From bfb4db83b618d57fcc5f0c9e9fdb3a7ff33d07f3 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Jos=C3=A9=20Fonseca?= Date: Thu, 11 Dec 2014 22:14:14 +0000 Subject: [PATCH] include: Add helper header to help trap includes inside extern C. This is just to help repro and fixing these issues with any C++ compiler -- Commiting this will of course wait until all issues are addressed. $ scons src/glsl/ scons: Reading SConscript files ... Checking for GCC ... yes Checking for Clang ... no Checking for X11 (x11 xext xdamage xfixes glproto >= 1.4.13)... yes Checking for XCB (x11-xcb xcb-glx >= 1.8.1 xcb-dri2 >= 1.8)... yes Checking for XF86VIDMODE (xxf86vm)... yes Checking for DRM (libdrm >= 2.4.38)... yes Checking for UDEV (libudev >= 151)... yes warning: LLVM disabled: not building llvmpipe scons: done reading SConscript files. scons: Building targets ... scons: building associated VariantDir targets: build/linux-x86_64-debug/glsl Compiling src/glsl/ast_array_index.cpp ... Compiling src/glsl/ast_expr.cpp ... Compiling src/glsl/ast_function.cpp ... Compiling src/glsl/ast_to_hir.cpp ... Compiling src/glsl/ast_type.cpp ... Compiling src/glsl/builtin_functions.cpp ... In file included from include/c99_compat.h:28:0, from src/mapi/u_compiler.h:4, from src/mapi/u_thread.h:47, from src/mapi/glapi/glapi.h:47, from src/mesa/main/mtypes.h:42, from src/mesa/main/errors.h:47, from src/mesa/main/imports.h:41, from src/mesa/main/core.h:44, from src/glsl/builtin_functions.cpp:58: include/no_extern_c.h:48:1: error: template with C linkage template class _IncludeInsideExternCNotPortable; ^ In file included from include/c99_compat.h:28:0, from include/c11/threads.h:38, from src/mapi/u_thread.h:49, from src/mapi/glapi/glapi.h:47, from src/mesa/main/mtypes.h:42, from src/mesa/main/errors.h:47, from src/mesa/main/imports.h:41, from src/mesa/main/core.h:44, from src/glsl/builtin_functions.cpp:58: include/no_extern_c.h:48:1: error: template with C linkage template class _IncludeInsideExternCNotPortable; ^ Compiling src/glsl/builtin_types.cpp ... Compiling src/glsl/builtin_variables.cpp ... scons: *** [build/linux-x86_64-debug/glsl/builtin_functions.os] Error 1 scons: building terminated because of errors. Reviewed-by: Mark Janes --- include/c99_compat.h | 2 ++ include/no_extern_c.h | 48 +++++++++++++++++++++++++++++++++++++++++++ src/util/u_atomic.h | 2 ++ 3 files changed, 52 insertions(+) create mode 100644 include/no_extern_c.h diff --git a/include/c99_compat.h b/include/c99_compat.h index f56f6f326f8..4fc91bc1357 100644 --- a/include/c99_compat.h +++ b/include/c99_compat.h @@ -25,6 +25,8 @@ * **************************************************************************/ +#include "no_extern_c.h" + #ifndef _C99_COMPAT_H_ #define _C99_COMPAT_H_ diff --git a/include/no_extern_c.h b/include/no_extern_c.h new file mode 100644 index 00000000000..f79602c0303 --- /dev/null +++ b/include/no_extern_c.h @@ -0,0 +1,48 @@ +/************************************************************************** + * + * Copyright 2014 VMware, Inc. + * All Rights Reserved. + * + * Permission is hereby granted, free of charge, to any person obtaining a + * copy of this software and associated documentation files (the "Software"), + * to deal in the Software without restriction, including without limitation + * the rights to use, copy, modify, merge, publish, distribute, sublicense, + * and/or sell copies of the Software, and to permit persons to whom the + * Software is furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be included + * in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS + * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR + * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, + * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR + * OTHER DEALINGS IN THE SOFTWARE. + * + **************************************************************************/ + + +/* + * Including system's headers inside `extern "C" { ... }` is not safe, as system + * headers may have C++ code in them, and C++ code inside extern "C" + * leads to syntatically incorrect code. + * + * This is because putting code inside extern "C" won't make __cplusplus define + * go away, that is, the system header being included thinks is free to use C++ + * as it sees fits. + * + * Including non-system headers inside extern "C" is not safe either, because + * non-system headers end up including system headers, hence fall in the above + * case too. + * + * Conclusion, includes inside extern "C" is simply not portable. + * + * + * This header helps surface these issues. + */ + +#ifdef __cplusplus +template class _IncludeInsideExternCNotPortable; +#endif diff --git a/src/util/u_atomic.h b/src/util/u_atomic.h index d15398e1e49..e38395ac633 100644 --- a/src/util/u_atomic.h +++ b/src/util/u_atomic.h @@ -6,6 +6,8 @@ * */ +#include "no_extern_c.h" + #ifndef U_ATOMIC_H #define U_ATOMIC_H -- 2.30.2