[CodeCompletion] Avoid spurious signature help for init-list args

Somewhat surprisingly, signature help is emitted as a side-effect of
computing the expected type of a function argument.
The reason is that both actions require enumerating the possible
function signatures and running partial overload resolution, and doing
this twice would be wasteful and complicated.

Change #1: document this, it's subtle :-)

However, sometimes we need to compute the expected type without having
reached the code completion cursor yet - in particular to allow
completion of designators.
eb4ab3358c did this but introduced a
regression - it emits signature help in the wrong location as a side-effect.

Change #2: only emit signature help if the code completion cursor was reached.

Currently there is PP.isCodeCompletionReached(), but we can't use it
because it's set *after* running code completion.
It'd be nice to set this implicitly when the completion token is lexed,
but ConsumeCodeCompletionToken() makes this complicated.

Change #3: call cutOffParsing() *first* when seeing a completion token.

After this, the fact that the Sema::Produce*SignatureHelp() functions
are even more confusing, as they only sometimes do that.
I don't want to rename them in this patch as it's another large
mechanical change, but we should soon.

Change #4: prepare to rename ProduceSignatureHelp() to GuessArgumentType() etc.

Differential Revision: https://reviews.llvm.org/D98488

clang-tools-extra/clangd/unittests/CodeCompleteTests.cpp

@@ -1253,6 +1253,19 @@ TEST(SignatureHelpTest, Overloads) {
   EXPECT_EQ(0, Results.activeParameter);
 }
 
+TEST(SignatureHelpTest, OverloadInitListRegression) {
+  auto Results = signatures(R"cpp(
+    struct A {int x;};
+    struct B {B(A);};
+    void f();
+    int main() {
+      B b({1});
+      f(^);
+    }
+  )cpp");
+  EXPECT_THAT(Results.signatures, UnorderedElementsAre(Sig("f() -> void")));
+}
+
 TEST(SignatureHelpTest, DefaultArgs) {
   auto Results = signatures(R"cpp(
     void bar(int x, int y = 0);

clang/include/clang/Sema/Sema.h

@@ -306,6 +306,9 @@ public:
   /// 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.
+  ///
+  /// The callback should also emit signature help as a side-effect, but only
+  /// if the completion point has been reached.
   void enterFunctionArgument(SourceLocation Tok,
                              llvm::function_ref<QualType()> ComputeType);
 
@@ -318,6 +321,12 @@ public:
   /// Handles all type casts, including C-style cast, C++ casts, etc.
   void enterTypeCast(SourceLocation Tok, QualType CastType);
 
+  /// Get the expected type associated with this location, if any.
+  ///
+  /// If the location is a function argument, determining the expected type
+  /// involves considering all function overloads and the arguments so far.
+  /// In this case, signature help for these function overloads will be reported
+  /// as a side-effect (only if the completion point has been reached).
   QualType get(SourceLocation Tok) const {
     if (!Enabled || Tok != ExpectedLoc)
       return QualType();
@@ -12216,8 +12225,14 @@ public:
                                       const VirtSpecifiers *VS = nullptr);
   void CodeCompleteBracketDeclarator(Scope *S);
   void CodeCompleteCase(Scope *S);
-  /// Reports signatures for a call to CodeCompleteConsumer and returns the
+  /// Determines the preferred type of the current function argument, by
-  /// preferred type for the current argument. Returned type can be null.
+  /// examining the signatures of all possible overloads.
+  /// Returns null if unknown or ambiguous, or if code completion is off.
+  ///
+  /// If the code completion point has been reached, also reports the function
+  /// signatures that were considered.
+  ///
+  /// FIXME: rename to GuessCallArgumentType to reduce confusion.
   QualType ProduceCallSignatureHelp(Scope *S, Expr *Fn, ArrayRef<Expr *> Args,
                                     SourceLocation OpenParLoc);
   QualType ProduceConstructorSignatureHelp(Scope *S, QualType Type,

clang/lib/Lex/PPDirectives.cpp

@@ -441,9 +441,9 @@ void Preprocessor::SkipExcludedConditionalBlock(SourceLocation HashTokenLoc,
     CurLexer->Lex(Tok);
 
     if (Tok.is(tok::code_completion)) {
+      setCodeCompletionReached();
       if (CodeComplete)
         CodeComplete->CodeCompleteInConditionalExclusion();
-      setCodeCompletionReached();
       continue;
     }
 
@@ -966,10 +966,10 @@ void Preprocessor::HandleDirective(Token &Result) {
   case tok::eod:
     return;   // null directive.
   case tok::code_completion:
+    setCodeCompletionReached();
     if (CodeComplete)
       CodeComplete->CodeCompleteDirective(
                                     CurPPLexer->getConditionalStackDepth() > 0);
-    setCodeCompletionReached();
     return;
   case tok::numeric_constant:  // # 7  GNU line marker directive.
     if (getLangOpts().AsmPreprocessor)

clang/lib/Lex/Preprocessor.cpp

@@ -442,15 +442,15 @@ bool Preprocessor::SetCodeCompletionPoint(const FileEntry *File,
 
 void Preprocessor::CodeCompleteIncludedFile(llvm::StringRef Dir,
                                             bool IsAngled) {
+  setCodeCompletionReached();
   if (CodeComplete)
     CodeComplete->CodeCompleteIncludedFile(Dir, IsAngled);
-  setCodeCompletionReached();
 }
 
 void Preprocessor::CodeCompleteNaturalLanguage() {
+  setCodeCompletionReached();
   if (CodeComplete)
     CodeComplete->CodeCompleteNaturalLanguage();
-  setCodeCompletionReached();
 }
 
