https://gcc.gnu.org/bugzilla/show_bug.cgi?id=80265
janisozaur+gcc at gmail dot com changed:
What |Removed |Added
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CC| |janisozaur+gcc at gmail dot com
--- Comment #37 from janisozaur+gcc at gmail dot com ---
Hi, I ran into what I think is a variant of this bug.
Here's the problem presented with godbolt: https://godbolt.org/z/SP-4uG
And the contents of that link, as reproduced on my machine, are:
#include <string_view>
#include <cwchar>
static const std::wstring_view foo = L"foo";
static constexpr std::wstring_view bar = L"bar";
$ g++ --version
g++ (GCC) 8.2.1 20181127
$ g++ -c test.cpp -Wall -Wextra -std=c++17 # exit code 0
$ gcc9/bin/g++ --version
g++ (GCC) 9.0.1 20190225 (experimental)
$ gcc9/bin/g++ -c test.cpp -Wall -Wextra -std=c++17 # exit code 0
$ clang++ --version
clang version 7.0.1 (tags/RELEASE_701/final)
$ clang++ -c -Wall -Wextra test.cpp -std=c++17 -Wno-unused-const-variable
-stdlib=libc++ # exit code 0
$ clang++ -c -Wall -Wextra test.cpp -std=c++17
test.cpp:4:36: error: constexpr variable 'bar' must be initialized by a
constant expression
static constexpr std::wstring_view bar = L"bar";
^ ~~~~~~
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/8.2.1/../../../../include/c++/8.2.1/bits/char_traits.h:431:11:
note: non-constexpr function 'wcslen' cannot be used in a constant expression
return wcslen(__s);
^
/usr/bin/../lib64/gcc/x86_64-pc-linux-gnu/8.2.1/../../../../include/c++/8.2.1/string_view:100:39:
note: in call to 'length(&L"bar"[0])'
: _M_len{__str == nullptr ? 0 : traits_type::length(__str)},
^
test.cpp:4:42: note: in call to 'basic_string_view(&L"bar"[0])'
static constexpr std::wstring_view bar = L"bar";
^
1 error generated.
Relevant piece of code from libstdc++:
https://github.com/gcc-mirror/gcc/blob/9fb89fa845c1b2e0a18d85ada0b077c84508ab78/libstdc%2B%2B-v3/include/bits/char_traits.h#L426-L431
Unfortunately, I can't really test clang with libstdc++ trunk. Please let me
know if it is sufficient to leave this comment here or should I open another
ticket?
