[RFA] Fix the clang build

Tom Tromey
2018-05-10T14:40:46Z

Simon pointed out that gdb would not build with clang, due to the
addition of -Wimplicit-fallthrough. This patch fixes the problem by
using -Wimplicit-fallthrough=3 -- this does not work with clang,
bypassing the issue.

Tested by rebuilding with both gcc and clang; and also by verifying
that -Wimplicit-fallthrough=3 is used in the gcc build.

I will file a follow-up bug to convert the fall-through comments to a
form that can be used by both clang and gcc.

gdb/ChangeLog
2018-05-10 Tom Tromey <tom@tromey.com>

* configure: Rebuild.
* warning.m4 (AM_GDB_WARNINGS): Use -Wimplicit-fallthrough=3.

gdb/gdbserver/ChangeLog
2018-05-10 Tom Tromey <tom@tromey.com>

* configure: Rebuild.
---
gdb/ChangeLog | 5 +++++
gdb/configure | 2 +-
gdb/gdbserver/ChangeLog | 4 ++++
gdb/gdbserver/configure | 2 +-
gdb/warning.m4 | 2 +-
5 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/gdb/configure b/gdb/configure
index 0eec780bd1..4186f7e160 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -15367,7 +15367,7 @@ build_warnings="-Wall -Wpointer-arith \
-Wno-mismatched-tags \
-Wno-error=deprecated-register \
-Wsuggest-override \
--Wimplicit-fallthrough \
+-Wimplicit-fallthrough=3 \
-Wduplicated-cond"

case "${host}" in
diff --git a/gdb/gdbserver/configure b/gdb/gdbserver/configure
index ac61ba3543..b2e2e8f955 100755
--- a/gdb/gdbserver/configure
+++ b/gdb/gdbserver/configure
@@ -7174,7 +7174,7 @@ build_warnings="-Wall -Wpointer-arith \
-Wno-mismatched-tags \
-Wno-error=deprecated-register \
-Wsuggest-override \
--Wimplicit-fallthrough \
+-Wimplicit-fallthrough=3 \
-Wduplicated-cond"

case "${host}" in
diff --git a/gdb/warning.m4 b/gdb/warning.m4
index cb23472ec6..632cc214ac 100644
--- a/gdb/warning.m4
+++ b/gdb/warning.m4
@@ -44,7 +44,7 @@ build_warnings="-Wall -Wpointer-arith \
-Wno-mismatched-tags \
-Wno-error=deprecated-register \
-Wsuggest-override \
--Wimplicit-fallthrough \
+-Wimplicit-fallthrough=3 \
-Wduplicated-cond"

case "${host}" in
--
2.13.6