Parse documentation for class aliases, fix for /// comments.

R=ahe@google.com, kmillikin@google.com, paulberry@google.com, sigmund@google.com
BUG=

Review-Url: https://codereview.chromium.org/2990523002 .

pkg/analyzer/test/src/summary/resynthesize_common.dart

@@ -1405,6 +1405,54 @@ class E {
 
   test_class_alias_documented() async {
     var library = await checkLibrary('''
+/**
+ * Docs
+ */
+class C = D with E;
+
+class D {}
+class E {}
+''');
+    checkElementText(library, r'''
+/**
+ * Docs
+ */
+class alias C extends D with E {
+  synthetic C() = D;
+}
+class D {
+}
+class E {
+}
+''');
+  }
+
+  test_class_alias_documented_tripleSlash() async {
+    var library = await checkLibrary('''
+/// aaa
+/// b
+/// cc
+class C = D with E;
+
+class D {}
+class E {}
+''');
+    checkElementText(library, r'''
+/// aaa
+/// b
+/// cc
+class alias C extends D with E {
+  synthetic C() = D;
+}
+class D {
+}
+class E {
+}
+''');
+  }
+
+  test_class_alias_documented_withLeadingNonDocumentation() async {
+    var library = await checkLibrary('''
 // Extra comment so doc comment offset != 0
 /**
  * Docs
@@ -1814,6 +1862,70 @@ class C {
 ''');
   }
 
+  test_class_documented_mix() async {
+    var library = await checkLibrary('''
+/**
+ * aaa
+ */
+/**
+ * bbb
+ */
+class A {}
+
+/**
+ * aaa
+ */
+/// bbb
+/// ccc
+class B {}
+
+/// aaa
+/// bbb
+/**
+ * ccc
+ */
+class C {}
+
+/// aaa
+/// bbb
+/**
+ * ccc
+ */
+/// ddd
+class D {}
+
+/**
+ * aaa
+ */
+// bbb
+class E {}
+''');
+    checkElementText(library, r'''
+/**
+ * bbb
+ */
+class A {
+}
+/// bbb
+/// ccc
+class B {
+}
+/**
+ * ccc
+ */
+class C {
+}
+/// ddd
+class D {
+}
+/**
+ * aaa
+ */
+class E {
+}
+''');
+  }
+
   test_class_documented_tripleSlash() async {
     var library = await checkLibrary('''
 /// aaa

pkg/analyzer/test/src/summary/resynthesize_kernel_test.dart

@@ -112,12 +112,6 @@ class ResynthesizeKernelStrongTest extends ResynthesizeTest {
   }
 
   @failingTest
-  test_class_alias_documented() async {
-    await super.test_class_alias_documented();
-  }
-
-  @failingTest
-  @_fastaProblem
   test_class_constructor_field_formal_multiple_matching_fields() async {
     // Fasta does not generate the class.
     // main() with a fatal error is generated instead.
@@ -125,17 +119,6 @@ class ResynthesizeKernelStrongTest extends ResynthesizeTest {
   }
 
   @failingTest
-  test_class_documented_tripleSlash() async {
-    await super.test_class_documented_tripleSlash();
-  }
-
-  @failingTest
-  test_class_documented_withLeadingNotDocumentation() async {
-    await super.test_class_documented_withLeadingNotDocumentation();
-  }
-
-  @failingTest
-  @_fastaProblem
   test_class_interfaces_unresolved() async {
     // Fasta generates additional `#errors` top-level variable.
     await super.test_class_interfaces_unresolved();

pkg/front_end/lib/src/fasta/kernel/kernel_library_builder.dart

@@ -271,7 +271,8 @@ class KernelLibraryBuilder
   }
 
   KernelTypeBuilder applyMixins(KernelTypeBuilder type,
-      {List<MetadataBuilder> metadata,
+      {String documentationComment,
+      List<MetadataBuilder> metadata,
       bool isSyntheticMixinImplementation: false,
       String name,
       String subclassName,
@@ -454,6 +455,7 @@ class KernelLibraryBuilder
       checkArguments(mixin);
 
