On Mon, Oct 12, 2015 at 9:41 AM, Steven Wu via cfe-commits <
cfe-commits@lists.llvm.org> wrote:
> Hi Richard
>
> Your splitting seems causing problem when using extern "C". Here is a test
> case:
>
> $ cat test.cpp
> #ifdef __cplusplus
> extern "C" {
> #endif
> #include <stdio.h>
> #ifdef __cplusplus
> }
> #endif
>
> Error:
> clang -fsyntax-only test.cpp
> In file included from test.cpp:4:
> In file included from /usr/bin/../include/c++/v1/stdio.h:102:
> /usr/bin/../include/c++/v1/__config:593:1: error:
> templates must have C++ linkage
> template <bool> struct __static_assert_test;
> ^~~~~~~~~~~~~~~
> /usr/bin/../include/c++/v1/__config:594:20: error:
> explicit specialization of non-template struct '__static_assert_test'
> template <> struct __static_assert_test<true> {};
> ^ ~~~~~~
> /usr/bin/../include/c++/v1/__config:595:1: error:
> templates must have C++ linkage
> template <unsigned> struct __static_assert_check {};
> ^~~~~~~~~~~~~~~~~~~
> 3 errors generated.
>
> Because the code is actually compiled in C++, the guard in the header
> failed to exclude the templates. In the meantime, I don't know if there are
> ways to detect the header is in extern "C".
>
This was supposed to work, but apparently I only tested it when compiling
as C++11; the static_assert emulation in C++98 mode needs some massaging to
cope with this.
Eric, Marshall: Are you OK with the attached patch? The idea is to make
<__config> be fine to include in extern "C" or extern "C++" modes (and
likewise for the <foo.h> headers). This is something that comes up pretty
often in practice (people wrap an include of a C header in 'extern "C"',
and that C header includes a <foo.h> file that libc++ provides).
> Steven
>
>
> > On Oct 8, 2015, at 6:29 PM, Richard Smith via cfe-commits <
> cfe-commits@lists.llvm.org> wrote:
> >
> > Author: rsmith
> > Date: Thu Oct 8 20:29:09 2015
> > New Revision: 249798
> >
> > URL: http://llvm.org/viewvc/llvm-project?rev=249798&view=rev
> > Log:
> > Split <stdio.h> out of <cstdio>.
> >
> > As with <stddef.h>, skip our custom header if __need_FILE or
> __need___FILE is defined.
> >
> > Added:
> > libcxx/trunk/include/stdio.h
> > - copied, changed from r249736, libcxx/trunk/include/cstdio
> > Modified:
> > libcxx/trunk/include/cstdio
> > libcxx/trunk/test/std/depr/depr.c.headers/stdio_h.pass.cpp
> >
> > Modified: libcxx/trunk/include/cstdio
> > URL:
> http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/cstdio?rev=249798&r1=249797&r2=249798&view=diff
> >
> ==============================================================================
> > --- libcxx/trunk/include/cstdio (original)
> > +++ libcxx/trunk/include/cstdio Thu Oct 8 20:29:09 2015
> > @@ -103,16 +103,6 @@ void perror(const char* s);
> > #pragma GCC system_header
> > #endif
> >
> > -// snprintf
> > -#if defined(_LIBCPP_MSVCRT)
> > -#include "support/win32/support.h"
> > -#endif
> > -
> > -#undef getc
> > -#undef putc
> > -#undef clearerr
> > -#undef feof
> > -#undef ferror
> > _LIBCPP_BEGIN_NAMESPACE_STD
> >
> > using ::FILE;
> >
> > Copied: libcxx/trunk/include/stdio.h (from r249736,
> libcxx/trunk/include/cstdio)
> > URL:
> http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/stdio.h?p2=libcxx/trunk/include/stdio.h&p1=libcxx/trunk/include/cstdio&r1=249736&r2=249798&rev=249798&view=diff
> >
> ==============================================================================
> > --- libcxx/trunk/include/cstdio (original)
> > +++ libcxx/trunk/include/stdio.h Thu Oct 8 20:29:09 2015
> > @@ -1,5 +1,5 @@
> > // -*- C++ -*-
> > -//===---------------------------- cstdio
> ----------------------------------===//
> > +//===---------------------------- stdio.h
> ---------------------------------===//
> > //
> > // The LLVM Compiler Infrastructure
> > //
> > @@ -8,11 +8,19 @@
> > //
> >
> //===----------------------------------------------------------------------===//
> >
> > -#ifndef _LIBCPP_CSTDIO
> > -#define _LIBCPP_CSTDIO
> > +#if defined(__need_FILE) || defined(__need___FILE)
> > +
> > +#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
> > +#pragma GCC system_header
> > +#endif
> > +
> > +#include_next <stdio.h>
> > +
> > +#elif !defined(_LIBCPP_STDIO_H)
> > +#define _LIBCPP_STDIO_H
> >
> > /*
> > - cstdio synopsis
> > + stdio.h synopsis
> >
> > Macros:
> >
> > @@ -33,9 +41,6 @@ Macros:
> > stdin
> > stdout
> >
> > -namespace std
> > -{
> > -
> > Types:
> >
> > FILE
> > @@ -92,20 +97,23 @@ void clearerr(FILE* stream);
> > int feof(FILE* stream);
> > int ferror(FILE* stream);
> > void perror(const char* s);
> > -
> > -} // std
> > */
> >
> > #include <__config>
> > -#include <stdio.h>
> >
> > #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
> > #pragma GCC system_header
> > #endif
> >
