https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110872
Bug ID: 110872
Summary: coroutine postcondition is not evaluated
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: akrzemi1 at gmail dot com
Target Milestone: ---
Created attachment 55673
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55673&action=edit
demo program
A postconditon declared on a coroutine should be evaluated when the coroutine
is invoked and returns to the caller. But it isn't as per the following
Compiler Explorer link.
https://godbolt.org/z/48fh3f34j
The expectation is enforced by the fact that the compiler allows mentioning the
return type of the coroutine declaration:
```
template <typename T>
struct generator
{
// ...
bool is_valid() { return false; }
};
generator<int> val(int v)
[[post g: g.is_valid()]]
{
co_yield v;
}
```
Generally, I would expect that preconditions and postconditions on coroutines
should work the same as if the call to the coroutine was wrapped in a
forwarding function containing the preconditions and postconditions:
```
awaitable<int> f1(int i) // coroutine
[[pre: p(i)]]
[[post r: q(r)]];
awaitable<int> f2(int i); // coroutine
awaitable<int> ff2(int i)
[[pre: p(i)]]
[[post r: q(r)]];
{
return f2(i);
}
void caller()
{
f1(1); // these two calls should have analogous
ff2(1); // precondition and postcondition semantics
}
```
