gh-125206: Correct detection of complex numbers support in libffi (#126104)

Misc/NEWS.d/next/Library/2024-10-29-07-24-52.gh-issue-125322.sstOM-.rst

@@ -0,0 +1 @@
+Correct detection of complex numbers support in libffi.

configure

@@ -15037,8 +15037,15 @@ if test ${ac_cv_ffi_complex_double_supported+y}
 then :
   printf %s "(cached) " >&6
 else $as_nop
-  ac_save_cc="$CC"
-CC="$CC -lffi"
+  save_CFLAGS=$CFLAGS
+save_CPPFLAGS=$CPPFLAGS
+save_LDFLAGS=$LDFLAGS
+save_LIBS=$LIBS
+
+
+ CPPFLAGS="$LIBFFI_CFLAGS $CPPFLAGS"
+ LDFLAGS="$LIBFFI_LIBS $LDFLAGS"
+ LIBS="$LIBFFI_LIBS $LIBS"
 if test "$cross_compiling" = yes
 then :
   ac_cv_ffi_complex_double_supported=no
@@ -15080,7 +15087,13 @@ rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
   conftest.$ac_objext conftest.beam conftest.$ac_ext
 fi
 
-CC="$ac_save_cc"
+
+CFLAGS=$save_CFLAGS
+CPPFLAGS=$save_CPPFLAGS
+LDFLAGS=$save_LDFLAGS
+LIBS=$save_LIBS
+
+
 fi
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $ac_cv_ffi_complex_double_supported" >&5
 printf "%s\n" "$ac_cv_ffi_complex_double_supported" >&6; }

configure.ac

@@ -4090,8 +4090,10 @@ AS_VAR_IF([have_libffi], [yes], [
 # See https://github.com/python/cpython/issues/125206 for more details.
 #
 AC_CACHE_CHECK([libffi has complex type support], [ac_cv_ffi_complex_double_supported],
-[ac_save_cc="$CC"
-CC="$CC -lffi"
+[WITH_SAVE_ENV([
+ CPPFLAGS="$LIBFFI_CFLAGS $CPPFLAGS"
+ LDFLAGS="$LIBFFI_LIBS $LDFLAGS"
+ LIBS="$LIBFFI_LIBS $LIBS"
 AC_RUN_IFELSE([AC_LANG_SOURCE([[
 #include <complex.h>
 #include <ffi.h>
@@ -4118,7 +4120,7 @@ int main(void)
 ]])], [ac_cv_ffi_complex_double_supported=yes],
 [ac_cv_ffi_complex_double_supported=no],
 [ac_cv_ffi_complex_double_supported=no])
-CC="$ac_save_cc"])
+])])
 if test "$ac_cv_ffi_complex_double_supported" = "yes"; then
     AC_DEFINE([Py_FFI_SUPPORT_C_COMPLEX], [1],
               [Defined if _Complex C type can be used with libffi.])