From 6347bdb31448f812cd726cfb3cdcdecf41a38b19 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 5 Apr 2015 13:01:55 -0400
Subject: [PATCH] Suppress clang's unhelpful gripes about -pthread switch being
unused.
Considering the number of cases in which "unused" command line arguments
are silently ignored by compilers, it's fairly astonishing that anybody
thought this warning was useful; it's certainly nothing but an annoyance
when building Postgres. One such case is that neither gcc nor clang
complain about unrecognized -Wno-foo switches, making it more difficult
to figure out whether the switch does anything than one could wish.
Back-patch to 9.3, which is as far back as the patch applies conveniently
(we'd have to back-patch PGAC_PROG_CC_VAR_OPT to go further, and it doesn't
seem worth that).
---
configure | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++
configure.in | 7 ++++++
2 files changed, 73 insertions(+)
diff --git a/configure b/configure
index 973881c0fe7..68e84b387e5 100755
--- a/configure
+++ b/configure
@@ -4503,6 +4503,72 @@ if test x"$pgac_cv_prog_cc_cflags__ftree_vectorize" = x"yes"; then
CFLAGS_VECTOR="${CFLAGS_VECTOR} -ftree-vectorize"
fi
+ # We want to suppress clang's unhelpful unused-command-line-argument warnings
+ # but gcc won't complain about unrecognized -Wno-foo switches, so we have to
+ # test for the positive form and if that works, add the negative form
+ { $as_echo "$as_me:$LINENO: checking whether $CC supports -Wunused-command-line-argument" >&5
+$as_echo_n "checking whether $CC supports -Wunused-command-line-argument... " >&6; }
+if test "${pgac_cv_prog_cc_cflags__Wunused_command_line_argument+set}" = set; then
+ $as_echo_n "(cached) " >&6
+else
+ pgac_save_CFLAGS=$CFLAGS
+CFLAGS="$pgac_save_CFLAGS -Wunused-command-line-argument"
+ac_save_c_werror_flag=$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__Wunused_command_line_argument=yes
+else
+ $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+ pgac_cv_prog_cc_cflags__Wunused_command_line_argument=no
+fi
+
+rm -f core conftest.err conftest.$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: $pgac_cv_prog_cc_cflags__Wunused_command_line_argument" >&5
+$as_echo "$pgac_cv_prog_cc_cflags__Wunused_command_line_argument" >&6; }
+if test x"$pgac_cv_prog_cc_cflags__Wunused_command_line_argument" = x"yes"; then
+ NOT_THE_CFLAGS="${NOT_THE_CFLAGS} -Wunused-command-line-argument"
+fi
+
+ if test -n "$NOT_THE_CFLAGS"; then
+ CFLAGS="$CFLAGS -Wno-unused-command-line-argument"
+ fi
elif test "$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
index d914dd07cfd..ea1569c87e9 100644
--- a/configure.in
+++ b/configure.in
@@ -427,6 +427,13 @@ if test "$GCC" = yes -a "$ICC" = no; then
# Optimization flags for specific files that benefit from vectorization
PGAC_PROG_CC_VAR_OPT(CFLAGS_VECTOR, [-funroll-loops])
PGAC_PROG_CC_VAR_OPT(CFLAGS_VECTOR, [-ftree-vectorize])
+ # We want to suppress clang's unhelpful unused-command-line-argument warnings
+ # but gcc won't complain about unrecognized -Wno-foo switches, so we have to
+ # test for the positive form and if that works, add the negative form
+ PGAC_PROG_CC_VAR_OPT(NOT_THE_CFLAGS, [-Wunused-command-line-argument])
+ if test -n "$NOT_THE_CFLAGS"; then
+ CFLAGS="$CFLAGS -Wno-unused-command-line-argument"
+ 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.
--
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