Pedro Alves de38d64ad2 Tweak gdbsupport/valid-expr.h for GCC 6, fix build ... 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 23:48:04 +01:00
..
basic_string_view
optional
array-view-selftests.c
child-path-selftests.c
cli-utils-selftests.c
command-def-selftests.c
common-utils-selftests.c
copy_bitwise-selftests.c
enum-flags-selftests.c
environ-selftests.c
filtered_iterator-selftests.c
format_pieces-selftests.c
function-view-selftests.c
lookup_name_info-selftests.c
main-thread-selftests.c
memory-map-selftests.c
memrange-selftests.c
mkdir-recursive-selftests.c
observable-selftests.c
offset-type-selftests.c
optional-selftests.c
parse-connection-spec-selftests.c
ptid-selftests.c
rsp-low-selftests.c
scoped_fd-selftests.c
scoped_mmap-selftests.c
scoped_restore-selftests.c
string_view-selftests.c
style-selftests.c
tracepoint-selftests.c
tui-selftests.c
unpack-selftests.c
utils-selftests.c
vec-utils-selftests.c
xml-utils-selftests.c