       KernelNamedTypeBuilder t = applyMixin(supertype, mixin, signature,
+          documentationComment: documentationComment,
           metadata: metadata,
           name: name,
           isSyntheticMixinImplementation: isSyntheticMixinImplementation,
@@ -476,6 +478,7 @@ class KernelLibraryBuilder
   }
 
   void addNamedMixinApplication(
+      String documentationComment,
       List<MetadataBuilder> metadata,
       String name,
       List<TypeVariableBuilder> typeVariables,
@@ -486,6 +489,7 @@ class KernelLibraryBuilder
     // Nested declaration began in `OutlineBuilder.beginNamedMixinApplication`.
     endNestedDeclaration(name).resolveTypes(typeVariables, this);
     KernelNamedTypeBuilder supertype = applyMixins(mixinApplication,
+        documentationComment: documentationComment,
         metadata: metadata,
         name: name,
         typeVariables: typeVariables,

pkg/front_end/lib/src/fasta/source/outline_builder.dart

@@ -285,13 +285,7 @@ class OutlineBuilder extends UnhandledListener {
       Token implementsKeyword,
       Token endToken) {
     debugEvent("endClassDeclaration");
-
-    String documentationComment = null;
-    if (beginToken.precedingComments != null) {
-      documentationComment = beginToken.precedingComments.lexeme;
-      // TODO(scheglov): Add support for line comments.
-    }
-
+    String documentationComment = _getDocumentationComment(beginToken);
     List<TypeBuilder> interfaces = popList(interfacesCount);
     TypeBuilder supertype = pop();
     List<TypeVariableBuilder> typeVariables = pop();
@@ -464,6 +458,7 @@ class OutlineBuilder extends UnhandledListener {
   void endNamedMixinApplication(Token beginToken, Token classKeyword,
       Token equals, Token implementsKeyword, Token endToken) {
     debugEvent("endNamedMixinApplication");
+    String documentationComment = _getDocumentationComment(beginToken);
     List<TypeBuilder> interfaces = popIfNotNull(implementsKeyword);
     TypeBuilder mixinApplication = pop();
     List<TypeVariableBuilder> typeVariables = pop();
@@ -471,8 +466,8 @@ class OutlineBuilder extends UnhandledListener {
     String name = pop();
     int modifiers = Modifier.validate(pop());
     List<MetadataBuilder> metadata = pop();
-    library.addNamedMixinApplication(metadata, name, typeVariables, modifiers,
-        mixinApplication, interfaces, charOffset);
+    library.addNamedMixinApplication(documentationComment, metadata, name,
+        typeVariables, modifiers, mixinApplication, interfaces, charOffset);
     checkEmpty(beginToken.charOffset);
   }
 
@@ -916,6 +911,34 @@ class OutlineBuilder extends UnhandledListener {
     return removeNativeClause(identifiers, stringExpectedAfterNative);
   }
 
+  /// Return the documentation comment for the entity that starts at the
+  /// given [token], or `null` if there is no preceding documentation comment.
+  String _getDocumentationComment(Token token) {
+    Token docToken = token.precedingComments;
+    if (docToken == null) return null;
+    bool inSlash = false;
+    var buffer = new StringBuffer();
+    while (docToken != null) {
+      String lexeme = docToken.lexeme;
+      if (lexeme.startsWith('/**')) {
+        inSlash = false;
+        buffer.clear();
+        buffer.write(lexeme);
+      } else if (lexeme.startsWith('///')) {
+        if (!inSlash) {
+          inSlash = true;
+          buffer.clear();
+        }
+        if (buffer.isNotEmpty) {
+          buffer.writeln();
+        }
+        buffer.write(lexeme);
+      }
+      docToken = docToken.next;
+    }
+    return buffer.toString();
+  }
+
   @override
   void debugEvent(String name) {
     // printEvent(name);

pkg/front_end/lib/src/fasta/source/source_library_builder.dart

@@ -207,6 +207,7 @@ abstract class SourceLibraryBuilder<T extends TypeBuilder, R>
       int charOffset);
 
   void addNamedMixinApplication(
+      String documentationComment,
       List<MetadataBuilder> metadata,
       String name,
       List<TypeVariableBuilder> typeVariables,