[clang] [coroutines] Introduce [[clang::coro_lifetimebound]] (PR #72851)
Utkarsh Saxena via cfe-commits
cfe-commits at lists.llvm.org
Mon Nov 20 03:18:28 PST 2023
https://github.com/usx95 created https://github.com/llvm/llvm-project/pull/72851
None
>From 28e9fda4b78e1e60287048891cc92bafdef3ac4c Mon Sep 17 00:00:00 2001
From: Utkarsh Saxena <usx at google.com>
Date: Mon, 20 Nov 2023 12:17:30 +0100
Subject: [PATCH] Introduce [[clang::coro_lifetimebound]]
---
clang/include/clang/Basic/Attr.td | 8 ++
clang/include/clang/Basic/AttrDocs.td | 8 +-
clang/lib/Sema/SemaInit.cpp | 7 +-
...a-attribute-supported-attributes-list.test | 3 +-
clang/test/SemaCXX/coro-lifetimebound.cpp | 93 +++++++++++++++++++
5 files changed, 116 insertions(+), 3 deletions(-)
create mode 100644 clang/test/SemaCXX/coro-lifetimebound.cpp
diff --git a/clang/include/clang/Basic/Attr.td b/clang/include/clang/Basic/Attr.td
index f7a2b83b15ef5bc..dfe6f8999f832a3 100644
--- a/clang/include/clang/Basic/Attr.td
+++ b/clang/include/clang/Basic/Attr.td
@@ -1110,6 +1110,14 @@ def CoroWrapper : InheritableAttr {
let SimpleHandler = 1;
}
+def CoroLifetimeBound : InheritableAttr {
+ let Spellings = [Clang<"coro_lifetimebound">];
+ let Subjects = SubjectList<[CXXRecord]>;
+ let LangOpts = [CPlusPlus];
+ let Documentation = [CoroLifetimeBoundDoc];
+ let SimpleHandler = 1;
+}
+
// OSObject-based attributes.
def OSConsumed : InheritableParamAttr {
let Spellings = [Clang<"os_consumed">];
diff --git a/clang/include/clang/Basic/AttrDocs.td b/clang/include/clang/Basic/AttrDocs.td
index 438d846c39eaa57..39efaee20694a43 100644
--- a/clang/include/clang/Basic/AttrDocs.td
+++ b/clang/include/clang/Basic/AttrDocs.td
@@ -7483,7 +7483,6 @@ generation of the other destruction cases, optimizing the above `foo.destroy` to
}];
}
-
def CoroReturnTypeAndWrapperDoc : Documentation {
let Category = DocCatDecl;
let Content = [{
@@ -7540,3 +7539,10 @@ Note: ``a_promise_type::get_return_object`` is exempted from this analysis as it
implementation detail of any coroutine library.
}];
}
+
+def CoroLifetimeBoundDoc : Documentation {
+ let Category = DocCatDecl;
+ let Content = [{
+asdam
+}];
+}
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index 80b51b09bf5445f..631b6a266412ccb 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -7580,10 +7580,15 @@ static void visitLifetimeBoundArguments(IndirectLocalPath &Path, Expr *Call,
if (ObjectArg && implicitObjectParamIsLifetimeBound(Callee))
VisitLifetimeBoundArg(Callee, ObjectArg);
+ bool checkCoroCall = false;
+ if (const auto *RD = Callee->getReturnType()->getAsRecordDecl()) {
+ checkCoroCall |= RD->hasAttr<CoroLifetimeBoundAttr>() &&
+ RD->hasAttr<CoroReturnTypeAttr>();
+ }
for (unsigned I = 0,
N = std::min<unsigned>(Callee->getNumParams(), Args.size());
I != N; ++I) {
- if (Callee->getParamDecl(I)->hasAttr<LifetimeBoundAttr>())
+ if (checkCoroCall || Callee->getParamDecl(I)->hasAttr<LifetimeBoundAttr>())
VisitLifetimeBoundArg(Callee->getParamDecl(I), Args[I]);
}
}
diff --git a/clang/test/Misc/pragma-attribute-supported-attributes-list.test b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
index a57bc011c059483..dd91f4f88ad685b 100644
--- a/clang/test/Misc/pragma-attribute-supported-attributes-list.test
+++ b/clang/test/Misc/pragma-attribute-supported-attributes-list.test
@@ -56,9 +56,10 @@
// CHECK-NEXT: ConsumableAutoCast (SubjectMatchRule_record)
// CHECK-NEXT: ConsumableSetOnRead (SubjectMatchRule_record)
// CHECK-NEXT: Convergent (SubjectMatchRule_function)
+// CHECK-NEXT: CoroLifetimeBound (SubjectMatchRule_record)
// CHECK-NEXT: CoroOnlyDestroyWhenComplete (SubjectMatchRule_record)
// CHECK-NEXT: CoroReturnType (SubjectMatchRule_record)
-// CHECK-NEXT: CoroWrapper
+// CHECK-NEXT: CoroWrapper (SubjectMatchRule_function)