 /// getSpelling - This method is used to get the spelling of a token into a

clang/lib/Parse/ParseDecl.cpp

@@ -1970,8 +1970,8 @@ Parser::DeclGroupPtrTy Parser::ParseDeclGroup(ParsingDeclSpec &DS,
   // Check to see if we have a function *definition* which must have a body.
   if (D.isFunctionDeclarator()) {
     if (Tok.is(tok::equal) && NextToken().is(tok::code_completion)) {
-      Actions.CodeCompleteAfterFunctionEquals(D);
       cutOffParsing();
+      Actions.CodeCompleteAfterFunctionEquals(D);
       return nullptr;
     }
     // Look at the next token to make sure that this isn't a function
@@ -2310,9 +2310,9 @@ Decl *Parser::ParseDeclarationAfterDeclaratorAndAttributes(
       InitializerScopeRAII InitScope(*this, D, ThisDecl);
 
       if (Tok.is(tok::code_completion)) {
+        cutOffParsing();
         Actions.CodeCompleteInitializer(getCurScope(), ThisDecl);
         Actions.FinalizeDeclaration(ThisDecl);
-        cutOffParsing();
         return nullptr;
       }
 
@@ -3090,10 +3090,11 @@ void Parser::ParseDeclarationSpecifiers(DeclSpec &DS,
           = DSContext == DeclSpecContext::DSC_top_level ||
             (DSContext == DeclSpecContext::DSC_class && DS.isFriendSpecified());
 
+        cutOffParsing();
         Actions.CodeCompleteDeclSpec(getCurScope(), DS,
                                      AllowNonIdentifiers,
                                      AllowNestedNameSpecifiers);
-        return cutOffParsing();
+        return;
       }
 
       if (getCurScope()->getFnParent() || getCurScope()->getBlockParent())
@@ -3106,8 +3107,9 @@ void Parser::ParseDeclarationSpecifiers(DeclSpec &DS,
       else if (CurParsedObjCImpl)
         CCC = Sema::PCC_ObjCImplementation;
 
+      cutOffParsing();
       Actions.CodeCompleteOrdinaryName(getCurScope(), CCC);
-      return cutOffParsing();
+      return;
     }
 
     case tok::coloncolon: // ::foo::bar
@@ -4362,8 +4364,9 @@ void Parser::ParseEnumSpecifier(SourceLocation StartLoc, DeclSpec &DS,
   // Parse the tag portion of this.
   if (Tok.is(tok::code_completion)) {
     // Code completion for an enum name.
+    cutOffParsing();
     Actions.CodeCompleteTag(getCurScope(), DeclSpec::TST_enum);
-    return cutOffParsing();
+    return;
   }
 
   // If attributes exist after tag, parse them.
@@ -5457,11 +5460,12 @@ void Parser::ParseTypeQualifierListOpt(
 
     switch (Tok.getKind()) {
     case tok::code_completion:
+      cutOffParsing();
       if (CodeCompletionHandler)
         (*CodeCompletionHandler)();
       else
         Actions.CodeCompleteTypeQualifiers(DS);
-      return cutOffParsing();
+      return;
 
     case tok::kw_const:
       isInvalid = DS.SetTypeQual(DeclSpec::TQ_const   , Loc, PrevSpec, DiagID,
@@ -6998,8 +7002,9 @@ void Parser::ParseBracketDeclarator(Declarator &D) {
                   std::move(attrs), T.getCloseLocation());
     return;
   } else if (Tok.getKind() == tok::code_completion) {
+    cutOffParsing();
     Actions.CodeCompleteBracketDeclarator(getCurScope());
-    return cutOffParsing();
+    return;
   }
 
   // If valid, this location is the position where we read the 'static' keyword.

clang/lib/Parse/ParseDeclCXX.cpp

@@ -63,8 +63,8 @@ Parser::DeclGroupPtrTy Parser::ParseNamespace(DeclaratorContext Context,
   ObjCDeclContextSwitch ObjCDC(*this);
 
   if (Tok.is(tok::code_completion)) {
-    Actions.CodeCompleteNamespaceDecl(getCurScope());
     cutOffParsing();
+    Actions.CodeCompleteNamespaceDecl(getCurScope());
     return nullptr;
   }
 
@@ -283,8 +283,8 @@ Decl *Parser::ParseNamespaceAlias(SourceLocation NamespaceLoc,
   ConsumeToken(); // eat the '='.
 
   if (Tok.is(tok::code_completion)) {
-    Actions.CodeCompleteNamespaceAliasDecl(getCurScope());
     cutOffParsing();
+    Actions.CodeCompleteNamespaceAliasDecl(getCurScope());
     return nullptr;
   }
 
@@ -471,8 +471,8 @@ Parser::ParseUsingDirectiveOrDeclaration(DeclaratorContext Context,
   SourceLocation UsingLoc = ConsumeToken();
 
   if (Tok.is(tok::code_completion)) {
-    Actions.CodeCompleteUsing(getCurScope());
     cutOffParsing();
+    Actions.CodeCompleteUsing(getCurScope());
     return nullptr;
   }
 
@@ -525,8 +525,8 @@ Decl *Parser::ParseUsingDirective(DeclaratorContext Context,
   SourceLocation NamespcLoc = ConsumeToken();
 
   if (Tok.is(tok::code_completion)) {
-    Actions.CodeCompleteUsingDirective(getCurScope());
     cutOffParsing();
+    Actions.CodeCompleteUsingDirective(getCurScope());
     return nullptr;
   }
 
@@ -1433,8 +1433,9 @@ void Parser::ParseClassSpecifier(tok::TokenKind TagTokKind,
 
   if (Tok.is(tok::code_completion)) {
     // Code completion for a struct, class, or union name.
+    cutOffParsing();
     Actions.CodeCompleteTag(getCurScope(), TagType);
-    return cutOffParsing();
+    return;
   }
 
