On Sat, Apr 11, 2020 at 02:47:34PM -0400, Tom Lane wrote:
> Julien Rouhaud <rjuju...@gmail.com> writes:
> > On Tue, Apr 7, 2020 at 10:28 PM Alvaro Herrera <alvhe...@alvh.no-ip.org>
> > wrote:
> >> Support FETCH FIRST WITH TIES
>
> > FTR I now get the following when compiling with -Wimplicit-fallthrough
> > -Werror:
>
> Yeah, assorted buildfarm animals are mentioning that too. I wonder
> if we should add that to the default warning options selected by
> configure? I don't remember if that's been discussed before.
>
I'm all for it. It seems like a trap easy to catch up early, and we do want to
enforce it anyway. I'm attaching a simple patch for that if needed, hopefully
with the correct autoconf version.
> > It seems that this fall-through comment:
> > /* fall-through */
> > Is not recognized by my compiler (gcc (Gentoo 9.3.0 p1) 9.3.0). If
> > that's something we should fix, PFA a naive patch for that.
>
> Hmm, I feel like this logic is baroque enough to need more of a rewrite
> than that :-(. But not sure exactly what would be better, so your
> patch seems reasonable for now. The comments could use some help too.
Yes I just checked the state machine to make sure that the fallthrough was
expected, but the comments are now way better, thanks!
diff --git a/configure b/configure
index 83abe872aa..739b30d5fa 100755
--- a/configure
+++ b/configure
@@ -5552,6 +5552,97 @@ if test
x"$pgac_cv_prog_CXX_cxxflags__Wmissing_format_attribute" = x"yes"; then
fi
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CC} supports
-Wimplicit-fallthrough, for CFLAGS" >&5
+$as_echo_n "checking whether ${CC} supports -Wimplicit-fallthrough, for
CFLAGS... " >&6; }
+if ${pgac_cv_prog_CC_cflags__Wimplicit_fallthrough+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ pgac_save_CFLAGS=$CFLAGS
+pgac_save_CC=$CC
+CC=${CC}
+CFLAGS="${CFLAGS} -Wimplicit-fallthrough"
+ac_save_c_werror_flag=$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__Wimplicit_fallthrough=yes
+else
+ pgac_cv_prog_CC_cflags__Wimplicit_fallthrough=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:
$pgac_cv_prog_CC_cflags__Wimplicit_fallthrough" >&5
+$as_echo "$pgac_cv_prog_CC_cflags__Wimplicit_fallthrough" >&6; }
+if test x"$pgac_cv_prog_CC_cflags__Wimplicit_fallthrough" = x"yes"; then
+ CFLAGS="${CFLAGS} -Wimplicit-fallthrough"
+fi
+
+
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CXX} supports
-Wimplicit-fallthrough, for CXXFLAGS" >&5
+$as_echo_n "checking whether ${CXX} supports -Wimplicit-fallthrough, for
CXXFLAGS... " >&6; }
+if ${pgac_cv_prog_CXX_cxxflags__Wimplicit_fallthrough+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ pgac_save_CXXFLAGS=$CXXFLAGS
+pgac_save_CXX=$CXX
+CXX=${CXX}
+CXXFLAGS="${CXXFLAGS} -Wimplicit-fallthrough"
+ac_save_cxx_werror_flag=$ac_cxx_werror_flag
+ac_cxx_werror_flag=yes
+ac_ext=cpp
+ac_cpp='$CXXCPP $CPPFLAGS'
+ac_compile='$CXX -c $CXXFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CXX -o conftest$ac_exeext $CXXFLAGS $CPPFLAGS $LDFLAGS
conftest.$ac_ext $LIBS >&5'
+ac_compiler_gnu=$ac_cv_cxx_compiler_gnu
+
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+
+int
+main ()
+{
+
+ ;
+ return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+ pgac_cv_prog_CXX_cxxflags__Wimplicit_fallthrough=yes
+else
+ pgac_cv_prog_CXX_cxxflags__Wimplicit_fallthrough=no
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ac_ext=c
+ac_cpp='$CPP $CPPFLAGS'
+ac_compile='$CC -c $CFLAGS $CPPFLAGS conftest.$ac_ext >&5'
+ac_link='$CC -o conftest$ac_exeext $CFLAGS $CPPFLAGS $LDFLAGS conftest.$ac_ext
$LIBS >&5'
+ac_compiler_gnu=$ac_cv_c_compiler_gnu
+
+ac_cxx_werror_flag=$ac_save_cxx_werror_flag
+CXXFLAGS="$pgac_save_CXXFLAGS"
+CXX="$pgac_save_CXX"
+fi
+{ $as_echo "$as_me:${as_lineno-$LINENO}: result:
$pgac_cv_prog_CXX_cxxflags__Wimplicit_fallthrough" >&5
+$as_echo "$pgac_cv_prog_CXX_cxxflags__Wimplicit_fallthrough" >&6; }
+if test x"$pgac_cv_prog_CXX_cxxflags__Wimplicit_fallthrough" = x"yes"; then
+ CXXFLAGS="${CXXFLAGS} -Wimplicit-fallthrough"
+fi
+
+
# This was included in -Wall/-Wformat in older GCC versions
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CC} supports
-Wformat-security, for CFLAGS" >&5
diff --git a/configure.in b/configure.in
index ecdf172396..49816a83dc 100644
--- a/configure.in
+++ b/configure.in
@@ -496,6 +496,8 @@ if test "$GCC" = yes -a "$ICC" = no; then
PGAC_PROG_CXX_CFLAGS_OPT([-Wendif-labels])
PGAC_PROG_CC_CFLAGS_OPT([-Wmissing-format-attribute])
PGAC_PROG_CXX_CFLAGS_OPT([-Wmissing-format-attribute])
+ PGAC_PROG_CC_CFLAGS_OPT([-Wimplicit-fallthrough])
+ PGAC_PROG_CXX_CFLAGS_OPT([-Wimplicit-fallthrough])
# This was included in -Wall/-Wformat in older GCC versions
PGAC_PROG_CC_CFLAGS_OPT([-Wformat-security])
PGAC_PROG_CXX_CFLAGS_OPT([-Wformat-security])
