https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84855
Bug ID: 84855
Summary: structered bindings require "decomposed" type to be
copy'able
Product: gcc
Version: 8.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: h2+bugs at fsfe dot org
Target Milestone: ---
Created attachment 43647
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=43647&action=edit
example
If I do
foobar f; // has tuple-like interface
auto [ a, b ] = f;
Then for some reason foo needs to be copyable and I don't understand why, i.e.
perceive this as a bug, although both GCC and Clang require it.
I have attached a file that illustrates this. I would assume that invoking the
structed bindings just calls get() twice on the f, but gobolting the attached
code without optimisations reveals that indeed f is being copied.
And the actual problem is that explicitly deleting the copy-constructor of
foobar makes the build fail.
Like I said, maybe I am missing something here, but why would there be a copy
involved of type f. [Obviously there is copy involved of the members of f,
depending on the return type of get(), but that's a different matter from f].
Thank you for your help!
Confirmed on
g++-7 (Debian 7.3.0-8)
g++-8 (Debian 8-20180308-1)
clang version 5.0.1-2