   // C++03 [temp.explicit] 14.7.2/8:
@@ -2749,8 +2750,8 @@ Parser::ParseCXXClassMemberDeclaration(AccessSpecifier AS,
         else if (KW.is(tok::kw_delete))
           DefinitionKind = FunctionDefinitionKind::Deleted;
         else if (KW.is(tok::code_completion)) {
-          Actions.CodeCompleteAfterFunctionEquals(DeclaratorInfo);
           cutOffParsing();
+          Actions.CodeCompleteAfterFunctionEquals(DeclaratorInfo);
           return nullptr;
         }
       }
@@ -3498,9 +3499,10 @@ void Parser::ParseConstructorInitializer(Decl *ConstructorDecl) {
 
   do {
     if (Tok.is(tok::code_completion)) {
+      cutOffParsing();
       Actions.CodeCompleteConstructorInitializer(ConstructorDecl,
                                                  MemInitializers);
-      return cutOffParsing();
+      return;
     }
 
     MemInitResult MemInit = ParseMemInitializer(ConstructorDecl);

clang/lib/Parse/ParseExpr.cpp

@@ -159,9 +159,9 @@ Parser::ParseExpressionWithLeadingExtension(SourceLocation ExtLoc) {
 /// Parse an expr that doesn't include (top-level) commas.
 ExprResult Parser::ParseAssignmentExpression(TypeCastState isTypeCast) {
   if (Tok.is(tok::code_completion)) {
+    cutOffParsing();
     Actions.CodeCompleteExpression(getCurScope(),
                                    PreferredType.get(Tok.getLocation()));
-    cutOffParsing();
     return ExprError();
   }
 
@@ -1156,9 +1156,9 @@ ExprResult Parser::ParseCastExpression(CastParseKind ParseKind,
       ConsumeToken();
 
       if (Tok.is(tok::code_completion) && &II != Ident_super) {
+        cutOffParsing();
         Actions.CodeCompleteObjCClassPropertyRefExpr(
             getCurScope(), II, ILoc, ExprStatementTokLoc == ILoc);
-        cutOffParsing();
         return ExprError();
       }
       // Allow either an identifier or the keyword 'class' (in C++).
@@ -1724,9 +1724,9 @@ ExprResult Parser::ParseCastExpression(CastParseKind ParseKind,
     Res = ParseBlockLiteralExpression();
     break;
   case tok::code_completion: {
+    cutOffParsing();
     Actions.CodeCompleteExpression(getCurScope(),
                                    PreferredType.get(Tok.getLocation()));
-    cutOffParsing();
     return ExprError();
   }
   case tok::l_square:
@@ -1856,9 +1856,9 @@ Parser::ParsePostfixExpressionSuffix(ExprResult LHS) {
       if (InMessageExpression)
         return LHS;
 
+      cutOffParsing();
       Actions.CodeCompletePostfixExpression(
           getCurScope(), LHS, PreferredType.get(Tok.getLocation()));
-      cutOffParsing();
       return ExprError();
 
     case tok::identifier:
@@ -2140,12 +2140,12 @@ Parser::ParsePostfixExpressionSuffix(ExprResult LHS) {
           CorrectedBase = Base;
 
         // Code completion for a member access expression.
+        cutOffParsing();
         Actions.CodeCompleteMemberReferenceExpr(
             getCurScope(), Base, CorrectedBase, OpLoc, OpKind == tok::arrow,
             Base && ExprStatementTokLoc == Base->getBeginLoc(),
             PreferredType.get(Tok.getLocation()));
 
-        cutOffParsing();
         return ExprError();
       }
 
@@ -2778,10 +2778,10 @@ Parser::ParseParenExpression(ParenParseOption &ExprType, bool stopIfCastExpr,
   CastTy = nullptr;
 
   if (Tok.is(tok::code_completion)) {
+    cutOffParsing();
     Actions.CodeCompleteExpression(
         getCurScope(), PreferredType.get(Tok.getLocation()),
         /*IsParenthesized=*/ExprType >= CompoundLiteral);
-    cutOffParsing();
     return ExprError();
   }
 
@@ -3412,8 +3412,9 @@ Parser::ParseSimpleExpressionList(SmallVectorImpl<Expr*> &Exprs,
 /// \endverbatim
 void Parser::ParseBlockId(SourceLocation CaretLoc) {
   if (Tok.is(tok::code_completion)) {
+    cutOffParsing();
     Actions.CodeCompleteOrdinaryName(getCurScope(), Sema::PCC_Type);
-    return cutOffParsing();
+    return;
   }
 
   // Parse the specifier-qualifier-list piece.
@@ -3598,8 +3599,8 @@ Optional<AvailabilitySpec> Parser::ParseAvailabilitySpec() {
   } else {
     // Parse the platform name.
     if (Tok.is(tok::code_completion)) {
-      Actions.CodeCompleteAvailabilityPlatformName();
       cutOffParsing();
+      Actions.CodeCompleteAvailabilityPlatformName();
       return None;
     }
     if (Tok.isNot(tok::identifier)) {

clang/lib/Parse/ParseExprCXX.cpp

@@ -235,6 +235,7 @@ bool Parser::ParseOptionalCXXScopeSpecifier(
   while (true) {
     if (HasScopeSpecifier) {
       if (Tok.is(tok::code_completion)) {
+        cutOffParsing();
         // Code completion for a nested-name-specifier, where the code
         // completion token follows the '::'.
         Actions.CodeCompleteQualifiedId(getCurScope(), SS, EnteringContext,
@@ -245,7 +246,6 @@ bool Parser::ParseOptionalCXXScopeSpecifier(
         // token will cause assertion in
         // Preprocessor::AnnotatePreviousCachedTokens.
         SS.setEndLoc(Tok.getLocation());
-        cutOffParsing();
         return true;
       }
 
