Make integer literals trivial, except when type is double

Change-Id: I27518d86b389ca455144111c18f18e995ae5ac4d
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/389702
Reviewed-by: Phil Quitslund <pquitslund@google.com>
Commit-Queue: Erik Ernst <eernst@google.com>

pkg/linter/lib/src/util/obvious_types.dart

@@ -127,9 +127,9 @@ extension ExpressionExtensions on Expression {
         return true;
       case Literal():
         // An atomic literal: `Literal` and not `TypedLiteral`.
-        if (self is IntegerLiteral) {
-          // An integer literal with type `double` is clearly not trivial,
-          // but even an `int` integer literal may be considered ambiguous.
+        if (self is IntegerLiteral &&
+            (self.staticType?.isDartCoreDouble ?? true)) {
+          // An integer literal with static type `double` is not trivial.
           return false;
         }
         return true;

pkg/linter/test/rules/omit_obvious_local_variable_types_test.dart

@@ -227,11 +227,13 @@ f() {
   }
 
   test_literal_int() async {
-    await assertNoDiagnostics(r'''
+    await assertDiagnostics(r'''
 f() {
   int i = 1;
 }
-''');
+''', [
+      lint(8, 3),
+    ]);
   }
 
   // `Null` is not obvious, the inferred type is `dynamic`.