With GCC 6.4 and 6.5 (at least), unit tests that use
gdbsupport/valid-expr.h's CHECK_VALID fail to compile, with:
In file included from src/gdb/unittests/offset-type-selftests.c:24:0:
src/gdb/unittests/offset-type-selftests.c: In substitution of 'template<class Expected, template<class ...> class Op, class ... Args> using is_detected_exact = std::is_same<Expected, typename gdb::detection_detail::detector<gdb::nonesuch, void, Op, Args ...>::type> [with Expected = selftests::offset_type::off_A&; Op = selftests::offset_type::check_valid_expr75::archetype; Args = {selftests::offset_type::off_A, selftests::offset_type::off_B}]':
src/gdb/unittests/offset-type-selftests.c:75:1: required from here
src/gdb/../gdbsupport/valid-expr.h:65:20: error: type/value mismatch at argument 2 in template parameter list for 'template<class Expected, template<class ...> class Op, class ... Args> using is_detected_exact = std::is_same<Expected, typename gdb::detection_detail::detector<gdb::nonesuch, void, Op, Args ...>::type>'
archetype, TYPES>::value == VALID, \
^
The important part is the "error: type/value mismatch" error. Seems
like that GCC doesn't understand that archetype is an alias template,
and is being strict in requiring a template class.
The fix here is then to make archetype a template class, to pacify
GCC. The resulting code looks like this:
template <TYPENAMES, typename = decltype (EXPR)>
struct archetype
{
};
static_assert (gdb::is_detected_exact<archetype<TYPES, EXPR_TYPE>,
archetype, TYPES>::value == VALID, "");
is_detected_exact<Expected, Op, Args> checks whether Op<Args> is type
Expected:
- For Expected, we pass the explicit EXPR_TYPE, overriding the
default parameter type of archetype.
- For Args we don't pass the last template parameter, so archtype
defaults to the EXPR's decltype.
So in essence, we're really checking whether EXPR_TYPE is the same as
decltype(EXPR).
We need to do the decltype in a template context in order to trigger
SFINAE instead of failing to compile.
The hunk in unittests/enum-flags-selftests.c becomes necessary,
because unlike with the current alias template version, this new
version makes GCC trigger -Wenum-compare warnings as well:
src/gdb/unittests/enum-flags-selftests.c:328:33: error: comparison between 'enum selftests::enum_flags_tests::RE' and 'enum selftests::enum_flags_tests::RE2' [-Werror=enum-compare]
CHECK_VALID (true, bool, RE () != RE2 ())
^
src/gdb/../gdbsupport/valid-expr.h:61:45: note: in definition of macro 'CHECK_VALID_EXPR_INT'
template <TYPENAMES, typename = decltype (EXPR)> \
^
Build-tested with:
- GCC {4.8.5, 6.4, 6.5, 7.3.1, 9.3.0, 11.0.0-
20200910}
- Clang 10.0.0
gdbsupport/ChangeLog:
* valid-expr.h (CHECK_VALID_EXPR_INT): Make archetype a template
class instead of an alias template and adjust static_assert.
gdb/ChangeLog:
* unittests/enum-flags-selftests.c: Check whether __GNUC__ is
defined before using '#pragma GCC diagnostic' instead of checking
__clang__.
+2020-09-29 Pedro Alves <pedro@palves.net>
+
+ * unittests/enum-flags-selftests.c: Check whether __GNUC__ is
+ defined before using '#pragma GCC diagnostic' instead of checking
+ __clang__.
+
2020-09-28 Tom Tromey <tom@tromey.com>
* infrun.c (displaced_step_fixup, thread_still_needs_step_over)
CHECK_VALID (false, void, EF () != RE2 ())
CHECK_VALID (false, void, RE () != EF2 ())
-/* On clang, disable -Wenum-compare due to "error: comparison of two
- values with different enumeration types [-Werror,-Wenum-compare]".
- clang doesn't suppress -Wenum-compare in SFINAE contexts. Not a
- big deal since misuses like these in GDB will be caught by -Werror
- anyway. This check is here mainly for completeness. */
-#if defined __clang__
+/* Disable -Wenum-compare due to:
+
+ Clang:
+
+ "error: comparison of two values with different enumeration types
+ [-Werror,-Wenum-compare]"
+
+ GCC:
+
+ "error: comparison between ‘enum selftests::enum_flags_tests::RE’
+ and ‘enum selftests::enum_flags_tests::RE2’
+ [-Werror=enum-compare]"
+
+ Not a big deal since misuses like these in GDB will be caught by
+ -Werror anyway. This check is here mainly for completeness. */
+#if defined __GNUC__
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wenum-compare"
#endif
CHECK_VALID (true, bool, RE () == RE2 ())
CHECK_VALID (true, bool, RE () != RE2 ())
-#if defined __clang__
+#if defined __GNUC__
# pragma GCC diagnostic pop
#endif
+2020-09-29 Pedro Alves <pedro@palves.net>
+
+ * valid-expr.h (CHECK_VALID_EXPR_INT): Make archetype a template
+ class instead of an alias template and adjust static_assert.
+
2020-09-24 Simon Marchi <simon.marchi@efficios.com>
* event-loop.c (struct file_handler): Remove typedef, re-format.
#define CHECK_VALID_EXPR_INT(TYPENAMES, TYPES, VALID, EXPR_TYPE, EXPR) \
namespace CONCAT (check_valid_expr, __LINE__) { \
\
- template <TYPENAMES> \
- using archetype = decltype (EXPR); \
+ template <TYPENAMES, typename = decltype (EXPR)> \
+ struct archetype \
+ { \
+ }; \
\
- static_assert (gdb::is_detected_exact<EXPR_TYPE, \
+ static_assert (gdb::is_detected_exact<archetype<TYPES, EXPR_TYPE>, \
archetype, TYPES>::value == VALID, \
""); \
} /* namespace */
projects / binutils-gdb.git / commitdiff