Analyzer: add ignore_for_file comment that ignores a type of problem for the whole file; add tests.

BUG=
R=brianwilkerson@google.com

Review-Url: https://codereview.chromium.org/2888953002 .

pkg/analyzer/lib/src/task/dart.dart

@@ -3005,7 +3005,8 @@ class GenerateLintsTask extends SourceBasedAnalysisTask {
 }
 
 /**
- * Information about analysis `//ignore:` comments within a source file.
+ * Information about analysis `//ignore:` and `//ignore_for_file` comments
+ * within a source file.
  */
 class IgnoreInfo {
   /**
@@ -3024,18 +3025,36 @@ class IgnoreInfo {
   static final RegExp _IGNORE_MATCHER =
       new RegExp(r'//[ ]*ignore:(.*)$', multiLine: true);
 
+  /**
+   * A regular expression for matching 'ignore_for_file' comments.  Produces
+   * matches containing 2 groups.  For example:
+   *
+   *     * ['//ignore_for_file: error_code', 'error_code']
+   *
+   * Resulting codes may be in a list ('error_code_1,error_code2').
+   */
+  static final RegExp _IGNORE_FOR_FILE_MATCHER =
+      new RegExp(r'//[ ]*ignore_for_file:(.*)$', multiLine: true);
+
   final Map<int, List<String>> _ignoreMap = new HashMap<int, List<String>>();
 
+  final Set<String> _ignoreForFileSet = new HashSet<String>();
+
   /**
    * Whether this info object defines any ignores.
    */
-  bool get hasIgnores => ignores.isNotEmpty;
+  bool get hasIgnores => ignores.isNotEmpty || _ignoreForFileSet.isNotEmpty;
 
   /**
    * Map of line numbers to associated ignored error codes.
    */
   Map<int, Iterable<String>> get ignores => _ignoreMap;
 
+  /**
+   * Iterable of error codes ignored for the whole file.
+   */
+  Iterable<String> get ignoreForFiles => _ignoreForFileSet;
+
   /**
    * Ignore this [errorCode] at [line].
    */
@@ -3050,10 +3069,18 @@ class IgnoreInfo {
     _ignoreMap.putIfAbsent(line, () => new List<String>()).addAll(errorCodes);
   }
 
+  /**
+   * Ignore these [errorCodes] in the whole file.
+   */
+  void addAllForFile(Iterable<String> errorCodes) {
+    _ignoreForFileSet.addAll(errorCodes);
+  }
+
   /**
    * Test whether this [errorCode] is ignored at the given [line].
    */
   bool ignoredAt(String errorCode, int line) =>
+      _ignoreForFileSet.contains(errorCode) ||
       _ignoreMap[line]?.contains(errorCode) == true;
 
   /**
@@ -3061,7 +3088,8 @@ class IgnoreInfo {
    */
   static IgnoreInfo calculateIgnores(String content, LineInfo info) {
     Iterable<Match> matches = _IGNORE_MATCHER.allMatches(content);
-    if (matches.isEmpty) {
+    Iterable<Match> fileMatches = _IGNORE_FOR_FILE_MATCHER.allMatches(content);
+    if (matches.isEmpty && fileMatches.isEmpty) {
       return _EMPTY_INFO;
     }
 
@@ -3074,6 +3102,13 @@ class IgnoreInfo {
           .map((String code) => code.trim().toLowerCase());
       ignoreInfo.addAll(info.getLocation(match.start).lineNumber, codes);
     }
+    for (Match match in fileMatches) {
+      Iterable<String> codes = match
+          .group(1)
+          .split(',')
+          .map((String code) => code.trim().toLowerCase());
+      ignoreInfo.addAllForFile(codes);
+    }
     return ignoreInfo;
   }
 }

pkg/analyzer/test/generated/error_suppression_test.dart

@@ -195,4 +195,35 @@ const y = x; //CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE
       CompileTimeErrorCode.CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE
     ]);
   }
+
+  test_ignore_for_file() async {
+    Source source = addSource('''
+int x = '';  //INVALID_ASSIGNMENT
+const y = x; //CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE
+// ignore_for_file: invalid_assignment
+''');
+    await computeAnalysisResult(source);
+    assertErrors(source,
+        [CompileTimeErrorCode.CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE]);
+  }
+
+  test_multiple_ignore_for_files() async {
+    Source source = addSource('''
+int x = '';  //INVALID_ASSIGNMENT
+const y = x; //CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE
+// ignore_for_file: invalid_assignment,const_initialized_with_non_constant_value
+''');
+    await computeAnalysisResult(source);
+    assertErrors(source, []);
+  }
+
+  test_ignore_for_file_whitespace_variant() async {
+    Source source = addSource('''
+//ignore_for_file:   const_initialized_with_non_constant_value , invalid_assignment
+int x = '';  //INVALID_ASSIGNMENT
+const y = x; //CONST_INITIALIZED_WITH_NON_CONSTANT_VALUE
+''');
+    await computeAnalysisResult(source);
+    assertErrors(source, []);
+  }
 }

pkg/analyzer/test/src/task/dart_test.dart

@@ -4360,16 +4360,20 @@ class ScanDartTaskTest extends _AbstractDartTaskTest {
   test_ignore_info() {
     _performScanTask('''
 //ignore: error_code
+//ignore_for_file: error_code
 var x = '';
 foo(); // ignore:   error_code_2
 bar(); //ignore: error_code, error_code_2
+// ignore_for_file:  error_code_2, error_code_3
 ''');
 
     IgnoreInfo info = outputs[IGNORE_INFO];
     expect(info.ignores.keys, hasLength(3));
     expect(info.ignores[1].first, 'error_code');
-    expect(info.ignores[3].first, 'error_code_2');
-    expect(info.ignores[4], unorderedEquals(['error_code', 'error_code_2']));
+    expect(info.ignores[4].first, 'error_code_2');
+    expect(info.ignores[5], unorderedEquals(['error_code', 'error_code_2']));
+    expect(info.ignoreForFiles,
+        unorderedEquals(['error_code', 'error_code_2', 'error_code_3']));
   }
 
   test_perform_errors() {