[dart2js] Removing switch class restrictions.

From the spec: `It is no longer required that the [case expression] evaluate to instances of the same class.`

Fixes #42409

Change-Id: Ieecd96cb75d683658ffc767d973b0ff2f5e6d834
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/153060
Reviewed-by: Stephen Adams <[email protected]>
Commit-Queue: Mark Zhou <[email protected]>

Author: Markzipan

pkg/compiler/lib/src/kernel/kernel_impact.dart

@@ -820,12 +820,6 @@ abstract class KernelImpactRegistryMixin implements ImpactRegistry {
 
   @override
   void registerSwitchStatementNode(ir.SwitchStatement node) {
-    // TODO(32557): Remove this when issue 32557 is fixed.
-    ir.TreeNode firstCase;
-    DartType firstCaseType;
-    DiagnosticMessage error;
-    List<DiagnosticMessage> infos = <DiagnosticMessage>[];
-
     bool overridesEquals(InterfaceType type) {
       if (type == commonElements.symbolImplementationType) {
         // Treat symbol constants as if Symbol doesn't override `==`.
@@ -850,50 +844,23 @@ abstract class KernelImpactRegistryMixin implements ImpactRegistry {
         ConstantValue value =
             elementMap.getConstantValue(staticTypeContext, expression);
         DartType type = value.getType(elementMap.commonElements);
-        if (firstCaseType == null) {
-          firstCase = expression;
-          firstCaseType = type;
-
-          // We only report the bad type on the first class element. All others
-          // get a "type differs" error.
-          if (type == commonElements.doubleType) {
-            reporter.reportErrorMessage(
-                computeSourceSpanFromTreeNode(expression),
-                MessageKind.SWITCH_CASE_VALUE_OVERRIDES_EQUALS,
-                {'type': "double"});
-          } else if (type == commonElements.functionType) {
-            reporter.reportErrorMessage(computeSourceSpanFromTreeNode(node),
-                MessageKind.SWITCH_CASE_FORBIDDEN, {'type': "Function"});
-          } else if (value.isObject &&
-              type != commonElements.typeLiteralType &&
-              overridesEquals(type)) {
-            reporter.reportErrorMessage(
-                computeSourceSpanFromTreeNode(firstCase),
-                MessageKind.SWITCH_CASE_VALUE_OVERRIDES_EQUALS,
-                {'type': typeToString(type)});
-          }
-        } else {
-          if (type != firstCaseType) {
-            if (error == null) {
-              error = reporter.createMessage(
-                  computeSourceSpanFromTreeNode(node),
-                  MessageKind.SWITCH_CASE_TYPES_NOT_EQUAL,
-                  {'type': typeToString(firstCaseType)});
-              infos.add(reporter.createMessage(
-                  computeSourceSpanFromTreeNode(firstCase),
-                  MessageKind.SWITCH_CASE_TYPES_NOT_EQUAL_CASE,
-                  {'type': typeToString(firstCaseType)}));
-            }
-            infos.add(reporter.createMessage(
-                computeSourceSpanFromTreeNode(expression),
-                MessageKind.SWITCH_CASE_TYPES_NOT_EQUAL_CASE,
-                {'type': typeToString(type)}));
-          }
+        if (type == commonElements.doubleType) {
+          reporter.reportErrorMessage(
+              computeSourceSpanFromTreeNode(expression),
+              MessageKind.SWITCH_CASE_VALUE_OVERRIDES_EQUALS,
+              {'type': "double"});
+        } else if (type == commonElements.functionType) {
+          reporter.reportErrorMessage(computeSourceSpanFromTreeNode(node),
+              MessageKind.SWITCH_CASE_FORBIDDEN, {'type': "Function"});
+        } else if (value.isObject &&
+            type != commonElements.typeLiteralType &&
+            overridesEquals(type)) {
+          reporter.reportErrorMessage(
+              computeSourceSpanFromTreeNode(expression),
+              MessageKind.SWITCH_CASE_VALUE_OVERRIDES_EQUALS,
+              {'type': typeToString(type)});
         }
       }
     }
-    if (error != null) {
-      reporter.reportError(error, infos);
-    }
   }
 }