https://bugs.llvm.org/show_bug.cgi?id=39728
Bug ID: 39728
Summary: Trivial type with defaulted assignment and destructor
is not usable in constexpr
Product: clang
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: enhancement
Priority: P
Component: Frontend
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected], [email protected],
[email protected]
The following code does not compile under Clang trunk (GCC compiles it):
----------------------------------------------------------
#include <type_traits>
struct Trivial {
Trivial& operator=(Trivial const&) = default;
~Trivial() = default;
};
static_assert(std::is_trivially_copy_assignable<Trivial>::value);
static_assert(std::is_trivially_destructible<Trivial>::value);
constexpr bool use() {
Trivial a{}, b{};
a = b;
return true;
}
static_assert(use());
----------------------------------------------------------
The command I use to reproduce is this:
----------------------------------------------------------
$ pbpaste | clang++ -std=c++2a -xc++ -fsyntax-only -
<stdin>:11:16: error: constexpr function never produces a constant expression
[-Winvalid-constexpr]
constexpr bool use() {
^
<stdin>:13:5: note: non-constexpr function 'operator=' cannot be used in a
constant expression
a = b;
^
<stdin>:4:14: note: declared here
Trivial& operator=(Trivial const&) = default;
^
<stdin>:17:15: error: static_assert expression is not an integral constant
expression
static_assert(use());
^~~~~
<stdin>:13:5: note: non-constexpr function 'operator=' cannot be used in a
constant expression
a = b;
^
<stdin>:17:15: note: in call to 'use()'
static_assert(use());
^
<stdin>:4:14: note: declared here
Trivial& operator=(Trivial const&) = default;
^
2 errors generated.
----------------------------------------------------------
Live example with Clang trunk: https://wandbox.org/permlink/gJWRWbzxfduLQnc5
Live example with GCC trunk: https://wandbox.org/permlink/jJU6pW9S6rAYdGrH
The problem seems to be that the defaulted assignment operator is not
constexpr. I think it should be (especially since it's trivial).
--
You are receiving this mail because:
You are on the CC list for the bug._______________________________________________
llvm-bugs mailing list
[email protected]
http://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-bugs
