Re: [PATCH v5] c-family: Implement __has_feature and __has_extension [PR60512]

[Alex Coplan <alex.coplan@arm.com>]

On 28/11/2023 17:03, Thomas Schwinge wrote:
> Hi!
> 
> On 2023-11-17T14:50:45+0000, Alex Coplan <alex.coplan@arm.com> wrote:
> > --- a/gcc/cp/cp-objcp-common.cc
> > +++ b/gcc/cp/cp-objcp-common.cc
> 
> > +/* Table of features for __has_{feature,extension}.  */
> > +
> > +static constexpr cp_feature_info cp_feature_table[] =
> > +{
> > +  { "cxx_exceptions", &flag_exceptions },
> > +  { "cxx_rtti", &flag_rtti },
> > +  { "cxx_access_control_sfinae", { cxx11, cxx98 } },
> 
> Here we see that 'cxx_exceptions', 'cxx_rtti' are dependent on
> '-fexceptions', '-frtti'.  Certain GCC configurations may decide to
> default to '-fno-exceptions' and/or '-fno-rtti'...
> 
> > --- /dev/null
> > +++ b/gcc/testsuite/g++.dg/ext/has-feature.C
> > @@ -0,0 +1,206 @@
> > +// { dg-do compile }
> > +// { dg-options "" }
> > +
> > +#define FEAT(x) (__has_feature(x) && __has_extension(x))
> > +#define CXX11 (__cplusplus >= 201103L)
> > +#define CXX14 (__cplusplus >= 201402L)
> > +
> > +#if !FEAT(cxx_exceptions) || !FEAT(cxx_rtti)
> > +#error
> > +#endif
> 
> ..., but here, they are assumed available unconditionally.  OK to push
> "Adjust 'g++.dg/ext/has-feature.C' for default-'-fno-exceptions', '-fno-rtti' configurations",
> see attached?

LGTM, but I can't approve the patch.

Sorry for the breakage and thanks for the fix.

Alex

> 
> 
> Grüße
>  Thomas
> 
> 
> -----------------
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> From 89482e73066fcd6da5dbc93402e77e28f948a96c Mon Sep 17 00:00:00 2001
> From: Thomas Schwinge <thomas@codesourcery.com>
> Date: Tue, 28 Nov 2023 15:57:09 +0100
> Subject: [PATCH] Adjust 'g++.dg/ext/has-feature.C' for
>  default-'-fno-exceptions', '-fno-rtti' configurations
> 
> ..., where you currently get:
> 
>     FAIL: g++.dg/ext/has-feature.C  -std=gnu++98 (test for excess errors)
>     [...]
> 
> Minor fix-up for recent commit 06280a906cb3dc80cf5e07cf3335b758848d488d
> "c-family: Implement __has_feature and __has_extension [PR60512]".
> 
> 	gcc/testsuite/
> 	* g++.dg/ext/has-feature.C: Adjust for default-'-fno-exceptions',
> 	'-fno-rtti' configurations.
> ---
>  gcc/testsuite/g++.dg/ext/has-feature.C | 6 +++++-
>  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> diff --git a/gcc/testsuite/g++.dg/ext/has-feature.C b/gcc/testsuite/g++.dg/ext/has-feature.C
> index 52191b78fd6..bcfe82469ae 100644
> --- a/gcc/testsuite/g++.dg/ext/has-feature.C
> +++ b/gcc/testsuite/g++.dg/ext/has-feature.C
> @@ -5,7 +5,11 @@
>  #define CXX11 (__cplusplus >= 201103L)
>  #define CXX14 (__cplusplus >= 201402L)
>  
> -#if !FEAT(cxx_exceptions) || !FEAT(cxx_rtti)
> +#if FEAT(cxx_exceptions) != !!__cpp_exceptions
> +#error
> +#endif
> +
> +#if FEAT(cxx_rtti) != !!__cpp_rtti
>  #error
>  #endif
>  
> -- 
> 2.34.1
>