CppEditor: Revert changes to parseExpressionStatement()

Amends c8f29b9e01.
It turns out that there are contexts where we want to parse an
expression statement even with the semicolon missing (e.g. completion on
incomplete code).
So leave the existing functions unchanged and do the thorough check
afterwards in parseIfStatement().

Change-Id: Id6209ef1abfe9d155c5b9381e6ae655cc721feb2
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Christian Stenger <christian.stenger@qt.io>

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

@@ -1779,7 +1779,6 @@ public:
     int if_token = 0;
     int constexpr_token = 0;
     int lparen_token = 0;
-    DeclarationAST *initDecl = nullptr;
     StatementAST *initStmt = nullptr;
     ExpressionAST *condition = nullptr;
     int rparen_token = 0;

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

@@ -785,8 +785,6 @@ IfStatementAST *IfStatementAST::clone(MemoryPool *pool) const
     ast->if_token = if_token;
     ast->constexpr_token = constexpr_token;
     ast->lparen_token = lparen_token;
-    if (initDecl)
-        ast->initDecl = initDecl->clone(pool);
     if (initStmt)
         ast->initStmt = initStmt->clone(pool);
     if (condition)

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

@@ -1318,11 +1318,6 @@ bool ASTMatcher::match(IfStatementAST *node, IfStatementAST *pattern)
 
     pattern->lparen_token = node->lparen_token;
 
-    if (!pattern->initDecl)
-        pattern->initDecl = node->initDecl;
-    else if (!AST::match(node->initDecl, pattern->initDecl, this))
-        return false;
-
     if (!pattern->initStmt)
         pattern->initStmt = node->initStmt;
     else if (!AST::match(node->initStmt, pattern->initStmt, this))

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

@@ -563,7 +563,6 @@ void ForStatementAST::accept0(ASTVisitor *visitor)
 void IfStatementAST::accept0(ASTVisitor *visitor)
 {
     if (visitor->visit(this)) {
-        accept(initDecl, visitor);
         accept(initStmt, visitor);
         accept(condition, visitor);
         accept(statement, visitor);

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

@@ -1528,9 +1528,7 @@ bool Bind::visit(IfStatementAST *ast)
     ast->symbol = block;
 
     Scope *previousScope = switchScope(block);
-    if (ast->initDecl)
+    if (ast->initStmt)
-        this->declaration(ast->initDecl);
-    else if (ast->initStmt)
         this->statement(ast->initStmt);
     /*ExpressionTy condition =*/ this->expression(ast->condition);
     this->statement(ast->statement);

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

@@ -3511,14 +3511,12 @@ bool Parser::parseExpressionStatement(StatementAST *&node)
 
     ExpressionAST *expression = nullptr;
     if (parseExpression(expression)) {
-        if (LA() == T_SEMICOLON) {
+        ExpressionStatementAST *ast = new (previousPool) ExpressionStatementAST;
-            ExpressionStatementAST *ast = new (previousPool) ExpressionStatementAST;
+        if (expression)
-            ast->semicolon_token = consumeToken();
+            ast->expression = expression->clone(previousPool);
-            if (expression)
+        match(T_SEMICOLON, &ast->semicolon_token);
-                ast->expression = expression->clone(previousPool);
+        node = ast;
-            node = ast;
+        parsed = true;
-            parsed = true;
-        }
     }
 
     _inExpressionStatement = wasInExpressionStatement;
@@ -4079,14 +4077,26 @@ bool Parser::parseIfStatement(StatementAST *&node)
         if (_languageFeatures.cxx17Enabled) {
             const int savedCursor = cursor();
             const bool savedBlockErrors = _translationUnit->blockErrors(true);
-            if (!parseSimpleDeclaration(ast->initDecl)) {
+            bool foundInitStmt = parseExpressionOrDeclarationStatement(ast->initStmt);
+            if (foundInitStmt)
+                foundInitStmt = ast->initStmt;
+            if (foundInitStmt) {
+                if (const auto exprStmt = ast->initStmt->asExpressionStatement()) {
+                    foundInitStmt = exprStmt->semicolon_token;
+                } else if (const auto declStmt = ast->initStmt->asDeclarationStatement()) {
+                    foundInitStmt = declStmt->declaration
+                            && declStmt->declaration->asSimpleDeclaration()
+                            && declStmt->declaration->asSimpleDeclaration()->semicolon_token;
+                } else {
+                    foundInitStmt = false;
+                }
+            }
+            if (!foundInitStmt) {
+                ast->initStmt = nullptr;
                 rewind(savedCursor);
-                if (!parseExpressionStatement(ast->initStmt))
-                    rewind(savedCursor);
             }
             _translationUnit->blockErrors(savedBlockErrors);
         }
-
         parseCondition(ast->condition);
         match(T_RPAREN, &ast->rparen_token);
         if (! parseStatement(ast->statement))