Clean up some warnings in the server code base

Change-Id: I762fcc704fe0fa0547bbbc347eb248853d358121
Reviewed-on: https://dart-review.googlesource.com/67842
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Brian Wilkerson <brianwilkerson@google.com>

pkg/analysis_server/benchmark/benchmarks.dart

@@ -105,6 +105,8 @@ class RunCommand extends Command {
         benchmarks.firstWhere((b) => b.id == benchmarkId, orElse: () {
       print("Benchmark '$benchmarkId' not found.");
       exit(1);
+      // Never reached.
+      return null;
     });
 
     int actualIterations = repeatCount;

pkg/analysis_server/lib/src/services/refactoring/rename_unit_member.dart

@@ -205,6 +205,7 @@ class _RenameUnitMemberValidator {
                 getElementQualifiedName(shadow));
             result.addError(message, newLocation_fromElement(shadow));
           }
+          return false;
         });
       }
     }

pkg/analysis_server/lib/src/services/search/element_visitors.dart

@@ -26,7 +26,7 @@ Element findElementByNameOffset(Element root, int nameOffset) {
  * Uses [processor] to visit all of the children of [element].
  * If [processor] returns `true`, then children of a child are visited too.
  */
-void visitChildren(Element element, ElementProcessor processor) {
+void visitChildren(Element element, BoolElementProcessor processor) {
   element.visitChildren(new _ElementVisitorAdapter(processor));
 }
 
@@ -34,7 +34,7 @@ void visitChildren(Element element, ElementProcessor processor) {
  * Uses [processor] to visit all of the top-level elements of [library].
  */
 void visitLibraryTopLevelElements(
-    LibraryElement library, ElementProcessor processor) {
+    LibraryElement library, VoidElementProcessor processor) {
   library.visitChildren(new _TopLevelElementsVisitor(processor));
 }
 
@@ -42,7 +42,12 @@ void visitLibraryTopLevelElements(
  * An [Element] processor function type.
  * If `true` is returned, children of [element] will be visited.
  */
-typedef bool ElementProcessor(Element element);
+typedef bool BoolElementProcessor(Element element);
+
+/**
+ * An [Element] processor function type.
+ */
+typedef void VoidElementProcessor(Element element);
 
 /**
  * A visitor that finds the deep-most [Element] that contains the [nameOffset].
@@ -66,7 +71,7 @@ class _ElementByNameOffsetVisitor extends GeneralizingElementVisitor {
  * A [GeneralizingElementVisitor] adapter for [ElementProcessor].
  */
 class _ElementVisitorAdapter extends GeneralizingElementVisitor {
-  final ElementProcessor processor;
+  final BoolElementProcessor processor;
 
   _ElementVisitorAdapter(this.processor);
 
@@ -83,7 +88,7 @@ class _ElementVisitorAdapter extends GeneralizingElementVisitor {
  * A [GeneralizingElementVisitor] for visiting top-level elements.
  */
 class _TopLevelElementsVisitor extends GeneralizingElementVisitor {
-  final ElementProcessor processor;
+  final VoidElementProcessor processor;
 
   _TopLevelElementsVisitor(this.processor);
 

pkg/analysis_server/lib/src/services/search/hierarchy.dart

@@ -19,6 +19,7 @@ List<Element> getChildren(Element parent, [String name]) {
     if (name == null || element.displayName == name) {
       children.add(element);
     }
+    return false;
   });
   return children;
 }

pkg/analysis_server/test/integration/analysis/get_hover_test.dart

@@ -75,7 +75,7 @@ main() {
     List<String> parameterRegexps: null,
   }) {
     int offset = text.indexOf(target);
-    return sendAnalysisGetHover(pathname, offset).then((result) {
+    return sendAnalysisGetHover(pathname, offset).then((result) async {
       expect(result.hovers, hasLength(1));
       HoverInformation info = result.hovers[0];
       expect(info.offset, equals(offset));
@@ -120,6 +120,7 @@ main() {
           expect(info.staticType, matches(staticTypeRegexp));
         }
       }
+      return null;
     });
   }
 

pkg/analysis_server/test/integration/support/integration_tests.dart

@@ -1040,5 +1040,6 @@ abstract class _RecursiveMatcher extends Matcher {
   MismatchDescriber simpleDescription(String description) =>
       (Description mismatchDescription) {
         mismatchDescription.add(description);
+        return mismatchDescription;
       };
 }