EricWF updated this revision to Diff 93739.
EricWF added a comment.

- Remove incorrectly added changes.

Note that this patch is built on top of https://reviews.llvm.org/D31487 and not 
trunk.


https://reviews.llvm.org/D31562

Files:
  include/clang/Basic/DiagnosticSemaKinds.td
  lib/Sema/SemaCoroutine.cpp
  test/SemaCXX/coroutines.cpp

Index: test/SemaCXX/coroutines.cpp
===================================================================
--- test/SemaCXX/coroutines.cpp
+++ test/SemaCXX/coroutines.cpp
@@ -654,6 +654,20 @@
   co_return; //expected-note {{function is a coroutine due to use of 'co_return' here}}
 }
 
+namespace std {
+  struct nothrow_t {};
+  constexpr nothrow_t nothrow = {};
+}
+
+using SizeT = decltype(sizeof(int));
+
+void* operator new(SizeT __sz, const std::nothrow_t&) noexcept;
+void  operator delete(void* __p, const std::nothrow_t&) noexcept;
+
+void* operator new[](SizeT __sz, const std::nothrow_t&) noexcept;
+void  operator delete[](void* __p, const std::nothrow_t&) noexcept;
+
+
 struct promise_on_alloc_failure_tag {};
 
 template<>
@@ -694,3 +708,25 @@
 }
 template coro<bad_promise_11> dependent_private_alloc_failure_handler(bad_promise_11);
 // expected-note@-1 {{requested here}}
+
+
+struct bad_promise_12 {
+  coro<bad_promise_12> get_return_object();
+  suspend_always initial_suspend();
+  suspend_always final_suspend();
+  void unhandled_exception();
+  void return_void();
+  static coro<bad_promise_12> get_return_object_on_allocation_failure();
+
+  static void* operator new(SizeT);
+  // expected-error@-1 2 {{'operator new' is required to have a non-throwing noexcept specification when the promise type declares 'get_return_object_on_allocation_failure()'}}
+};
+coro<bad_promise_12> throwing_in_class_new() { // expected-note {{call to 'operator new' implicitly required by coroutine function here}}
+  co_return;
+}
+
+template <class T>
+coro<T> dependent_throwing_in_class_new(T) { // expected-note {{call to 'operator new' implicitly required by coroutine function here}}
+   co_return;
+}
+template coro<bad_promise_12> dependent_throwing_in_class_new(bad_promise_12); // expected-note {{requested here}}
Index: lib/Sema/SemaCoroutine.cpp
===================================================================
--- lib/Sema/SemaCoroutine.cpp
+++ lib/Sema/SemaCoroutine.cpp
@@ -454,7 +454,7 @@
                                          /*IsImplicit*/ true);
     Suspend = S.ActOnFinishFullExpr(Suspend.get());
     if (Suspend.isInvalid()) {
-      S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
+      S.Diag(Loc, diag::note_coroutine_promise_suspend_implicitly_required)
           << ((Name == "initial_suspend") ? 0 : 1);
       S.Diag(KWLoc, diag::note_declared_coroutine_here) << Keyword;
       return StmtError();
@@ -660,6 +660,37 @@
   return Res;
 }
 
+/// Look up the std::nothrow object.
+static Expr *buildStdNoThrowDeclRef(Sema &S, SourceLocation Loc) {
+  NamespaceDecl *Std = S.getStdNamespace();
+  assert(Std && "Should already be diagnosed");
+
+  LookupResult Result(S, &S.PP.getIdentifierTable().get("nothrow"), Loc,
+                      Sema::LookupOrdinaryName);
+  if (!S.LookupQualifiedName(Result, Std)) {
+    // FIXME: <experimental/coroutine> should have been included already.
+    // If we require it to include <new> then this diagnostic is no longer
+    // needed.
+    S.Diag(Loc, diag::err_implicit_coroutine_std_nothrow_type_not_found);
+    return nullptr;
+  }
+
+  auto *VD = Result.getAsSingle<VarDecl>();
+  if (!VD) {
+    Result.suppressDiagnostics();
+    // We found something weird. Complain about the first thing we found.
+    NamedDecl *Found = *Result.begin();
+    S.Diag(Found->getLocation(), diag::err_malformed_std_nothrow);
+    return nullptr;
+  }
+
+  ExprResult DR = S.BuildDeclRefExpr(VD, VD->getType(), VK_LValue, Loc);
+  if (DR.isInvalid())
+    return nullptr;
+
+  return DR.get();
+}
+
 // Find an appropriate delete for the promise.
 static FunctionDecl *findDeleteForPromise(Sema &S, SourceLocation Loc,
                                           QualType PromiseType) {
@@ -815,23 +846,51 @@
   if (S.RequireCompleteType(Loc, PromiseType, diag::err_incomplete_type))
     return false;
 
-  // FIXME: Add nothrow_t placement arg for global alloc
-  //        if ReturnStmtOnAllocFailure != nullptr.
+  const bool RequiresNoThrowAlloc = ReturnStmtOnAllocFailure != nullptr;
+
   // FIXME: Add support for stateful allocators.
 
