[Bug c++/70816] bogus error __builtin_strcmp is not a constant expression in a constexpr function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70816 Martin Sebor changed: What|Removed |Added Assignee|msebor at gcc dot gnu.org |unassigned at gcc dot gnu.org Status|ASSIGNED|NEW --- Comment #5 from Martin Sebor --- I'm not working on this anymore.
[Bug c++/70816] bogus error __builtin_strcmp is not a constant expression in a constexpr function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70816 --- Comment #4 from Jonathan Wakely --- Our std::char_traits has similar branches for constant evaluation (and the rest of the library does too for memcpy etc.)
[Bug c++/70816] bogus error __builtin_strcmp is not a constant expression in a constexpr function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70816 Louis Dionne changed: What|Removed |Added CC||ldionne.2 at gmail dot com --- Comment #3 from Louis Dionne --- We are having to add a workaround in libc++ to implement constexpr std::string: https://reviews.llvm.org/D115795 It would be awesome if this could be fixed! (if so, please drop us a line and we'll remove our workaround)
[Bug c++/70816] bogus error __builtin_strcmp is not a constant expression in a constexpr function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70816 Arthur O'Dwyer changed: What|Removed |Added CC||arthur.j.odwyer at gmail dot com --- Comment #2 from Arthur O'Dwyer --- Confirmed, I'm also seeing this in C++20 mode. This affects libc++'s `char_traits::length(const char *)`. Example test case: https://godbolt.org/z/MTq1ex
[Bug c++/70816] bogus error __builtin_strcmp is not a constant expression in a constexpr function
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70816
Martin Sebor changed:
What|Removed |Added
Status|UNCONFIRMED |ASSIGNED
Last reconfirmed||2016-06-08
Ever confirmed|0 |1
Known to fail|6.0 |6.1.0, 7.0
--- Comment #1 from Martin Sebor ---
The same limitation affects other string builtins such as __builtin_strlen or
__builtin_strchr.
$ cat cst.C && /home/msebor/build/gcc-6-branch/gcc/xgcc
-B/home/msebor/build/gcc-6-branch/gcc -S -Wall -Wextra -Wpedantic cst.C
-fdump-tree-optimized=/dev/stdout -o/dev/stdout
constexpr int chr (int c)
{
const char a[] = "123";
return __builtin_strchr (a, c) - a;
}
constexpr int i = chr ('3');
constexpr int cmp (const char *a)
{
const char b[] = "123";
return __builtin_strcmp (a, b);
}
constexpr int j = cmp ("345");
constexpr unsigned len ()
{
const char s[] = "123";
return __builtin_strlen (s);
}
constexpr unsigned n = len ();
.file "cst.C"
cst.C:7:23: in constexpr expansion of ‘chr(51)’
cst.C:4:27: error: ‘__builtin_strchr(((const char*)(& a)), 51)’ is not a
constant expression
return __builtin_strchr (a, c) - a;
~^~
cst.C:15:23: in constexpr expansion of ‘cmp(((const char*)"345"))’
cst.C:12:27: error: ‘__builtin_strcmp(((const char*)"345"), ((const char*)(&
b)))’ is not a constant expression
return __builtin_strcmp (a, b);
~^~
cst.C:23:28: in constexpr expansion of ‘len()’
cst.C:20:27: error: ‘__builtin_strlen(((const char*)(& s)))’ is not a constant
expression
return __builtin_strlen (s);
~^~~
