https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87512
Bug ID: 87512
Summary: Error: the type ‘const auto’ of ‘constexpr’ variable
is not literal
Product: gcc
Version: 8.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: officesamurai at gmail dot com
Target Milestone: ---
Created attachment 44779
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44779&action=edit
Preprocessed source
The following code fails to compile:
==
#include <type_traits>
template <typename T>
inline constexpr auto IsPtr = std::is_pointer<T>::value;
class Foo;
class Bar;
template <typename T1, typename T2>
void foo(T1, T2);
template <typename T>
std::enable_if_t<IsPtr<T>> foo(T, Foo);
template <>
void foo<Bar>(Bar, Bar);
==
The error:
==
$ g++-8.2.0 -c -std=c++17 test.cpp
test.cpp: In instantiation of ‘constexpr const auto IsPtr<Bar>’:
test.cpp:13:18: required by substitution of ‘template<class T>
std::enable_if_t<IsPtr<T> > foo(T, Foo) [with T = Bar]’
test.cpp:16:23: required from here
test.cpp:4:23: error: the type ‘const auto’ of ‘constexpr’ variable
‘IsPtr<Bar>’ is not literal
inline constexpr auto IsPtr = std::is_pointer<T>::value;
^~~~~
test.cpp:4:23: error: ‘const auto IsPtr<Bar>’ has incomplete type
==
GCC version:
==
$ g++-8.2.0 -v
Using built-in specs.
COLLECT_GCC=g++-8.2.0
COLLECT_LTO_WRAPPER=/home/brd/soft/gcc-8.2.0/libexec/gcc/x86_64-pc-linux-gnu/8.2.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ./configure --prefix=/home/brd/soft/gcc-8.2.0
Thread model: posix
gcc version 8.2.0 (GCC)
==
The preprocessed source is attached.
P.S.
1) Clang is able to compile it.
2) Changing "auto" to "bool" in the definition of IsPtr fixes the error.
