Issue #12542: new TreeWalker property to skip exceptions

config/ant-phase-verify.xml

@@ -166,7 +166,8 @@
           <exclude name="**/InputMainFrameModelIncorrectClass.java"/>
           <exclude name="**/InputBeforeExecutionExclusionFileFilterIncorrectClass.java"/>
           <exclude name="**/InputJavaParser.java"/>
-
+          <exclude name="**/InputTreeWalkerSkipParsingException.java"/>
+          <exclude name="**/InputTreeWalkerSkipParsingExceptionConfig.java"/>
         </fileset>
       </path>
       <formatter type="plain"/>
@@ -203,6 +204,8 @@
           <exclude name="**/InputMainFrameModelIncorrectClass.java"/>
           <exclude name="**/InputBeforeExecutionExclusionFileFilterIncorrectClass.java"/>
           <exclude name="**/InputJavaParser.java"/>
+          <exclude name="**/InputTreeWalkerSkipParsingException.java"/>
+          <exclude name="**/InputTreeWalkerSkipParsingExceptionConfig.java"/>
           <!-- This check does not apply to grammar input files -->
           <exclude name="**/grammar/**/*"/>
           <!-- No need to check xpathmapper files -->

src/main/java/com/puppycrawl/tools/checkstyle/TreeWalker.java

@@ -79,6 +79,9 @@ public final class TreeWalker extends AbstractFileSetCheck implements ExternalRe
     /** A factory for creating submodules (i.e. the Checks) */
     private ModuleFactory moduleFactory;
 
+    /** Control whether to skip files with Java parsing errors. */
+    private boolean skipFileOnJavaParseException;
+
     /**
      * Creates a new {@code TreeWalker} instance.
      */
@@ -95,6 +98,16 @@ public void setModuleFactory(ModuleFactory moduleFactory) {
         this.moduleFactory = moduleFactory;
     }
 
+    /**
+     * Setter to control whether to skip files with Java parsing errors.
+     *
+     *  @param skipFileOnJavaParseException whether to always check for a trailing comma.
+     *  @since 10.16.0
+     */
+    public void setSkipFileOnJavaParseException(boolean skipFileOnJavaParseException) {
+        this.skipFileOnJavaParseException = skipFileOnJavaParseException;
+    }
+
     @Override
     public void finishLocalSetup() {
         final DefaultContext checkContext = new DefaultContext();
@@ -149,23 +162,40 @@ protected void processFiltered(File file, FileText fileText) throws CheckstyleEx
         // check if already checked and passed the file
         if (!ordinaryChecks.isEmpty() || !commentChecks.isEmpty()) {
             final FileContents contents = getFileContents();
-            final DetailAST rootAST = JavaParser.parse(contents);
-            if (!ordinaryChecks.isEmpty()) {
-                walk(rootAST, contents, AstState.ORDINARY);
-            }
-            if (!commentChecks.isEmpty()) {
-                final DetailAST astWithComments = JavaParser.appendHiddenCommentNodes(rootAST);
-                walk(astWithComments, contents, AstState.WITH_COMMENTS);
+            DetailAST rootAST = null;
+            // whether skip the procedure after parsing Java files.
+            boolean skip = false;
+
+            try {
+                rootAST = JavaParser.parse(contents);
             }
-            if (filters.isEmpty()) {
-                addViolations(violations);
+            catch (CheckstyleException ex) {
+                if (skipFileOnJavaParseException) {
+                    skip = true;
+                }
+                else {
+                    throw ex;
+                }
             }
-            else {
-                final SortedSet<Violation> filteredViolations =
-                    getFilteredViolations(file.getAbsolutePath(), contents, rootAST);
-                addViolations(filteredViolations);
+
+            if (!skip) {
+                if (!ordinaryChecks.isEmpty()) {
+                    walk(rootAST, contents, AstState.ORDINARY);
+                }
+                if (!commentChecks.isEmpty()) {
+                    final DetailAST astWithComments = JavaParser.appendHiddenCommentNodes(rootAST);
+                    walk(astWithComments, contents, AstState.WITH_COMMENTS);
+                }
+                if (filters.isEmpty()) {
+                    addViolations(violations);
+                }
+                else {
+                    final SortedSet<Violation> filteredViolations =
+                            getFilteredViolations(file.getAbsolutePath(), contents, rootAST);
+                    addViolations(filteredViolations);
+                }
+                violations.clear();
             }
-            violations.clear();
         }
     }
 

src/test/java/com/puppycrawl/tools/checkstyle/TreeWalkerTest.java

@@ -35,8 +35,10 @@
 import java.util.Arrays;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
+import java.util.Map;
 import java.util.Set;
 import java.util.UUID;
 import java.util.regex.Matcher;
@@ -673,6 +675,57 @@ public void testOrderOfCheckExecution() throws Exception {
         }
     }
 
