On 5/29/25 6:56 AM, Iain Sandoe wrote:
Tested on x86_64-darwin, confirming that the original reported code fails without the change here. Unfortunately, if we add a move constructor to the reduced case, it no longer fails on unpatched trunk - so not proposing to add that as a testcase (since it tests something unrelated to coroutines).
Actually, I think I was wrong and the reduced testcase is fine after all -- the problem was indeed of trying to check the conversion for a class without a move constructor, when we want to avoid that check with NRVO in a ramp.
In the original testcase TaskBase has a move constructor, but LazyTask still doesn't. Adding a move constructor to TaskBase and a destructor to LazyTask in the reduced testcase would more precisely preserve the situation, but I think the reduced testcase without changes is good enough.
So please do add the testcase. OK with that change.
OK for trunk? thanks Iain --- 8< --- The existing implementation, incorrectly, tried to use DECL_RAMP_FN in check_return_expr to determine if we are handling a ramp func. However, that query is only set for the resume/destroy functions. Replace the use of DECL_RAMP_FN with a new query. PR c++/120453 gcc/cp/ChangeLog: * cp-tree.h (DECL_RAMP_P): New. * typeck.cc (check_return_expr): Use DECL_RAMP_P instead of DECL_RAMP_FN. Signed-off-by: Iain Sandoe <i...@sandoe.co.uk> --- gcc/cp/cp-tree.h | 4 ++++ gcc/cp/typeck.cc | 2 +- 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/gcc/cp/cp-tree.h b/gcc/cp/cp-tree.h index 19c0b452d86..d9fc80b92e5 100644 --- a/gcc/cp/cp-tree.h +++ b/gcc/cp/cp-tree.h @@ -5522,6 +5522,10 @@ decl_template_parm_check (const_tree t, const char *f, int l, const char *fn) #define DECL_RAMP_FN(NODE) \ (coro_get_ramp_function (NODE))+/* For a FUNCTION_DECL this is true if it is a coroutine ramp. */+#define DECL_RAMP_P(NODE) \ + DECL_COROUTINE_P (NODE) && !DECL_RAMP_FN (NODE) + /* True for an OMP_ATOMIC that has dependent parameters. These are stored as an expr in operand 1, and integer_zero_node or clauses in operand 0. */ #define OMP_ATOMIC_DEPENDENT_P(NODE) \ diff --git a/gcc/cp/typeck.cc b/gcc/cp/typeck.cc index af2cbaff8fd..ac1eb397f01 100644 --- a/gcc/cp/typeck.cc +++ b/gcc/cp/typeck.cc @@ -11466,7 +11466,7 @@ check_return_expr (tree retval, bool *no_warning, bool *dangling) /* Don't check copy-initialization for NRV in a coroutine ramp; we implement this case as NRV, but it's specified as directly initializing the return value from get_return_object(). */ - if (DECL_RAMP_FN (current_function_decl) && named_return_value_okay_p) + if (DECL_RAMP_P (current_function_decl) && named_return_value_okay_p) converted = true;/* First convert the value to the function's return type, then
