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| author | Stephan Bergmann <sbergman@redhat.com> | 2019-12-06 16:36:01 +0100 |
|---|---|---|
| committer | Thorsten Behrens <thorsten.behrens@allotropia.de> | 2021-04-09 23:22:01 +0200 |
| commit | 6572dbc2fa36fb9189bd1ed21748e73a88418e15 (patch) | |
| tree | 6d222150affeba0b7ec98f4b3479f06801c0a96d /configure.ac | |
| parent | Add --with-latest-c++ to explicitly opt in for -std=c++20/-std:c++latest (diff) | |
| download | core-6572dbc2fa36fb9189bd1ed21748e73a88418e15.tar.gz core-6572dbc2fa36fb9189bd1ed21748e73a88418e15.zip | |
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).
Reviewed-on: https://gerrit.libreoffice.org/84652
Tested-by: Jenkins
Reviewed-by: Stephan Bergmann <sbergman@redhat.com>
(cherry picked from commit 8e6865188242bccb3d8aa857ddc990d72a058d3d)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/87757
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
(cherry picked from commit bb9833594b031c6d0ec91422f85968c4b1f2f8bc)
Change-Id: I6ddf424ffb7941da3f69ad66fd29ecd35f09afae
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 2b33e5f0bc0a..0e61b295b66f 100644 --- a/configure.ac +++ b/configure.ac @@ -6766,6 +6766,22 @@ AC_COMPILE_IFELSE([AC_LANG_SOURCE([ CXXFLAGS=$save_CXXFLAGS AC_LANG_POP([C++]) +AC_MSG_CHECKING([whether $CXX supports C++2a <span> with unsigned size_type]) +AC_LANG_PUSH([C++]) +save_CXXFLAGS=$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 $CXX has GCC bug 87150]) AC_LANG_PUSH([C++]) save_CXXFLAGS=$CXXFLAGS |