// CHECK-NEXT: CountedBy (SubjectMatchRule_field)
// CHECK-NEXT: DLLExport (SubjectMatchRule_function, SubjectMatchRule_variable, SubjectMatchRule_record, SubjectMatchRule_objc_interface)
// CHECK-NEXT: DLLImport (SubjectMatchRule_function, SubjectMatchRule_variable, SubjectMatchRule_record, SubjectMatchRule_objc_interface)
diff --git a/clang/test/SemaCXX/coro-lifetimebound.cpp b/clang/test/SemaCXX/coro-lifetimebound.cpp
new file mode 100644
index 000000000000000..3f719866eae0ee4
--- /dev/null
+++ b/clang/test/SemaCXX/coro-lifetimebound.cpp
@@ -0,0 +1,93 @@
+// RUN: %clang_cc1 -triple x86_64-apple-darwin9 %s -std=c++20 -fsyntax-only -verify -Wall -Wextra -Wno-error=unreachable-code -Wno-unused
+
+#include "Inputs/std-coroutine.h"
+
+using std::suspend_always;
+using std::suspend_never;
+
+template <typename T> struct [[clang::coro_lifetimebound, clang::coro_return_type]] Gen {
+ struct promise_type {
+ Gen<T> get_return_object() {
+ return {};
+ }
+ suspend_always initial_suspend();
+ suspend_always final_suspend() noexcept;
+ void unhandled_exception();
+ void return_value(const T &t);
+
+ template <typename U>
+ auto await_transform(const Gen<U> &) {
+ struct awaitable {
+ bool await_ready() noexcept { return false; }
+ void await_suspend(std::coroutine_handle<>) noexcept {}
+ U await_resume() noexcept { return {}; }
+ };
+ return awaitable{};
+ }
+ };
+};
+
+template <typename T> using Co = Gen<T>;
+
+Gen<int> foo_coro(const int& b);
+
+Gen<int> foo_coro(const int& b) {
+ if (b > 0)
+ co_return 1;
+ co_return 2;
+}
+
+int getInt() { return 0; }
+
+Co<int> bar_coro(const int &b, int c) {
+ int x = co_await foo_coro(b);
+ int y = co_await foo_coro(1);
+ int z = co_await foo_coro(getInt());
+ auto unsafe1 = foo_coro(1); // expected-warning {{temporary whose address is used as value of local variable}}
+ auto unsafe2 = foo_coro(getInt()); // expected-warning {{temporary whose address is used as value of local variable}}
+ auto safe1 = foo_coro(b);
+ auto safe2 = foo_coro(c);
+ co_return co_await foo_coro(co_await foo_coro(1));
+}
+
+[[clang::coro_wrapper]] Gen<int> plain_return_co(int b) {
+ return foo_coro(b); // expected-warning {{address of stack memory associated with parameter}}
+}
+
+[[clang::coro_wrapper]] Gen<int> safe_forwarding(const int& b) {
+ return foo_coro(b);
+}
+
+[[clang::coro_wrapper]] Gen<int> unsafe_wrapper(int b) {
+ return safe_forwarding(b); // expected-warning {{address of stack memory associated with parameter}}
+}
+
+[[clang::coro_wrapper]] Co<int> complex_plain_return(int b) {
+ return b > 0
+ ? foo_coro(1) // expected-warning {{returning address of local temporary object}}
+ : bar_coro(0, 1); // expected-warning {{returning address of local temporary object}}
+}
+
+#define CORO_WRAPPER \
+ _Pragma("clang diagnostic push") \
+ _Pragma("clang diagnostic ignored \"-Wc++23-extensions\"") \
+ [[clang::coro_wrapper]] \
+ _Pragma("clang diagnostic pop")
+
+void lambdas() {
+ auto unsafe_lambda = [] CORO_WRAPPER (int b) {
+ return foo_coro(b); // expected-warning {{address of stack memory associated with parameter}}
+ };
+ auto safe_lambda = [](int b) -> Co<int> {
+ int x = co_await foo_coro(1);
+ co_return x + co_await foo_coro(b);
+ };
+}
+// =============================================================================
+// Safe usage when parameters are value
+// =============================================================================
+namespace by_value {
+Gen<int> value_coro(int b) { co_return co_await foo_coro(b); }
+[[clang::coro_wrapper]] Gen<int> wrapper1(int b) { return value_coro(b); }
+[[clang::coro_wrapper]] Gen<int> wrapper2(const int& b) { return value_coro(b); }
+}
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