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

[ilya-biryukov]

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).

[kadircet]

clang/include/clang/Sema/Sema.h

294

Is it only to avoid copy costs?

clang/lib/Parse/ParseDeclCXX.cpp

3490

IIUC, deleting this call is safe, since it is going to be called in ParseAssignmentExpression. Could you add a comment stating that?(same for other deleted call sites of this function.)

clang/unittests/Sema/CodeCompleteTest.cpp

457

Can you also try in the middle of an identifier, like vec^tor()

458

maybe add a test for second parameter as well?

[xbolva00]

clang/lib/Sema/SemaCodeComplete.cpp

494

Typo?

[ilya-biryukov]

• Check in the middle and at the end of identifiers.
• Add a test for the second parameter and a class member function

clang/include/clang/Sema/Sema.h

294

Using std::function won't help much, all functions we pass here actually capture local variables by reference.

clang/lib/Parse/ParseDeclCXX.cpp

3490

Exactly! I changed the description of the change instead of adding a comment.
In the new version ParseExpressionList is not responsible for the code completion anymore and leaving the comment merely for historical reasons does not look appealing.

[ilya-biryukov]

• Fix a typo

clang/lib/Sema/SemaCodeComplete.cpp

494

Fixed it. Thanks.

[kadircet]

Thanks!

clang/include/clang/Parse/Parser.h

ExprResult ParseExprAfterUnaryExprOrTypeTrait(const Token &OpTok,
                                                      bool &isCastExpr,
                                                      ParsedType &CastTy,
                                                      SourceRange &CastRange);
 
   typedef SmallVector<Expr*, 20> ExprListTy;
   typedef SmallVector<SourceLocation, 20> CommaLocsTy;
 
   /// ParseExpressionList - Used for C/C++ (argument-)expression-list.
-  bool ParseExpressionList(
-      SmallVectorImpl<Expr *> &Exprs,
+  bool ParseExpressionList(SmallVectorImpl<Expr *> &Exprs,
                            SmallVectorImpl<SourceLocation> &CommaLocs,
-      llvm::function_ref<void()> Completer = llvm::function_ref<void()>());
+                           llvm::function_ref<void()> ExpressionStarts =
+                               llvm::function_ref<void()>());
 
   /// ParseSimpleExpressionList - A simple comma-separated list of expressions,
   /// used for misc language extensions.
   bool ParseSimpleExpressionList(SmallVectorImpl<Expr*> &Exprs,
                                  SmallVectorImpl<SourceLocation> &CommaLocs);
 
 
   /// ParenParseOption - Control what ParseParenExpression will parse.

clang/include/clang/Sema/Sema.h

 class PreferredTypeBuilder {
 public:
   PreferredTypeBuilder() = default;
   explicit PreferredTypeBuilder(QualType Type) : Type(Type) {}
 
   void enterCondition(Sema &S, SourceLocation Tok);
   void enterReturn(Sema &S, SourceLocation Tok);
   void enterVariableInit(SourceLocation Tok, Decl *D);
+  /// Computing a type for the function argument may require running
+  /// overloading, so we postpone its computation until it is actually needed.
+  ///
+  /// Clients should be very careful when using this funciton, as it stores a
+  /// function_ref, clients should make sure all calls to get() with the same
+  /// location happen while function_ref is alive.
+  void enterFunctionArgument(SourceLocation Tok,
+                             llvm::function_ref<QualType()> ComputeType);
 
   void enterParenExpr(SourceLocation Tok, SourceLocation LParLoc);
   void enterUnary(Sema &S, SourceLocation Tok, tok::TokenKind OpKind,
                   SourceLocation OpLoc);
   void enterBinary(Sema &S, SourceLocation Tok, Expr *LHS, tok::TokenKind Op);
   void enterMemAccess(Sema &S, SourceLocation Tok, Expr *Base);
   void enterSubscript(Sema &S, SourceLocation Tok, Expr *LHS);
   /// Handles all type casts, including C-style cast, C++ casts, etc.
   void enterTypeCast(SourceLocation Tok, QualType CastType);
 
   QualType get(SourceLocation Tok) const {
-    if (Tok == ExpectedLoc)
+    if (Tok != ExpectedLoc)
+      return QualType();
+    if (!Type.isNull())
       return Type;
+    if (ComputeType)
+      return ComputeType();
     return QualType();
   }
 
 private:
   /// Start position of a token for which we store expected type.
   SourceLocation ExpectedLoc;
   /// Expected type for a token starting at ExpectedLoc.
   QualType Type;
+  /// A function to compute expected type at ExpectedLoc. It is only considered
+  /// if Type is null.
+  llvm::function_ref<QualType()> ComputeType;
 };
 
