https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69059
Bug ID: 69059
Summary: [C++14] Invalid rejection of expression as
not-a-constant-expression
Product: gcc
Version: 6.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: ldionne.2 at gmail dot com
Target Milestone: ---
The following code does not compile with GCC trunk (g++ 6.0.0 20151226
experimental):
template <typename T>
struct holder { T value; };
template <typename T>
constexpr holder<char const*> make_holder_impl(T&& t) {
return {static_cast<T&&>(t)};
}
template <typename T>
constexpr auto make_holder(T&& t) {
return make_holder_impl(static_cast<T&&>(t));
}
constexpr int my_strlen(char const* s) {
int n = 0;
while (*s++ != '\0')
++n;
return n;
}
constexpr int len = my_strlen(make_holder("name").value);
The error is
[snip]/bin/g++ -pedantic -std=c++1y -W -Wall -Wextra -c ../test/worksheet.cpp
../test/worksheet.cpp:1221:30: in constexpr expansion of
‘my_strlen(make_holder<const char (&)[5]>("name").holder<const
char*>::value)’
../test/worksheet.cpp:1216:12: error: ‘t’ is not a constant expression
while (*s++ != '\0')
^~~~
Live example: http://melpon.org/wandbox/permlink/77rNCLjwmz1P1xG2
