Allow identical as a compile-time constant.

pkg/front_end/lib/src/fasta/kernel/body_builder.dart

Index: pkg/front_end/lib/src/fasta/kernel/body_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
index 1e034529bf260b3f24d8dd24b0060cf783703d59..8f76e3ba6d991fa1e84fed42c81c54496f77a78d 100644
--- a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
@@ -519,7 +519,12 @@ class BodyBuilder extends ScopeListener<JumpTarget> implements BuilderHelper {
   finishSend(Object receiver, Arguments arguments, int charOffset) {
     if (receiver is BuilderAccessor) {
       if (constantExpressionRequired) {
-        addCompileTimeError(charOffset, "Not a constant expression.");
+        if (!(receiver is StaticAccessor &&

[karlklose, 2017/03/24 08:42:30]

Maybe move the checks in l. 523-525 to a helper called 'isIdentical' and merge
the condition with l. 521.

[ahe, 2017/03/24 13:14:35]

Done.

+            receiver.readTarget ==
+                coreTypes.tryGetTopLevelMember(
+                    "dart:core", null, "identical"))) {
+          addCompileTimeError(charOffset, "Not a constant expression.");
+        }
       }
       return receiver.doInvocation(charOffset, arguments);
     } else if (receiver is UnresolvedIdentifier) {
@@ -799,7 +804,9 @@ class BodyBuilder extends ScopeListener<JumpTarget> implements BuilderHelper {
           new StaticAccessor.fromBuilder(this, builder, charOffset, setter);
       if (constantExpressionRequired) {
         Member readTarget = accessor.readTarget;
-        if (!(readTarget is Field && readTarget.isConst)) {
+        if (!(readTarget is Field && readTarget.isConst ||
+            // Static tear-offs are also compile time constants.
+            readTarget is Procedure)) {
           addCompileTimeError(charOffset, "Not a constant expression.");
         }
       }