 /// Sema - This implements semantic analysis and AST building for C.
 class Sema {
   Sema(const Sema &) = delete;
   void operator=(const Sema &) = delete;
 
   ///Source of additional semantic information.
OMPClause *ActOnOpenMPDefaultClause(OpenMPDefaultClauseKind Kind,
                                       SourceLocation LParenLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed 'proc_bind' clause.
   OMPClause *ActOnOpenMPProcBindClause(OpenMPProcBindClauseKind Kind,
                                        SourceLocation KindLoc,
                                        SourceLocation StartLoc,
                                        SourceLocation LParenLoc,
                                        SourceLocation EndLoc);
-  
   OMPClause *ActOnOpenMPSingleExprWithArgClause(
       OpenMPClauseKind Kind, ArrayRef<unsigned> Arguments, Expr *Expr,
       SourceLocation StartLoc, SourceLocation LParenLoc,
       ArrayRef<SourceLocation> ArgumentsLoc, SourceLocation DelimLoc,
       SourceLocation EndLoc);
   /// Called on well-formed 'schedule' clause.
   OMPClause *ActOnOpenMPScheduleClause(
       OpenMPScheduleClauseModifier M1, OpenMPScheduleClauseModifier M2,
OMPClause *ActOnOpenMPNogroupClause(SourceLocation StartLoc,
                                       SourceLocation EndLoc);
   /// Called on well-formed 'unified_address' clause.
   OMPClause *ActOnOpenMPUnifiedAddressClause(SourceLocation StartLoc,
                                              SourceLocation EndLoc);
 
   /// Called on well-formed 'unified_address' clause.
   OMPClause *ActOnOpenMPUnifiedSharedMemoryClause(SourceLocation StartLoc,
                                                   SourceLocation EndLoc);
-  
   /// Called on well-formed 'reverse_offload' clause.
   OMPClause *ActOnOpenMPReverseOffloadClause(SourceLocation StartLoc,
                                              SourceLocation EndLoc);
 
   /// Called on well-formed 'dynamic_allocators' clause.
   OMPClause *ActOnOpenMPDynamicAllocatorsClause(SourceLocation StartLoc,
                                                 SourceLocation EndLoc);
 

clang/lib/Parse/ParseDecl.cpp

if (isTokenEqualOrEqualTypo()) {
     BalancedDelimiterTracker T(*this, tok::l_paren);
     T.consumeOpen();
 
     ExprVector Exprs;
     CommaLocsTy CommaLocs;
 
     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(),
             ThisDecl->getLocation(), Exprs, T.getOpenLocation());
         CalledSignatureHelp = true;
       }
       Actions.ActOnInitializerError(ThisDecl);
       SkipUntil(tok::r_paren, StopAtSemi);

clang/lib/Parse/ParseDeclCXX.cpp

return Actions.ActOnMemInitializer(ConstructorDecl, getCurScope(), SS, II,
                                        InitList.get(), EllipsisLoc);
   } else if(Tok.is(tok::l_paren)) {
     BalancedDelimiterTracker T(*this, tok::l_paren);
     T.consumeOpen();
 
     // Parse the optional expression-list.
     ExprVector ArgExprs;
     CommaLocsTy CommaLocs;
-    if (Tok.isNot(tok::r_paren) &&
-        ParseExpressionList(ArgExprs, CommaLocs, [&] {
-          QualType PreferredType = Actions.ProduceCtorInitMemberSignatureHelp(
-              getCurScope(), ConstructorDecl, SS, TemplateTypeTy, ArgExprs, II,
-              T.getOpenLocation());
-          CalledSignatureHelp = true;
-          Actions.CodeCompleteExpression(getCurScope(), PreferredType);
+    auto RunSignatureHelp = [&] {
+      return PreferredType;
+    };
+    if (Tok.isNot(tok::r_paren) &&
+        ParseExpressionList(ArgExprs, CommaLocs, [&] {
+          PreferredType.enterFunctionArgument(Tok.getLocation(),
+                                              RunSignatureHelp);
         })) {
-      if (PP.isCodeCompletionReached() && !CalledSignatureHelp) {
-        Actions.ProduceCtorInitMemberSignatureHelp(
-            getCurScope(), ConstructorDecl, SS, TemplateTypeTy, ArgExprs, II,
-            T.getOpenLocation());
-        CalledSignatureHelp = true;
-      }
+      if (PP.isCodeCompletionReached() && !CalledSignatureHelp)
+        RunSignatureHelp();
       SkipUntil(tok::r_paren, StopAtSemi);
       return true;
     }
 
