[coroutines] Sema: Allow co_return all by itself.

Reviewers: rsmith, EricWF

Subscribers: mehdi_amini, llvm-commits, EricWF

Differential Revision: https://reviews.llvm.org/D26038

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@291513 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 1 insertions, 17 deletions

diff --git a/include/clang/Basic/DiagnosticSemaKinds.td b/include/clang/Basic/DiagnosticSemaKinds.td
index 6a8933f23e..3971cf60d5 100644
--- a/include/clang/Basic/DiagnosticSemaKinds.td
+++ b/include/clang/Basic/DiagnosticSemaKinds.td
@@ -8720,10 +8720,6 @@ def err_coroutine_invalid_func_context : Error<
   "|a copy assignment operator|a move assignment operator|the 'main' function"
   "|a constexpr function|a function with a deduced return type"
   "|a varargs function}0">;
-def ext_coroutine_without_co_await_co_yield : ExtWarn<
-  "'co_return' used in a function "
-  "that uses neither 'co_await' nor 'co_yield'">,
-  InGroup<DiagGroup<"coreturn-without-coawait">>;
 def err_implied_std_coroutine_traits_not_found : Error<
   "you need to include <experimental/coroutine> before defining a coroutine">;
 def err_malformed_std_coroutine_traits : Error<
diff --git a/lib/Sema/SemaCoroutine.cpp b/lib/Sema/SemaCoroutine.cpp
index 3109358df4..f6115c1bee 100644
--- a/lib/Sema/SemaCoroutine.cpp
+++ b/lib/Sema/SemaCoroutine.cpp
@@ -578,17 +578,6 @@ void Sema::CheckCompletedCoroutineBody(FunctionDecl *FD, Stmt *&Body) {
             isa<CoyieldExpr>(First) ? 1 : 2);
   }
 
-  bool AnyCoawaits = false;
-  bool AnyCoyields = false;
-  for (auto *CoroutineStmt : Fn->CoroutineStmts) {
-    AnyCoawaits |= isa<CoawaitExpr>(CoroutineStmt);
-    AnyCoyields |= isa<CoyieldExpr>(CoroutineStmt);
-  }
-
-  if (!AnyCoawaits && !AnyCoyields)
-    Diag(Fn->CoroutineStmts.front()->getLocStart(),
-         diag::ext_coroutine_without_co_await_co_yield);
-
   SourceLocation Loc = FD->getLocation();
 
   // Form a declaration statement for the promise declaration, so that AST
diff --git a/test/SemaCXX/coroutines.cpp b/test/SemaCXX/coroutines.cpp
index a22383cd56..158b1a7c7d 100644
--- a/test/SemaCXX/coroutines.cpp
+++ b/test/SemaCXX/coroutines.cpp
@@ -154,12 +154,11 @@ void mixed_await() {
 }
 
 void only_coreturn(void_tag) {
-  co_return; // expected-warning {{'co_return' used in a function that uses neither 'co_await' nor 'co_yield'}}
+  co_return; // OK
 }
 
 void mixed_coreturn(void_tag, bool b) {
   if (b)
-    // expected-warning@+1 {{'co_return' used in a function that uses neither}}
     co_return; // expected-note {{use of 'co_return'}}
   else
     return; // expected-error {{not allowed in coroutine}}