DartVM: Prefix beginning with the underscore

[DartBot]

This issue was originally filed by ief...@unipro.ru

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What steps will reproduce the problem?
Run the following test:

import("lib.dart", prefix:"_abc");

main() {
  _abc.accessibleVariable = 54;
  Expect.equals(1, _abc.accessibleVariable);
}

What is the expected output? What do you see instead?
Expected: successful completion. The spec doesn't prevent us from using leading underscore in a prefix.

Actual:
 Error: line 17 pos 3: identifier '_abc@4d2aa44' is not declared in this scope
  _abc.accessibleVariable = 54;

What version of the product are you using? On what operating system?
DartVM r5705

[DartBot]

This comment was originally written by ief...@unipro.ru

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Note: lib.dart obviously contains an accessible variable
var accessibleVariable;

[anders-sandholm]

Added Area-VM, Triaged labels.

[iposva-google]

Set owner to @a-siva.
Added this to the M1 milestone.
Added Accepted label.

[a-siva]

Does this have any effect on the proposed library re-export proposal?

#library("lib1.dart");
#import("lib2.dart", prefix:"_abc", export: true)

Does this cause the "lib2.dart" namespace being imported to be exported namespace of "lib2.dart" or does the '_' in front of the prefix make everything private to "lib1.dart" and hence none of the imported namespace to be exported?

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cc @gbracha.

[gbracha]

The VM behavior is correct wrt the spec, but I believe the spec should be changed so this situation is treated as a compile-time error. Otherwise, you would think you were exporting the namespace, but in fact none of it would be accessible outside the library. The spec implies the latter behavior, but it should be adjusted. In no case is the expected behavior that this actually allows you to access elements via private names as the bug seems to imply.

[a-siva]

Added AsDesigned label.

[DartBot]

This comment was originally written by @mhausner

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This is fixed as of r12216.

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Added Fixed label.

[DartBot]

This comment was originally written by rodion...@unipro.ru

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There seems to be no mention of special handling for prefixes beginning with an underscore in the spec and the test quoted here doesn't fail on VM as of r13590

What did you decide on in the end?

[DartBot]

This comment was originally written by rodion...@unipro.ru

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co19 test in question:
Language/03_Overview/2_Privacy_A01_t16