     T.consumeClose();
 
     SourceLocation EllipsisLoc;
     TryConsumeToken(tok::ellipsis, EllipsisLoc);

clang/lib/Parse/ParseExpr.cpp

case tok::lesslessless: {  // p-e: p-e '<<<' argument-expression-list '>>>'
         }
       } else {
         PT.consumeOpen();
         Loc = PT.getOpenLocation();
       }
 
       ExprVector ArgExprs;
       CommaLocsTy CommaLocs;
-
-      if (Tok.is(tok::code_completion)) {
+      auto RunSignatureHelp = [&]() -> QualType {
         QualType PreferredType = Actions.ProduceCallSignatureHelp(
-            getCurScope(), LHS.get(), None, PT.getOpenLocation());
+            getCurScope(), LHS.get(), ArgExprs, PT.getOpenLocation());
         CalledSignatureHelp = true;
-        Actions.CodeCompleteExpression(getCurScope(), PreferredType);
-        cutOffParsing();
-        return ExprError();
-      }
-
+        return PreferredType;
+      };
       if (OpKind == tok::l_paren || !LHS.isInvalid()) {
         if (Tok.isNot(tok::r_paren)) {
           if (ParseExpressionList(ArgExprs, CommaLocs, [&] {
-                QualType PreferredType = Actions.ProduceCallSignatureHelp(
-                    getCurScope(), LHS.get(), ArgExprs, PT.getOpenLocation());
-                CalledSignatureHelp = true;
-                Actions.CodeCompleteExpression(getCurScope(), PreferredType);
+                PreferredType.enterFunctionArgument(Tok.getLocation(),
+                                                    RunSignatureHelp);
               })) {
             (void)Actions.CorrectDelayedTyposInExpr(LHS);
             // If we got an error when parsing expression list, we don't call
             // the CodeCompleteCall handler inside the parser. So call it here
             // to make sure we get overload suggestions even when we are in the
             // middle of a parameter.
-            if (PP.isCodeCompletionReached() && !CalledSignatureHelp) {
-              Actions.ProduceCallSignatureHelp(getCurScope(), LHS.get(),
-                                               ArgExprs, PT.getOpenLocation());
-              CalledSignatureHelp = true;
-            }
+            if (PP.isCodeCompletionReached() && !CalledSignatureHelp)
+              RunSignatureHelp();
             LHS = ExprError();
           } else if (LHS.isInvalid()) {
             for (auto &E : ArgExprs)
               Actions.CorrectDelayedTyposInExpr(E);
           }
         }
       }
 

 /// [C++0x]   initializer-list , initializer-clause ...[opt]
 ///
 /// [C++0x] initializer-clause:
 /// [C++0x]   assignment-expression
 /// [C++0x]   braced-init-list
 /// \endverbatim
 bool Parser::ParseExpressionList(SmallVectorImpl<Expr *> &Exprs,
                                  SmallVectorImpl<SourceLocation> &CommaLocs,
-                                 llvm::function_ref<void()> Completer) {
+                                 llvm::function_ref<void()> ExpressionStarts) {
   bool SawError = false;
   while (1) {
-    if (Tok.is(tok::code_completion)) {
-      if (Completer)
-        Completer();
-      else
-        Actions.CodeCompleteExpression(getCurScope(),
-                                       PreferredType.get(Tok.getLocation()));
-      cutOffParsing();
-      return true;
-    }
+    if (ExpressionStarts)
+      ExpressionStarts();
 
     ExprResult Expr;
     if (getLangOpts().CPlusPlus11 && Tok.is(tok::l_brace)) {
       Diag(Tok, diag::warn_cxx98_compat_generalized_initializer_lists);
       Expr = ParseBraceInitializer();
     } else
       Expr = ParseAssignmentExpression();
 

clang/lib/Parse/ParseExprCXX.cpp

if (Tok.is(tok::l_brace)) {
     BalancedDelimiterTracker T(*this, tok::l_paren);
     T.consumeOpen();
 
     PreferredType.enterTypeCast(Tok.getLocation(), TypeRep.get());
 
     ExprVector Exprs;
     CommaLocsTy CommaLocs;
 
