From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sat, 16 Jun 2018 19:34:07 +0000 (-0400)
Subject: Use -Wno-format-truncation and -Wno-stringop-truncation, if available.
X-Git-Tag: REL_11_BETA2~47
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=e716585235b175de767d3b210f0a963457dfa77f;p=postgresql

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

gcc 8 has started emitting some warnings that are largely useless for
our purposes, particularly since they complain about code following
the project-standard coding convention that path names are assumed
to be shorter than MAXPGPATH.  Even if we make the effort to remove
that assumption in some future release, the changes wouldn't get
back-patched.  Hence, just suppress these warnings, on compilers that
have these switches.

Backpatch to all supported branches.

Discussion: https://postgr.es/m/1524563856.26306.9.camel@gunduz.org
---

diff --git a/configure b/configure
index 3d219c802b..000c63d40c 100755
--- a/configure
+++ b/configure
@@ -5815,6 +5815,7 @@ 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:${as_lineno-$LINENO}: checking whether ${CC} supports -Wunused-command-line-argument, for NOT_THE_CFLAGS" >&5
 $as_echo_n "checking whether ${CC} supports -Wunused-command-line-argument, for NOT_THE_CFLAGS... " >&6; }
 if ${pgac_cv_prog_CC_cflags__Wunused_command_line_argument+:} false; then :
@@ -5857,6 +5858,93 @@ fi
   if test -n "$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:${as_lineno-$LINENO}: checking whether ${CC} supports -Wformat-truncation, for NOT_THE_CFLAGS" >&5
+$as_echo_n "checking whether ${CC} supports -Wformat-truncation, for NOT_THE_CFLAGS... " >&6; }
+if ${pgac_cv_prog_CC_cflags__Wformat_truncation+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  pgac_save_CFLAGS=$CFLAGS
+pgac_save_CC=$CC
+CC=${CC}
+CFLAGS="${NOT_THE_CFLAGS} -Wformat-truncation"
+ac_save_c_werror_flag=$ac_c_werror_flag
+ac_c_werror_flag=yes
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  pgac_cv_prog_CC_cflags__Wformat_truncation=yes
+else
+  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"
+CC="$pgac_save_CC"
+fi
+{ $as_echo "$as_me:${as_lineno-$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:${as_lineno-$LINENO}: checking whether ${CC} supports -Wstringop-truncation, for NOT_THE_CFLAGS" >&5
+$as_echo_n "checking whether ${CC} supports -Wstringop-truncation, for NOT_THE_CFLAGS... " >&6; }
+if ${pgac_cv_prog_CC_cflags__Wstringop_truncation+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  pgac_save_CFLAGS=$CFLAGS
+pgac_save_CC=$CC
+CC=${CC}
+CFLAGS="${NOT_THE_CFLAGS} -Wstringop-truncation"
+ac_save_c_werror_flag=$ac_c_werror_flag
+ac_c_werror_flag=yes
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+
+int
+main ()
+{
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+  pgac_cv_prog_CC_cflags__Wstringop_truncation=yes
+else
+  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"
+CC="$pgac_save_CC"
+fi
+{ $as_echo "$as_me:${as_lineno-$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 862d8b128d..03fc5023a4 100644
--- a/configure.in
+++ b/configure.in
@@ -498,10 +498,22 @@ if test "$GCC" = yes -a "$ICC" = no; then
   # 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.