Iain Sandoe <i...@sandoe.co.uk> wrote:
> Nathan Sidwell <nat...@acm.org> wrote:
>
>> On 6/8/20 5:17 AM, Iain Sandoe wrote:
>>> + r = gro_is_void_p ? integer_zero_node : rvalue (gro);
>>> + /* The return object is constructed, even if the gro is void. */
>>
>> Would error_mark_node work here? I presume we've already diagnosed the
>> problem, so will result in no cascade of errors.
>
> We have not diagnosed the problem - it’s valid to have a void g-r-o and a
> non-void function
> return.
>
> I am not sure the circumstance has been identified specifically where this
> (valid) permutation
> is found together with a specialization of the traits that has a non-class
> return type. (I spotted
> this as a corner-case while working on the code).
>
> Perhaps I should construct a test-case and see how the other compilers handle
> it.
I did this anyway …
To answer your original question, we need to diagnose this specifically.
clang does so, I’ve now matched the diagnostic for GCC.
we can then propagate an error_mark_node onwards.
OK now?
Iain
===
The PR reports that we fail to destroy the object initially created from
the get-return-object call. Fixed by adding a cleanup when the DTOR is
non-trivial. In addition, to meet the specific wording that the call to
get_return_object creates the glvalue for the return, we must construct
that in-place in the return object to avoid a second copy/move CTOR.
gcc/cp/ChangeLog:
PR c++/95477
* coroutines.cc (morph_fn_to_coro): Apply a cleanup to
the get return object when the DTOR is non-trivial.
gcc/testsuite/ChangeLog:
PR c++/95477
* g++.dg/coroutines/pr95477.C: New test.
* g++.dg/coroutines/void-gro-non-class-coro.C: New test.
---
gcc/cp/coroutines.cc | 69 ++++++++++++++++---
gcc/testsuite/g++.dg/coroutines/pr95477.C | 37 ++++++++++
.../coroutines/void-gro-non-class-coro.C | 59 ++++++++++++++++
3 files changed, 155 insertions(+), 10 deletions(-)
create mode 100644 gcc/testsuite/g++.dg/coroutines/pr95477.C
create mode 100644 gcc/testsuite/g++.dg/coroutines/void-gro-non-class-coro.C
diff --git a/gcc/cp/coroutines.cc b/gcc/cp/coroutines.cc
index 11fca9954ac..d4f582e91e2 100644
--- a/gcc/cp/coroutines.cc
+++ b/gcc/cp/coroutines.cc
@@ -4280,12 +4280,34 @@ morph_fn_to_coro (tree orig, tree *resumer, tree
*destroyer)
tree gro = NULL_TREE;
tree gro_bind_vars = NULL_TREE;
+ tree gro_cleanup_stmt = NULL_TREE;
/* We have to sequence the call to get_return_object before initial
suspend. */
if (gro_is_void_p)
- finish_expr_stmt (get_ro);
+ r = get_ro;
+ else if (same_type_p (gro_type, fn_return_type))
+ {
+ /* [dcl.fct.def.coroutine] / 7
+ The expression promise.get_return_object() is used to initialize the
+ glvalue result or... (see below)
+ Construct the return result directly. */
+ if (TYPE_NEEDS_CONSTRUCTING (gro_type))
+ {
+ vec<tree, va_gc> *arg = make_tree_vector_single (get_ro);
+ r = build_special_member_call (DECL_RESULT (orig),
+ complete_ctor_identifier,
+ &arg, gro_type, LOOKUP_NORMAL,
+ tf_warning_or_error);
+ release_tree_vector (arg);
+ }
+ else
+ r = build2_loc (fn_start, INIT_EXPR, gro_type,
+ DECL_RESULT (orig), get_ro);
+ }
else
{
+ /* ... or ... Construct an object that will be used as the single
+ param to the CTOR for the return object. */
gro = build_lang_decl (VAR_DECL, get_identifier ("coro.gro"), gro_type);
DECL_CONTEXT (gro) = current_scope ();
DECL_ARTIFICIAL (gro) = true;
@@ -4302,8 +4324,21 @@ morph_fn_to_coro (tree orig, tree *resumer, tree
*destroyer)
}
else
r = build2_loc (fn_start, INIT_EXPR, gro_type, gro, get_ro);
- finish_expr_stmt (r);
+ /* The constructed object might require a cleanup. */
+ if (TYPE_HAS_NONTRIVIAL_DESTRUCTOR (gro_type))
+ {
+ tree cleanup
+ = build_special_member_call (gro, complete_dtor_identifier,
+ NULL, gro_type, LOOKUP_NORMAL,
+ tf_warning_or_error);
+ gro_cleanup_stmt = build_stmt (input_location, CLEANUP_STMT, NULL,
+ cleanup, gro);
+ }
}
+ finish_expr_stmt (r);
+
+ if (gro_cleanup_stmt)
+ CLEANUP_BODY (gro_cleanup_stmt) = push_stmt_list ();
/* Initialize the resume_idx_name to 0, meaning "not started". */
tree resume_idx_m