-    if (Tok.isNot(tok::r_paren)) {
-      if (ParseExpressionList(Exprs, CommaLocs, [&] {
-            QualType PreferredType = Actions.ProduceConstructorSignatureHelp(
-                getCurScope(), TypeRep.get()->getCanonicalTypeInternal(),
-                DS.getEndLoc(), Exprs, T.getOpenLocation());
-            CalledSignatureHelp = true;
-            Actions.CodeCompleteExpression(getCurScope(), PreferredType);
+    auto RunSignatureHelp = [&]() {
+      return PreferredType;
+    };
+
+    if (Tok.isNot(tok::r_paren)) {
+      if (ParseExpressionList(Exprs, CommaLocs, [&] {
+            PreferredType.enterFunctionArgument(Tok.getLocation(),
+                                                RunSignatureHelp);
           })) {
-        if (PP.isCodeCompletionReached() && !CalledSignatureHelp) {
-          Actions.ProduceConstructorSignatureHelp(
-              getCurScope(), TypeRep.get()->getCanonicalTypeInternal(),
-              DS.getEndLoc(), Exprs, T.getOpenLocation());
-          CalledSignatureHelp = true;
-        }
+        if (PP.isCodeCompletionReached() && !CalledSignatureHelp)
+          RunSignatureHelp();
         SkipUntil(tok::r_paren, StopAtSemi);
         return ExprError();
       }
     }
 
     // Match the ')'.
     T.consumeClose();
 
Parser::ParseCXXNewExpression(bool UseGlobal, SourceLocation Start) {
   if (Tok.is(tok::l_paren)) {
     SourceLocation ConstructorLParen, ConstructorRParen;
     ExprVector ConstructorArgs;
     BalancedDelimiterTracker T(*this, tok::l_paren);
     T.consumeOpen();
     ConstructorLParen = T.getOpenLocation();
     if (Tok.isNot(tok::r_paren)) {
       CommaLocsTy CommaLocs;
-      if (ParseExpressionList(ConstructorArgs, CommaLocs, [&] {
-            ParsedType TypeRep =
-                Actions.ActOnTypeName(getCurScope(), DeclaratorInfo).get();
-            QualType PreferredType = Actions.ProduceConstructorSignatureHelp(
-                getCurScope(), TypeRep.get()->getCanonicalTypeInternal(),
-                DeclaratorInfo.getEndLoc(), ConstructorArgs, ConstructorLParen);
-            CalledSignatureHelp = true;
-            Actions.CodeCompleteExpression(getCurScope(), PreferredType);
+      auto RunSignatureHelp = [&]() {
+        return PreferredType;
+      };
+      if (ParseExpressionList(ConstructorArgs, CommaLocs, [&] {
+            PreferredType.enterFunctionArgument(Tok.getLocation(),
+                                                RunSignatureHelp);
           })) {
-        if (PP.isCodeCompletionReached() && !CalledSignatureHelp) {
-          ParsedType TypeRep =
-              Actions.ActOnTypeName(getCurScope(), DeclaratorInfo).get();
-          Actions.ProduceConstructorSignatureHelp(
-              getCurScope(), TypeRep.get()->getCanonicalTypeInternal(),
-              DeclaratorInfo.getEndLoc(), ConstructorArgs, ConstructorLParen);
-          CalledSignatureHelp = true;
-        }
+        if (PP.isCodeCompletionReached() && !CalledSignatureHelp)
+          RunSignatureHelp();
         SkipUntil(tok::semi, StopAtSemi | StopBeforeMatch);
         return ExprError();
       }
     }
     T.consumeClose();
     ConstructorRParen = T.getCloseLocation();
     if (ConstructorRParen.isInvalid()) {
       SkipUntil(tok::semi, StopAtSemi | StopBeforeMatch);

clang/lib/Parse/ParseOpenMP.cpp

if (isTokenEqualOrEqualTypo()) {
     // Parse C++ direct initializer: '(' expression-list ')'
     BalancedDelimiterTracker T(*this, tok::l_paren);
     T.consumeOpen();
 
     ExprVector Exprs;
     CommaLocsTy CommaLocs;
 
