Improved parsing of ambiguous statements.

Done with Erik Verbruggen

src/shared/cplusplus/Parser.cpp

@@ -56,7 +56,7 @@
 #include <cstdlib>
 #include <cstring>
 #include <cassert>
-#include <QDebug>
+
 CPLUSPLUS_BEGIN_NAMESPACE
 
 Parser::Parser(TranslationUnit *unit)
@@ -2041,10 +2041,68 @@ bool Parser::maybeSimpleExpression(SimpleDeclarationAST *simpleDecl) const
 {
     if (! simpleDecl->declarators)  {
         SpecifierAST *spec = simpleDecl->decl_specifier_seq;
-        if (spec && ! spec->next && spec->asNamedTypeSpecifier()) {
+
+        if (spec && ! spec->next && spec->asNamedTypeSpecifier())
             return true;
+    }
+
+    return false;
+}
+
+bool Parser::isPointerDeclaration(DeclarationStatementAST *ast) const
+{
+    if (! ast)
+        return false;
+
+    if (SimpleDeclarationAST *declaration = ast->declaration->asSimpleDeclaration()) {
+        if (SpecifierAST *spec = declaration->decl_specifier_seq) {
+            if (spec->asNamedTypeSpecifier() && ! spec->next) {
+                if (DeclaratorListAST *declarators = declaration->declarators) {
+                    if (DeclaratorAST *declarator = declarators->declarator) {
+                        if (declarator->ptr_operators && declarator->equals_token && declarator->initializer) {
+                            return true;
+                        }
+                    }
+                }
+            }
         }
     }
+
+    return false;
+}
+
+bool Parser::maybeAmbiguousStatement(DeclarationStatementAST *ast) const
+{
+    if (! ast)
+        return false;
+
+    if (SimpleDeclarationAST *declaration = ast->declaration->asSimpleDeclaration()) {
+        if (SpecifierAST *spec = declaration->decl_specifier_seq) {
+            if (spec->asNamedTypeSpecifier() && ! spec->next) {
+                if (DeclaratorListAST *declarators = declaration->declarators) {
+                    if (DeclaratorAST *declarator = declarators->declarator) {
+                        if (declarator->core_declarator &&
+                            declarator->core_declarator->asNestedDeclarator()) {
+                            // recognized name(id-expression)
+                            return true;
+                        }
+                    }
+                }
+            }
+
+        } else if (DeclaratorListAST *declarators = declaration->declarators) {
+            // no decl_specifiers...
+            if (DeclaratorAST *declarator = declarators->declarator) {
+                if (declarator->postfix_declarators && declarator->postfix_declarators->asFunctionDeclarator()
+                                                     && ! declarator->initializer) {
+                    return false;
+                }                
+            }
+
+            return true;
+        }
+    }
+
     return false;
 }
 
@@ -2055,31 +2113,35 @@ bool Parser::parseExpressionOrDeclarationStatement(StatementAST *&node)
 
     unsigned start = cursor();
     bool blocked = blockErrors(true);
+
     if (parseDeclarationStatement(node)) {
         DeclarationStatementAST *stmt = static_cast<DeclarationStatementAST *>(node);
-        SimpleDeclarationAST *simpleDecl = 0;
-        if (stmt->declaration)
-            simpleDecl = stmt->declaration->asSimpleDeclaration();
 
-        if (simpleDecl && simpleDecl->decl_specifier_seq &&
-                ! maybeFunctionCall(simpleDecl) && ! maybeSimpleExpression(simpleDecl)) {
+        if (isPointerDeclaration(stmt)) {
+            blockErrors(blocked);
+            return true;
+        }
+
+        if (! maybeAmbiguousStatement(stmt)) {
             unsigned end_of_declaration_statement = cursor();
             rewind(start);
+
             StatementAST *expression = 0;
-            if (! parseExpressionStatement(expression) || cursor() != end_of_declaration_statement) {
-                rewind(end_of_declaration_statement);
-            } else {
-                ExpressionOrDeclarationStatementAST *ast =
-                        new (_pool) ExpressionOrDeclarationStatementAST;
+            if (parseExpressionStatement(expression) && cursor() == end_of_declaration_statement) {
+                // it's an ambiguous expression-or-declaration statement.
+                ExpressionOrDeclarationStatementAST *ast = new (_pool) ExpressionOrDeclarationStatementAST;
                 ast->declaration = node;
                 ast->expression = expression;
                 node = ast;
             }
+
+            rewind(end_of_declaration_statement);
             blockErrors(blocked);
             return true;
         }
     }
 
