[RFA 13/13] Add -Wunused-variable to warnings.m4

Tom Tromey
2018-07-12T20:52:18Z

This adds -Wunused-variable to the build. This required a special
check in configure in order to work around a bug in GCC 4.9. Simon
ound the correct test to use, so I've added him to the ChangeLog.

2018-07-12 Simon Marchi <simon.marchi@polymtl.ca>
Tom Tromey <tom@tromey.com>

* warning.m4 (AM_GDB_WARNINGS): Add -Wunused-variable and special
test for it.
* configure: Rebuild.

gdb/gdbserver/ChangeLog
2018-07-12 Tom Tromey <tom@tromey.com>

* configure: Rebuild.
---
gdb/ChangeLog | 7 +++++++
gdb/configure | 28 ++++++++++++++++++++++++++--
gdb/gdbserver/ChangeLog | 4 ++++
gdb/gdbserver/configure | 28 ++++++++++++++++++++++++++--
gdb/warning.m4 | 17 +++++++++++++++--
5 files changed, 78 insertions(+), 6 deletions(-)

diff --git a/gdb/configure b/gdb/configure
index 28756ed9826..1a1b3e9dafd 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -15467,7 +15467,7 @@ fi

# The options we'll try to enable.
build_warnings="-Wall -Wpointer-arith \
--Wno-unused -Wunused-value -Wunused-function \
+-Wno-unused -Wunused-value -Wunused-variable -Wunused-function \
-Wno-switch -Wno-char-subscripts \
-Wempty-body -Wunused-but-set-parameter -Wunused-but-set-variable \
-Wno-sign-compare -Wno-narrowing -Wno-error=maybe-uninitialized \
@@ -15556,7 +15556,30 @@ $as_echo_n "checking compiler warning flags... " >&6; }
CFLAGS="$CFLAGS -Werror $wtest"
saved_CXXFLAGS="$CXXFLAGS"
CXXFLAGS="$CXXFLAGS -Werror $wtest"
- cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+ if test "x$w" = "x-Wunused-variable"; then
+ # Check for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38958,
+ # fixed in GCC 4.9. This test is derived from the gdb
+ # source code that triggered this bug in GCC.
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+struct scoped_restore_base {};
+ struct scoped_restore_tmpl : public scoped_restore_base {
+ ~scoped_restore_tmpl() {}
+ };
+int
+main ()
+{
+const scoped_restore_base &b = scoped_restore_tmpl();
+ ;
+ return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+ WARN_CFLAGS="${WARN_CFLAGS} $w"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ else
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */

int
@@ -15571,6 +15594,7 @@ if ac_fn_cxx_try_compile "$LINENO"; then :
WARN_CFLAGS="${WARN_CFLAGS} $w"
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ fi
CFLAGS="$saved_CFLAGS"
CXXFLAGS="$saved_CXXFLAGS"
esac
diff --git a/gdb/gdbserver/configure b/gdb/gdbserver/configure
index 6064a1eb10f..043bc216e43 100755
--- a/gdb/gdbserver/configure
+++ b/gdb/gdbserver/configure
@@ -7237,7 +7237,7 @@ fi

# The options we'll try to enable.
build_warnings="-Wall -Wpointer-arith \
--Wno-unused -Wunused-value -Wunused-function \
+-Wno-unused -Wunused-value -Wunused-variable -Wunused-function \
-Wno-switch -Wno-char-subscripts \
-Wempty-body -Wunused-but-set-parameter -Wunused-but-set-variable \
-Wno-sign-compare -Wno-narrowing -Wno-error=maybe-uninitialized \
@@ -7326,7 +7326,30 @@ $as_echo_n "checking compiler warning flags... " >&6; }
CFLAGS="$CFLAGS -Werror $wtest"
saved_CXXFLAGS="$CXXFLAGS"
CXXFLAGS="$CXXFLAGS -Werror $wtest"
- cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+ if test "x$w" = "x-Wunused-variable"; then
+ # Check for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38958,
+ # fixed in GCC 4.9. This test is derived from the gdb
+ # source code that triggered this bug in GCC.
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h. */
+struct scoped_restore_base {};
+ struct scoped_restore_tmpl : public scoped_restore_base {
+ ~scoped_restore_tmpl() {}
+ };
+int
+main ()
+{
+const scoped_restore_base &b = scoped_restore_tmpl();
+ ;
+ return 0;
+}
+_ACEOF
+if ac_fn_cxx_try_compile "$LINENO"; then :
+ WARN_CFLAGS="${WARN_CFLAGS} $w"
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ else
+ cat confdefs.h - <<_ACEOF >conftest.$ac_ext
/* end confdefs.h. */

int
@@ -7341,6 +7364,7 @@ if ac_fn_cxx_try_compile "$LINENO"; then :
WARN_CFLAGS="${WARN_CFLAGS} $w"
fi
rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+ fi
CFLAGS="$saved_CFLAGS"
CXXFLAGS="$saved_CXXFLAGS"
esac
diff --git a/gdb/warning.m4 b/gdb/warning.m4
index 632cc214ac0..00e7cd60508 100644
--- a/gdb/warning.m4
+++ b/gdb/warning.m4
@@ -37,7 +37,7 @@ fi

# The options we'll try to enable.
build_warnings="-Wall -Wpointer-arith \
--Wno-unused -Wunused-value -Wunused-function \
+-Wno-unused -Wunused-value -Wunused-variable -Wunused-function \
-Wno-switch -Wno-char-subscripts \
-Wempty-body -Wunused-but-set-parameter -Wunused-but-set-variable \
-Wno-sign-compare -Wno-narrowing -Wno-error=maybe-uninitialized \
@@ -118,7 +118,20 @@ then
CFLAGS="$CFLAGS -Werror $wtest"
saved_CXXFLAGS="$CXXFLAGS"
CXXFLAGS="$CXXFLAGS -Werror $wtest"
- AC_TRY_COMPILE([],[],WARN_CFLAGS="${WARN_CFLAGS} $w",)
+ if test "x$w" = "x-Wunused-variable"; then
+ # Check for https://gcc.gnu.org/bugzilla/show_bug.cgi?id=38958,
+ # fixed in GCC 4.9. This test is derived from the gdb
+ # source code that triggered this bug in GCC.
+ AC_TRY_COMPILE(
+ [struct scoped_restore_base {};
+ struct scoped_restore_tmpl : public scoped_restore_base {
+ ~scoped_restore_tmpl() {}
+ };],
+ [const scoped_restore_base &b = scoped_restore_tmpl();],
+ WARN_CFLAGS="${WARN_CFLAGS} $w",)
+ else
+ AC_TRY_COMPILE([],[],WARN_CFLAGS="${WARN_CFLAGS} $w",)
+ fi
CFLAGS="$saved_CFLAGS"
CXXFLAGS="$saved_CXXFLAGS"
esac
--
2.13.6