+    @Test
+    public void testSkipFileOnJavaParseExceptionTrue() throws Exception {
+        final DefaultConfiguration config = createModuleConfig(TreeWalker.class);
+        config.addProperty("skipFileOnJavaParseException", "true");
+        config.addChild(createModuleConfig(ConstantNameCheck.class));
+
+        final File[] files = {
+            new File(getNonCompilablePath("InputTreeWalkerSkipParsingException.java")),
+            new File(getPath("InputTreeWalkerProperFileExtension.java")),
+            new File(getNonCompilablePath("InputTreeWalkerSkipParsingException.java")),
+        };
+
+        final Checker checker = createChecker(config);
+        final Map<String, List<String>> expectedViolation = new HashMap<>();
+        expectedViolation.put(getPath("InputTreeWalkerProperFileExtension.java"),
+                Collections.singletonList(
+                        "10:27: " + getCheckMessage(ConstantNameCheck.class,
+                        MSG_INVALID_PATTERN, "k", "^[A-Z][A-Z0-9]*(_[A-Z0-9]+)*$")));
+        verify(checker, files, expectedViolation);
+    }
+
+    @Test
+    public void testSkipFileOnJavaParseExceptionFalse() throws Exception {
+        final DefaultConfiguration config = createModuleConfig(TreeWalker.class);
+        config.addProperty("skipFileOnJavaParseException", "false");
+        config.addChild(createModuleConfig(ConstantNameCheck.class));
+
+        final String[] files = {
+            getNonCompilablePath("InputTreeWalkerSkipParsingException.java"),
+            getPath("InputTreeWalkerProperFileExtension.java"),
+            getNonCompilablePath("InputTreeWalkerSkipParsingException.java"),
+        };
+
+        try {
+            execute(config, files);
+            assertWithMessage("Exception is expected").fail();
+        }
+        catch (CheckstyleException exception) {
+            assertWithMessage("Error message is unexpected")
+                    .that(exception.getMessage())
+                    .contains("Exception was thrown while processing ");
+        }
+    }
+
+    @Test
+    public void testSkipFileOnJavaParseExceptionConfig() throws Exception {
+        final String path = getNonCompilablePath("InputTreeWalkerSkipParsingExceptionConfig.java");
+        final String[] expected = {};
+        verifyWithInlineXmlConfig(path, expected);
+    }
+
     public static class BadJavaDocCheck extends AbstractCheck {
 
         @Override

src/test/resources-noncompilable/com/puppycrawl/tools/checkstyle/treewalker/InputTreeWalkerSkipParsingException.java

@@ -0,0 +1,3 @@
+//non-compiled syntax: bad file for testing
+
+public clazz InputTreeWalkerSkipParsingException {}

src/test/resources-noncompilable/com/puppycrawl/tools/checkstyle/treewalker/InputTreeWalkerSkipParsingExceptionConfig.java

@@ -0,0 +1,11 @@
+/*xml
+<module name="Checker">
+  <module name="TreeWalker">
+    <property name="skipFileOnJavaParseException" value="true"/>
+    <module name="ConstantName"/>
+  </module>
+</module>
+*/
+
+//non-compiled syntax: bad file for testing
+public clazz InputTreeWalkerSkipParsingExceptionConfig {}

src/xdocs/config.xml

@@ -539,6 +539,13 @@
               <td><code>.java</code></td>
               <td>3.0</td>
             </tr>
+            <tr>
+              <td>skipFileOnJavaParseException</td>
+              <td>Control whether to skip files with Java parsing errors.</td>
+              <td><a href="property_types.html#boolean">boolean</a></td>
+              <td><code>false</code></td>
+              <td>10.16.0</td>
+            </tr>
           </table>
         </div>
       </subsection>