https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117966
Bug ID: 117966
Summary: [12/13/14/15 regression] constexpr std::span
construction fails to compile with D_GLIBCXX_DEBUG
Product: gcc
Version: 15.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: gnu.ojxq8 at dralias dot com
Target Milestone: ---
GCC-11 is fine, but any later version fails when running
g++ /tmp/a.cpp -std=c++20 -D_GLIBCXX_DEBUG -o /tmp/a
The file is:
#include <array>
#include <span>
struct A {
constexpr A(std::span<const unsigned char>) {}
};
constexpr A val{std::array<unsigned char, 2>{0x11, 0x22}};
An error message may look like:
<source>:6:22: in 'constexpr' expansion of 'std::span<const unsigned
char>(std::array<unsigned char, 2>{std::__array_traits<unsigned char,
2>::_Type{17, 34}})'
/opt/compiler-explorer/gcc-trunk-20241209/include/c++/15.0.0/span:207:57: in
'constexpr' expansion of '((std::span<const unsigned
char>*)this)->std::span<const unsigned char>::span<const unsigned char*>((&
__arr)->std::array<unsigned char, 2>::data(), 2)'
/opt/compiler-explorer/gcc-trunk-20241209/include/c++/15.0.0/span:170:11:
error: '__builtin_expect(((long int)(! __gnu_debug::__valid_range<const
unsigned char*>(__first, (__first + ((sizetype)__count))))), 0)' is not a
constant expression
170 | __glibcxx_requires_valid_range(__first, __first + __count);
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Compiler returned: 1
