analyzer: Make SourceFactory.resolveUri take non-nullable parameters

The function mostly returned null/nonsense if given a null argument,
and the few call sites with nullable arguments (in tests and tools)
are easily tweaked.

Change-Id: I7f9993696c4bd822b648a5a89114e6af25eac552
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/490020
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Samuel Rawlins <srawlins@google.com>

Author: srawlins

pkg/analyzer/lib/src/context/source.dart

@@ -122,10 +122,7 @@ class SourceFactoryImpl implements SourceFactory {
   }
 
   @override
-  Source? resolveUri(Source? containingSource, String? containedUri) {
-    if (containedUri == null) {
-      return null;
-    }
+  Source? resolveUri(Source containingSource, String containedUri) {
     if (containedUri.isEmpty) {
       return containingSource;
     }
@@ -138,9 +135,7 @@ class SourceFactoryImpl implements SourceFactory {
     } on FormatException {
       return null;
     } catch (exception, stackTrace) {
-      String containingFullName = containingSource != null
-          ? containingSource.fullName
-          : '<null>';
+      String containingFullName = containingSource.fullName;
       // TODO(39284): should this exception be silent?
       AnalysisEngine.instance.instrumentationService.logException(
         SilentException(

pkg/analyzer/lib/src/generated/source.dart

@@ -152,7 +152,7 @@ abstract class SourceFactory {
   /// [containingSource], whether or not the resulting source exists, or `null`
   /// if either the [containedUri] is invalid or if it cannot be resolved
   /// against the [containingSource]'s URI.
-  Source? resolveUri(Source? containingSource, String? containedUri);
+  Source? resolveUri(Source containingSource, String containedUri);
 }
 
 /// The abstract class `UriResolver` defines the behavior of objects that are

pkg/analyzer/test/generated/source_factory_test.dart

@@ -59,7 +59,9 @@ class SourceFactoryTest with ResourceProviderMixin {
   void test_resolveUri_absolute() {
     UriResolver_absolute resolver = UriResolver_absolute();
     SourceFactory factory = SourceFactory([resolver]);
-    factory.resolveUri(null, "dart:core");
+    String sourcePath = convertPath('/does/not/exist.dart');
+    Source sourceSource = FileSource(getFile(sourcePath));
+    factory.resolveUri(sourceSource, "dart:core");
     expect(resolver.invoked, isTrue);
   }
 

pkg/analyzer_cli/tool/perf.dart

@@ -78,7 +78,7 @@ void collectSources(Source? start, Set<Source?> files) {
   var unit = parseDirectives(start!);
   for (var directive in unit.directives) {
     if (directive is UriBasedDirective) {
-      var next = sources.resolveUri(start, directive.uri.stringValue);
+      var next = sources.resolveUri(start, directive.uri.stringValue!);
       collectSources(next, files);
     }
   }

pkg/front_end/tool/perf.dart

@@ -103,7 +103,7 @@ void collectSources(Source start, Set<Source> files) {
   var unit = parseDirectives(start);
   for (var directive in unit.directives) {
     if (directive is UriBasedDirective) {
-      var next = sources.resolveUri(start, directive.uri.stringValue)!;
+      var next = sources.resolveUri(start, directive.uri.stringValue!)!;
       collectSources(next, files);
     }
   }