vendor/clang/clang-trunk-r366426

1 files changed, 63 insertions, 39 deletions

diff --git a/lib/Sema/SemaCoroutine.cpp b/lib/Sema/SemaCoroutine.cpp
index 181efa6d3dd0..f0347af6a1bb 100644
--- a/lib/Sema/SemaCoroutine.cpp
+++ b/lib/Sema/SemaCoroutine.cpp
@@ -1,9 +1,8 @@
-//===--- SemaCoroutines.cpp - Semantic Analysis for Coroutines ------------===//
+//===-- SemaCoroutine.cpp - Semantic Analysis for Coroutines --------------===//
 //
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
@@ -186,21 +185,8 @@ static QualType lookupCoroutineHandleType(Sema &S, QualType PromiseType,
 
 static bool isValidCoroutineContext(Sema &S, SourceLocation Loc,
                                     StringRef Keyword) {
-  // 'co_await' and 'co_yield' are not permitted in unevaluated operands,
-  // such as subexpressions of \c sizeof.
-  //
-  // [expr.await]p2, emphasis added: "An await-expression shall appear only in
-  // a *potentially evaluated* expression within the compound-statement of a
-  // function-body outside of a handler [...] A context within a function where
-  // an await-expression can appear is called a suspension context of the
-  // function." And per [expr.yield]p1: "A yield-expression shall appear only
-  // within a suspension context of a function."
-  if (S.isUnevaluatedContext()) {
-    S.Diag(Loc, diag::err_coroutine_unevaluated_context) << Keyword;
-    return false;
-  }
-
-  // Per [expr.await]p2, any other usage must be within a function.
+  // [expr.await]p2 dictates that 'co_await' and 'co_yield' must be used within
+  // a function body.
   // FIXME: This also covers [expr.await]p2: "An await-expression shall not
   // appear in a default argument." But the diagnostic QoI here could be
   // improved to inform the user that default arguments specifically are not
@@ -218,12 +204,11 @@ static bool isValidCoroutineContext(Sema &S, SourceLocation Loc,
   enum InvalidFuncDiag {
     DiagCtor = 0,
     DiagDtor,
-    DiagCopyAssign,
-    DiagMoveAssign,
     DiagMain,
     DiagConstexpr,
     DiagAutoRet,
     DiagVarargs,
+    DiagConsteval,
   };
   bool Diagnosed = false;
   auto DiagInvalid = [&](InvalidFuncDiag ID) {
@@ -232,23 +217,15 @@ static bool isValidCoroutineContext(Sema &S, SourceLocation Loc,
     return false;
   };
 
-  // Diagnose when a constructor, destructor, copy/move assignment operator,
+  // Diagnose when a constructor, destructor
   // or the function 'main' are declared as a coroutine.
   auto *MD = dyn_cast<CXXMethodDecl>(FD);
-  // [class.ctor]p6: "A constructor shall not be a coroutine."
+  // [class.ctor]p11: "A constructor shall not be a coroutine."
   if (MD && isa<CXXConstructorDecl>(MD))
     return DiagInvalid(DiagCtor);
   // [class.dtor]p17: "A destructor shall not be a coroutine."
   else if (MD && isa<CXXDestructorDecl>(MD))
     return DiagInvalid(DiagDtor);
-  // N4499 [special]p6: "A special member function shall not be a coroutine."
-  // Per C++ [special]p1, special member functions are the "default constructor,
-  // copy constructor and copy assignment operator, move constructor and move
-  // assignment operator, and destructor."
-  else if (MD && MD->isCopyAssignmentOperator())
-    return DiagInvalid(DiagCopyAssign);
-  else if (MD && MD->isMoveAssignmentOperator())
-    return DiagInvalid(DiagMoveAssign);
   // [basic.start.main]p3: "The function main shall not be a coroutine."
   else if (FD->isMain())
     return DiagInvalid(DiagMain);
@@ -258,7 +235,7 @@ static bool isValidCoroutineContext(Sema &S, SourceLocation Loc,
   // evaluation of e [...] would evaluate one of the following expressions:
   // [...] an await-expression [...] a yield-expression."
   if (FD->isConstexpr())
-    DiagInvalid(DiagConstexpr);
+    DiagInvalid(FD->isConsteval() ? DiagConsteval : DiagConstexpr);
   // [dcl.spec.auto]p15: "A function declared with a return type that uses a
   // placeholder type shall not be a coroutine."
   if (FD->getReturnType()->isUndeducedType())
@@ -326,7 +303,7 @@ static Expr *buildBuiltinCall(Sema &S, SourceLocation Loc, Builtin::ID Id,
   assert(DeclRef.isUsable() && "Builtin reference cannot fail");
 
   ExprResult Call =
-      S.ActOnCallExpr(/*Scope=*/nullptr, DeclRef.get(), Loc, CallArgs, Loc);
+      S.BuildCallExpr(/*Scope=*/nullptr, DeclRef.get(), Loc, CallArgs, Loc);
 
   assert(!Call.isInvalid() && "Call to builtin cannot fail!");
   return Call.get();
@@ -356,7 +333,7 @@ static ExprResult buildCoroutineHandle(Sema &S, QualType PromiseType,
   if (FromAddr.isInvalid())
     return ExprError();
 
