Hi John, > | foo.cc: In function ‘int main()’: > | foo.cc:21: warning: call to ‘open’ declared with attribute warning: The > symbol ::open refers to the system function. Use gnulib::open instead. > > Will this warning happen on all systems when a module is used, or just > when the replacement function is needed?
It will happen on all systems, assuming g++ is used. > How does this macro avoid > causing trouble with things like myclass::open? It uses the _GL_WARN_ON_USE macro. > I guess I would > have a better understanding if I could see your latest version of the code. Find the latest c++defs.h attached. > Are your updated changes available somewhere for testing? I'm currently testing them on Linux, MacOS X, Solaris, and will commit them afterwards. Bruno ============================= build-aux/c++defs.h ============================= /* C++ compatible function declaration macros. Copyright (C) 2010 Free Software Foundation, Inc. This program is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ #ifndef _GL_CXXDEFS_H #define _GL_CXXDEFS_H /* The three most frequent use cases of these macros are: * For providing a substitute for a function that is missing on some platforms, but is declared and works fine on the platforms on which it exists: #if @GNULIB_FOO@ # if !...@have_foo@ _GL_FUNCDECL_SYS (foo, ...); # endif _GL_CXXALIAS_SYS (foo, ...); _GL_CXXALIASWARN (foo); #elif defined GNULIB_POSIXCHECK ... #endif * For providing a replacement for a function that exists on all platforms, but is broken/insufficient and needs to be replaced on some platforms: #if @GNULIB_FOO@ # if @REPLACE_FOO@ # if !(defined __cplusplus && defined GNULIB_NAMESPACE) # undef foo # define foo rpl_foo # endif _GL_FUNCDECL_RPL (foo, ...); _GL_CXXALIAS_RPL (foo, ...); # else _GL_CXXALIAS_SYS (foo, ...); # endif _GL_CXXALIASWARN (foo); #elif defined GNULIB_POSIXCHECK ... #endif * For providing a replacement for a function that exists on some platforms but is broken/insufficient and needs to be replaced on some of them and is additionally either missing or undeclared on some other platforms: #if @GNULIB_FOO@ # if @REPLACE_FOO@ # if !(defined __cplusplus && defined GNULIB_NAMESPACE) # undef foo # define foo rpl_foo # endif _GL_FUNCDECL_RPL (foo, ...); _GL_CXXALIAS_RPL (foo, ...); # else # if !...@have_foo@ or if !...@have_decl_foo@ _GL_FUNCDECL_SYS (foo, ...); # endif _GL_CXXALIAS_SYS (foo, ...); # endif _GL_CXXALIASWARN (foo); #elif defined GNULIB_POSIXCHECK ... #endif */ /* _GL_EXTERN_C declaration; performs the declaration with C linkage. */ #if defined __cplusplus # define _GL_EXTERN_C extern "C" #else # define _GL_EXTERN_C extern #endif /* _GL_FUNCDECL_RPL (func, rettype, parameters_and_attributes); declares a replacement function, named rpl_func, with the given prototype, consisting of return type, parameters, and attributes. Example: _GL_FUNCDECL_RPL (open, int, (const char *filename, int flags, ...) _GL_ARG_NONNULL ((1))); */ #define _GL_FUNCDECL_RPL(func,rettype,parameters_and_attributes) \ _GL_FUNCDECL_RPL_1 (rpl_##func, rettype, parameters_and_attributes) #define _GL_FUNCDECL_RPL_1(rpl_func,rettype,parameters_and_attributes) \ _GL_EXTERN_C rettype rpl_func parameters_and_attributes /* _GL_FUNCDECL_SYS (func, rettype, parameters_and_attributes); declares the system function, named func, with the given prototype, consisting of return type, parameters, and attributes. Example: _GL_FUNCDECL_SYS (open, int, (const char *filename, int flags, ...) _GL_ARG_NONNULL ((1))); */ #define _GL_FUNCDECL_SYS(func,rettype,parameters_and_attributes) \ _GL_EXTERN_C rettype func parameters_and_attributes /* _GL_CXXALIAS_RPL (func, rettype, parameters) declares a C++ alias called GNULIB_NAMESPACE::func that redirects to rpl_func, if GNULIB_NAMESPACE is defined. Example: _GL_CXXALIAS_RPL (open, int, (const char *filename, int flags, ...)); */ #define _GL_CXXALIAS_RPL(func,rettype,parameters) \ _GL_CXXALIAS_RPL_1 (func, rpl_##func, rettype, parameters) #if defined __cplusplus && defined GNULIB_NAMESPACE # define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \ namespace GNULIB_NAMESPACE \ { \ rettype (*const func) parameters = ::rpl_func; \ } \ _GL_EXTERN_C int _gl_cxxalias_dummy #else # define _GL_CXXALIAS_RPL_1(func,rpl_func,rettype,parameters) \ _GL_EXTERN_C int _gl_cxxalias_dummy #endif /* _GL_CXXALIAS_SYS (func, rettype, parameters) declares a C++ alias called GNULIB_NAMESPACE::func that redirects to the system provided function func, if GNULIB_NAMESPACE is defined. Example: _GL_CXXALIAS_SYS (open, int, (const char *filename, int flags, ...)); */ #if defined __cplusplus && defined GNULIB_NAMESPACE /* If we were to write rettype (*const func) parameters = ::func; like above in _GL_CXXALIAS_RPL_1, the compiler could optimize calls better (remove an indirection through a 'static' pointer variable), but then the _GL_CXXALIASWARN macro below would cause a warning not only for uses of ::func but also for uses of GNULIB_NAMESPACE::func. */ # define _GL_CXXALIAS_SYS(func,rettype,parameters) \ namespace GNULIB_NAMESPACE \ { \ static rettype (*func) parameters = ::func; \ } \ _GL_EXTERN_C int _gl_cxxalias_dummy #else # define _GL_CXXALIAS_SYS(func,rettype,parameters) \ _GL_EXTERN_C int _gl_cxxalias_dummy #endif /* _GL_CXXALIASWARN (func); causes a warning to be emitted when ::func is used but not when GNULIB_NAMESPACE::func is used. */ #if defined __cplusplus && defined GNULIB_NAMESPACE # define _GL_CXXALIASWARN(func) \ _GL_CXXALIASWARN1 (func, GNULIB_NAMESPACE) # define _GL_CXXALIASWARN1(func,namespace) \ _GL_CXXALIASWARN2 (func, namespace) # define _GL_CXXALIASWARN2(func,namespace) \ _GL_WARN_ON_USE (func, \ "The symbol ::" #func " refers to the system function. " \ "Use " #namespace "::" #func " instead.") #else # define _GL_CXXALIASWARN(func) \ _GL_EXTERN_C int _gl_cxxalias_dummy #endif #endif /* _GL_CXXDEFS_H */
