CPlusPlus: Allow empty argument list in member initialization

Fixes: QTCREATORBUG-30797
Change-Id: I6de0f05e071a5e73317d7a8e3d035e23e23a41aa
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

src/libs/3rdparty/cplusplus/Parser.cpp

@@ -20,7 +20,6 @@
 
 #include "Parser.h"
 #include "Token.h"
-#include "Lexer.h"
 #include "Control.h"
 #include "AST.h"
 #include "Literals.h"
@@ -30,7 +29,6 @@
 #include <unordered_map>
 #include <utility>
 
-#include <string>
 #include <cstdio> // for putchar
 
 #if defined(__INTEL_COMPILER) && !defined(va_copy)
@@ -3088,7 +3086,7 @@ bool Parser::parseInitializer0x(ExpressionAST *&node, int *equals_token)
     }
 
     else if (LA() == T_LPAREN) {
-        return parseExpressionListParen(node);
+        return parseExpressionListParen(node, false);
     }
 
     return false;
@@ -3258,7 +3256,7 @@ bool Parser::parseMemInitializer(MemInitializerListAST *&node)
     ast->name = name;
 
     if (LA() == T_LPAREN) {
-        parseExpressionListParen(ast->expression);
+        parseExpressionListParen(ast->expression, true);
     } else if (_languageFeatures.cxx11Enabled && LA() == T_LBRACE) {
         parseBracedInitList0x(ast->expression);
     } else {
@@ -5452,7 +5450,7 @@ bool Parser::parseTypenameCallExpression(ExpressionAST *&node)
             ast->typename_token = typename_token;
             ast->name = name;
             if (LA() == T_LPAREN) {
-                parseExpressionListParen(ast->expression);
+                parseExpressionListParen(ast->expression, false);
             } else { // T_LBRACE
                 parseBracedInitList0x(ast->expression);
             }
@@ -5511,7 +5509,7 @@ bool Parser::parseCorePostfixExpression(ExpressionAST *&node)
                 (LA() == T_LPAREN || (_languageFeatures.cxx11Enabled && LA() == T_LBRACE))) {
             ExpressionAST *expr = nullptr;
             if (LA() == T_LPAREN) {
-                parseExpressionListParen(expr);
+                parseExpressionListParen(expr, false);
             } else { // T_LBRACE
                 parseBracedInitList0x(expr);
             }
@@ -5707,13 +5705,14 @@ bool Parser::parseUnaryExpression(ExpressionAST *&node)
 }
 
 // new-placement ::= T_LPAREN expression-list T_RPAREN
-bool Parser::parseExpressionListParen(ExpressionAST *&node)
+bool Parser::parseExpressionListParen(ExpressionAST *&node, bool allowEmpty)
 {
     DEBUG_THIS_RULE();
     if (LA() == T_LPAREN) {
         int lparen_token = consumeToken();
         ExpressionListAST *expression_list = nullptr;
-        if (parseExpressionList(expression_list) && LA() == T_RPAREN) {
+        const bool hasList = parseExpressionList(expression_list);
+        if ((hasList || allowEmpty) && LA() == T_RPAREN) {
             int rparen_token = consumeToken();
             ExpressionListParenAST *ast = new (_pool) ExpressionListParenAST;
             ast->lparen_token = lparen_token;
@@ -5746,7 +5745,7 @@ bool Parser::parseNewExpression(ExpressionAST *&node)
 
     ExpressionAST *parenExpressionList = nullptr;
 
-    if (parseExpressionListParen(parenExpressionList)) {
+    if (parseExpressionListParen(parenExpressionList, false)) {
         int after_new_placement = cursor();
 
         NewTypeIdAST *new_type_id = nullptr;
@@ -5839,7 +5838,7 @@ bool Parser::parseNewInitializer(ExpressionAST *&node)
 {
     DEBUG_THIS_RULE();
     if (LA() == T_LPAREN)
-        return parseExpressionListParen(node);
+        return parseExpressionListParen(node, false);
     else if (_languageFeatures.cxx11Enabled && LA() == T_LBRACE)
         return parseBracedInitList0x(node);
     return false;

src/libs/3rdparty/cplusplus/Parser.h

@@ -117,7 +117,7 @@ public:
     bool parseNamespaceAliasDefinition(DeclarationAST *&node);
     bool parseNewArrayDeclarator(NewArrayDeclaratorListAST *&node);
     bool parseNewExpression(ExpressionAST *&node);
-    bool parseExpressionListParen(ExpressionAST *&node);
+    bool parseExpressionListParen(ExpressionAST *&node, bool allowEmpty);
     bool parseNewInitializer(ExpressionAST *&node);
     bool parseNewTypeId(NewTypeIdAST *&node);
     bool parseOperator(OperatorAST *&node);

tests/auto/cplusplus/ast/tst_ast.cpp

@@ -112,6 +112,7 @@ private slots:
     void templated_dtor_3();
     void templated_dtor_4();
     void templated_dtor_5();
+    void emptyMemberInitialization();
 
     // possible declaration-or-expression statements
     void call_call_1();
@@ -2061,6 +2062,14 @@ void tst_AST::invalidFunctionInitializer()
     QVERIFY(diag.errorCount != 0);
 }
 
+void tst_AST::emptyMemberInitialization()
+{
+    const std::shared_ptr<TranslationUnit> unit(parse(
+        "struct S\n{\n    S(): i() {}\n    int i;};", TranslationUnit::ParseTranlationUnit));
+    QVERIFY(unit->ast());
+    QCOMPARE(diag.errorCount, 0);
+}
+
 void tst_AST::initTestCase()
 {
     control.setDiagnosticClient(&diag);