Mark rethrow_located as [[noreturn]]

[WardBrian]

Submission Checklist

• Run unit tests: ./runTests.py src/test/unit
• Run cpplint: make cpplint
• Declare copyright holder and open-source license: see below

Summary

Marks rethrow_located as never returning using the noreturn attribute. This should allow us to simplify the existing code generation in stanc3, as currently we generate this code:

    try {
        ....
    } catch (const std::exception& e) {
      stan::lang::rethrow_located(e, locations_array__[current_statement__]);
      // Next line prevents compiler griping about no return
      throw std::runtime_error("*** IF YOU SEE THIS, PLEASE REPORT A BUG ***"); 
    }

This should make that extra throw unnecessary.

Intended Effect

Let the compiler know that rethrow_located will never return

How to Verify

I've tested this in a local cmdstan instance, though I was not able to get the error described in the comment to appear, with or without this change.

Side Effects

None

Documentation

None

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):
Simons Foundation

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/)

[stan-buildbot]

---

Name	Old Result	New Result	Ratio	Performance change( 1 - new / old )
gp_pois_regr/gp_pois_regr.stan	3.45	3.52	0.98	-1.87% slower
low_dim_corr_gauss/low_dim_corr_gauss.stan	0.02	0.02	0.99	-0.9% slower
eight_schools/eight_schools.stan	0.09	0.09	0.98	-1.65% slower
gp_regr/gp_regr.stan	0.14	0.14	1.01	0.85% faster
irt_2pl/irt_2pl.stan	5.02	5.2	0.96	-3.7% slower
performance.compilation	91.8	89.0	1.03	3.05% faster
low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan	8.13	8.13	1.0	-0.0% slower
pkpd/one_comp_mm_elim_abs.stan	31.35	30.79	1.02	1.77% faster
sir/sir.stan	127.91	118.09	1.08	7.67% faster
gp_regr/gen_gp_data.stan	0.03	0.03	0.98	-1.76% slower
low_dim_gauss_mix/low_dim_gauss_mix.stan	2.99	2.98	1.0	0.35% faster
pkpd/sim_one_comp_mm_elim_abs.stan	0.39	0.4	0.98	-1.9% slower
arK/arK.stan	2.06	2.05	1.0	0.45% faster
arma/arma.stan	0.23	0.25	0.91	-9.87% slower
garch/garch.stan	0.65	0.6	1.08	7.58% faster
Mean result: 1.00175460523

---

Jenkins Console Log
Blue Ocean
Commit hash: 9ad8d3b

---

Machine information

ProductName: Mac OS X ProductVersion: 10.11.6 BuildVersion: 15G22010

CPU:
Intel(R) Xeon(R) CPU E5-1680 v2 @ 3.00GHz

G++:
Configured with: --prefix=/Applications/Xcode.app/Contents/Developer/usr --with-gxx-include-dir=/usr/include/c++/4.2.1
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin15.6.0
Thread model: posix

Clang:
Apple LLVM version 7.0.2 (clang-700.1.81)
Target: x86_64-apple-darwin15.6.0
Thread model: posix

[bob-carpenter]

Looks good. Thanks to @blackwer for suggesting this fix.