diff options
| author | Stephan Bergmann <sbergman@redhat.com> | 2019-12-06 16:36:01 +0100 |
|---|---|---|
| committer | Stephan Bergmann <sbergman@redhat.com> | 2019-12-07 09:00:00 +0100 |
| commit | 8e6865188242bccb3d8aa857ddc990d72a058d3d (patch) | |
| tree | 31a19fba39c6c7f85e1561a8e73e25a6e71cb50f /configure.ac | |
| parent | c1fbdc8717fa68f4c432511ace8b58c97b1386ad (diff) | |
Adapt o3tl::span to P1872R0
..."span should have size_type, not index_type"
(<http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2019/p1872r0.pdf>), as
implemented by libc++ since <https://github.com/llvm/llvm-project/commit/
1466335cf4b2854a0be1defcf279fe50772bad6f> "[libc++][P1872] span should have
size_type, not index_type."
All uses of index_type had been added to mitigate the previous std::span change
from signed (ptrdiff_t) to unsigned (size_t) index_type, see
6ef8420fdbf8dff16de13147c5ab833bc5e01121 "Adapt o3tl::span to updated C++2a
std::span". There is no easy solution to transparently support all three
std::span variants currently out there (signed index_type, unsigned index_type,
unsigned size_type), without causing compilation failures due to
CPPUNIT_ASSERT_EQUAL with arguments of different types, or compiler warnings
about mixed signed/unsigned comparisons. So rule out the oldest std::span
variant (signed index_type) in configure.ac (so that o3tl::span will use its
own hand-rolled code in that case) and simplify the uses of index_type to
std::size_t (as had already been mentioned in
6ef8420fdbf8dff16de13147c5ab833bc5e01121).
Change-Id: I6ddf424ffb7941da3f69ad66fd29ecd35f09afae
Reviewed-on: https://gerrit.libreoffice.org/84652
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
Diffstat (limited to 'configure.ac')
| -rw-r--r-- | configure.ac | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/configure.ac b/configure.ac index 651e9d60c2d4..194a3cc80fa5 100644 --- a/configure.ac +++ b/configure.ac @@ -6701,6 +6701,22 @@ AC_COMPILE_IFELSE([AC_LANG_SOURCE([ CXXFLAGS=$save_CXXFLAGS AC_LANG_POP([C++]) +AC_MSG_CHECKING([whether $CXX_BASE supports C++2a <span> with unsigned size_type]) +AC_LANG_PUSH([C++]) +save_CXXFLAGS=$CXXFLAGS +CXXFLAGS="$CXXFLAGS $CXXFLAGS_CXX11" +AC_COMPILE_IFELSE([AC_LANG_SOURCE([ + #include <span> + #include <type_traits> + // Don't check size_type directly, as it was called index_type before P1872R0: + void f(std::span<int> s) { static_assert(std::is_unsigned_v<decltype(s.size())>); }; + ])], [ + AC_DEFINE([HAVE_CPP_SPAN],[1]) + AC_MSG_RESULT([yes]) + ], [AC_MSG_RESULT([no])]) +CXXFLAGS=$save_CXXFLAGS +AC_LANG_POP([C++]) + AC_MSG_CHECKING([whether $CXX_BASE has GCC bug 87150]) AC_LANG_PUSH([C++]) save_CXXFLAGS=$CXXFLAGS |