In the wild:

https://github.com/oprypin/crystal-chipmunk/runs/796810944?check_suite_focus=true#step:16:12

My shard became not installable as a dependency ever since crystal-1.0.0-dev.

I think that (despite @jhass hinting that this might be intentional), from the point of view of any user, this looks like a bug in Shards. Some things come to mind:

• Is it that >= 0.25.1 and < 1.0.0 are conflicting?
• Wait, there's never any < 1.0.0 specified..?
• Why did it stop working?

Repro:

$ cat shard.yml

name: main
version: 0.1.0

dependencies:
  sub:
    path: sub

$ cat sub/shard.yml

name: sub
version: 0.1.0

$ PATH=~/repos/crystal/.build:/usr/bin shards install

Resolving dependencies
Unable to satisfy the following requirements:

- `crystal (< 1.0.0)` required by `sub 0.1.0`
Failed to resolve dependencies

$ shards --version

Shards 0.11.1 (2020-06-21)

$ ~/repos/crystal/.build/crystal env

CRYSTAL_CACHE_DIR=/tmp/cache-blaxpirit/crystal
CRYSTAL_PATH=lib
CRYSTAL_VERSION=1.0.0-dev
CRYSTAL_LIBRARY_PATH=''
CRYSTAL_OPTS=''