@@ -877,9 +877,9 @@ bool Parser::ParseLambdaIntroducer(LambdaIntroducer &Intro,
         // expression parser perform the completion.
         if (Tok.is(tok::code_completion) &&
             !(getLangOpts().ObjC && Tentative)) {
+          cutOffParsing();
           Actions.CodeCompleteLambdaIntroducer(getCurScope(), Intro,
                                                /*AfterAmpersand=*/false);
-          cutOffParsing();
           break;
         }
 
@@ -891,6 +891,7 @@ bool Parser::ParseLambdaIntroducer(LambdaIntroducer &Intro,
     }
 
     if (Tok.is(tok::code_completion)) {
+      cutOffParsing();
       // If we're in Objective-C++ and we have a bare '[', then this is more
       // likely to be a message receiver.
       if (getLangOpts().ObjC && Tentative && First)
@@ -898,7 +899,6 @@ bool Parser::ParseLambdaIntroducer(LambdaIntroducer &Intro,
       else
         Actions.CodeCompleteLambdaIntroducer(getCurScope(), Intro,
                                              /*AfterAmpersand=*/false);
-      cutOffParsing();
       break;
     }
 
@@ -943,9 +943,9 @@ bool Parser::ParseLambdaIntroducer(LambdaIntroducer &Intro,
         ConsumeToken();
 
         if (Tok.is(tok::code_completion)) {
+          cutOffParsing();
           Actions.CodeCompleteLambdaIntroducer(getCurScope(), Intro,
                                                /*AfterAmpersand=*/true);
-          cutOffParsing();
           break;
         }
       }
@@ -1996,8 +1996,8 @@ Sema::ConditionResult Parser::ParseCXXCondition(StmtResult *InitStmt,
   PreferredType.enterCondition(Actions, Tok.getLocation());
 
   if (Tok.is(tok::code_completion)) {
-    Actions.CodeCompleteOrdinaryName(getCurScope(), Sema::PCC_Condition);
     cutOffParsing();
+    Actions.CodeCompleteOrdinaryName(getCurScope(), Sema::PCC_Condition);
     return Sema::ConditionError();
   }
 
@@ -2608,10 +2608,10 @@ bool Parser::ParseUnqualifiedIdOperator(CXXScopeSpec &SS, bool EnteringContext,
     }
 
     case tok::code_completion: {
+      // Don't try to parse any further.
+      cutOffParsing();
       // Code completion for the operator name.
       Actions.CodeCompleteOperatorName(getCurScope());
-      cutOffParsing();
-      // Don't try to parse any further.
       return true;
     }
 

clang/lib/Parse/ParseInit.cpp

@@ -200,9 +200,9 @@ ExprResult Parser::ParseInitializerWithPotentialDesignator(
       SourceLocation DotLoc = ConsumeToken();
 
       if (Tok.is(tok::code_completion)) {
+        cutOffParsing();
         Actions.CodeCompleteDesignator(DesignatorCompletion.PreferredBaseType,
                                        DesignatorCompletion.InitExprs, Desig);
-        cutOffParsing();
         return ExprError();
       }
       if (Tok.isNot(tok::identifier)) {

clang/lib/Parse/ParseObjc.cpp

@@ -50,8 +50,8 @@ Parser::ParseObjCAtDirectives(ParsedAttributesWithRange &Attrs) {
   SourceLocation AtLoc = ConsumeToken(); // the "@"
 
   if (Tok.is(tok::code_completion)) {
-    Actions.CodeCompleteObjCAtDirective(getCurScope());
     cutOffParsing();
+    Actions.CodeCompleteObjCAtDirective(getCurScope());
     return nullptr;
   }
 
@@ -219,8 +219,8 @@ Decl *Parser::ParseObjCAtInterfaceDeclaration(SourceLocation AtLoc,
 
   // Code completion after '@interface'.
   if (Tok.is(tok::code_completion)) {
-    Actions.CodeCompleteObjCInterfaceDecl(getCurScope());
     cutOffParsing();
+    Actions.CodeCompleteObjCInterfaceDecl(getCurScope());
     return nullptr;
   }
 
@@ -253,8 +253,8 @@ Decl *Parser::ParseObjCAtInterfaceDeclaration(SourceLocation AtLoc,
     SourceLocation categoryLoc;
     IdentifierInfo *categoryId = nullptr;
     if (Tok.is(tok::code_completion)) {
-      Actions.CodeCompleteObjCInterfaceCategory(getCurScope(), nameId, nameLoc);
       cutOffParsing();
+      Actions.CodeCompleteObjCInterfaceCategory(getCurScope(), nameId, nameLoc);
       return nullptr;
     }
 
@@ -308,8 +308,8 @@ Decl *Parser::ParseObjCAtInterfaceDeclaration(SourceLocation AtLoc,
 
     // Code completion of superclass names.
     if (Tok.is(tok::code_completion)) {
-      Actions.CodeCompleteObjCSuperclass(getCurScope(), nameId, nameLoc);
       cutOffParsing();
+      Actions.CodeCompleteObjCSuperclass(getCurScope(), nameId, nameLoc);
       return nullptr;
     }
 
@@ -472,8 +472,8 @@ ObjCTypeParamList *Parser::parseObjCTypeParamListOrProtocolRefs(
       if (Tok.is(tok::code_completion)) {
         // FIXME: If these aren't protocol references, we'll need different
         // completions.
-        Actions.CodeCompleteObjCProtocolReferences(protocolIdents);
         cutOffParsing();
+        Actions.CodeCompleteObjCProtocolReferences(protocolIdents);
 
