Add support for ^ constraints in pub.

Add support for ^ constraints in pub.

R=rnystrom@google.com
BUG=17172
Committed: https://code.google.com/p/dart/source/detail?r=41538

[Bob Nystrom, 2014-11-05 20:12:32]

One suggestion, but LGTM!

https://codereview.chromium.org/686323002/diff/1/sdk/lib/_internal/pub/lib/sr...
File sdk/lib/_internal/pub/lib/src/validator/dependency.dart (right):

https://codereview.chromium.org/686323002/diff/1/sdk/lib/_internal/pub/lib/sr...
sdk/lib/_internal/pub/lib/src/validator/dependency.dart:31: bool get _caretSafe
=> entrypoint.root.pubspec.environment.sdkVersion
How about "safe" -> "allowed"?

[Sean Eagan, 2014-11-05 22:27:07]

https://chromiumcodereview.appspot.com/686323002/diff/1/sdk/lib/_internal/pub...
File sdk/lib/_internal/pub/lib/src/validator/dependency.dart (right):

https://chromiumcodereview.appspot.com/686323002/diff/1/sdk/lib/_internal/pub...
sdk/lib/_internal/pub/lib/src/validator/dependency.dart:186: "  sdk:
\"$newSdkConstraint\"\n"
When `newSdkConstraint == VersionConstraint.empty` might want a warning about
that.  Just seeing `sdk: "<empty>"` might look like a bug.

[Sean Eagan, 2014-11-05 22:33:42]

seaneagan1@gmail.com changed reviewers:
+ seaneagan1@gmail.com

[Sean Eagan, 2014-11-05 22:33:43]

https://chromiumcodereview.appspot.com/686323002/diff/1/sdk/lib/_internal/pub...
File sdk/lib/_internal/pub/lib/src/validator/dependency.dart (right):

https://chromiumcodereview.appspot.com/686323002/diff/1/sdk/lib/_internal/pub...
sdk/lib/_internal/pub/lib/src/validator/dependency.dart:25: final
_postCaretPubVersions = new VersionConstraint.parse("^1.8.0-dev.2.0");
This is pretty cool.  I think when this feature is announced, it would be good
to give an example of using it to protect your package from breaking changes in
dart 2.0.

[nweiz, 2014-11-05 23:49:12]

Code review changes

[nweiz, 2014-11-05 23:52:03]

https://codereview.chromium.org/686323002/diff/1/sdk/lib/_internal/pub/lib/sr...
File sdk/lib/_internal/pub/lib/src/validator/dependency.dart (right):

https://codereview.chromium.org/686323002/diff/1/sdk/lib/_internal/pub/lib/sr...
sdk/lib/_internal/pub/lib/src/validator/dependency.dart:31: bool get _caretSafe
=> entrypoint.root.pubspec.environment.sdkVersion
On 2014/11/05 20:12:32, Bob Nystrom wrote:
> How about "safe" -> "allowed"?

Done.

https://codereview.chromium.org/686323002/diff/1/sdk/lib/_internal/pub/lib/sr...
sdk/lib/_internal/pub/lib/src/validator/dependency.dart:186: "  sdk:
\"$newSdkConstraint\"\n"
On 2014/11/05 22:27:07, Sean Eagan wrote:
> When `newSdkConstraint == VersionConstraint.empty` might want a warning about
> that.  Just seeing `sdk: "<empty>"` might look like a bug.

Done.

[nweiz, 2014-11-05 23:57:41]

Committed patchset #2 (id:20001) manually as 41538 (presubmit successful).