+    // it's not a declaration statement.
     blockErrors(blocked);
     rewind(start);
     return parseExpressionStatement(node);
@@ -2653,6 +2715,12 @@ bool Parser::parseSimpleDeclaration(DeclarationAST *&node,
             return false;
     }
 
+    // if there is no valid declarator
+    // and it doesn't look like a fwd or a class declaration
+    // then it's not a declarations
+    if (! declarator && ! maybeForwardOrClassDeclaration(decl_specifier_seq))
+        return false;
+
     DeclaratorAST *firstDeclarator = declarator;
 
     if (declarator) {
@@ -2709,6 +2777,19 @@ bool Parser::parseSimpleDeclaration(DeclarationAST *&node,
     return false;
 }
 
+bool Parser::maybeForwardOrClassDeclaration(SpecifierAST *decl_specifier_seq) const
+{
+    // look at the decl_specifier for possible fwd or class declarations.
+    if (SpecifierAST *spec = decl_specifier_seq) {
+        if (! spec->next && (spec->asElaboratedTypeSpecifier() ||
+                             spec->asEnumSpecifier() ||
+                             spec->asClassSpecifier()))
+            return true;
+    }
+
+    return false;
+}
+
 bool Parser::parseFunctionBody(StatementAST *&node)
 {
     if (_translationUnit->skipFunctionBody()) {

src/shared/cplusplus/Parser.h

@@ -264,8 +264,11 @@ public:
 
     void match(int kind, unsigned *token);
 
+    bool maybeAmbiguousStatement(DeclarationStatementAST *ast) const;
     bool maybeFunctionCall(SimpleDeclarationAST *simpleDecl) const;
     bool maybeSimpleExpression(SimpleDeclarationAST *simpleDecl) const;
+    bool maybeForwardOrClassDeclaration(SpecifierAST *decl_specifier_seq) const;
+    bool isPointerDeclaration(DeclarationStatementAST *ast) const;
 
 private:
     bool switchTemplateArguments(bool templateArguments);

tests/auto/cplusplus/ast/tst_ast.cpp

@@ -58,6 +58,12 @@ private slots:
     void while_condition_statement();
     void for_statement();
     void cpp_initializer_or_function_declaration();
+    void simple_declaration_1();
+    void function_call_1();
+    void function_call_2();
+    void function_call_3();
+    void nested_deref_expression();
+    void assignment_1();
 
     // objc++
     void objc_attributes_followed_by_at_keyword();
@@ -78,6 +84,19 @@ void tst_AST::gcc_attributes_1()
     ));
 }
 
+void tst_AST::simple_declaration_1()
+{
+    QSharedPointer<TranslationUnit> unit(parseStatement("\n"
+"a * b = 10;"
+    ));
+
+    AST *ast = unit->ast();
+    QVERIFY(ast);
+
+    DeclarationStatementAST *declStmt = ast->asDeclarationStatement();
+    QVERIFY(declStmt);
+}
+
 void tst_AST::simple_name()
 {
     QSharedPointer<TranslationUnit> unit(parseExpression("a"));
@@ -161,7 +180,7 @@ void tst_AST::new_expression_2()
 void tst_AST::condition_1()
 {
     QSharedPointer<TranslationUnit> unit(parseExpression("\n"
-"(x < 0 && y > (int) a"
+"(x < 0 && y > (int) a)"
     ));
 
     AST *ast = unit->ast();
@@ -178,6 +197,46 @@ void tst_AST::init_1()
     QVERIFY(ast != 0);
 }
 