         // FIXME: Better recovery here?.
         return nullptr;
@@ -635,10 +635,11 @@ void Parser::ParseObjCInterfaceDeclList(tok::ObjCKeywordKind contextKey,
 
     // Code completion within an Objective-C interface.
     if (Tok.is(tok::code_completion)) {
+      cutOffParsing();
       Actions.CodeCompleteOrdinaryName(getCurScope(),
                             CurParsedObjCImpl? Sema::PCC_ObjCImplementation
                                              : Sema::PCC_ObjCInterface);
-      return cutOffParsing();
+      return;
     }
 
     // If we don't have an @ directive, parse it as a function definition.
@@ -668,8 +669,9 @@ void Parser::ParseObjCInterfaceDeclList(tok::ObjCKeywordKind contextKey,
     // Otherwise, we have an @ directive, eat the @.
     SourceLocation AtLoc = ConsumeToken(); // the "@"
     if (Tok.is(tok::code_completion)) {
+      cutOffParsing();
       Actions.CodeCompleteObjCAtDirective(getCurScope());
-      return cutOffParsing();
+      return;
     }
 
     tok::ObjCKeywordKind DirectiveKind = Tok.getObjCKeywordID();
@@ -778,8 +780,9 @@ void Parser::ParseObjCInterfaceDeclList(tok::ObjCKeywordKind contextKey,
   // We break out of the big loop in two cases: when we see @end or when we see
   // EOF.  In the former case, eat the @end.  In the later case, emit an error.
   if (Tok.is(tok::code_completion)) {
+    cutOffParsing();
     Actions.CodeCompleteObjCAtDirective(getCurScope());
-    return cutOffParsing();
+    return;
   } else if (Tok.isObjCAtKeyword(tok::objc_end)) {
     ConsumeToken(); // the "end" identifier
   } else {
@@ -847,8 +850,9 @@ void Parser::ParseObjCPropertyAttribute(ObjCDeclSpec &DS) {
 
   while (1) {
     if (Tok.is(tok::code_completion)) {
+      cutOffParsing();
       Actions.CodeCompleteObjCPropertyFlags(getCurScope(), DS);
-      return cutOffParsing();
+      return;
     }
     const IdentifierInfo *II = Tok.getIdentifierInfo();
 
@@ -893,11 +897,12 @@ void Parser::ParseObjCPropertyAttribute(ObjCDeclSpec &DS) {
       }
 
       if (Tok.is(tok::code_completion)) {
+        cutOffParsing();
         if (IsSetter)
           Actions.CodeCompleteObjCPropertySetter(getCurScope());
         else
           Actions.CodeCompleteObjCPropertyGetter(getCurScope());
-        return cutOffParsing();
+        return;
       }
 
       SourceLocation SelLoc;
@@ -1146,9 +1151,10 @@ void Parser::ParseObjCTypeQualifierList(ObjCDeclSpec &DS,
 
   while (1) {
     if (Tok.is(tok::code_completion)) {
+      cutOffParsing();
       Actions.CodeCompleteObjCPassingType(
           getCurScope(), DS, Context == DeclaratorContext::ObjCParameter);
-      return cutOffParsing();
+      return;
     }
 
     if (Tok.isNot(tok::identifier))
@@ -1335,9 +1341,9 @@ Decl *Parser::ParseObjCMethodDecl(SourceLocation mLoc,
   ParsingDeclRAIIObject PD(*this, ParsingDeclRAIIObject::NoParent);
 
   if (Tok.is(tok::code_completion)) {
+    cutOffParsing();
     Actions.CodeCompleteObjCMethodDecl(getCurScope(), mType == tok::minus,
                                        /*ReturnType=*/nullptr);
-    cutOffParsing();
     return nullptr;
   }
 
@@ -1354,9 +1360,9 @@ Decl *Parser::ParseObjCMethodDecl(SourceLocation mLoc,
                        methodAttrs);
 
   if (Tok.is(tok::code_completion)) {
+    cutOffParsing();
     Actions.CodeCompleteObjCMethodDecl(getCurScope(), mType == tok::minus,
                                        ReturnType);
-    cutOffParsing();
     return nullptr;
   }
 
@@ -1416,12 +1422,12 @@ Decl *Parser::ParseObjCMethodDecl(SourceLocation mLoc,
 
     // Code completion for the next piece of the selector.
     if (Tok.is(tok::code_completion)) {
+      cutOffParsing();
       KeyIdents.push_back(SelIdent);
       Actions.CodeCompleteObjCMethodDeclSelector(getCurScope(),
                                                  mType == tok::minus,
                                                  /*AtParameterName=*/true,
                                                  ReturnType, KeyIdents);
-      cutOffParsing();
       return nullptr;
     }
 
@@ -1441,11 +1447,11 @@ Decl *Parser::ParseObjCMethodDecl(SourceLocation mLoc,
 
     // Code completion for the next piece of the selector.
     if (Tok.is(tok::code_completion)) {
+      cutOffParsing();
       Actions.CodeCompleteObjCMethodDeclSelector(getCurScope(),
                                                  mType == tok::minus,
                                                  /*AtParameterName=*/false,
                                                  ReturnType, KeyIdents);
-      cutOffParsing();
       return nullptr;
     }
 
@@ -1527,8 +1533,8 @@ ParseObjCProtocolReferences(SmallVectorImpl<Decl *> &Protocols,
 
   while (1) {
     if (Tok.is(tok::code_completion)) {
-      Actions.CodeCompleteObjCProtocolReferences(ProtocolIdents);
       cutOffParsing();
+      Actions.CodeCompleteObjCProtocolReferences(ProtocolIdents);
       return true;
     }
 
@@ -1626,12 +1632,12 @@ void Parser::parseObjCTypeArgsOrProtocolQualifiers(
       }
 
