Add a context message to not_a_type diagnostics

Fixes #55947

Change-Id: I38b838c59d3c2983ac26efda7a5ab20f3d29485e
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/433362
Commit-Queue: Brian Wilkerson <[email protected]>
Reviewed-by: Konstantin Shcheglov <[email protected]>

Author: bwilkerson

pkg/analyzer/lib/src/dart/resolver/named_type_resolver.dart

@@ -17,6 +17,7 @@ import 'package:analyzer/src/dart/element/type.dart';
 import 'package:analyzer/src/dart/element/type_constraint_gatherer.dart';
 import 'package:analyzer/src/dart/element/type_system.dart';
 import 'package:analyzer/src/dart/resolver/flow_analysis_visitor.dart';
+import 'package:analyzer/src/diagnostic/diagnostic.dart';
 import 'package:analyzer/src/diagnostic/diagnostic_factory.dart';
 import 'package:analyzer/src/error/codes.dart';
 import 'package:analyzer/src/generated/scope_helpers.dart';
@@ -386,11 +387,36 @@ class NamedTypeResolver with ScopeHelpers {
       _ErrorHelper(errorReporter).reportNewWithNonType(node);
     } else {
       node.type = InvalidTypeImpl.instance;
+      Element? element = importPrefixElement;
+      String name = node.name.lexeme;
+      if (importPrefixElement is InstanceElement) {
+        if (importPrefixElement is InterfaceElement) {
+          element = importPrefixElement.getNamedConstructor2(name);
+        }
+        element ??=
+            importPrefixElement.getField(name) ??
+            importPrefixElement.getGetter(name) ??
+            importPrefixElement.getMethod(name) ??
+            importPrefixElement.getSetter(name);
+      }
+      var fragment = element?.firstFragment;
+      var source = fragment?.libraryFragment?.source;
+      var nameOffset = fragment?.nameOffset2;
       errorReporter.atOffset(
         offset: importPrefix.offset,
         length: nameToken.end - importPrefix.offset,
         diagnosticCode: CompileTimeErrorCode.NOT_A_TYPE,
         arguments: ['${importPrefix.name.lexeme}.${nameToken.lexeme}'],
+        contextMessages: [
+          if (source != null && nameOffset != null)
+            DiagnosticMessageImpl(
+              filePath: source.fullName,
+              message: "The declaration of '$name' is here.",
+              offset: nameOffset,
+              length: name.length,
+              url: null,
+            ),
+        ],
       );
     }
   }
@@ -639,11 +665,25 @@ class _ErrorHelper {
 
     if (element != null) {
       var errorRange = _getErrorRange(node);
+      var name = node.name.lexeme;
+      var fragment = element.firstFragment;
+      var source = fragment.libraryFragment?.source;
+      var nameOffset = fragment.nameOffset2;
       errorReporter.atOffset(
         offset: errorRange.offset,
         length: errorRange.length,
         diagnosticCode: CompileTimeErrorCode.NOT_A_TYPE,
-        arguments: [node.name.lexeme],
+        arguments: [name],
+        contextMessages: [
+          if (source != null && nameOffset != null)
+            DiagnosticMessageImpl(
+              filePath: source.fullName,
+              message: "The declaration of '$name' is here.",
+              offset: nameOffset,
+              length: name.length,
+              url: null,
+            ),
+        ],
       );
       return;
     }

pkg/analyzer/test/src/dart/resolution/named_type_test.dart

@@ -565,7 +565,14 @@ import 'dart:math' as prefix;
 
 void f(prefix a) {}
 ''',
-      [error(CompileTimeErrorCode.NOT_A_TYPE, 38, 6)],
+      [
+        error(
+          CompileTimeErrorCode.NOT_A_TYPE,
+          38,
+          6,
+          contextMessages: [message(testFile, 22, 6)],
+        ),
+      ],
     );
 
     var node = findNode.namedType('prefix a');
@@ -584,7 +591,14 @@ import 'dart:math' as prefix;
 
 void f(prefix<int> a) {}
 ''',
-      [error(CompileTimeErrorCode.NOT_A_TYPE, 38, 6)],
+      [
+        error(
+          CompileTimeErrorCode.NOT_A_TYPE,
+          38,
+          6,
+          contextMessages: [message(testFile, 22, 6)],
+        ),
+      ],
     );
 
     var node = findNode.namedType('prefix<int>');
@@ -657,7 +671,14 @@ void f(T a) {}
 
 void T() {}
 ''',
-      [error(CompileTimeErrorCode.NOT_A_TYPE, 7, 1)],
+      [
+        error(
+          CompileTimeErrorCode.NOT_A_TYPE,
+          7,
+          1,
+          contextMessages: [message(testFile, 21, 1)],
+        ),
+      ],
     );
 
     var node = findNode.namedType('T a');
@@ -676,7 +697,14 @@ void f(T<int> a) {}
 
 void T() {}
 ''',
-      [error(CompileTimeErrorCode.NOT_A_TYPE, 7, 1)],
+      [
+        error(
+          CompileTimeErrorCode.NOT_A_TYPE,
+          7,
+          1,
+          contextMessages: [message(testFile, 26, 1)],
+        ),
+      ],
     );
 
     var node = findNode.namedType('T<int>');

pkg/analyzer/test/src/diagnostics/not_a_type_test.dart

@@ -24,7 +24,14 @@ class A {
 
 A.foo bar() {}
 ''',
-      [error(CompileTimeErrorCode.NOT_A_TYPE, 24, 5)],
+      [
+        error(
+          CompileTimeErrorCode.NOT_A_TYPE,
+          24,
+          5,
+          contextMessages: [message(testFile, 14, 3)],
+        ),
+      ],
     );
   }
 
@@ -37,7 +44,14 @@ class A {
 
 A.foo bar() {}
 ''',
-      [error(CompileTimeErrorCode.NOT_A_TYPE, 36, 5)],
+      [
+        error(
+          CompileTimeErrorCode.NOT_A_TYPE,
+          36,
+          5,
+          contextMessages: [message(testFile, 24, 3)],
+        ),
+      ],
     );
   }
 
@@ -47,7 +61,14 @@ A.foo bar() {}
 extension E on int {}
 E a;
 ''',
-      [error(CompileTimeErrorCode.NOT_A_TYPE, 22, 1)],
+      [
+        error(
+          CompileTimeErrorCode.NOT_A_TYPE,
+          22,
+          1,
+          contextMessages: [message(testFile, 10, 1)],
+        ),
+      ],
     );
 
     var node = findNode.namedType('E a;');
@@ -67,7 +88,12 @@ main() {
   f v = null;
 }''',
       [
-        error(CompileTimeErrorCode.NOT_A_TYPE, 18, 1),
+        error(
+          CompileTimeErrorCode.NOT_A_TYPE,
+          18,
+          1,
+          contextMessages: [message(testFile, 0, 1)],
+        ),
         error(WarningCode.UNUSED_LOCAL_VARIABLE, 20, 1),
       ],
     );