Expected? cmdstan considers binary up-to-date when make is run with different build args

Summary:

cmdstan does not automatically recompile a model when build args change. If this is expected, would be good to document.

Description:

Doc states

If the you call Make with target bernoulli twice in a row, without any editing bernoulli.stan or otherwise changing the system, on the second invocation, Make will determine that the executable is already newer than the Stan source file and will not recompile the program:

It's unclear whether changing a build arg such as STAN_THREADS or STAN_OPENCL constitutes "otherwise changing the system". Would be good to clarify this.

Reproducible Steps:

make examples/bernoulli/bernoulli
STAN_THREADS=true make examples/bernoulli/bernoulli

I got the same behavior editing make/local.

Current Output:

make: 'examples/bernoulli/bernoulli' is up to date.

Expected Output:

Describe what you expect the output to be. Knowing the correct behavior is also very useful.

Additional Information:

Related cmdstanr discussions:
https://github.com/stan-dev/cmdstanr/issues/1019
https://github.com/stan-dev/cmdstanr/pull/1022

Current Version:

v2.35.0

Start with the CmdStan Guide's compiling Stan programs section at the dependencies anchor, then run the two bernoulli make commands from the issue and compare the behavior after editing make/local. Clarify whether changes to STAN_THREADS, STAN_OPENCL, or make/local should trigger recompilation, and document the expected behavior.