tree c396d230835344d746ced889e98182b9bd542b89
parent b8ee603eb2163eefa26817d2aa78386a0621e0d4
author Daniel Hillerström <hillerstrom@google.com> 1535035000 +0000
committer commit-bot@chromium.org <commit-bot@chromium.org> 1535035000 +0000

Checks whether an interface is implemented multiple times.

It is a compile-time error if an interface appears multiple times
across the extends and implements clauses.

This CL implements a check to detect the aforementioned case. A
previous commit implemented this by expanding and refactoring the
restricted super types check in source_loader.dart
(c.f. checkSemantics method). The restricted super types check decides
whether a type is allowed to appear in an 'extends', 'implements', or
'with' clause. However, it turned out it may have sat too early in the
compilation pipeline as it failed to detect the following case

   class A implements Object {}

I decided that it was somewhat suboptimal to implement a special case
for "Object". Therefore I have moved the check to a later stage in the
pipeline, where classes without a super class have had the Object
class injected as their default super class. The check is now
implemented in kernel_class_builder.dart (c.f. checkSupertypes
method).

Closes https://github.com/dart-lang/sdk/issues/34193

Change-Id: Ie7153c896337b589118cac4b80e9df8ea5a09daa
Reviewed-on: https://dart-review.googlesource.com/70864
Commit-Queue: Daniel Hillerström <hillerstrom@google.com>
Reviewed-by: Aske Simon Christensen <askesc@google.com>