https://gcc.gnu.org/bugzilla/show_bug.cgi?id=117620
Bug ID: 117620
Summary: Problem passing rvalue to co_yield (maybe?)
Product: gcc
Version: 14.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: mwd at md5i dot com
Target Milestone: ---
Created attachment 59606
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=59606&action=edit
Example code
When I compile the attached test code with -std=c++20, I get the following
error:
foo.cpp: In function ‘void get_values_2(get_values_2(int,
int)::_Z12get_values_2ii.Frame*)’:
foo.cpp:218:1: error: use of deleted function ‘constexpr
Generator<int>::Generator(const Generator<int>&)’
218 | }
| ^
foo.cpp:15:7: note: ‘constexpr Generator<int>::Generator(const
Generator<int>&)’ is implicitly declared as deleted because ‘Generator<int>’
declares a move constructor or move assignment operator
15 | class Generator : std::ranges::view_interface<Generator<T>>
| ^~~~~~~~~
foo.cpp:215:1: note: use ‘-fdiagnostics-all-candidates’ to display considered
candidates
218 | }
| ^
Setting aside the fact that there are non-demangled identifiers in the output,
this is triggered by the co_yield on line 214 of the code, which reads:
co_yield elements_of{get_values(low, high)};
If I rewrite the code (recompile with -DFIXED) as follows:
auto x = elements_of{get_values(low, high)};
co_yield std::move(x);
I do not get an error and everything runs correctly. I cannot understand why
these should generate different results. I also cannot figure out how and
where the call to the purported Generator<int> copy constructor occurs.
