https://gcc.gnu.org/g:303bed670af962c01b77a4f0c51de97f70e8167e
commit r15-2932-g303bed670af962c01b77a4f0c51de97f70e8167e
Author: Patrick Palka <ppa...@redhat.com>
Date: Thu Aug 15 10:20:18 2024 -0400
c++/coroutines: fix passing *this to promise type, again [PR116327]
In r15-2210 we got rid of the unnecessary cast to lvalue reference when
passing *this to the promise type ctor, and as a drive-by change we also
simplified the code to use cp_build_fold_indirect_ref.
But it turns out cp_build_fold_indirect_ref does too much here, namely
it has a shortcut for returning current_class_ref if the operand is
current_class_ptr. The problem with that shortcut is current_class_ref
might have gotten clobbered earlier if it appeared in the function body,
since rewrite_param_uses walks and rewrites in-place all local variable
uses to their corresponding frame copy.
So later cp_build_fold_indirect_ref for *this will instead return the
clobbered current_class_ref i.e. *frame_ptr->this, which doesn't make
sense here since we're in the ramp function and not the actor function
where frame_ptr is in scope.
This patch fixes this by using the build_fold_indirect_ref instead of
cp_build_fold_indirect_ref.
PR c++/116327
PR c++/104981
PR c++/115550
gcc/cp/ChangeLog:
* coroutines.cc (morph_fn_to_coro): Use build_fold_indirect_ref
instead of cp_build_fold_indirect_ref.
gcc/testsuite/ChangeLog:
* g++.dg/coroutines/pr104981-preview-this.C: Improve coverage by
adding a non-static data member use within the coroutine member
function.
* g++.dg/coroutines/pr116327-preview-this.C: New test.
Reviewed-by: Jason Merrill <ja...@redhat.com>
Diff:
---
gcc/cp/coroutines.cc | 8 ++++++--
.../g++.dg/coroutines/pr104981-preview-this.C | 4 +++-
.../g++.dg/coroutines/pr116327-preview-this.C | 22 ++++++++++++++++++++++
3 files changed, 31 insertions(+), 3 deletions(-)
diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index 145ec4b1d16..f7791cbfb9a 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -4850,7 +4850,9 @@ morph_fn_to_coro (tree orig, tree *resumer, tree
*destroyer)
if (parm_i->this_ptr || parm_i->lambda_cobj)
{
/* We pass a reference to *this to the allocator lookup. */
- tree this_ref = cp_build_fold_indirect_ref (arg);
+ /* It's unsafe to use the cp_ version here since current_class_ref
+ might've gotten clobbered earlier during rewrite_param_uses.
*/
+ tree this_ref = build_fold_indirect_ref (arg);
vec_safe_push (args, this_ref);
}
else
@@ -5070,7 +5072,9 @@ morph_fn_to_coro (tree orig, tree *resumer, tree
*destroyer)
if (parm.this_ptr || parm.lambda_cobj)
{
/* We pass a reference to *this to the param preview. */
- tree this_ref = cp_build_fold_indirect_ref (arg);
+ /* It's unsafe to use the cp_ version here since current_class_ref
+ might've gotten clobbered earlier during rewrite_param_uses.
*/
+ tree this_ref = build_fold_indirect_ref (arg);
vec_safe_push (promise_args, this_ref);
}
else if (parm.rv_ref)
diff --git a/gcc/testsuite/g++.dg/coroutines/pr104981-preview-this.C
b/gcc/testsuite/g++.dg/coroutines/pr104981-preview-this.C
index 81eb963db4a..9f1e3970ce3 100644
--- a/gcc/testsuite/g++.dg/coroutines/pr104981-preview-this.C
+++ b/gcc/testsuite/g++.dg/coroutines/pr104981-preview-this.C
@@ -23,8 +23,10 @@ struct PromiseType {
};
struct Derived : Base {
+ int m = 41;
Result f() {
- co_return 42;
+ ++m;
+ co_return m;
}
};
diff --git a/gcc/testsuite/g++.dg/coroutines/pr116327-preview-this.C
b/gcc/testsuite/g++.dg/coroutines/pr116327-preview-this.C
new file mode 100644
index 00000000000..27b69a41392
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/pr116327-preview-this.C
@@ -0,0 +1,22 @@
+// PR c++/116327 - ICE in coroutine with parameter preview on lambda with
captures
+
+#include <coroutine>
+
+struct coroutine{
+ struct promise_type{
+ promise_type(const auto &...){}
+ std::suspend_never initial_suspend(){ return {}; }
+ std::suspend_always final_suspend()noexcept{ return {}; }
+ void unhandled_exception(){}
+ coroutine get_return_object(){ return {}; }
+ void return_value(int)noexcept{}
+ };
+};
+
+int main(){
+ auto f = [a=0](auto) -> coroutine {
+ co_return 2;
+ };
+ f(0);
+ return 0;
+}
