https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91766
--- Comment #11 from Kamlesh Kumar <kamleshbhalui at gmail dot com> ---
is this good?
diff --git a/gcc/c-family/c-opts.c b/gcc/c-family/c-opts.c
index 0fffe60..9fead56 100644
--- a/gcc/c-family/c-opts.c
+++ b/gcc/c-family/c-opts.c
@@ -814,6 +814,10 @@ c_common_post_options (const char **pfilename)
&& flag_unsafe_math_optimizations == 0)
flag_fp_contract_mode = FP_CONTRACT_OFF;
+ /* defaults to flag_no_common unless disabled with fcommon. */
+ if (!global_options_set.x_flag_no_common)
+ flag_no_common = 1;
+
/* If we are compiling C, and we are outside of a standards mode,
we can permit the new values from ISO/IEC TS 18661-3 for
FLT_EVAL_METHOD. Otherwise, we must restrict the possible values to
