Control: tags -1 patch On 2021-08-26 00:09:07 +0200, Vincent Lefevre wrote: > On 2021-08-25 23:56:45 +0200, Vincent Lefevre wrote: > > I've found the cause. With Autoconf 2.69, there was > > > > #ifdef __cplusplus > > extern "C" > > #endif > > > > at the beginning of the test program generated by Autoconf. > > This is no longer the case with Autoconf 2.71. A manual test > > confirms that these 3 lines make the difference. > > It seems that upstream commit 326c9a547423d25c621bc5c0ef76edbf6eda8c92 > is the cause. I'm going to test with the 3 lines re-added and provide > a patch if this works.
Patch attached. I tested it and solves the failure with GNU MPFR. -- Vincent Lefèvre <vinc...@vinc17.net> - Web: <https://www.vinc17.net/> 100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/> Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)
Description: Fix generation of C code for C++ compilers. AC_CHECK_LIB fails with a C++ compiler (e.g., g++) because #ifdef __cplusplus extern "C" #endif is missing in the generated C code. There 3 lines were removed in commit 326c9a547423d25c621bc5c0ef76edbf6eda8c92 on 2020-10-09 with the comment "(AC_LANG_CALL(C)): Remove #ifdef __cplusplus, this macro is no longer used to generate C++ code." but this is actually C code compiled with a C++ compiler, not C++ code. Author: Vincent Lefevre <vinc...@vinc17.net> Bug-Debian: https://bugs.debian.org/992981 Last-Update: 2021-08-25 Index: b/lib/autoconf/c.m4 =================================================================== --- a/lib/autoconf/c.m4 +++ b/lib/autoconf/c.m4 @@ -127,6 +127,9 @@ m4_if([$2], [main], , [/* Override any GCC internal prototype to avoid an error. Use char because int might match the return type of a GCC builtin and then its argument prototype would still apply. */ +#ifdef __cplusplus +extern "C" +#endif char $2 ();])], [return $2 ();])])
