SONARPY-1210 except* can not contain continue, break or return instruction (#1307)

Author: rudy-regazzoni-sonarsource

python-frontend/src/main/java/org/sonar/python/tree/ExceptGroupJumpInstructionsCheck.java

@@ -0,0 +1,57 @@
+/*
+ * SonarQube Python Plugin
+ * Copyright (C) 2011-2022 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+package org.sonar.python.tree;
+
+import org.sonar.plugins.python.api.tree.BaseTreeVisitor;
+import org.sonar.plugins.python.api.tree.BreakStatement;
+import org.sonar.plugins.python.api.tree.ContinueStatement;
+import org.sonar.plugins.python.api.tree.ReturnStatement;
+import org.sonar.plugins.python.api.tree.Tree;
+
+/**
+ * Purpose of this class is to detect and throw exception if the scanned tree that contain invalid syntax regarding the except* instruction.
+ * It is currently not valid to have a break, continue or return statement in an except* body.
+ */
+public class ExceptGroupJumpInstructionsCheck extends BaseTreeVisitor {
+  @Override
+  public void visitBreakStatement(BreakStatement breakStatement) {
+    checkExceptGroupStatement(breakStatement, "break statement cannot appear in except* block",
+      Tree.Kind.EXCEPT_GROUP_CLAUSE, Tree.Kind.FOR_STMT, Tree.Kind.WHILE_STMT);
+  }
+
+  @Override
+  public void visitContinueStatement(ContinueStatement continueStatement) {
+    checkExceptGroupStatement(continueStatement, "continue statement cannot appear in except* block",
+      Tree.Kind.EXCEPT_GROUP_CLAUSE, Tree.Kind.FOR_STMT, Tree.Kind.WHILE_STMT);
+  }
+
+  @Override
+  public void visitReturnStatement(ReturnStatement returnStatement) {
+    checkExceptGroupStatement(returnStatement, "return statement cannot appear in except* block",
+      Tree.Kind.EXCEPT_GROUP_CLAUSE, Tree.Kind.FUNCDEF);
+  }
+
+  private static void checkExceptGroupStatement(Tree statement, String message, Tree.Kind... possibleParents) {
+    Tree parent = TreeUtils.firstAncestorOfKind(statement, possibleParents);
+    if (parent != null && parent.is(Tree.Kind.EXCEPT_GROUP_CLAUSE)) {
+      PythonTreeMaker.recognitionException(statement.firstToken().line(), message);
+    }
+  }
+}

python-frontend/src/main/java/org/sonar/python/tree/PythonTreeMaker.java

@@ -120,10 +120,11 @@ public FileInput fileInput(AstNode astNode) {
     Token endOfFile = toPyToken(astNode.getFirstChild(GenericTokenType.EOF).getToken());
     FileInputImpl pyFileInputTree = new FileInputImpl(statementList, endOfFile, DocstringExtractor.extractDocstring(statementList));
     setParents(pyFileInputTree);
+    pyFileInputTree.accept(new ExceptGroupJumpInstructionsCheck());
     return pyFileInputTree;
   }
 
-  private static void recognitionException(int line, String message) {
+  public static void recognitionException(int line, String message) {
     throw new RecognitionException(line, "Parse error at line " + line + ": " + message + ".");
   }
 

python-frontend/src/test/java/org/sonar/python/tree/PythonTreeMakerTest.java

@@ -2597,6 +2597,72 @@ public void except_group() {
       .hasMessage("Parse error at line 2: except* clause must specify the type of the expected exception.");
   }
 
+  /**
+   * except* body cannot contain continue, break or return instruction
+   */
+  @Test
+  public void except_group_invalid_instruction() {
+    String code1 = "try:pass\n" +
+      "except* OSError:\n" +
+      "  continue";
+    assertThatThrownBy(() -> parse(code1, treeMaker::fileInput))
+      .isInstanceOf(RecognitionException.class)
+      .hasMessage("Parse error at line 3: continue statement cannot appear in except* block.");
+
+    String code2 = "try:pass\n" +
+      "except* OSError:\n" +
+      "  break";
+    assertThatThrownBy(() -> parse(code2, treeMaker::fileInput))
+      .isInstanceOf(RecognitionException.class)
+      .hasMessage("Parse error at line 3: break statement cannot appear in except* block.");
+
+    String code3 = "try:pass\n" +
+      "except* OSError:\n" +
+      "  return";
+    assertThatThrownBy(() -> parse(code3, treeMaker::fileInput))
+      .isInstanceOf(RecognitionException.class)
+      .hasMessage("Parse error at line 3: return statement cannot appear in except* block.");
+
+    // should not return parse error if continue/break is in a loop
+    String code4 = "try:pass\n" +
+      "except* OSError:\n" +
+      "  while true:break";
+    FileInput tree = parse(code4, treeMaker::fileInput);
+    TryStatement tryStatement = (TryStatement) tree.statements().statements().get(0);
+    assertThat(tryStatement.exceptClauses().get(0).getKind()).isEqualTo(Kind.EXCEPT_GROUP_CLAUSE);
+
+    String code5 = "try:pass\n" +
+      "except* OSError:\n" +
+      "  for x in \"bob\":continue";
+    tree = parse(code5, treeMaker::fileInput);
+    tryStatement = (TryStatement) tree.statements().statements().get(0);
+    assertThat(tryStatement.exceptClauses().get(0).getKind()).isEqualTo(Kind.EXCEPT_GROUP_CLAUSE);
+
+    // should not return parse error if return is in a function
+    String code6 = "try:pass\n" +
+      "except* OSError:\n" +
+      "  def foo():return";
+    tree = parse(code6, treeMaker::fileInput);
+    tryStatement = (TryStatement) tree.statements().statements().get(0);
+    assertThat(tryStatement.exceptClauses().get(0).getKind()).isEqualTo(Kind.EXCEPT_GROUP_CLAUSE);
+
+    String code7 = "for x in range(42):\n" +
+      "  try:pass\n" +
+      "  except* OSError:\n" +
+      "    continue";
+    assertThatThrownBy(() -> parse(code7, treeMaker::fileInput))
+      .isInstanceOf(RecognitionException.class)
+      .hasMessage("Parse error at line 4: continue statement cannot appear in except* block.");
+
+    String code8 = "def foo():\n" +
+      "  try:pass\n" +
+      "  except* OSError:\n" +
+      "    continue";
+    assertThatThrownBy(() -> parse(code8, treeMaker::fileInput))
+      .isInstanceOf(RecognitionException.class)
+      .hasMessage("Parse error at line 4: continue statement cannot appear in except* block.");
+  }
+
   @Test
   public void except_group_multiple() {
     FileInput tree = parse("try:pass\nexcept* OSError:pass\nexcept* ValueError:pass", treeMaker::fileInput);