On Sun, Apr 12, 2020 at 5:25 PM Mark Dilger
<[email protected]> wrote:
>
> > On Apr 12, 2020, at 7:55 AM, Tom Lane <[email protected]> wrote:
> >
> > Poking around in the archives, it seems like the only previous formal
> > proposal to add -Wimplicit-fallthrough was in the context of a much
> > more aggressive proposal to make a lot of non-Wall warnings into
> > errors [1], which people did not like.
>
> That was from me.
>
> > The only more-restrictive alternative, short of disabling
> > the comments altogether, is
> >
> > * -Wimplicit-fallthrough=4 case sensitively matches one of the
> > following regular expressions:
> >
> > *<"-fallthrough">
> > *<"@fallthrough@">
> > *<"lint -fallthrough[ \t]*">
> > *<"[ \t]*FALLTHR(OUGH|U)[ \t]*">
> >
> > Thoughts?
>
> Naturally, I'm +1 for this.
+1 too, obviously.
diff --git a/configure b/configure
index 83abe872aa..4dfe4fcfe1 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 ${CC} supports -Wimplicit-fallthrough=4, for CFLAGS" >&5
+$as_echo_n "checking whether ${CC} supports -Wimplicit-fallthrough=4, for CFLAGS... " >&6; }
+if ${pgac_cv_prog_CC_cflags__Wimplicit_fallthrough_4+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ pgac_save_CFLAGS=$CFLAGS
+pgac_save_CC=$CC
+CC=${CC}
+CFLAGS="${CFLAGS} -Wimplicit-fallthrough=4"
+ac_save_c_werror_flag=$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_4=yes
+else
+ pgac_cv_prog_CC_cflags__Wimplicit_fallthrough_4=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: $pgac_cv_prog_CC_cflags__Wimplicit_fallthrough_4" >&5
+$as_echo "$pgac_cv_prog_CC_cflags__Wimplicit_fallthrough_4" >&6; }
+if test x"$pgac_cv_prog_CC_cflags__Wimplicit_fallthrough_4" = x"yes"; then
+ CFLAGS="${CFLAGS} -Wimplicit-fallthrough=4"
+fi
+
+
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CXX} supports -Wimplicit-fallthrough=4, for CXXFLAGS" >&5
+$as_echo_n "checking whether ${CXX} supports -Wimplicit-fallthrough=4, for CXXFLAGS... " >&6; }
+if ${pgac_cv_prog_CXX_cxxflags__Wimplicit_fallthrough_4+:} false; then :
+ $as_echo_n "(cached) " >&6
+else
+ pgac_save_CXXFLAGS=$CXXFLAGS
+pgac_save_CXX=$CXX
+CXX=${CXX}
+CXXFLAGS="${CXXFLAGS} -Wimplicit-fallthrough=4"
+ac_save_cxx_werror_flag=$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_4=yes
+else
+ pgac_cv_prog_CXX_cxxflags__Wimplicit_fallthrough_4=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: $pgac_cv_prog_CXX_cxxflags__Wimplicit_fallthrough_4" >&5
+$as_echo "$pgac_cv_prog_CXX_cxxflags__Wimplicit_fallthrough_4" >&6; }
+if test x"$pgac_cv_prog_CXX_cxxflags__Wimplicit_fallthrough_4" = x"yes"; then
+ CXXFLAGS="${CXXFLAGS} -Wimplicit-fallthrough=4"
+fi
+
+
# This was included in -Wall/-Wformat in older GCC versions
{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether ${CC} supports -Wformat-security, for CFLAGS" >&5
diff --git a/configure.in b/configure.in
index ecdf172396..94fba67261 100644
--- a/configure.in
+++ b/configure.in
@@ -496,6 +496,8 @@ if test "$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=4])
+ PGAC_PROG_CXX_CFLAGS_OPT([-Wimplicit-fallthrough=4])
# This was included in -Wall/-Wformat in older GCC versions
PGAC_PROG_CC_CFLAGS_OPT([-Wformat-security])
PGAC_PROG_CXX_CFLAGS_OPT([-Wformat-security])