@@ -4345,16 +4380,15 @@ morph_fn_to_coro (tree orig, tree *resumer, tree
*destroyer)
promise was constructed. We now supply a reference to that var,
either as the return value (if it's the same type) or to the CTOR
for an object of the return type. */
- if (gro_is_void_p)
- r = NULL_TREE;
- else
- r = rvalue (gro);
- if (!same_type_p (gro_type, fn_return_type))
+ if (same_type_p (gro_type, fn_return_type))
+ r = gro_is_void_p ? NULL_TREE : DECL_RESULT (orig);
+ else
{
- /* The return object is , even if the gro is void. */
if (CLASS_TYPE_P (fn_return_type))
{
+ /* For class type return objects, we can attempt to construct,
+ even if the gro is void. */
vec<tree, va_gc> *args = NULL;
vec<tree, va_gc> **arglist = NULL;
if (!gro_is_void_p)
@@ -4370,12 +4404,27 @@ morph_fn_to_coro (tree orig, tree *resumer, tree
*destroyer)
if (args)
release_tree_vector (args);
}
- else /* ??? suppose we have non-class return and void gro? */
- r = build1_loc (input_location, CONVERT_EXPR, fn_return_type, r);
+ else if (gro_is_void_p)
+ {
+ /* We can't initialize a non-class return value from void. */
+ error_at (input_location, "cannot initialize a return object of type"
+ " %qT with an rvalue of type %<void%>", fn_return_type);
+ r = error_mark_node;
+ }
+ else
+ r = build1_loc (input_location, CONVERT_EXPR,
+ fn_return_type, rvalue (gro));
}
finish_return_stmt (r);
+ if (gro_cleanup_stmt)
+ {
+ CLEANUP_BODY (gro_cleanup_stmt)
+ = pop_stmt_list (CLEANUP_BODY (gro_cleanup_stmt));
+ add_stmt (gro_cleanup_stmt);
+ }
+
/* Finish up the ramp function. */
BIND_EXPR_VARS (gro_context_bind) = gro_bind_vars;
BIND_EXPR_BODY (gro_context_bind) = pop_stmt_list (gro_context_body);
diff --git a/gcc/testsuite/g++.dg/coroutines/pr95477.C
b/gcc/testsuite/g++.dg/coroutines/pr95477.C
new file mode 100644
index 00000000000..7050aee0078
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/pr95477.C
@@ -0,0 +1,37 @@
+// { dg-do run }
+
+#include "coro.h"
+
+struct simple {
+ static inline int alive = 0;
+ simple() { ++alive; }
+ simple(simple&&) { ++alive; }
+ ~simple() { --alive; }
+
+ struct promise_type {
+ simple get_return_object() { return simple{}; }
+ void return_void() {}
+ void unhandled_exception() {}
+ auto initial_suspend() noexcept { return coro::suspend_never{}; }
+ auto final_suspend() noexcept { return coro::suspend_never{}; }
+ };
+};
+
+simple
+f()
+{
+ co_return;
+}
+
+int main() {
+ {
+ f();
+ }
+
+ if (simple::alive != 0)
+ {
+ PRINTF ("something wrong with dtors: %d\n", simple::alive);
+ abort ();
+ }
+ return 0;
+}
diff --git a/gcc/testsuite/g++.dg/coroutines/void-gro-non-class-coro.C
b/gcc/testsuite/g++.dg/coroutines/void-gro-non-class-coro.C
new file mode 100644
index 00000000000..d9e53fe4c76
--- /dev/null
+++ b/gcc/testsuite/g++.dg/coroutines/void-gro-non-class-coro.C
@@ -0,0 +1,59 @@
+// Test handling of the case where we have a void g-r-o and a non-void
+// and non-class-type ramp return.
+
+#include "coro.h"
+
+int g_promise = -1;
+
+template<typename R, typename HandleRef, typename ...T>
+struct std::coroutine_traits<R, HandleRef, T...> {
+ struct promise_type {
+ promise_type (HandleRef h, T ...args)
+ { h = std::coroutine_handle<promise_type>::from_promise (*this);
+ PRINT ("Created Promise");
+ g_promise = 1;
+ }
+ ~promise_type () { PRINT ("Destroyed Promise"); g_promise = 0;}
+ void get_return_object() {}
+
+ auto initial_suspend() {
+ return std::suspend_always{};
+ }
+ auto final_suspend() { return std::suspend_never{}; }
+
+ void return_void() {}
+ void unhandled_exception() {}
+ };
+};
+
+int
+my_coro (std::coroutine_handle<>& h)
+{
+ PRINT ("coro1: about to return");
+ co_return;
+} // dg-error {cannot initialize a return object of type ‘int’ with an rvalue
of type ‘void’}
+
+int main ()
+{
+ std::coroutine_handle<> h;
+ int t = my_coro (h);
+
+ if (h.done())
+ {
+ PRINT ("main: apparently was already done...");
+ abort ();
+ }
+
+ // initial suspend.
+ h.resume ();
+
+ // The coro should have self-destructed.
+ if (g_promise)
+ {
+ PRINT ("main: apparently we did not complete...");
+ abort ();
+ }
+
+ PRINT ("main: returning");
+ return 0;
+}
--
2.24.1
