(1.24.3) pub get spins forever on a mix of dart_style, http, and test

[jakobr-google]

Steps to reproduce:

1. Create pubspec.yaml with these contents:

name: publoop

dependencies:
  dart_style: '>=1.0.7 <2.0.0'
  http: '>=0.11.1 <0.12.0'

dev_dependencies:
  test: '^0.12.0'

2. Run pub get.

Expected result: Success, dependencies resolved.

Actual result:

jakobr@jakobr-goobuntu:~/tmp/publoop$ pub --version
Pub 1.24.3
jakobr@jakobr-goobuntu:~/tmp/publoop$ pub get
Resolving dependencies... (1:03.7s)^C
jakobr@jakobr-goobuntu:~/tmp/publoop$ 

(yeah, I have tried letting it run longer than 1 minute. Travis killed it after waiting for about 50 minutes in dart-archive/discoveryapis_generator#185).

Workaround:

Change the dart_style dependency to >=1.0.7 <=1.0.9+1. The issue seems to be caused by dart_style 1.0.10 depending on analyzer 0.31.2-alpha.0, which requires SDK >=2.0.0-dev. Which 1.24.3 isn't, but for some reason, pub still tries to go with it.

Removing any one of the dependencies in pubspec.yaml also makes the bug disappear. All 3 are needed to cause the loop.

[nex3]

Duplicate of #912. This isn't actually spinning forever, it's just going exponential due to flaws in pub's old algorithm. The new version solver will fix cases like this (although note that it won't be in 1.24, since there are no new 1.x releases being cut).