+void tst_AST::function_call_1()
+{
+    QSharedPointer<TranslationUnit> unit(parseStatement("retranslateUi(blah);"));
+    AST *ast = unit->ast();
+    QVERIFY(ast != 0);
+    QVERIFY(ast->asExpressionStatement());
+}
+
+void tst_AST::function_call_2()
+{
+    QSharedPointer<TranslationUnit> unit(parseStatement("retranslateUi(10);"));
+    AST *ast = unit->ast();
+    QVERIFY(ast != 0);
+    QVERIFY(ast->asExpressionStatement());
+}
+
+void tst_AST::function_call_3()
+{
+    QSharedPointer<TranslationUnit> unit(parseStatement("(*blah) = 10;"));
+    AST *ast = unit->ast();
+    QVERIFY(ast != 0);
+    QVERIFY(ast->asExpressionStatement());
+}
+
+void tst_AST::nested_deref_expression()
+{
+    QSharedPointer<TranslationUnit> unit(parseStatement("(*blah);"));
+    AST *ast = unit->ast();
+    QVERIFY(ast != 0);
+    QVERIFY(ast->asExpressionStatement());
+}
+
+void tst_AST::assignment_1()
+{
+    QSharedPointer<TranslationUnit> unit(parseStatement("a(x) = 3;"));
+    AST *ast = unit->ast();
+    QVERIFY(ast != 0);
+    QVERIFY(ast->asExpressionStatement());
+}
+
 void tst_AST::if_statement()
 {
     QSharedPointer<TranslationUnit> unit(parseStatement("if (a) b;"));
@@ -195,7 +254,7 @@ void tst_AST::if_statement()
     QCOMPARE(stmt->else_token, 0U);
     QVERIFY(stmt->else_statement == 0);
 
-    // check the `then' statement
+    // check the `then' statement1
     ExpressionStatementAST *then_stmt = stmt->statement->asExpressionStatement();
     QVERIFY(then_stmt != 0);
     QVERIFY(then_stmt->expression != 0);
@@ -435,7 +494,7 @@ void tst_AST::normal_array_access()
 {
     QSharedPointer<TranslationUnit> unit(parseDeclaration("\n"
                                                           "int f() {\n"
-                                                          "  int a[15];\n"
+                                                          "  int a[10];\n"
                                                           "  int b = 1;\n"
                                                           "  return a[b];\n"
                                                           "}"
@@ -447,7 +506,10 @@ void tst_AST::normal_array_access()
     QVERIFY(func);
 
     StatementListAST *bodyStatements = func->function_body->asCompoundStatement()->statements;
-    QVERIFY(bodyStatements && bodyStatements->next && bodyStatements->next->next && bodyStatements->next->next->statement);
+    QVERIFY(bodyStatements);
+    QVERIFY(bodyStatements->next);
+    QVERIFY(bodyStatements->next->next);
+    QVERIFY(bodyStatements->next->next->statement);
     ExpressionAST *expr = bodyStatements->next->next->statement->asReturnStatement()->expression;
     QVERIFY(expr);
 
@@ -536,9 +598,9 @@ void tst_AST::objc_msg_send_expression()
     QVERIFY(bodyStatements && bodyStatements->next && !bodyStatements->next->next && bodyStatements->next->statement);
 
     {// check the NSObject declaration
-        ExpressionOrDeclarationStatementAST *firstStatement = bodyStatements->statement->asExpressionOrDeclarationStatement();
-        QVERIFY(firstStatement && firstStatement->declaration && firstStatement->declaration->asDeclarationStatement());
-        DeclarationAST *objDecl = firstStatement->declaration->asDeclarationStatement()->declaration;
+        DeclarationStatementAST *firstStatement = bodyStatements->statement->asDeclarationStatement();
+        QVERIFY(firstStatement);
+        DeclarationAST *objDecl = firstStatement->declaration;
         QVERIFY(objDecl);
         SimpleDeclarationAST *simpleDecl = objDecl->asSimpleDeclaration();
         QVERIFY(simpleDecl);