[I sent a similar message a couple weeks ago, but since I got no
answer, I'll try to paraphrase it]
Hello,
I am compiling a C++ program (LyX) with compaq cxx 6.2 in strict ansi
mode. It happens that no C functions are found by autoconf 2.52
AC_CHECK_FUNC macro, because the program bug1.C (attached, taken from
what autoconf uses) produces:
fantomas: cxx -std strict_ansi bug1.C
cxx: Error: bug1.C, line 22: a value of type "char (*)() C" cannot be
assigned to an entity of type "char (*)()"
f = memmove;
--^
cxx: Info: 1 error detected in the compilation of "bug1.C".
I get only a warning in normal 'ansi' mode (but I cannot compile LyX
in ansi mode, so...)
The solution is to declare also f as 'extern "C"'.In this case, I only
get the warning (which is probably not a problem)
fantomas: cxx -std strict_ansi bug1.C
cxx: Warning: bug2.C, line 6: Expected type
"void *(void *, const void *, unsigned long) C" is incompatible with
declared type "char () C", function will not be made intrinsic
char memmove ();
-----^
Here is a proposed patch I use to be able to compile LyX with cxx 6.2.
It just changes AC_LANG_FUNC_LINK_TRY(C) to add an extra extern "C"
when needed. I tested it with g++ 2.95.2 nd got no problem.
Please let me know if you need more information on this. I'd be
grateful to see this fixed in next release.
JMarc
/* System header to define __stub macros and hopefully few prototypes,
which can conflict with char memmove (); below. */
#include <assert.h>
/* Override any gcc2 internal prototype to avoid an error. */
#ifdef __cplusplus
extern "C"
#endif
/* We use char because int might match the return type of a gcc2
builtin and then its argument prototype would still apply. */
char memmove ();
char (*f) ();
int
main ()
{
/* The GNU C library defines this for functions which it implements
to always fail with ENOSYS. Some functions are actually named
something starting with __ and the normal name is an alias. */
#if defined (__stub_memmove) || defined (__stub___memmove)
choke me
#else
f = memmove;
#endif
;
return 0;
}
--- aclang.m4~ Wed Oct 17 11:51:59 2001
+++ aclang.m4 Thu Nov 8 14:54:06 2001
@@ -402,6 +402,9 @@
/* We use char because int might match the return type of a gcc2
builtin and then its argument prototype would still apply. */
char $1 ();
+#ifdef __cplusplus
+extern "C"
+#endif
char (*f) ();
],
[/* The GNU C library defines this for functions which it implements
