It is possible to use parameters of a parent function of a lambda in
unevaluated contexts without capturing them. By not capturing them, we
work around the usual mechanism we use to prevent rewriting captured
parameters. Prevent this by simply skipping rewrites in unevaluated
contexts. Those won't mind the value not being present anyway.
gcc/cp/ChangeLog:
PR c++/111728
* coroutines.cc (rewrite_param_uses): Skip unevaluated
subexpressions.
gcc/testsuite/ChangeLog:
PR c++/111728
* g++.dg/coroutines/pr111728.C: New test.
---
Evening!
This 'series' contains two patches for the coroutine implementation to
address two unrelated PRs.
The first prevents an ICE during coroutine parameter substitution by not
performing it in unevaluated contexts. Those contexts can contain names
that were not captured by lambdas but *are* parameters to coroutines.
In the testcase from the PR, the rewriting machinery finds a param in
the body of the coroutine, which it did not previously encounter while
processing the coroutine declaration, and that does not have a
DECL_VALUE_EXPR, and fails.
Since it is not really useful to rewrite parameter uses in unevaluated
contexts, we can just ignore those, preventing confusion (and the ICE).
Regression tested on x86_64-pc-linux-gnu.
OK for trunk?
TIA, have a lovely night.
gcc/cp/coroutines.cc | 6 +++++
gcc/testsuite/g++.dg/coroutines/pr111728.C | 29 ++++++++++++++++++++++
2 files changed, 35 insertions(+)
create mode 100644 gcc/testsuite/g++.dg/coroutines/pr111728.C
diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index e8f028df3ad..fb8f24e6c61 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -3755,6 +3755,12 @@ rewrite_param_uses (tree *stmt, int *do_subtree
ATTRIBUTE_UNUSED, void *d)
return cp_walk_tree (&t, rewrite_param_uses, d, NULL);
}
+ if (unevaluated_p (TREE_CODE (*stmt)))
+ {
+ *do_subtree = 0; // Nothing to do.
+ return NULL_TREE;
+ }
+
if (TREE_CODE (*stmt) != PARM_DECL)
return NULL_TREE;
diff --git a/gcc/testsuite/g++.dg/coroutines/pr111728.C
b/gcc/testsuite/g++.dg/coroutines/pr111728.C
new file mode 100644
index 00000000000..c1fee4b36a1
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/pr111728.C
@@ -0,0 +1,29 @@
+// { dg-do compile }
+// https://gcc.gnu.org/PR111728
+#include <coroutine>
+struct promise;
+struct coroutine : std::coroutine_handle<promise>
+{
+ using promise_type = ::promise;
+ bool await_ready() { return false; }
+ void await_suspend(coroutine_handle h) {}
+ int await_resume() { return {} ;}
+};
+struct promise
+{
+ coroutine get_return_object() { return {coroutine::from_promise(*this)}; }
+ std::suspend_always initial_suspend() noexcept { return {}; }
+ std::suspend_always final_suspend() noexcept { return {}; }
+ void return_void() {}
+ void unhandled_exception() {}
+};
+coroutine
+write_fields() {
+ int static_buffer[10];
+ co_await [](auto)
+ -> coroutine
+ {
+ if (sizeof(static_buffer));
+ co_return;
+ }(0);
+}
--
2.45.2
