warn.c
> @@ -34,6 +34,7 @@ along with GCC; see the file COPYING3.  If not see
>  #include "gcc-rich-location.h"
>  #include "gimplify.h"
>  #include "c-family/c-indentation.h"
> +#include "c-family/c-spellcheck.h"
>  #include "calls.h"
>  #include "stor-layout.h"
>  
> @@ -1628,6 +1629,15 @@ c_do_switch_warnings (splay_tree cases, location_t switch_location,
>        if (cond && tree_int_cst_compare (cond, value))
>  	continue;
>  
> +      /* If the enumerator is defined in a system header and uses a reserved
> +	 name, then we continue to avoid throwing a warning.  */
> +      location_t loc = DECL_SOURCE_LOCATION
> +	    (TYPE_STUB_DECL (TYPE_MAIN_VARIANT (type)));
> +      if (in_system_header_at (loc)
> +	  && name_reserved_for_implementation_p
> +	      (IDENTIFIER_POINTER (TREE_PURPOSE (chain))))
> +	continue;
> +
>        /* If there is a default_node, the only relevant option is
>  	 Wswitch-enum.  Otherwise, if both are enabled then we prefer
>  	 to warn using -Wswitch because -Wswitch is enabled by -Wall
> diff --git gcc/testsuite/c-c++-common/pr90590-1.c gcc/testsuite/c-c++-common/pr90590-1.c
> new file mode 100644
> index 00000000000..4e11debb7fa
> --- /dev/null
> +++ gcc/testsuite/c-c++-common/pr90590-1.c
> @@ -0,0 +1,15 @@
> +// PR c++/90590
> +// { dg-options -Wswitch }
> +#include "pr90590-1.h"
> +
> +void
> +g ()
> +{
> +  enum E e = _A;
> +  switch (e) // { dg-bogus "enumeration value '_C' not handled in switch" }
> +    {
> +    case _A:
> +    case _B:
> +      break;
> +    }
> +}
> diff --git gcc/testsuite/c-c++-common/pr90590-1.h gcc/testsuite/c-c++-common/pr90590-1.h
> new file mode 100644
> index 00000000000..22f1a7d5d52
> --- /dev/null
> +++ gcc/testsuite/c-c++-common/pr90590-1.h
> @@ -0,0 +1,2 @@
> +#pragma GCC system_header
> +enum E { _A, _B, _C };
> diff --git gcc/testsuite/c-c++-common/pr90590-2.c gcc/testsuite/c-c++-common/pr90590-2.c
> new file mode 100644
> index 00000000000..23da97f9d74
> --- /dev/null
> +++ gcc/testsuite/c-c++-common/pr90590-2.c
> @@ -0,0 +1,11 @@
> +// PR c++/90590
> +// { dg-options -Wswitch }
> +
> +#include "pr90590-2.h"
> +
> +void
> +fn ()
> +{
> +  switch (c.b) // { dg-bogus "enumeration value" }
> +    ;
> +}
> diff --git gcc/testsuite/c-c++-common/pr90590-2.h gcc/testsuite/c-c++-common/pr90590-2.h
> new file mode 100644
> index 00000000000..e4f8635576f
> --- /dev/null
> +++ gcc/testsuite/c-c++-common/pr90590-2.h
> @@ -0,0 +1,4 @@
> +#pragma GCC system_header
> +struct {
> +  enum { _A } b;
> +} c;


Marek