gh-61103: Support double complex (_Complex) type in ctypes (#120894)

Example:

```pycon
>>> import ctypes
>>> ctypes.__STDC_IEC_559_COMPLEX__
1
>>> libm = ctypes.CDLL('libm.so.6')
>>> libm.clog.argtypes = [ctypes.c_double_complex]
>>> libm.clog.restype = ctypes.c_double_complex
>>> libm.clog(1+1j)
(0.34657359027997264+0.7853981633974483j)
```

Co-authored-by: Nice Zombies <nineteendo19d0@gmail.com>
Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>
Co-authored-by: Victor Stinner <vstinner@python.org>

1 files changed, 47 insertions, 2 deletions

diff --git a/configure b/configure
index 963ceb9..922d33e 100755
--- a/configure
+++ b/configure
@@ -13999,6 +13999,51 @@ printf "%s\n" "$AIX_BUILDDATE" >&6; }
 	*) ;;
 esac
 
+# check for _Complex C type
+#
+# Note that despite most compilers define __STDC_IEC_559_COMPLEX__ - almost
+# none properly support C11+ Annex G (where pure imaginary types
+# represented by _Imaginary are mandatory).  This is a bug (see e.g.
+# llvm/llvm-project#60269), so we don't rely on presence
+# of __STDC_IEC_559_COMPLEX__.
+if test "$cross_compiling" = yes
+then :
+  ac_cv_c_complex_supported=no
+else $as_nop
+  cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+#include <complex.h>
+#define test(type, out)                                \
+{                                                      \
+    type complex z = 1 + 2*I; z = z*z;                 \
+    (out) = (out) || creal(z) != -3 || cimag(z) != 4;  \
+}
+int main(void)
+{
+   int res = 0;
+   test(float, res);
+   test(double, res);
+   test(long double, res);
+   return res;
+}
+_ACEOF
+if ac_fn_c_try_run "$LINENO"
+then :
+  ac_cv_c_complex_supported=yes
+else $as_nop
+  ac_cv_c_complex_supported=no
+fi
+rm -f core *.core core.conftest.* gmon.out bb.out conftest$ac_exeext \
+  conftest.$ac_objext conftest.beam conftest.$ac_ext
+fi
+
+if test "$ac_cv_c_complex_supported" = "yes"; then
+
+printf "%s\n" "#define Py_HAVE_C_COMPLEX 1" >>confdefs.h
+
+fi
+
 # check for systems that require aligned memory access
 { printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking aligned memory access is required" >&5
 printf %s "checking aligned memory access is required... " >&6; }
@@ -31487,8 +31532,8 @@ fi
   if test "x$py_cv_module__ctypes_test" = xyes
 then :
 
-
-    as_fn_append MODULE_BLOCK "MODULE__CTYPES_TEST_LDFLAGS=$LIBM$as_nl"
+    as_fn_append MODULE_BLOCK "MODULE__CTYPES_TEST_CFLAGS=$LIBFFI_CFLAGS$as_nl"
+    as_fn_append MODULE_BLOCK "MODULE__CTYPES_TEST_LDFLAGS=$LIBFFI_LIBS $LIBM$as_nl"
 
 fi
    if test "$py_cv_module__ctypes_test" = yes; then