suggest format method after error due to old syntax

[jgabry]

Submission Checklist

• Run unit tests
• Declare copyright holder and agree to license (see below)

Summary

Advances #849 (doesn't address the interactive part)

Suggests format method if compilation error due to old syntax. This doesn't yet do the formatting if in interactive mode, just suggests looking at the example in the doc for format. I added an example to that doc showing how to change old syntax.

Copyright and Licensing

Please list the copyright holder for the work you are submitting
(this will be you or your assignee, such as a university or company):
Columbia University

By submitting this pull request, the copyright holder is agreeing to
license the submitted work under the following licenses:

• Code: BSD 3-clause (https://opensource.org/licenses/BSD-3-Clause)
• Documentation: CC-BY 4.0 (https://creativecommons.org/licenses/by/4.0/)

[jgabry]

Example

f <- write_stan_file(
"
parameters {
  real x[3];
}
model {
 x ~ normal(0, 1);
}
"
)
m <- cmdstan_model(f)

Compiling Stan program...
Error in '/var/folders/s0/zfzm55px2nd2v__zlw5xfj2h0000gn/T/RtmpjGrUuu/model-14ede482935d4.stan', line 3, column 2: Declaration
    of arrays by placing brackets after a variable name was removed in Stan
    2.33.0. Instead use the array keyword before the type. This can be
    changed automatically using the auto-format flag to stanc

make: *** [/var/folders/s0/zfzm55px2nd2v__zlw5xfj2h0000gn/T/RtmpjGrUuu/model-14ede482935d4.hpp] Error 65

Error: An error occured during compilation! See the message above for more information. 
To fix deprecated or removed syntax please see ?cmdstanr::format for an example.

The last line of the error message is new. But instead of suggesting how to call the format method I have it point to the example in the format doc that I updated. The user needs to set compile=FALSE when calling cmdstan_model and then run the format method, which is a bit much to describe in the error message. Easier to just see the example in the doc.

We can also do this interactively in the future, but as a start this message should help.

[jgabry]

This might conflict with changes in #836, so we should merge that first.

[jgabry]

This might conflict with changes in #836, so we should merge that first.

Just merged that branch into this one, so I can avoid conflicts

[jgabry]

@andrjohns @rok-cesnovar @avehtari This is ready for a look if any of you have a chance. We should wait to merge it until #836 is merged (I'll merge that one if the checks that are running pass).

[codecov-commenter]

Codecov Report

Merging #852 (1dc3b50) into master (22ee5fc) will increase coverage by 0.00%.
The diff coverage is 100.00%.

❗ Current head 1dc3b50 differs from pull request most recent head 480a775. Consider uploading reports for the commit 480a775 to get more accurate results

@@           Coverage Diff           @@
##           master     #852   +/-   ##
=======================================
  Coverage   88.18%   88.19%           
=======================================
  Files          12       12           
  Lines        4215     4218    +3     
=======================================
+ Hits         3717     3720    +3     
  Misses        498      498           

Files Changed	Coverage Δ
R/model.R	91.82% <100.00%> (+0.03%)	⬆️

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more

[avehtari]

The proposed error message is fine, I'd make changes to the format doc

[rok-cesnovar]

Awesome, thanks!

[jgabry]

I updated the doc based on @avehtari's suggestion. Will merge if everything passes.