This PR modifies the parser, so that `%` is parsed as a `DEPENDENCY`, and all
node properties that follow are associated to the name after the `%`. e.g.,
in `foo %gcc +binutils` the `+binutils` refers to `gcc` and not to `foo`.
`%` is still parsed as a build-type dependency, at the moment.
Environments, config files and `package.py` files from before Spack v1.0 may have
spec strings with package variants, targets, etc. *after* a build dependency, and these
will need to be updated. You can use the `spack style --spec-strings` command to do this.
To see what strings will be parsed differently under Spack v1.0, run:
```
spack style --spec-strings FILES
```
where `FILES` is a list of filenames that may contain old specs. To update these spec
strings so that they parse correctly under both Spack 1.0 and Spack 0.x, you can run:
```
spack style --fix --spec-strings FILES
```
In the example above, `foo %gcc +binutils` would be rewritten as `foo +binutils %gcc`,
which parses the same in any Spack version.
In addition, this PR fixes several issues with `%` dependencies:
- [x] Ensure we can still constrain compilers on reuse
- [x] Ensure we can reuse a compiler by hash
- [x] Add tests
---------
Signed-off-by: Massimiliano Culpo <massimiliano.culpo@gmail.com>
f8538a1b1c