> > +#include_next <stdio.h>
> > +
> > +#ifdef __cplusplus
> > +
> > // snprintf
> > #if defined(_LIBCPP_MSVCRT)
> > +extern "C++" {
> > #include "support/win32/support.h"
> > +}
> > #endif
> >
> > #undef getc
> > @@ -113,72 +121,7 @@ void perror(const char* s);
> > #undef clearerr
> > #undef feof
> > #undef ferror
> > -_LIBCPP_BEGIN_NAMESPACE_STD
> > -
> > -using ::FILE;
> > -using ::fpos_t;
> > -using ::size_t;
> > -
> > -using ::fclose;
> > -using ::fflush;
> > -using ::setbuf;
> > -using ::setvbuf;
> > -using ::fprintf;
> > -using ::fscanf;
> > -using ::snprintf;
> > -using ::sprintf;
> > -using ::sscanf;
> > -#ifndef _LIBCPP_MSVCRT
> > -using ::vfprintf;
> > -using ::vfscanf;
> > -using ::vsscanf;
> > -#endif // _LIBCPP_MSVCRT
> > -using ::vsnprintf;
> > -using ::vsprintf;
> > -using ::fgetc;
> > -using ::fgets;
> > -using ::fputc;
> > -using ::fputs;
> > -using ::getc;
> > -using ::putc;
> > -using ::ungetc;
> > -using ::fread;
> > -using ::fwrite;
> > -using ::fgetpos;
> > -using ::fseek;
> > -using ::fsetpos;
> > -using ::ftell;
> > -using ::rewind;
> > -using ::clearerr;
> > -using ::feof;
> > -using ::ferror;
> > -using ::perror;
> > -
> > -#ifndef _LIBCPP_HAS_NO_GLOBAL_FILESYSTEM_NAMESPACE
> > -using ::fopen;
> > -using ::freopen;
> > -using ::remove;
> > -using ::rename;
> > -using ::tmpfile;
> > -using ::tmpnam;
> > -#endif
> >
> > -#ifndef _LIBCPP_HAS_NO_STDIN
> > -using ::getchar;
> > -#if _LIBCPP_STD_VER <= 11
> > -using ::gets;
> > #endif
> > -using ::scanf;
> > -using ::vscanf;
> > -#endif
> > -
> > -#ifndef _LIBCPP_HAS_NO_STDOUT
> > -using ::printf;
> > -using ::putchar;
> > -using ::puts;
> > -using ::vprintf;
> > -#endif
> > -
> > -_LIBCPP_END_NAMESPACE_STD
> >
> > -#endif // _LIBCPP_CSTDIO
> > +#endif // _LIBCPP_STDIO_H
> >
> > Modified: libcxx/trunk/test/std/depr/depr.c.headers/stdio_h.pass.cpp
> > URL:
> http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/depr/depr.c.headers/stdio_h.pass.cpp?rev=249798&r1=249797&r2=249798&view=diff
> >
> ==============================================================================
> > --- libcxx/trunk/test/std/depr/depr.c.headers/stdio_h.pass.cpp (original)
> > +++ libcxx/trunk/test/std/depr/depr.c.headers/stdio_h.pass.cpp Thu Oct
> 8 20:29:09 2015
> > @@ -13,6 +13,26 @@
> > #include <type_traits>
> > #include "test_macros.h"
> >
> > +#ifdef getc
> > +#error getc is defined
> > +#endif
> > +
> > +#ifdef putc
> > +#error putc is defined
> > +#endif
> > +
> > +#ifdef clearerr
> > +#error clearerr is defined
> > +#endif
> > +
> > +#ifdef feof
> > +#error feof is defined
> > +#endif
> > +
> > +#ifdef ferror
> > +#error ferror is defined
> > +#endif
> > +
> > #ifndef BUFSIZ
> > #error BUFSIZ not defined
> > #endif
> >
> >
> > _______________________________________________
> > cfe-commits mailing list
> > cfe-commits@lists.llvm.org
> > http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
>
> _______________________________________________
> cfe-commits mailing list
> cfe-commits@lists.llvm.org
> http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
>
Index: include/__config
===================================================================
--- include/__config (revision 250073)
+++ include/__config (working copy)
@@ -591,9 +591,11 @@
#ifdef _LIBCPP_HAS_NO_STATIC_ASSERT
+extern "C++" {
template <bool> struct __static_assert_test;
template <> struct __static_assert_test<true> {};
template <unsigned> struct __static_assert_check {};
+}
#define static_assert(__b, __m) \
typedef __static_assert_check<sizeof(__static_assert_test<(__b)>)> \
_LIBCPP_CONCAT(__t, __LINE__)
Index: test/std/depr/depr.c.headers/extern_c.pass.cpp
===================================================================
--- test/std/depr/depr.c.headers/extern_c.pass.cpp (revision 0)
+++ test/std/depr/depr.c.headers/extern_c.pass.cpp (working copy)
@@ -0,0 +1,43 @@
+//===----------------------------------------------------------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// Sometimes C++'s <foo.h> headers get included within extern "C" contexts.
This
+// is ill-formed (no diagnostic required), per [using.headers]p3, but we permit
+// it as an extension.
+
+extern "C" {
+#include <assert.h>
+// complex.h is not supported in extern "C".
+#include <ctype.h>
+#include <errno.h>
+#include <fenv.h>
+#include <float.h>
+#include <inttypes.h>
+#include <iso646.h>
+#include <limits.h>
+#include <locale.h>
+#include <math.h>
+#include <setjmp.h>
+#include <signal.h>
+#include <stdalign.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+// tgmath.h is not supported in extern "C".
+#include <time.h>
+// FIXME: #include <uchar.h>
+#include <wchar.h>
+#include <wctype.h>
+}
+
+int main() {}
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