From 788b962aa00959e861b45767c5c88ec41ca30c21 Mon Sep 17 00:00:00 2001 From: Iain Sandoe Date: Tue, 23 Jun 2020 10:06:21 +0100 Subject: [PATCH] coroutines: Add a cleanup expression for g-r-o when needed [PR95477]. 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 | 71 ++++++++++++++++--- gcc/testsuite/g++.dg/coroutines/pr95477.C | 37 ++++++++++ .../coroutines/void-gro-non-class-coro.C | 59 +++++++++++++++ 3 files changed, 156 insertions(+), 11 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 3aaa3d4cd57..9cdb0c591d5 100644 --- a/gcc/cp/coroutines.cc +++ b/gcc/cp/coroutines.cc @@ -4279,12 +4279,34 @@ 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 *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; @@ -4301,8 +4323,21 @@ 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 @@ -4344,21 +4379,20 @@ 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 *args = NULL; vec **arglist = NULL; if (!gro_is_void_p) { - args = make_tree_vector_single (r); + args = make_tree_vector_single (rvalue (gro)); arglist = &args; } r = build_special_member_call (NULL_TREE, @@ -4369,12 +4403,27 @@ 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 %", 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..8176c8a10af --- /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 +struct std::coroutine_traits { + struct promise_type { + promise_type (HandleRef h, T ...args) + { h = std::coroutine_handle::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; +} -- 2.30.2