math: Only build tests for _Complex __int128 iff compiler supports it

clang fails building test-tgmath3-atan2.c:

  error: '_Complex __int128' is invalid
  _Complex __int128 var__Complex___int128 __attribute__ ((unused));

since it does not support _Complex with __int128.  So disable
the test in such case.

configure

@@ -7912,6 +7912,36 @@ printf "%s\n" "$libc_cv_cc_rounding_math" >&6; }
 config_vars="$config_vars
 config-cflags-frounding-math = $libc_cv_cc_rounding_math"
 
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: checking whether compiler supports _Complex with __int128" >&5
+printf %s "checking whether compiler supports _Complex with __int128... " >&6; }
+if test ${libc_cv_complex_int128+y}
+then :
+  printf %s "(cached) " >&6
+else case e in #(
+  e) cat > conftest.c <<EOF
+#ifndef __SIZEOF_INT128__
+# error "__int128 not supported"
+#endif
+_Complex __int128 var;
+EOF
+libc_cv_complex_int128=no
+if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS -c conftest.c 1>&5'
+  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
+  (eval $ac_try) 2>&5
+  ac_status=$?
+  printf "%s\n" "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
+  test $ac_status = 0; }; }
+then
+  libc_cv_complex_int128=yes
+fi
+rm -f conftest* ;;
+esac
+fi
+{ printf "%s\n" "$as_me:${as_lineno-$LINENO}: result: $libc_cv_complex_int128" >&5
+printf "%s\n" "$libc_cv_complex_int128" >&6; }
+config_vars="$config_vars
+config-complex-int128 = $libc_cv_complex_int128"
+
 conftest_code="
 void
 __attribute__ ((__optimize__ (\"-fno-tree-loop-distribute-patterns\")))

configure.ac

@@ -1566,6 +1566,23 @@ LIBC_TRY_CC_OPTION([-Werror -frounding-math],
 LIBC_CONFIG_VAR([config-cflags-frounding-math],
                 [$libc_cv_cc_rounding_math])
 
+AC_CACHE_CHECK([whether compiler supports _Complex with __int128],
+               [libc_cv_complex_int128], [dnl
+cat > conftest.c <<EOF
+#ifndef __SIZEOF_INT128__
+# error "__int128 not supported"
+#endif
+_Complex __int128 var;
+EOF
+libc_cv_complex_int128=no
+if AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS -c conftest.c 1>&AS_MESSAGE_LOG_FD])
+then
+  libc_cv_complex_int128=yes
+fi
+rm -f conftest*])
+LIBC_CONFIG_VAR([config-complex-int128],
+                [$libc_cv_complex_int128])
+
 conftest_code="
 void
 __attribute__ ((__optimize__ (\"-fno-tree-loop-distribute-patterns\")))

math/Makefile

@@ -1057,7 +1057,7 @@ $(tgmath3-macro-tests:%=$(objpfx)%.o): CFLAGS += -fno-builtin
 $(foreach m,$(tgmath3-macros),\
 	    $(objpfx)test-tgmath3-$(m).c): $(objpfx)test-tgmath3-%.c: \
 					   gen-tgmath-tests.py
-	$(PYTHON) gen-tgmath-tests.py $* > $@
+	$(PYTHON) gen-tgmath-tests.py --complex-int128 $(config-complex-int128) $* > $@
 
 # Verify that the list of supported macros is in sync between the
 # Makefile and gen-tgmath-tests.py.

math/gen-tgmath-tests.py

@@ -53,6 +53,7 @@
 # supported on any given configuration of glibc, the MANT_DIG value
 # uniquely determines the format.
 
+import argparse
 import string
 import sys
 
@@ -182,7 +183,7 @@ class Type(object):
         return self.name
 
     @staticmethod
-    def init_types():
+    def init_types(complex_int128):
         """Initialize all the known types."""
         Type.create_type('_Float16', 'f16', 'FLT16_MANT_DIG',
                          complex_name='__CFLOAT16',
@@ -219,9 +220,11 @@ class Type(object):
         Type.create_type('long long int', integer=True)
         Type.create_type('unsigned long long int', integer=True)
         Type.create_type('__int128', integer=True,
-                         condition='defined __SIZEOF_INT128__')
+                         condition='defined __SIZEOF_INT128__',
+                         complex_ok=complex_int128)
         Type.create_type('unsigned __int128', integer=True,
-                         condition='defined __SIZEOF_INT128__')
+                         condition='defined __SIZEOF_INT128__',
+                         complex_ok=complex_int128)
         Type.create_type('enum e', integer=True, complex_ok=False)
         Type.create_type('_Bool', integer=True, complex_ok=False)
         Type.create_type('bit_field', integer=True, complex_ok=False)
@@ -848,15 +851,32 @@ class Tests(object):
             print('error: macro list mismatch')
             sys.exit(1)
 
-def main():
+def get_parser():
+    def strbool(string):
+        return True if string.lower() == 'yes' else False
+
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument('--complex-int128', dest='complex_int128',
+                        help='Generate tests for _Complex __int128',
+                        type=strbool)
+    parser.add_argument('--check-list', action='store_true',
+                        help='Verify that the list of supported macros')
+    parser.add_argument('macro',
+                        help='macro to test',
+                        nargs='*')
+    return parser
+
+def main(argv):
     """The main entry point."""
-    Type.init_types()
+    parser = get_parser()
+    opts = parser.parse_args(argv)
+    Type.init_types(True if opts.complex_int128 == 'yes' else False)
     t = Tests()
-    if sys.argv[1] == 'check-list':
+    if opts.check_list:
         macro = None
-        macro_list = sys.argv[2:]
+        macro_list = opts.macro
     else:
-        macro = sys.argv[1]
+        macro = opts.macro
         macro_list = []
     t.add_all_tests(macro)
     if macro:
@@ -865,4 +885,4 @@ def main():
         t.check_macro_list(macro_list)
 
 if __name__ == '__main__':
-    main()
+    main(sys.argv[1:])