Use -Wno-format-truncation and -Wno-stringop-truncation, if available.

This back-patches commit e71658523 into out-of-support branches,
pursuant to newly-established project policy.  The point is to
suppress scary-looking warnings so that people building these
branches needn't expend brain cells verifying that it's safe
to ignore the warnings.

Also back-patch the adjacent test from commit 73b416b2e (Suppress
clang's unhelpful gripes about -pthread switch being unused) and
the necessary autoconf macro from fdea2530b.

Discussion: https://postgr.es/m/[email protected]

3 files changed, 240 insertions, 0 deletions

diff --git a/config/c-compiler.m4 b/config/c-compiler.m4
index 349e0932a9f..fbbeaeb5368 100644
--- a/config/c-compiler.m4
+++ b/config/c-compiler.m4
@@ -158,6 +158,31 @@ undefine([Ac_cachevar])dnl
 
 
 
+# PGAC_PROG_CC_VAR_OPT
+# -----------------------
+# Given a variable name and a string, check if the compiler supports
+# the string as a command-line option. If it does, add the string to
+# the given variable.
+AC_DEFUN([PGAC_PROG_CC_VAR_OPT],
+[define([Ac_cachevar], [AS_TR_SH([pgac_cv_prog_cc_cflags_$2])])dnl
+AC_CACHE_CHECK([whether $CC supports $2], [Ac_cachevar],
+[pgac_save_CFLAGS=$CFLAGS
+CFLAGS="$pgac_save_CFLAGS $2"
+ac_save_c_werror_flag=$ac_c_werror_flag
+ac_c_werror_flag=yes
+_AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
+                   [Ac_cachevar=yes],
+                   [Ac_cachevar=no])
+ac_c_werror_flag=$ac_save_c_werror_flag
+CFLAGS="$pgac_save_CFLAGS"])
+if test x"$Ac_cachevar" = x"yes"; then
+  $1="${$1} $2"
+fi
+undefine([Ac_cachevar])dnl
+])# PGAC_PROG_CC_CFLAGS_OPT
+
+
+
 # PGAC_PROG_CC_LDFLAGS_OPT
 # ------------------------
 # Given a string, check if the compiler supports the string as a
diff --git a/configure b/configure
index 23486236442..c864825785c 100755
--- a/configure
+++ b/configure
@@ -4407,6 +4407,202 @@ if test x"$pgac_cv_prog_cc_cflags__fexcess_precision_standard" = x"yes"; then
   CFLAGS="$CFLAGS -fexcess-precision=standard"
 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
+  NOT_THE_CFLAGS=""
+  { $as_echo "$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
+  # Similarly disable useless truncation warnings from gcc 8+
+  NOT_THE_CFLAGS=""
+  { $as_echo "$as_me:$LINENO: checking whether $CC supports -Wformat-truncation" >&5
+$as_echo_n "checking whether $CC supports -Wformat-truncation... " >&6; }
+if test "${pgac_cv_prog_cc_cflags__Wformat_truncation+set}" = set; then
+  $as_echo_n "(cached) " >&6
+else
+  pgac_save_CFLAGS=$CFLAGS
+CFLAGS="$pgac_save_CFLAGS -Wformat-truncation"
+ac_save_c_werror_flag=$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__Wformat_truncation=yes
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	pgac_cv_prog_cc_cflags__Wformat_truncation=no
+fi
+
+rm -f core conftest.err conftest.$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: $pgac_cv_prog_cc_cflags__Wformat_truncation" >&5
+$as_echo "$pgac_cv_prog_cc_cflags__Wformat_truncation" >&6; }
+if test x"$pgac_cv_prog_cc_cflags__Wformat_truncation" = x"yes"; then
+  NOT_THE_CFLAGS="${NOT_THE_CFLAGS} -Wformat-truncation"
+fi
+
+  if test -n "$NOT_THE_CFLAGS"; then
+    CFLAGS="$CFLAGS -Wno-format-truncation"
+  fi
+  NOT_THE_CFLAGS=""
+  { $as_echo "$as_me:$LINENO: checking whether $CC supports -Wstringop-truncation" >&5
+$as_echo_n "checking whether $CC supports -Wstringop-truncation... " >&6; }
+if test "${pgac_cv_prog_cc_cflags__Wstringop_truncation+set}" = set; then
+  $as_echo_n "(cached) " >&6
+else
+  pgac_save_CFLAGS=$CFLAGS
+CFLAGS="$pgac_save_CFLAGS -Wstringop-truncation"
+ac_save_c_werror_flag=$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__Wstringop_truncation=yes
+else
+  $as_echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	pgac_cv_prog_cc_cflags__Wstringop_truncation=no
+fi
+
+rm -f core conftest.err conftest.$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: $pgac_cv_prog_cc_cflags__Wstringop_truncation" >&5
+$as_echo "$pgac_cv_prog_cc_cflags__Wstringop_truncation" >&6; }
+if test x"$pgac_cv_prog_cc_cflags__Wstringop_truncation" = x"yes"; then
+  NOT_THE_CFLAGS="${NOT_THE_CFLAGS} -Wstringop-truncation"
+fi
+
+  if test -n "$NOT_THE_CFLAGS"; then
+    CFLAGS="$CFLAGS -Wno-stringop-truncation"
+  fi
 elif test "$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 fad6316e5ff..d030f83f796 100644
--- a/configure.in
+++ b/configure.in
@@ -426,6 +426,25 @@ if test "$GCC" = yes -a "$ICC" = no; then
   PGAC_PROG_CC_CFLAGS_OPT([-fwrapv])
   # Disable FP optimizations that cause various errors on gcc 4.5+ or maybe 4.6+
   PGAC_PROG_CC_CFLAGS_OPT([-fexcess-precision=standard])
+  # 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
+  NOT_THE_CFLAGS=""
+  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
+  # Similarly disable useless truncation warnings from gcc 8+
+  NOT_THE_CFLAGS=""
+  PGAC_PROG_CC_VAR_OPT(NOT_THE_CFLAGS, [-Wformat-truncation])
+  if test -n "$NOT_THE_CFLAGS"; then
+    CFLAGS="$CFLAGS -Wno-format-truncation"
+  fi
+  NOT_THE_CFLAGS=""
+  PGAC_PROG_CC_VAR_OPT(NOT_THE_CFLAGS, [-Wstringop-truncation])
+  if test -n "$NOT_THE_CFLAGS"; then
+    CFLAGS="$CFLAGS -Wno-stringop-truncation"
+  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.