       QualType BaseT = Actions.GetTypeFromParser(baseType);
+      cutOffParsing();
       if (!BaseT.isNull() && BaseT->acceptsObjCTypeParams()) {
         Actions.CodeCompleteOrdinaryName(getCurScope(), Sema::PCC_Type);
       } else {
         Actions.CodeCompleteObjCProtocolReferences(identifierLocPairs);
       }
-      cutOffParsing();
       return;
     }
 
@@ -1920,8 +1926,9 @@ void Parser::ParseObjCClassInstanceVariables(Decl *interfaceDecl,
     // Set the default visibility to private.
     if (TryConsumeToken(tok::at)) { // parse objc-visibility-spec
       if (Tok.is(tok::code_completion)) {
+        cutOffParsing();
         Actions.CodeCompleteObjCAtVisibility(getCurScope());
-        return cutOffParsing();
+        return;
       }
 
       switch (Tok.getObjCKeywordID()) {
@@ -1950,9 +1957,10 @@ void Parser::ParseObjCClassInstanceVariables(Decl *interfaceDecl,
     }
 
     if (Tok.is(tok::code_completion)) {
+      cutOffParsing();
       Actions.CodeCompleteOrdinaryName(getCurScope(),
                                        Sema::PCC_ObjCInstanceVariableList);
-      return cutOffParsing();
+      return;
     }
 
     // This needs to duplicate a small amount of code from
@@ -2017,8 +2025,8 @@ Parser::ParseObjCAtProtocolDeclaration(SourceLocation AtLoc,
   ConsumeToken(); // the "protocol" identifier
 
   if (Tok.is(tok::code_completion)) {
-    Actions.CodeCompleteObjCProtocolDecl(getCurScope());
     cutOffParsing();
+    Actions.CodeCompleteObjCProtocolDecl(getCurScope());
     return nullptr;
   }
 
@@ -2101,8 +2109,8 @@ Parser::ParseObjCAtImplementationDeclaration(SourceLocation AtLoc,
 
   // Code completion after '@implementation'.
   if (Tok.is(tok::code_completion)) {
-    Actions.CodeCompleteObjCImplementationDecl(getCurScope());
     cutOffParsing();
+    Actions.CodeCompleteObjCImplementationDecl(getCurScope());
     return nullptr;
   }
 
@@ -2139,8 +2147,8 @@ Parser::ParseObjCAtImplementationDeclaration(SourceLocation AtLoc,
     IdentifierInfo *categoryId = nullptr;
 
     if (Tok.is(tok::code_completion)) {
-      Actions.CodeCompleteObjCImplementationCategory(getCurScope(), nameId, nameLoc);
       cutOffParsing();
+      Actions.CodeCompleteObjCImplementationCategory(getCurScope(), nameId, nameLoc);
       return nullptr;
     }
 
@@ -2309,8 +2317,8 @@ Decl *Parser::ParseObjCPropertySynthesize(SourceLocation atLoc) {
 
   while (true) {
     if (Tok.is(tok::code_completion)) {
-      Actions.CodeCompleteObjCPropertyDefinition(getCurScope());
       cutOffParsing();
+      Actions.CodeCompleteObjCPropertyDefinition(getCurScope());
       return nullptr;
     }
 
@@ -2327,8 +2335,8 @@ Decl *Parser::ParseObjCPropertySynthesize(SourceLocation atLoc) {
     if (TryConsumeToken(tok::equal)) {
       // property '=' ivar-name
       if (Tok.is(tok::code_completion)) {
-        Actions.CodeCompleteObjCPropertySynthesizeIvar(getCurScope(), propertyId);
         cutOffParsing();
+        Actions.CodeCompleteObjCPropertySynthesizeIvar(getCurScope(), propertyId);
         return nullptr;
       }
 
@@ -2387,8 +2395,8 @@ Decl *Parser::ParseObjCPropertyDynamic(SourceLocation atLoc) {
 
   while (true) {
     if (Tok.is(tok::code_completion)) {
-      Actions.CodeCompleteObjCPropertyDefinition(getCurScope());
       cutOffParsing();
+      Actions.CodeCompleteObjCPropertyDefinition(getCurScope());
       return nullptr;
     }
 
@@ -2724,8 +2732,8 @@ Decl *Parser::ParseObjCMethodDefinition() {
 StmtResult Parser::ParseObjCAtStatement(SourceLocation AtLoc,
                                         ParsedStmtContext StmtCtx) {
   if (Tok.is(tok::code_completion)) {
-    Actions.CodeCompleteObjCAtStatement(getCurScope());
     cutOffParsing();
+    Actions.CodeCompleteObjCAtStatement(getCurScope());
     return StmtError();
   }
 
@@ -2765,8 +2773,8 @@ StmtResult Parser::ParseObjCAtStatement(SourceLocation AtLoc,
 ExprResult Parser::ParseObjCAtExpression(SourceLocation AtLoc) {
   switch (Tok.getKind()) {
   case tok::code_completion:
-    Actions.CodeCompleteObjCAtExpression(getCurScope());
     cutOffParsing();
+    Actions.CodeCompleteObjCAtExpression(getCurScope());
     return ExprError();
 
   case tok::minus:
@@ -3012,8 +3020,8 @@ ExprResult Parser::ParseObjCMessageExpression() {
   SourceLocation LBracLoc = ConsumeBracket(); // consume '['
 
   if (Tok.is(tok::code_completion)) {
-    Actions.CodeCompleteObjCMessageReceiver(getCurScope());
     cutOffParsing();
+    Actions.CodeCompleteObjCMessageReceiver(getCurScope());
     return ExprError();
   }
 
