Disable -Wsometimes-uninitialized warnings in the 9.2 branch.

tglsfdc · tglsfdc · commit cea316881f1f · 2021-12-13T01:28:13.000-05:00
In 9.2, we didn't yet teach the compiler that elog(ERROR) doesn't return, which means that the compiler's opinion about whether variable dereferences are reachable isn't worth much. Back-patching the commits that fixed that seems unduly invasive, so instead silence related complaints with a big hammer. -Wsometimes-uninitialized is a clang-ism; gcc seems to spell this warning option differently. However, I do not observe any such compiler warnings in 9.2 with gcc 11.2.1, so for now we needn't do anything for gcc. Discussion: https://postgr.es/m/d0316012-ece7-7b7e-2d36-9c38cb77cb3b@enterprisedb.com
diff --git a/configure b/configure
@@ -4670,6 +4670,73 @@ fi
   if test -n "$NOT_THE_CFLAGS"; then
     CFLAGS="$CFLAGS -Wno-stringop-truncation"
   fi
+  # Similarly disable sometimes-uninitialized warnings, because in this
+  # branch we have not taught the compiler that elog(ERROR) doesn't return,
+  # so that the compiler's opinion about this isn't worth much.
+  NOT_THE_CFLAGS=""
+  { $as_echo "$as_me:$LINENO: checking whether $CC supports -Wsometimes-uninitialized" >&5
+$as_echo_n "checking whether $CC supports -Wsometimes-uninitialized... " >&6; }
+if test "${pgac_cv_prog_cc_cflags__Wsometimes_uninitialized+set}" = set; then
+  $as_echo_n "(cached) " >&6
+else
+  pgac_save_CFLAGS=$CFLAGS
+CFLAGS="$pgac_save_CFLAGS -Wsometimes-uninitialized"
+ac_save_c_werror_flag=$ac_c_werror_flag
+ac_c_werror_flag=yes
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval ac_try_echo="\"\$as_me:$LINENO: $ac_try_echo\""
+$as_echo "$ac_try_echo") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  $as_echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } && {
+	 test -z "$ac_c_werror_flag" ||
+	 test ! -s conftest.err
+       } && test -s conftest.$ac_objext; then
+  pgac_cv_prog_cc_cflags__Wsometimes_uninitialized=yes
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	pgac_cv_prog_cc_cflags__Wsometimes_uninitialized=no
+fi
+
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ac_c_werror_flag=$ac_save_c_werror_flag
+CFLAGS="$pgac_save_CFLAGS"
+fi
+{ $as_echo "$as_me:$LINENO: result: $pgac_cv_prog_cc_cflags__Wsometimes_uninitialized" >&5
+$as_echo "$pgac_cv_prog_cc_cflags__Wsometimes_uninitialized" >&6; }
+if test x"$pgac_cv_prog_cc_cflags__Wsometimes_uninitialized" = x"yes"; then
+  NOT_THE_CFLAGS="${NOT_THE_CFLAGS} -Wsometimes-uninitialized"
+fi
+
+  if test -n "$NOT_THE_CFLAGS"; then
+    CFLAGS="$CFLAGS -Wno-sometimes-uninitialized"
+  fi
 elif test "$ICC" = yes; then
   # Intel's compiler has a bug/misoptimization in checking for
   # division by NAN (NaN == 0), -mp1 fixes it, so add it to the CFLAGS.
diff --git a/configure.in b/configure.in
@@ -453,6 +453,14 @@ if test "$GCC" = yes -a "$ICC" = no; then
   if test -n "$NOT_THE_CFLAGS"; then
     CFLAGS="$CFLAGS -Wno-stringop-truncation"
   fi
+  # Similarly disable sometimes-uninitialized warnings, because in this
+  # branch we have not taught the compiler that elog(ERROR) doesn't return,
+  # so that the compiler's opinion about this isn't worth much.
+  NOT_THE_CFLAGS=""
+  PGAC_PROG_CC_VAR_OPT(NOT_THE_CFLAGS, [-Wsometimes-uninitialized])
+  if test -n "$NOT_THE_CFLAGS"; then
+    CFLAGS="$CFLAGS -Wno-sometimes-uninitialized"
+  fi
 elif test "$ICC" = yes; then
   # Intel's compiler has a bug/misoptimization in checking for
   # division by NAN (NaN == 0), -mp1 fixes it, so add it to the CFLAGS.
