[CodeComplete] Propagate preferred type for function arguments in more cases

Summary:
See the added test for some new cases.
This change also removes special code completion calls inside the
ParseExpressionList function now that we properly propagate expected
type to the function responsible for parsing elements of the expression list
(ParseAssignmentExpression).

Reviewers: kadircet

Reviewed By: kadircet

Subscribers: xbolva00, jdoerfert, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D58541

llvm-svn: 354864

1 files changed, 10 insertions, 8 deletions

diff --git a/clang/lib/Parse/ParseDecl.cpp b/clang/lib/Parse/ParseDecl.cpp
index 882972d428c..84d79d9a473 100644
--- a/clang/lib/Parse/ParseDecl.cpp
+++ b/clang/lib/Parse/ParseDecl.cpp
@@ -2332,25 +2332,27 @@ Decl *Parser::ParseDeclarationAfterDeclaratorAndAttributes(
 
     InitializerScopeRAII InitScope(*this, D, ThisDecl);
 
-    llvm::function_ref<void()> ExprListCompleter;
     auto ThisVarDecl = dyn_cast_or_null<VarDecl>(ThisDecl);
-    auto ConstructorCompleter = [&, ThisVarDecl] {
+    auto RunSignatureHelp = [&]() {
       QualType PreferredType = Actions.ProduceConstructorSignatureHelp(
           getCurScope(), ThisVarDecl->getType()->getCanonicalTypeInternal(),
           ThisDecl->getLocation(), Exprs, T.getOpenLocation());
       CalledSignatureHelp = true;
-      Actions.CodeCompleteExpression(getCurScope(), PreferredType);
+      return PreferredType;
     };
+    auto SetPreferredType = [&] {
+      PreferredType.enterFunctionArgument(Tok.getLocation(), RunSignatureHelp);
+    };
+
+    llvm::function_ref<void()> ExpressionStarts;
     if (ThisVarDecl) {
       // ParseExpressionList can sometimes succeed even when ThisDecl is not
       // VarDecl. This is an error and it is reported in a call to
       // Actions.ActOnInitializerError(). However, we call
-      // ProduceConstructorSignatureHelp only on VarDecls, falling back to
-      // default completer in other cases.
-      ExprListCompleter = ConstructorCompleter;
+      // ProduceConstructorSignatureHelp only on VarDecls.
+      ExpressionStarts = SetPreferredType;
     }
-
-    if (ParseExpressionList(Exprs, CommaLocs, ExprListCompleter)) {
+    if (ParseExpressionList(Exprs, CommaLocs, ExpressionStarts)) {
       if (ThisVarDecl && PP.isCodeCompletionReached() && !CalledSignatureHelp) {
         Actions.ProduceConstructorSignatureHelp(
             getCurScope(), ThisVarDecl->getType()->getCanonicalTypeInternal(),