[backported/clang-7] Optionally add code completion results for arrow instead of dot

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* https://reviews.llvm.org/D41537
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Currently getting such completions requires source correction,
reparsing and calling completion again. And if it shows no results
and rollback is required then it costs one more reparse.
With this change it's possible to get all results which can be
later filtered to split changes which require correction.

Change-Id: Id2fc3f0518fd53f2a6d0097da3ee723ddeb372ab
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@qt.io>

1 files changed, 21 insertions, 5 deletions

diff --git a/lib/Parse/ParseExpr.cpp b/lib/Parse/ParseExpr.cpp
index 1b8865edb7..cb28fcf9bd 100644
--- a/lib/Parse/ParseExpr.cpp
+++ b/lib/Parse/ParseExpr.cpp
@@ -1686,8 +1686,10 @@ Parser::ParsePostfixExpressionSuffix(ExprResult LHS) {
       CXXScopeSpec SS;
       ParsedType ObjectType;
       bool MayBePseudoDestructor = false;
+      Expr* OrigLHS = !LHS.isInvalid() ? LHS.get() : nullptr;
+
       if (getLangOpts().CPlusPlus && !LHS.isInvalid()) {
-        Expr *Base = LHS.get();
+        Expr *Base = OrigLHS;
         const Type* BaseType = Base->getType().getTypePtrOrNull();
         if (BaseType && Tok.is(tok::l_paren) &&
             (BaseType->isFunctionType() ||
@@ -1712,11 +1714,25 @@ Parser::ParsePostfixExpressionSuffix(ExprResult LHS) {
       }
 
       if (Tok.is(tok::code_completion)) {
+        tok::TokenKind CorrectedOpKind =
+            OpKind == tok::arrow ? tok::period : tok::arrow;
+        ExprResult CorrectedLHS(/*IsInvalid=*/true);
+        if (getLangOpts().CPlusPlus && OrigLHS) {
+          const bool DiagsAreSuppressed = Diags.getSuppressAllDiagnostics();
+          Diags.setSuppressAllDiagnostics(true);
+          CorrectedLHS = Actions.ActOnStartCXXMemberReference(
+              getCurScope(), OrigLHS, OpLoc, CorrectedOpKind, ObjectType,
+              MayBePseudoDestructor);
+          Diags.setSuppressAllDiagnostics(DiagsAreSuppressed);
+        }
+
+        Expr *Base = LHS.get();
+        Expr *CorrectedBase = CorrectedLHS.get();
+
         // Code completion for a member access expression.
-        if (Expr *Base = LHS.get())
-          Actions.CodeCompleteMemberReferenceExpr(
-              getCurScope(), Base, OpLoc, OpKind == tok::arrow,
-              ExprStatementTokLoc == Base->getLocStart());
+        Actions.CodeCompleteMemberReferenceExpr(
+            getCurScope(), Base, CorrectedBase, OpLoc, OpKind == tok::arrow,
+            Base && ExprStatementTokLoc == Base->getLocStart());
 
         cutOffParsing();
         return ExprError();