https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89311
Bug ID: 89311
Summary: Brace initialization needlessly invokes destructor
Product: gcc
Version: 8.2.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: raphael.kubo.da.costa at intel dot com
Target Milestone: ---
This is related to bug 85552 and bug 57082 as far as I can see.
GCC and ICC fail to compile this (I'm using -std=gnu++14), whereas MSVC and
clang accept it:
#include <vector>
template <class T>
struct S {
~S() {
for (size_t i = 0; i < sources_.size(); ++i)
sources_[i]->frob();
}
private:
std::vector<T*> sources_;
};
class C;
struct T {
S<C> s_{};
};
<source>: In instantiation of 'S<Source>::~S() [with T = C]':
<source>:16:11: required from here
<source>:7:20: error: invalid use of incomplete type 'class C'
7 | sources_[i]->frob();
| ~~~~~~~~~~~~~^~~~
<source>:13:7: note: forward declaration of 'class C'
13 | class C;
| ^
which ends up requiring C to be fully declared before it can be used in T.
I think https://bugs.llvm.org/show_bug.cgi?id=39363#c8 touches upon this in
"The list-initialization case does not potentially-invoke the destructor in
C++11 or C++14 either (unlike non-list copy-initialization, list-initialization
directly executes a constructor on the destination object even in C++11, and as
a result there is no temporary object created to trigger the potential
invocation of a destructor). Clang gets that case right, but GCC has another
bug there".
