Hi, I believe I've found a bug with this macro in Libtool. When the current compiler is SGI MIPSpro CC v7.30 (this is a C++ compiler, BTW), using AC_CHECK_LIB with "main" as the function to look for will never work. I.e.: AC_CHECK_LIB($libname, main) ..always gives a false result -- no matter the value of $libname -- as the SGI CC compiler will complain with (snipped from config.log): == snip start ================================= cc-1364 CC: ERROR File = configure, Line = 912 The function "main" cannot be called or have its address taken. main() ^ 1 error detected in the compilation of "conftest.c". configure: failed program was: #line 909 "configure" #include "confdefs.h" int main() { main() ; return 0; } == snip end ================================== I tried patching it to use sin() instead, but that won't work either, as the C++ compiler and/or linker want the function signature in the testcode to match the actual signature. I wrote a completely new math library check instead, which I of course would be more than willing to submit as a replacement for AC_CHECK_LIBM, if this sounds like a good idea. If anyone of the libtool maintainers want to give it a look-over: cvs -d :pserver:[EMAIL PROTECTED]:/export/cvsroot login CVS password: (use "cvs") cvs -d :pserver:[EMAIL PROTECTED]:/export/cvsroot checkout conf-macros more conf-macros/check_mathlib.m4 Regards, Morten Eriksen