     SourceLocation LParLoc = T.getOpenLocation();
-    if (ParseExpressionList(
-            Exprs, CommaLocs, [this, OmpPrivParm, LParLoc, &Exprs] {
-              QualType PreferredType = Actions.ProduceConstructorSignatureHelp(
-                  getCurScope(),
-                  OmpPrivParm->getType()->getCanonicalTypeInternal(),
-                  OmpPrivParm->getLocation(), Exprs, LParLoc);
-              CalledSignatureHelp = true;
-              Actions.CodeCompleteExpression(getCurScope(), PreferredType);
-            })) {
-      if (PP.isCodeCompletionReached() && !CalledSignatureHelp) {
-        Actions.ProduceConstructorSignatureHelp(
-            getCurScope(), OmpPrivParm->getType()->getCanonicalTypeInternal(),
-            OmpPrivParm->getLocation(), Exprs, LParLoc);
-        CalledSignatureHelp = true;
-      }
+    auto RunSignatureHelp = [this, OmpPrivParm, LParLoc, &Exprs]() {
+      return PreferredType;
+    };
+    if (ParseExpressionList(Exprs, CommaLocs, [&] {
+          PreferredType.enterFunctionArgument(Tok.getLocation(),
+                                              RunSignatureHelp);
+        })) {
+      if (PP.isCodeCompletionReached() && !CalledSignatureHelp)
+        RunSignatureHelp();
       Actions.ActOnInitializerError(OmpPrivParm);
       SkipUntil(tok::r_paren, tok::annot_pragma_openmp_end, StopBeforeMatch);
     } else {
       // Match the ')'.
       SourceLocation RLoc = Tok.getLocation();
       if (!T.consumeClose())
         RLoc = T.getCloseLocation();
 
case OMPD_threadprivate: {
     break;
   }
   case OMPD_requires: {
     SourceLocation StartLoc = ConsumeToken();
     SmallVector<OMPClause *, 5> Clauses;
     SmallVector<llvm::PointerIntPair<OMPClause *, 1, bool>, OMPC_unknown + 1>
     FirstClauses(OMPC_unknown + 1);
     if (Tok.is(tok::annot_pragma_openmp_end)) {
-      Diag(Tok, diag::err_omp_expected_clause) 
+      Diag(Tok, diag::err_omp_expected_clause)
           << getOpenMPDirectiveName(OMPD_requires);
       break;
     }
     while (Tok.isNot(tok::annot_pragma_openmp_end)) {
       OpenMPClauseKind CKind = Tok.isAnnotation()
                                    ? OMPC_unknown
                                    : getOpenMPClauseKind(PP.getSpelling(Tok));
       Actions.StartOpenMPClause(CKind);
static OpenMPMapClauseKind isMapType(Parser &P) {
   Preprocessor &PP = P.getPreprocessor();
   OpenMPMapClauseKind MapType = static_cast<OpenMPMapClauseKind>(
       getOpenMPSimpleClauseType(OMPC_map, PP.getSpelling(Tok)));
   return MapType;
 }
 
 /// Parse map-type in map clause.
 /// map([ [map-type-modifier[,] [map-type-modifier[,] ...] map-type : ] list)
-/// where, map-type ::= to | from | tofrom | alloc | release | delete 
+/// where, map-type ::= to | from | tofrom | alloc | release | delete
 static void parseMapType(Parser &P, Parser::OpenMPVarListDataTy &Data) {
   Token Tok = P.getCurToken();
   if (Tok.is(tok::colon)) {
     P.Diag(Tok, diag::err_omp_map_type_missing);
     return;
   }
   Data.MapType = isMapType(P);
   if (Data.MapType == OMPC_MAP_unknown)

clang/lib/Sema/SemaCodeComplete.cpp

public:
   bool IsImpossibleToSatisfy(const NamedDecl *ND) const;
   //@}
 };
 } // namespace
 
 void PreferredTypeBuilder::enterReturn(Sema &S, SourceLocation Tok) {
   if (isa<BlockDecl>(S.CurContext)) {
     if (sema::BlockScopeInfo *BSI = S.getCurBlock()) {
+      ComputeType = nullptr;
       Type = BSI->ReturnType;
       ExpectedLoc = Tok;
     }
   } else if (const auto *Function = dyn_cast<FunctionDecl>(S.CurContext)) {
+    ComputeType = nullptr;
     Type = Function->getReturnType();
     ExpectedLoc = Tok;
   } else if (const auto *Method = dyn_cast<ObjCMethodDecl>(S.CurContext)) {
+    ComputeType = nullptr;
     Type = Method->getReturnType();
     ExpectedLoc = Tok;
   }
 }
 
 void PreferredTypeBuilder::enterVariableInit(SourceLocation Tok, Decl *D) {
   auto *VD = llvm::dyn_cast_or_null<ValueDecl>(D);
+  ComputeType = nullptr;
   Type = VD ? VD->getType() : QualType();
   ExpectedLoc = Tok;
 }
 
