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[C++] - SD-6 Implementation Part 2 - __has_include macro and C++ language feature macros.

Message ID 54052049.5040707@verizon.net
State New
Headers show

Commit Message

Ed Smith-Rowland Sept. 2, 2014, 1:41 a.m. UTC 
Greetings,

I am finally getting back to my SD-6 C++ features test work.

This second part adds a __has_include function-like macro that will 
return true if a header exists. I also added a __has_include_next 
function-like macro as an extension. Clang has this extension.
These macros just wrap the built-ins introduced in the previous patch.

As requested by folk I have rearranged which language-feature macros are available with what .

There is one bit: arrays of runtime bound.  These got kicked out of C++14 I think and is languishing in a TS.
OTOH, we still support it.  It's better than the C99 version we supported.
What direction should I take?

Bootstrapped and tested under x86_64-linux.

OK?

Ed
2014-09-02  Edward Smith-Rowland  <3dw4rd@verizon.net>

	Implement SD-6: SG10 Feature Test Recommendations
	* c-cppbuiltin.c (c_cpp_builtins()): Define language feature
	macros and the __has_header macro.

Comments

Jason Merrill Sept. 25, 2014, 5:37 p.m. UTC | #1 
On 09/01/2014 09:41 PM, Ed Smith-Rowland wrote:
> +	  /* Return type deduction was added as an extension to C++11
> +	     and was standardized for C+14.  */
> +	  cpp_define (pfile, "__cpp_return_type_deduction=201304");

When I try to use it with -std=c++11 I get

wa.C:1:8: error: ‘f’ function uses ‘auto’ type specifier without 
trailing return type
  auto f() { return 42; }
         ^
wa.C:1:8: note: deduced return type only available with -std=c++14 or 
-std=gnu++14

Let's move it to the C++14 section.

> There is one bit: arrays of runtime bound.  These got kicked out of C++14 I think and is languishing in a TS.
> OTOH, we still support it.  It's better than the C99 version we supported.
> What direction should I take?
> /* .... Runtime sized arrays
> +	 have C++14 semantics even for C++98.  */

The comment is inaccurate; most of the restrictions on arrays of runtime 
bound are only applied in C++14 mode.  Let's put this macro in the C++14 
section as well until there's a value or separate macro indicating C99 
VLA support.

Jason
Jason Merrill Sept. 25, 2014, 5:40 p.m. UTC | #2 
On 09/01/2014 09:41 PM, Ed Smith-Rowland wrote:
> +	  cpp_define (pfile, "__cpp_attribute_deprecated=201309");

Don't we support attribute deprecated in C++11?

Jason
Ed Smith-Rowland Sept. 26, 2014, 2:20 p.m. UTC | #3 
On 09/25/2014 01:40 PM, Jason Merrill wrote:
> On 09/01/2014 09:41 PM, Ed Smith-Rowland wrote:
>> +      cpp_define (pfile, "__cpp_attribute_deprecated=201309");
>
> Don't we support attribute deprecated in C++11?
>
> Jason
>
>
We support [[gnu::deprecated]] in C++11 bit not [[deprecated]] until C++14.
Ed
Jason Merrill Sept. 26, 2014, 5:46 p.m. UTC | #4 
On 09/26/2014 10:20 AM, Ed Smith-Rowland wrote:
> On 09/25/2014 01:40 PM, Jason Merrill wrote:
>> Don't we support attribute deprecated in C++11?
>>
> We support [[gnu::deprecated]] in C++11 bit not [[deprecated]] until C++14.

Hmm, that seems unnecessary.  I'd allow it in C++11 as well, and *maybe* 
complain if -pedantic; 7.6/5 says "For an attribute-token not specified 
in this International Standard, the behavior is implementation defined" 
so allowing it is conforming.

Jason
diff mbox

Patch

Index: c-cppbuiltin.c
===================================================================
--- c-cppbuiltin.c	(revision 214680)
+++ c-cppbuiltin.c	(working copy)
@@ -794,6 +794,12 @@ 
   /* For stddef.h.  They require macros defined in c-common.c.  */
   c_stddef_cpp_builtins ();
 
+  /* Set include test macros for all C/C++ (not for just C++11 etc.)
+     the builtins __has_include__ and __has_include_next__ are defined
+     in libcpp.  */
+  cpp_define (pfile, "__has_include(STR)=__has_include__(STR)");
+  cpp_define (pfile, "__has_include_next(STR)=__has_include_next__(STR)");
+
   if (c_dialect_cxx ())
     {
       if (flag_weak && SUPPORTS_ONE_ONLY)
@@ -800,12 +806,57 @@ 
 	cpp_define (pfile, "__GXX_WEAK__=1");
       else
 	cpp_define (pfile, "__GXX_WEAK__=0");
+
       if (warn_deprecated)
 	cpp_define (pfile, "__DEPRECATED");
+
       if (flag_rtti)
 	cpp_define (pfile, "__GXX_RTTI");
+
       if (cxx_dialect >= cxx11)
         cpp_define (pfile, "__GXX_EXPERIMENTAL_CXX0X__");
+
+      /* Binary literals and variable length arrays have been allowed in g++
+	 before C++11 and were standardized for C++14.  Runtime sized arrays
+	 have C++14 semantics even for C++98.  */
+      if (!pedantic || cxx_dialect > cxx11)
+	{
+	  cpp_define (pfile, "__cpp_binary_literals=201304");
+	  cpp_define (pfile, "__cpp_runtime_arrays=201304");
+	}
+      if (cxx_dialect >= cxx11)
+	{
+	  /* Set feature test macros for C++11  */
+	  cpp_define (pfile, "__cpp_unicode_characters=200704");
+	  cpp_define (pfile, "__cpp_raw_strings=200710");
+	  cpp_define (pfile, "__cpp_unicode_literals=200710");
+	  cpp_define (pfile, "__cpp_user_defined_literals=200809");
+	  cpp_define (pfile, "__cpp_lambdas=200907");
+	  cpp_define (pfile, "__cpp_constexpr=200704");
+	  cpp_define (pfile, "__cpp_static_assert=200410");
+	  cpp_define (pfile, "__cpp_decltype=200707");
+	  cpp_define (pfile, "__cpp_attributes=200809");
+	  cpp_define (pfile, "__cpp_rvalue_reference=200610");
+	  cpp_define (pfile, "__cpp_variadic_templates=200704");
+	  cpp_define (pfile, "__cpp_alias_templates=200704");
+	  /* Return type deduction was added as an extension to C++11
+	     and was standardized for C+14.  */
+	  cpp_define (pfile, "__cpp_return_type_deduction=201304");
+	}
+      if (cxx_dialect > cxx11)
+	{
+	  /* Set feature test macros for C++14  */
+	  cpp_define (pfile, "__cpp_init_captures=201304");
+	  cpp_define (pfile, "__cpp_generic_lambdas=201304");
+	  //cpp_undef (pfile, "__cpp_constexpr");
+	  //cpp_define (pfile, "__cpp_constexpr=201304");
+	  cpp_define (pfile, "__cpp_decltype_auto=201304");
+	  //cpp_define (pfile, "__cpp_aggregate_nsdmi=201304");
+	  cpp_define (pfile, "__cpp_variable_templates=201304");
+	  cpp_define (pfile, "__cpp_digit_separators=201309");
+	  cpp_define (pfile, "__cpp_attribute_deprecated=201309");
+	  //cpp_define (pfile, "__cpp_sized_deallocation=201309");
+	}
     }
   /* Note that we define this for C as well, so that we know if
      __attribute__((cleanup)) will interface with EH.  */