   FunctionDecl *OperatorNew = nullptr;
   FunctionDecl *OperatorDelete = nullptr;
   FunctionDecl *UnusedResult = nullptr;
   bool PassAlignment = false;
+  MultiExprArg PlacementArgs = None;
 
   S.FindAllocationFunctions(Loc, SourceRange(),
                             /*UseGlobal*/ false, PromiseType,
-                            /*isArray*/ false, PassAlignment,
-                            /*PlacementArgs*/ None, OperatorNew, UnusedResult);
+                            /*isArray*/ false, PassAlignment, PlacementArgs,
+                            OperatorNew, UnusedResult);
+
+  bool IsGlobalOverload =
+      OperatorNew && !isa<CXXRecordDecl>(OperatorNew->getDeclContext());
+  // If we didn't find a class-local new declaration and non-throwing new
+  // was is required then we need to lookup the non-throwing global operator
+  // instead.
+  if (RequiresNoThrowAlloc && (!OperatorNew || IsGlobalOverload)) {
+    auto *StdNoThrow = buildStdNoThrowDeclRef(S, Loc);
+    if (!StdNoThrow)
+      return false;
+    PlacementArgs = MultiExprArg(StdNoThrow);
+    OperatorNew = nullptr;
+    S.FindAllocationFunctions(Loc, SourceRange(),
+                              /*UseGlobal*/ true, PromiseType,
+                              /*isArray*/ false, PassAlignment, PlacementArgs,
+                              OperatorNew, UnusedResult);
+  }
 
-  OperatorDelete = findDeleteForPromise(S, Loc, PromiseType);
+  if (OperatorNew && RequiresNoThrowAlloc) {
+    const auto *FT = OperatorNew->getType()->getAs<FunctionProtoType>();
+    if (!FT->isNothrow(S.Context, /*ResultIfDependent*/ false)) {
+      S.Diag(OperatorNew->getLocation(),
+             diag::err_coroutine_promise_new_requires_nothrow)
+          << OperatorNew;
+      S.Diag(Loc, diag::note_coroutine_promise_call_implicitly_required)
+          << OperatorNew;
+      return false;
+    }
+  }
 
-  if (!OperatorDelete || !OperatorNew)
+  if ((OperatorDelete = findDeleteForPromise(S, Loc, PromiseType)) == nullptr)
     return false;
 
   Expr *FramePtr =
@@ -847,8 +906,12 @@
   if (NewRef.isInvalid())
     return false;
 
+  SmallVector<Expr *, 2> NewArgs{FrameSize};
+  for (auto Arg : PlacementArgs)
+    NewArgs.push_back(Arg);
+
   ExprResult NewExpr =
-      S.ActOnCallExpr(S.getCurScope(), NewRef.get(), Loc, FrameSize, Loc);
+      S.ActOnCallExpr(S.getCurScope(), NewRef.get(), Loc, NewArgs, Loc);
   if (NewExpr.isInvalid())
     return false;
 
@@ -869,7 +932,7 @@
   // Check if we need to pass the size.
   const auto *OpDeleteType =
       OpDeleteQualType.getTypePtr()->getAs<FunctionProtoType>();
-  if (OpDeleteType->getNumParams() > 1)
+  if ((OpDeleteType->getNumParams() - PlacementArgs.size()) > 1)
     DeleteArgs.push_back(FrameSize);
 
   ExprResult DeleteExpr =
Index: include/clang/Basic/DiagnosticSemaKinds.td
===================================================================
--- include/clang/Basic/DiagnosticSemaKinds.td
+++ include/clang/Basic/DiagnosticSemaKinds.td
@@ -8851,6 +8851,11 @@
 def err_implied_coroutine_type_not_found : Error<
   "%0 type was not found; include <experimental/coroutine> before defining "
   "a coroutine">;
+def err_implicit_coroutine_std_nothrow_type_not_found : Error<
+  "std::nothrow was not found; include <new> before defining a coroutine which "
+  "uses get_return_object_on_allocation_failure()">;
+def err_malformed_std_nothrow : Error<
+  "std::nothrow must be a valid variable declaration">;
 def err_malformed_std_coroutine_handle : Error<
   "std::experimental::coroutine_handle must be a class template">;
 def err_coroutine_handle_missing_member : Error<
@@ -8870,7 +8875,7 @@
   "%0 declares both 'return_value' and 'return_void'">;
 def note_coroutine_promise_implicit_await_transform_required_here : Note<
   "call to 'await_transform' implicitly required by 'co_await' here">;
-def note_coroutine_promise_call_implicitly_required : Note<
+def note_coroutine_promise_suspend_implicitly_required : Note<
   "call to '%select{initial_suspend|final_suspend}0' implicitly "
   "required by the %select{initial suspend point|final suspend point}0">;
 def err_coroutine_promise_unhandled_exception_required : Error<
@@ -8880,6 +8885,11 @@
   InGroup<Coroutine>;
 def err_coroutine_promise_get_return_object_on_allocation_failure : Error<
   "%0: 'get_return_object_on_allocation_failure()' must be a static member function">;
+def err_coroutine_promise_new_requires_nothrow : Error<
+  "%0 is required to have a non-throwing noexcept specification when the promise "
+   "type declares 'get_return_object_on_allocation_failure()'">;
+def note_coroutine_promise_call_implicitly_required : Note<
+  "call to %0 implicitly required by coroutine function here">;
 }
 
 let CategoryName = "Documentation Issue" in {
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