Andrew Johnson

The model methods implementation is currently undergoing a [fairly significant rework](https://github.com/stan-dev/cmdstanr/pull/894), I'd recommend waiting until that's finished before spending too much time on debugging and workarounds for a package

Oh excellent catch, thanks Jonah! I'll update the examples and draft some vignettes for the model methods and expose-functions over the next few days. In terms of simplifying the approach...

Good ideas all! I completely agree @jgabry and @n-kall, I'll make those updates @mitzimorris the `cmdstanr` methods don't use the `cmdstan` `log_prob` function, so that's not an issue here

The model methods functions exposed to R via c++ (`log_prob`, `grad_log_prob`, `hessian`) take their inputs on the unconstrained scale

> this proposal only goes halfway towards validating the inputs - it provides names for the variables, but not structure The structure is the point of this proposal. Similar to...

> what does the input for a matrix look like? The same as for data and initial values (either an R matrix or dataframe), we then handle the serialisation internally

Just wanted to flag that this bug is affecting more use-cases now that the [js_of_ocaml](https://github.com/ocsigen/js_of_ocaml) Ocaml->JS compiler has moved to heavy use of labels and break statements for [control flow](https://github.com/ocsigen/js_of_ocaml/pull/1496)...

Summary of failures: - [test/unit/math/prim/prob/neg_binomial_test.cpp](https://github.com/stan-dev/math/actions/runs/8942975899/job/24566717971#step:5:4777) - [test/unit/math/prim/prob/skew_normal_test.cpp](https://github.com/stan-dev/math/actions/runs/8942975899/job/24566717971#step:5:5666) - [test/unit/math/prim/fun/offset_multiplier_transform_test.cpp](https://github.com/stan-dev/math/actions/runs/8942975899/job/24566717971#step:5:10736) - [test/unit/math/prim/fun/mdivide_right_test.cpp](https://github.com/stan-dev/math/actions/runs/8942975899/job/24566717971#step:5:12903) - [test/unit/math/prim/fun/inv_Phi_test.cpp](https://github.com/stan-dev/math/actions/runs/8942975899/job/24566717971#step:5:13773) - [test/unit/math/prim/fun/mdivide_left_test.cpp](https://github.com/stan-dev/math/actions/runs/8942975899/job/24566717971#step:5:14013) - [test/unit/math/rev/functor/algebra_solver_fp_test.cpp](https://github.com/stan-dev/math/actions/runs/8942975899/job/24566717971#step:5:15222) - [test/unit/math/rev/prob/lkj_corr_cholesky_test.cpp](https://github.com/stan-dev/math/actions/runs/8942975899/job/24566717971#step:5:18204) - [test/unit/math/fwd/core/std_numeric_limits_test.cpp](https://github.com/stan-dev/math/actions/runs/8942975899/job/24566716537#step:6:521) - [test/unit/math/mix/core/std_numeric_limits_test.cpp](https://github.com/stan-dev/math/actions/runs/8942975899/job/24566716537#step:6:1706) - [test/unit/math/mix/fun/abs_test.cpp](https://github.com/stan-dev/math/actions/runs/8942975899/job/24566717605#step:5:340) - [test/unit/math/mix/fun/diag_post_multiply_test.cpp](https://github.com/stan-dev/math/actions/runs/8942975899/job/24566717605#step:5:1287) - [test/unit/math/mix/fun/diag_pre_multiply_test.cpp](https://github.com/stan-dev/math/actions/runs/8942975899/job/24566717605#step:5:1582) -...

Remaining failures after adding `-ffp-contract=off`: - [test/unit/math/prim/prob/neg_binomial_test.cpp](https://github.com/stan-dev/math/actions/runs/8950243011/job/24585400256?pr=3059#step:5:4778) - [test/unit/math/prim/fun/offset_multiplier_transform_test.cpp](https://github.com/stan-dev/math/actions/runs/8950243011/job/24585400256?pr=3059#step:5:10720) - [test/unit/math/fwd/core/std_numeric_limits_test.cpp](https://github.com/stan-dev/math/actions/runs/8950243011/job/24585399929?pr=3059#step:6:521) - [test/unit/math/mix/core/std_numeric_limits_test.cpp](https://github.com/stan-dev/math/actions/runs/8950243011/job/24585399929?pr=3059#step:6:1707) - [test/unit/math/mix/fun/exp_test.cpp](https://github.com/stan-dev/math/actions/runs/8950243011/job/24585400008?pr=3059#step:5:1411) - [test/unit/math/mix/fun/inv_cloglog_test.cpp](https://github.com/stan-dev/math/actions/runs/8950243011/job/24585400111?pr=3059#step:5:486) - [test/unit/math/mix/fun/inv_sqrt_test.cpp](https://github.com/stan-dev/math/actions/runs/8950243011/job/24585400111?pr=3059#step:5:714)

All fixes are in, updated title and description, ready for review