@@ -3149,6 +3157,7 @@ Parser::ParseObjCMessageExpressionBody(SourceLocation LBracLoc,
   InMessageExpressionRAIIObject InMessage(*this, true);
 
   if (Tok.is(tok::code_completion)) {
+    cutOffParsing();
     if (SuperLoc.isValid())
       Actions.CodeCompleteObjCSuperMessage(getCurScope(), SuperLoc, None,
                                            false);
@@ -3158,7 +3167,6 @@ Parser::ParseObjCMessageExpressionBody(SourceLocation LBracLoc,
     else
       Actions.CodeCompleteObjCInstanceMessage(getCurScope(), ReceiverExpr,
                                               None, false);
-    cutOffParsing();
     return ExprError();
   }
 
@@ -3187,6 +3195,7 @@ Parser::ParseObjCMessageExpressionBody(SourceLocation LBracLoc,
       ///  Parse the expression after ':'
 
       if (Tok.is(tok::code_completion)) {
+        cutOffParsing();
         if (SuperLoc.isValid())
           Actions.CodeCompleteObjCSuperMessage(getCurScope(), SuperLoc,
                                                KeyIdents,
@@ -3200,7 +3209,6 @@ Parser::ParseObjCMessageExpressionBody(SourceLocation LBracLoc,
                                                   KeyIdents,
                                                   /*AtArgumentExpression=*/true);
 
-        cutOffParsing();
         return ExprError();
       }
 
@@ -3225,6 +3233,7 @@ Parser::ParseObjCMessageExpressionBody(SourceLocation LBracLoc,
 
       // Code completion after each argument.
       if (Tok.is(tok::code_completion)) {
+        cutOffParsing();
         if (SuperLoc.isValid())
           Actions.CodeCompleteObjCSuperMessage(getCurScope(), SuperLoc,
                                                KeyIdents,
@@ -3237,7 +3246,6 @@ Parser::ParseObjCMessageExpressionBody(SourceLocation LBracLoc,
           Actions.CodeCompleteObjCInstanceMessage(getCurScope(), ReceiverExpr,
                                                   KeyIdents,
                                                 /*AtArgumentExpression=*/false);
-        cutOffParsing();
         return ExprError();
       }
 
@@ -3577,8 +3585,8 @@ ExprResult Parser::ParseObjCSelectorExpression(SourceLocation AtLoc) {
     ConsumeParen();
 
   if (Tok.is(tok::code_completion)) {
-    Actions.CodeCompleteObjCSelector(getCurScope(), KeyIdents);
     cutOffParsing();
+    Actions.CodeCompleteObjCSelector(getCurScope(), KeyIdents);
     return ExprError();
   }
 
@@ -3603,8 +3611,8 @@ ExprResult Parser::ParseObjCSelectorExpression(SourceLocation AtLoc) {
         break;
 
       if (Tok.is(tok::code_completion)) {
-        Actions.CodeCompleteObjCSelector(getCurScope(), KeyIdents);
         cutOffParsing();
+        Actions.CodeCompleteObjCSelector(getCurScope(), KeyIdents);
         return ExprError();
       }
 

clang/lib/Parse/ParseOpenMP.cpp

@@ -441,9 +441,9 @@ void Parser::ParseOpenMPReductionInitializerForDecl(VarDecl *OmpPrivParm) {
     ConsumeToken();
 
     if (Tok.is(tok::code_completion)) {
+      cutOffParsing();
       Actions.CodeCompleteInitializer(getCurScope(), OmpPrivParm);
       Actions.FinalizeDeclaration(OmpPrivParm);
-      cutOffParsing();
       return;
     }
 

clang/lib/Parse/ParseStmt.cpp

@@ -178,8 +178,8 @@ Retry:
     }
 
   case tok::code_completion:
-    Actions.CodeCompleteOrdinaryName(getCurScope(), Sema::PCC_Statement);
     cutOffParsing();
+    Actions.CodeCompleteOrdinaryName(getCurScope(), Sema::PCC_Statement);
     return StmtError();
 
   case tok::identifier: {
@@ -726,8 +726,8 @@ StmtResult Parser::ParseCaseStatement(ParsedStmtContext StmtCtx,
     ColonLoc = SourceLocation();
 
     if (Tok.is(tok::code_completion)) {
-      Actions.CodeCompleteCase(getCurScope());
       cutOffParsing();
+      Actions.CodeCompleteCase(getCurScope());
       return StmtError();
     }
 
@@ -1472,8 +1472,8 @@ StmtResult Parser::ParseIfStatement(SourceLocation *TrailingElseLoc) {
     // Pop the 'else' scope if needed.
     InnerScope.Exit();
   } else if (Tok.is(tok::code_completion)) {
-    Actions.CodeCompleteAfterIf(getCurScope(), IsBracedThen);
     cutOffParsing();
+    Actions.CodeCompleteAfterIf(getCurScope(), IsBracedThen);
     return StmtError();
   } else if (InnerStatementTrailingElseLoc.isValid()) {
     Diag(InnerStatementTrailingElseLoc, diag::warn_dangling_else);
@@ -1827,10 +1827,10 @@ StmtResult Parser::ParseForStatement(SourceLocation *TrailingElseLoc) {
   FullExprArg ThirdPart(Actions);
 
   if (Tok.is(tok::code_completion)) {
+    cutOffParsing();
     Actions.CodeCompleteOrdinaryName(getCurScope(),
                                      C99orCXXorObjC? Sema::PCC_ForInit
                                                    : Sema::PCC_Expression);
-    cutOffParsing();
     return StmtError();
   }
 
