linter: fix omit_local_variable_types for coerced int

Fixes https://github.com/dart-lang/linter/issues/5010

Cq-Include-Trybots: luci.dart.try:flutter-analyze-try,analyzer-win-release-try,pkg-win-release-try
Change-Id: Id302aceb24bb9a80f0f13b3ec91b7a57c09a7d52
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/381101
Reviewed-by: Phil Quitslund <pquitslund@google.com>
Commit-Queue: Samuel Rawlins <srawlins@google.com>

pkg/linter/lib/src/rules/omit_local_variable_types.dart

@@ -6,9 +6,9 @@ import 'package:analyzer/dart/ast/ast.dart';
 import 'package:analyzer/dart/ast/visitor.dart';
 import 'package:analyzer/dart/element/element.dart';
 import 'package:analyzer/dart/element/type.dart';
+import 'package:analyzer/dart/element/type_provider.dart';
 
 import '../analyzer.dart';
-import '../extensions.dart';
 import '../linter_lint_codes.dart';
 
 const _desc = r'Omit type annotations for local variables.';
@@ -84,7 +84,7 @@ class OmitLocalVariableTypes extends LintRule {
   @override
   void registerNodeProcessors(
       NodeLintRegistry registry, LinterContext context) {
-    var visitor = _Visitor(this);
+    var visitor = _Visitor(this, context.typeProvider);
     registry.addForStatement(this, visitor);
     registry.addVariableDeclarationStatement(this, visitor);
   }
@@ -93,7 +93,9 @@ class OmitLocalVariableTypes extends LintRule {
 class _Visitor extends SimpleAstVisitor<void> {
   final LintRule rule;
 
-  _Visitor(this.rule);
+  final TypeProvider typeProvider;
+
+  _Visitor(this.rule, this.typeProvider);
 
   @override
   void visitForStatement(ForStatement node) {
@@ -103,18 +105,16 @@ class _Visitor extends SimpleAstVisitor<void> {
     } else if (loopParts is ForEachPartsWithDeclaration) {
       var loopVariableType = loopParts.loopVariable.type;
       var staticType = loopVariableType?.type;
-      if (staticType == null || staticType is DynamicType) {
-        return;
-      }
-      var iterableType = loopParts.iterable.staticType;
-      if (iterableType is InterfaceType) {
-        // TODO(srawlins): Is `DartType.asInstanceOf` the more correct API here?
-        var iterableInterfaces = iterableType.implementedInterfaces
-            .where((type) => type.isDartCoreIterable);
-        if (iterableInterfaces.length == 1 &&
-            iterableInterfaces.first.typeArguments.first == staticType) {
-          rule.reportLint(loopVariableType);
-        }
+      if (staticType == null || staticType is DynamicType) return;
+
+      var loopType = loopParts.iterable.staticType;
+      if (loopType is! InterfaceType) return;
+
+      var iterableType = loopType.asInstanceOf(typeProvider.iterableElement);
+      if (iterableType == null) return;
+      if (iterableType.typeArguments.isNotEmpty &&
+          iterableType.typeArguments.first == staticType) {
+        rule.reportLint(loopVariableType);
       }
     }
   }
@@ -124,20 +124,6 @@ class _Visitor extends SimpleAstVisitor<void> {
     _visitVariableDeclarationList(node.variables);
   }
 
-  bool _dependsOnDeclaredTypeForInference(Expression? initializer) {
-    if (initializer is MethodInvocation) {
-      if (initializer.typeArguments == null) {
-        var element = initializer.methodName.staticElement;
-        if (element is FunctionElement) {
-          if (element.returnType is TypeParameterType) {
-            return true;
-          }
-        }
-      }
-    }
-    return false;
-  }
-
   void _visitVariableDeclarationList(VariableDeclarationList node) {
     var staticType = node.type?.type;
     if (staticType == null ||
@@ -147,13 +133,33 @@ class _Visitor extends SimpleAstVisitor<void> {
     }
     for (var child in node.variables) {
       var initializer = child.initializer;
-      if (initializer?.staticType != staticType) {
+      if (initializer == null || initializer.staticType != staticType) {
         return;
       }
-      if (_dependsOnDeclaredTypeForInference(initializer)) {
+
+      if (initializer is IntegerLiteral && !staticType.isDartCoreInt) {
+        // Coerced int.
+        return;
+      }
+
+      if (initializer.dependsOnDeclaredTypeForInference) {
         return;
       }
     }
     rule.reportLint(node.type);
   }
 }
+
+extension on Expression {
+  bool get dependsOnDeclaredTypeForInference {
+    if (this case MethodInvocation(:var methodName, typeArguments: null)) {
+      var element = methodName.staticElement;
+      if (element is FunctionElement) {
+        if (element.returnType is TypeParameterType) {
+          return true;
+        }
+      }
+    }
+    return false;
+  }
+}

pkg/linter/test/rules/omit_local_variable_types_test.dart

@@ -201,6 +201,14 @@ f() {
 ''');
   }
 
+  test_rightSideIsInt_typedWithDouble() async {
+    await assertNoDiagnostics(r'''
+void f() {
+  double x = 0;
+}
+''');
+  }
+
   test_rightSideIsInt_typedWithDynamic() async {
     await assertNoDiagnostics(r'''
 void f() {