Hi all,
I might have found a bug in gcc or mingw, but I'm not really sure.
For the following version:
g++ (x86_64-win32-seh-rev0, Built by MinGW-W64 project) 8.1.0
A short example:
#include <cstddef>
#include <cstdio>
#include <cstdint>
#include <array>
int main()
{
const char istr[] = "Hello";
std::array<char16_t, std::char_traits<char>::length( istr )> str16;
return 0;
}
Now the compile step:
g++ -c -std=c++17 -pedantic -Wextra -Wlogical-op test.cpp
In file included from
C:/dev/x86_64-8.1.0-release-win32-seh-rt_v6-rev0/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/string:40,
from
C:/dev/x86_64-8.1.0-release-win32-seh-rt_v6-rev0/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/stdexcept:39,
from
C:/dev/x86_64-8.1.0-release-win32-seh-rt_v6-rev0/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/array:39,
from test.cpp:4:
C:/dev/x86_64-8.1.0-release-win32-seh-rt_v6-rev0/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/bits/char_traits.h:
In function 'int main()':
test.cpp:9:54: in 'constexpr' expansion of
'std::char_traits<char>::length(((const char*)(& istr)))'
C:/dev/x86_64-8.1.0-release-win32-seh-rt_v6-rev0/mingw64/lib/gcc/x86_64-w64-mingw32/8.1.0/include/c++/bits/char_traits.h:320:25:
error: '__builtin_strlen(((const char_type*)(& istr)))' is not a constant
expression
return __builtin_strlen(__s);
~~~~~~~~~~~~~~~~^~~~~
test.cpp:9:54: note: in template argument for type 'long long unsigned int'
std::array<char16_t, std::char_traits<char>::length( istr )> str16;
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~
mingw32-make.exe: *** [C:\dev\mydesign\SW\C++\win32\array_test\test.mak:9:
test.o] Error 1
This shouldn't be, right? As it succesfully selects the constexpr function
variant for the second template argument it should also work further down, I
believe.
Best regards,
Maarten Verhage
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