+void PreferredTypeBuilder::enterFunctionArgument(
+    SourceLocation Tok, llvm::function_ref<QualType()> ComputeType) {
+  this->ComputeType = ComputeType;
+  Type = QualType();
+  ExpectedLoc = Tok;
+}
+
 void PreferredTypeBuilder::enterParenExpr(SourceLocation Tok,
                                           SourceLocation LParLoc) {
   // expected type for parenthesized expression does not change.
   if (ExpectedLoc == LParLoc)
     ExpectedLoc = Tok;
 }
 
 static QualType getPreferredTypeOfBinaryRHS(Sema &S, Expr *LHS,
case tok::plusplus:
     if (ContextType.isNull())
       return S.getASTContext().IntTy;
     // leave as is, these operators typically return the same type.
     return ContextType;
   case tok::kw___real:
   case tok::kw___imag:
     return QualType();
   default:
     assert(false && "unhnalded unary op");
     return QualType();
   }
 }
 
 void PreferredTypeBuilder::enterBinary(Sema &S, SourceLocation Tok, Expr *LHS,
                                        tok::TokenKind Op) {
+  ComputeType = nullptr;
   Type = getPreferredTypeOfBinaryRHS(S, LHS, Op);
   ExpectedLoc = Tok;
 }
 
 void PreferredTypeBuilder::enterMemAccess(Sema &S, SourceLocation Tok,
                                           Expr *Base) {
   if (!Base)
     return;
-  Type = this->get(Base->getBeginLoc());
+  // Do we have expected type for Base?
+  if (ExpectedLoc != Base->getBeginLoc())
+    return;
+  // Keep the expected type, only update the location.
   ExpectedLoc = Tok;
+  return;
 }
 
 void PreferredTypeBuilder::enterUnary(Sema &S, SourceLocation Tok,
                                       tok::TokenKind OpKind,
                                       SourceLocation OpLoc) {
+  ComputeType = nullptr;
   Type = getPreferredTypeOfUnaryArg(S, this->get(OpLoc), OpKind);
   ExpectedLoc = Tok;
 }
 
 void PreferredTypeBuilder::enterSubscript(Sema &S, SourceLocation Tok,
                                           Expr *LHS) {
+  ComputeType = nullptr;
   Type = S.getASTContext().IntTy;
   ExpectedLoc = Tok;
 }
 
 void PreferredTypeBuilder::enterTypeCast(SourceLocation Tok,
                                          QualType CastType) {
+  ComputeType = nullptr;
   Type = !CastType.isNull() ? CastType.getCanonicalType() : QualType();
   ExpectedLoc = Tok;
 }
 
 void PreferredTypeBuilder::enterCondition(Sema &S, SourceLocation Tok) {
+  ComputeType = nullptr;
   Type = S.getASTContext().BoolTy;
   ExpectedLoc = Tok;
 }
 
 class ResultBuilder::ShadowMapEntry::iterator {
   llvm::PointerUnion<const NamedDecl *, const DeclIndexPair *> DeclOrIterator;
   unsigned SingleDeclIndex;
 

clang/unittests/Sema/CodeCompleteTest.cpp

 }
 
 TEST(PreferredTypeTest, ParenExpr) {
   StringRef Code = R"cpp(
     const int *i = ^(^(^(^10)));
   )cpp";
   EXPECT_THAT(collectPreferredTypes(Code), Each("const int *"));
 }
+
+TEST(PreferredTypeTest, FunctionArguments) {
+  StringRef Code = R"cpp(
+    void foo(const int*);
+
+    void bar(const int*);
+    void bar(const int*, int b);
+
+    struct vector {
+      const int *data();
+    };
+    void test() {
+      foo(^(^(^(^vec^tor^().^da^ta^()))));
+      bar(^(^(^(^vec^tor^().^da^ta^()))));
+    }
+  )cpp";
+  EXPECT_THAT(collectPreferredTypes(Code), Each("const int *"));
+
+  Code = R"cpp(
+    void bar(int, volatile double *);
+    void bar(int, volatile double *, int, int);
+
+    struct vector {
+      double *data();
+    };
+
+    struct class_members {
+      void bar(int, volatile double *);
+      void bar(int, volatile double *, int, int);
+    };
+    void test() {
+      bar(10, ^(^(^(^vec^tor^().^da^ta^()))));
+      class_members().bar(10, ^(^(^(^vec^tor^().^da^ta^()))));
+    }
+  )cpp";
+  EXPECT_THAT(collectPreferredTypes(Code), Each("volatile double *"));
+}
 } // namespace