This is a small change that allows some better 'scriptability' of the compiler, e.g.

 $ cat test/integration/good/for_early_return.stan | stanc - --auto-format
functions {
  real ends() {
    for (i in 1 : 10) {
      return 1;
    }
  }
}
transformed parameters {
  real a = ends();
}

Submission Checklist

• Run unit tests
• Documentation
  • If a user-facing facing change was made, the documentation PR is here: Update page on stanc3 arguments docs#845

Release notes

The compiler now accepts - as a model argument, in which case it reads from standard input

Copyright and Licensing

By submitting this pull request, the copyright holder is agreeing to
license the submitted work under the BSD 3-clause license (https://opensource.org/licenses/BSD-3-Clause)