[coroutines] Add DependentCoawaitExpr and fix re-building CoroutineBodyStmt.

Summary:
The changes contained in this patch are:

1. Defines a new AST node `CoawaitDependentExpr` for representing co_await expressions while the promise type is still dependent.
2. Correctly detect and transform the 'co_await' operand to  `p.await_transform(<expr>)`  when possible.
3. Change the initial/final suspend points to build during the initial parse, so they have the correct operator co_await lookup results.
4.  Fix transformation of the CoroutineBodyStmt so that it doesn't re-build the final/initial suspends.


@rsmith: This change is a little big, but it's not trivial for me to split it up. Please let me know if you would prefer this submitted as multiple patches.



Reviewers: rsmith, GorNishanov

Reviewed By: rsmith

Subscribers: ABataev, rsmith, mehdi_amini, cfe-commits

Differential Revision: https://reviews.llvm.org/D26057

llvm-svn: 297093

6 files changed, 20 insertions, 0 deletions

diff --git a/clang/lib/AST/Expr.cpp b/clang/lib/AST/Expr.cpp
index c22661758c8..224dec17f14 100644
--- a/clang/lib/AST/Expr.cpp
+++ b/clang/lib/AST/Expr.cpp
@@ -2958,6 +2958,7 @@ bool Expr::HasSideEffects(const ASTContext &Ctx,
   case CXXNewExprClass:
   case CXXDeleteExprClass:
   case CoawaitExprClass:
+  case DependentCoawaitExprClass:
   case CoyieldExprClass:
     // These always have a side-effect.
     return true;
diff --git a/clang/lib/AST/ExprClassification.cpp b/clang/lib/AST/ExprClassification.cpp
index adb74b80b19..76c548f82ab 100644
--- a/clang/lib/AST/ExprClassification.cpp
+++ b/clang/lib/AST/ExprClassification.cpp
@@ -129,6 +129,7 @@ static Cl::Kinds ClassifyInternal(ASTContext &Ctx, const Expr *E) {
   case Expr::UnresolvedLookupExprClass:
   case Expr::UnresolvedMemberExprClass:
   case Expr::TypoExprClass:
+  case Expr::DependentCoawaitExprClass:
   case Expr::CXXDependentScopeMemberExprClass:
   case Expr::DependentScopeDeclRefExprClass:
     // ObjC instance variables are lvalues
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index ddc48de2c67..ae8a63693f2 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -10216,6 +10216,7 @@ static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) {
   case Expr::LambdaExprClass:
   case Expr::CXXFoldExprClass:
   case Expr::CoawaitExprClass:
+  case Expr::DependentCoawaitExprClass:
   case Expr::CoyieldExprClass:
     return ICEDiag(IK_NotICE, E->getLocStart());
 
diff --git a/clang/lib/AST/ItaniumMangle.cpp b/clang/lib/AST/ItaniumMangle.cpp
index 084b6c3d731..82ae9c0e328 100644
--- a/clang/lib/AST/ItaniumMangle.cpp
+++ b/clang/lib/AST/ItaniumMangle.cpp
@@ -4034,6 +4034,12 @@ recurse:
     mangleExpression(cast<CoawaitExpr>(E)->getOperand());
     break;
 
+  case Expr::DependentCoawaitExprClass:
+    // FIXME: Propose a non-vendor mangling.
+    Out << "v18co_await";
+    mangleExpression(cast<DependentCoawaitExpr>(E)->getOperand());
+    break;
+
   case Expr::CoyieldExprClass:
     // FIXME: Propose a non-vendor mangling.
     Out << "v18co_yield";
diff --git a/clang/lib/AST/StmtPrinter.cpp b/clang/lib/AST/StmtPrinter.cpp
index 1ba1aa40ec5..21f5259c3ca 100644
--- a/clang/lib/AST/StmtPrinter.cpp
+++ b/clang/lib/AST/StmtPrinter.cpp
@@ -2475,6 +2475,13 @@ void StmtPrinter::VisitCoawaitExpr(CoawaitExpr *S) {
   PrintExpr(S->getOperand());
 }
 
+
+void StmtPrinter::VisitDependentCoawaitExpr(DependentCoawaitExpr *S) {
+  OS << "co_await ";
+  PrintExpr(S->getOperand());
+}
+
+
 void StmtPrinter::VisitCoyieldExpr(CoyieldExpr *S) {
   OS << "co_yield ";
   PrintExpr(S->getOperand());
diff --git a/clang/lib/AST/StmtProfile.cpp b/clang/lib/AST/StmtProfile.cpp
index 5f3a50b155b..f1fbe2806b5 100644
--- a/clang/lib/AST/StmtProfile.cpp
+++ b/clang/lib/AST/StmtProfile.cpp
@@ -1725,6 +1725,10 @@ void StmtProfiler::VisitCoawaitExpr(const CoawaitExpr *S) {
   VisitExpr(S);
 }
 
+void StmtProfiler::VisitDependentCoawaitExpr(const DependentCoawaitExpr *S) {
+  VisitExpr(S);
+}
+
 void StmtProfiler::VisitCoyieldExpr(const CoyieldExpr *S) {
   VisitExpr(S);
 }