@@ -1898,8 +1898,8 @@ StmtResult Parser::ParseForStatement(SourceLocation *TrailingElseLoc) {
       ConsumeToken(); // consume 'in'
 
       if (Tok.is(tok::code_completion)) {
-        Actions.CodeCompleteObjCForCollection(getCurScope(), DG);
         cutOffParsing();
+        Actions.CodeCompleteObjCForCollection(getCurScope(), DG);
         return StmtError();
       }
       Collection = ParseExpression();
@@ -1934,8 +1934,8 @@ StmtResult Parser::ParseForStatement(SourceLocation *TrailingElseLoc) {
       ConsumeToken(); // consume 'in'
 
       if (Tok.is(tok::code_completion)) {
-        Actions.CodeCompleteObjCForCollection(getCurScope(), nullptr);
         cutOffParsing();
+        Actions.CodeCompleteObjCForCollection(getCurScope(), nullptr);
         return StmtError();
       }
       Collection = ParseExpression();
@@ -2188,9 +2188,9 @@ StmtResult Parser::ParseReturnStatement() {
       PreferredType.enterReturn(Actions, Tok.getLocation());
     // FIXME: Code completion for co_return.
     if (Tok.is(tok::code_completion) && !IsCoreturn) {
+      cutOffParsing();
       Actions.CodeCompleteExpression(getCurScope(),
                                      PreferredType.get(Tok.getLocation()));
-      cutOffParsing();
       return StmtError();
     }
 

clang/lib/Parse/Parser.cpp

@@ -870,6 +870,7 @@ Parser::ParseExternalDeclaration(ParsedAttributesWithRange &attrs,
     SingleDecl = ParseObjCMethodDefinition();
     break;
   case tok::code_completion:
+    cutOffParsing();
     if (CurParsedObjCImpl) {
       // Code-complete Objective-C methods even without leading '-'/'+' prefix.
       Actions.CodeCompleteObjCMethodDecl(getCurScope(),
@@ -879,7 +880,6 @@ Parser::ParseExternalDeclaration(ParsedAttributesWithRange &attrs,
     Actions.CodeCompleteOrdinaryName(
         getCurScope(),
         CurParsedObjCImpl ? Sema::PCC_ObjCImplementation : Sema::PCC_Namespace);
-    cutOffParsing();
     return nullptr;
   case tok::kw_import:
     SingleDecl = ParseModuleImport(SourceLocation());
@@ -2114,21 +2114,21 @@ SourceLocation Parser::handleUnexpectedCodeCompletionToken() {
 
   for (Scope *S = getCurScope(); S; S = S->getParent()) {
     if (S->getFlags() & Scope::FnScope) {
+      cutOffParsing();
       Actions.CodeCompleteOrdinaryName(getCurScope(),
                                        Sema::PCC_RecoveryInFunction);
-      cutOffParsing();
       return PrevTokLocation;
     }
 
     if (S->getFlags() & Scope::ClassScope) {
-      Actions.CodeCompleteOrdinaryName(getCurScope(), Sema::PCC_Class);
       cutOffParsing();
+      Actions.CodeCompleteOrdinaryName(getCurScope(), Sema::PCC_Class);
       return PrevTokLocation;
     }
   }
 
-  Actions.CodeCompleteOrdinaryName(getCurScope(), Sema::PCC_Namespace);
   cutOffParsing();
+  Actions.CodeCompleteOrdinaryName(getCurScope(), Sema::PCC_Namespace);
   return PrevTokLocation;
 }
 
@@ -2452,8 +2452,8 @@ bool Parser::ParseModuleName(
   while (true) {
     if (!Tok.is(tok::identifier)) {
       if (Tok.is(tok::code_completion)) {
-        Actions.CodeCompleteModuleImport(UseLoc, Path);
         cutOffParsing();
+        Actions.CodeCompleteModuleImport(UseLoc, Path);
         return true;
       }
 

clang/lib/Sema/SemaCodeComplete.cpp

@@ -5711,8 +5711,9 @@ ProduceSignatureHelp(Sema &SemaRef, Scope *S,
                      unsigned CurrentArg, SourceLocation OpenParLoc) {
   if (Candidates.empty())
     return QualType();
-  SemaRef.CodeCompleter->ProcessOverloadCandidates(
+  if (SemaRef.getPreprocessor().isCodeCompletionReached())
-      SemaRef, CurrentArg, Candidates.data(), Candidates.size(), OpenParLoc);
+    SemaRef.CodeCompleter->ProcessOverloadCandidates(
+        SemaRef, CurrentArg, Candidates.data(), Candidates.size(), OpenParLoc);
   return getParamType(SemaRef, Candidates, CurrentArg);
 }
 

clang/test/CodeCompletion/desig-init.cpp

@@ -62,3 +62,18 @@ void aux() {
   Test<T> X{.x = T(2)};
   // RUN: %clang_cc1 -fsyntax-only -code-completion-patterns -code-completion-at=%s:62:14 %s -o - -std=c++2a | FileCheck -check-prefix=CHECK-CC3 %s
 }
+
+namespace signature_regression {
+  // Verify that an old bug is gone: passing an init-list as a constructor arg
+  // would emit overloads as a side-effect.
+  struct S{int x;};
+  int wrongFunction(S);
+  int rightFunction();
+  int dummy = wrongFunction({1});
+  int x = rightFunction();
+  // RUN: %clang_cc1 -fsyntax-only -code-completion-at=%s:73:25 %s -o - -std=c++2a | FileCheck -check-prefix=CHECK-SIGNATURE-REGRESSION %s
+  // CHECK-SIGNATURE-REGRESSION-NOT: OVERLOAD: [#int#]wrongFunction
+  // CHECK-SIGNATURE-REGRESSION:     OVERLOAD: [#int#]rightFunction
+  // CHECK-SIGNATURE-REGRESSION-NOT: OVERLOAD: [#int#]wrongFunction
+}
+