fix(Compiler): Fail with better errors on an invalid implicit provider.

Previously, we would give a mysterious type error attempting to cast to ClassElement. We also now include the file entrypoint being parsed, and the source of the type itself in the error message.

Closes #1633.

PiperOrigin-RevId: 216255169

angular/CHANGELOG.md

@@ -204,6 +204,10 @@
     messages with meanings that are formatted differently will now properly be
     treated as the same message.
 
+*  [#1633][]: Using a function type or any non-class `Type` inside of the
+   `@GenerateInjector([...])` annotation would cause a non-ideal error to be
+   produced. It now includes more information where available.
+
 [#434]: https://github.com/dart-lang/angular/issues/434
 [#880]: https://github.com/dart-lang/angular/issues/880
 [#930]: https://github.com/dart-lang/angular/issues/930
@@ -217,6 +221,7 @@
 [#1591]: https://github.com/dart-lang/angular/issues/1591
 [#1598]: https://github.com/dart-lang/angular/issues/1598
 [#1625]: https://github.com/dart-lang/angular/issues/1625
+[#1633]: https://github.com/dart-lang/angular/issues/1633
 
 ### Other improvements
 

angular_compiler/lib/src/analyzer/di/injector.dart

@@ -104,6 +104,9 @@ class InjectorReader {
         _throwParseError(e.constant);
       } on NullFactoryException catch (e) {
         _throwFactoryProvider(e.constant);
+      } on BuildError {
+        logWarning('An error occurred parsing providers on $doNotScope');
+        rethrow;
       }
     }
     return _providers;

angular_compiler/lib/src/analyzer/di/providers.dart

@@ -1,6 +1,7 @@
 import 'package:analyzer/dart/constant/value.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
+import 'package:angular_compiler/cli.dart';
 import 'package:meta/meta.dart';
 import 'package:source_gen/source_gen.dart';
 
@@ -35,8 +36,8 @@ class ProviderReader {
       throw ArgumentError.notNull();
     }
     if (isType(o)) {
-      // Represents "Foo", which is supported short-hand for "Provider(Foo)".
-      return _parseType(o);
+      // Represents "Foo", which is legacy short-hand for "ClassProvider(Foo)".
+      return _parseTypeAsImplicitClassProvider(o);
     }
     if (!isProvider(o)) {
       final typeName = getTypeName(o.type);
@@ -172,16 +173,19 @@ class ProviderReader {
   }
 
   /// Returns a provider element representing a single type.
-  ProviderElement _parseType(DartObject o) {
+  ProviderElement _parseTypeAsImplicitClassProvider(DartObject o) {
     final reader = ConstantReader(o);
-    final clazz = reader.typeValue.element as ClassElement;
-    final token = linkTypeOf(clazz.type);
-    return UseClassProviderElement(
-      TypeTokenElement(token),
-      linkTypeOf(typeArgumentOf(o)),
-      token,
-      dependencies: _dependencyReader.parseDependencies(clazz),
-    );
+    final element = reader.typeValue.element;
+    if (element is ClassElement) {
+      final token = linkTypeOf(element.type);
+      return UseClassProviderElement(
+        TypeTokenElement(token),
+        linkTypeOf(typeArgumentOf(o)),
+        token,
+        dependencies: _dependencyReader.parseDependencies(element),
+      );
+    }
+    return BuildError.throwForElement(element, 'Not a class element');
   }
 }
 

angular_compiler/lib/src/cli/logging.dart

@@ -114,7 +114,10 @@ class BuildError extends Error {
     // https://github.com/dart-lang/angular/issues/902#issuecomment-366330965
     final source = element.source;
     if (source == null || source.contents.data.isEmpty) {
-      logWarning('Could not find source $element: the next error may be terse');
+      final warning = source == null
+          ? 'No source text available for $element'
+          : 'No source text available for $element (${source.uri})';
+      logWarning('$warning: the next error may be terse');
       throw BuildError(message, trace);
     }
     final sourceUrl = source.uri;