-  return S.ActOnCallExpr(nullptr, FromAddr.get(), Loc, FramePtr, Loc);
+  return S.BuildCallExpr(nullptr, FromAddr.get(), Loc, FramePtr, Loc);
 }
 
 struct ReadySuspendResumeResult {
@@ -388,7 +365,7 @@ static ExprResult buildMemberCall(Sema &S, Expr *Base, SourceLocation Loc,
     return ExprError();
   }
 
-  return S.ActOnCallExpr(nullptr, Result.get(), Loc, Args, Loc, nullptr);
+  return S.BuildCallExpr(nullptr, Result.get(), Loc, Args, Loc, nullptr);
 }
 
 // See if return type is coroutine-handle and if so, invoke builtin coro-resume
@@ -669,12 +646,57 @@ bool Sema::ActOnCoroutineBodyStart(Scope *SC, SourceLocation KWLoc,
   return true;
 }
 
+// Recursively walks up the scope hierarchy until either a 'catch' or a function
+// scope is found, whichever comes first.
+static bool isWithinCatchScope(Scope *S) {
+  // 'co_await' and 'co_yield' keywords are disallowed within catch blocks, but
+  // lambdas that use 'co_await' are allowed. The loop below ends when a
+  // function scope is found in order to ensure the following behavior:
+  //
+  // void foo() {      // <- function scope
+  //   try {           //
+  //     co_await x;   // <- 'co_await' is OK within a function scope
+  //   } catch {       // <- catch scope
+  //     co_await x;   // <- 'co_await' is not OK within a catch scope
+  //     []() {        // <- function scope
+  //       co_await x; // <- 'co_await' is OK within a function scope
+  //     }();
+  //   }
+  // }
+  while (S && !(S->getFlags() & Scope::FnScope)) {
+    if (S->getFlags() & Scope::CatchScope)
+      return true;
+    S = S->getParent();
+  }
+  return false;
+}
+
+// [expr.await]p2, emphasis added: "An await-expression shall appear only in
+// a *potentially evaluated* expression within the compound-statement of a
+// function-body *outside of a handler* [...] A context within a function
+// where an await-expression can appear is called a suspension context of the
+// function."
+static void checkSuspensionContext(Sema &S, SourceLocation Loc,
+                                   StringRef Keyword) {
+  // First emphasis of [expr.await]p2: must be a potentially evaluated context.
+  // That is, 'co_await' and 'co_yield' cannot appear in subexpressions of
+  // \c sizeof.
+  if (S.isUnevaluatedContext())
+    S.Diag(Loc, diag::err_coroutine_unevaluated_context) << Keyword;
+
+  // Second emphasis of [expr.await]p2: must be outside of an exception handler.
+  if (isWithinCatchScope(S.getCurScope()))
+    S.Diag(Loc, diag::err_coroutine_within_handler) << Keyword;
+}
+
 ExprResult Sema::ActOnCoawaitExpr(Scope *S, SourceLocation Loc, Expr *E) {
   if (!ActOnCoroutineBodyStart(S, Loc, "co_await")) {
     CorrectDelayedTyposInExpr(E);
     return ExprError();
   }
 
+  checkSuspensionContext(*this, Loc, "co_await");
+
   if (E->getType()->isPlaceholderType()) {
     ExprResult R = CheckPlaceholderExpr(E);
     if (R.isInvalid()) return ExprError();
@@ -772,6 +794,8 @@ ExprResult Sema::ActOnCoyieldExpr(Scope *S, SourceLocation Loc, Expr *E) {
     return ExprError();
   }
 
+  checkSuspensionContext(*this, Loc, "co_yield");
+
   // Build yield_value call.
   ExprResult Awaitable = buildPromiseCall(
       *this, getCurFunction()->CoroutinePromise, Loc, "yield_value", E);
@@ -1072,7 +1096,7 @@ bool CoroutineStmtBuilder::makeReturnOnAllocFailure() {
     return false;
 
   ExprResult ReturnObjectOnAllocationFailure =
-      S.ActOnCallExpr(nullptr, DeclNameExpr.get(), Loc, {}, Loc);
+      S.BuildCallExpr(nullptr, DeclNameExpr.get(), Loc, {}, Loc);
   if (ReturnObjectOnAllocationFailure.isInvalid())
     return false;
 
@@ -1235,7 +1259,7 @@ bool CoroutineStmtBuilder::makeNewAndDeleteExpr() {
     NewArgs.push_back(Arg);
 
   ExprResult NewExpr =
-      S.ActOnCallExpr(S.getCurScope(), NewRef.get(), Loc, NewArgs, Loc);
+      S.BuildCallExpr(S.getCurScope(), NewRef.get(), Loc, NewArgs, Loc);
   NewExpr = S.ActOnFinishFullExpr(NewExpr.get(), /*DiscardedValue*/ false);
   if (NewExpr.isInvalid())
     return false;
@@ -1261,7 +1285,7 @@ bool CoroutineStmtBuilder::makeNewAndDeleteExpr() {
     DeleteArgs.push_back(FrameSize);
 
   ExprResult DeleteExpr =
-      S.ActOnCallExpr(S.getCurScope(), DeleteRef.get(), Loc, DeleteArgs, Loc);
+      S.BuildCallExpr(S.getCurScope(), DeleteRef.get(), Loc, DeleteArgs, Loc);
   DeleteExpr =
       S.ActOnFinishFullExpr(DeleteExpr.get(), /*DiscardedValue*/ false);
   if (DeleteExpr.isInvalid())