Apply subst to USER_HEADER

[ndabas]

Submisison Checklist

• Run tests: ./runCmdStanTests.py src/test
• Declare copyright holder and open-source license: see below

Summary:

Currently, make/program applies $(subst \,/,...) to every path it hands to a tool, with one exception: USER_HEADER on line 47.

On Windows this matters because Stan Math sets SHELL when a Unix shell is available, which it always is with RTools on PATH.

Assigning SHELL in a makefile takes GNU Make off its direct-exec fast path, so recipes are run through sh, and sh strips the backslashes from the unquoted -include argument. The compiler is then handed a path with no separators at all and fails to find the header:

<built-in>:1:10: fatal error: 'C:UsersndabaDocumentsGitHubcmdstanpytestdatareturn_one.hpp' file not found
    1 | #include "C:UsersndabaDocumentsGitHubcmdstanpytestdatareturn_one.hpp"
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
make: *** [make/program:83: .../external.o] Error 1

This is a shell-quoting problem, not a compiler problem: replacing the compiler with an argv-dumping stub in the failing build shows the separators are already gone by the time the compiler is invoked, and both clang and GCC accept the backslash form when it reaches them intact.

This came up in stan-dev/cmdstanpy#864, where cmdstanpy currently works around it by converting user_header to a POSIX path before passing it to make.

Intended Effect:

-include receives a forward-slash path, matching how every other path in this file is passed to a tool. No behaviour change on Unix, or on Windows where USER_HEADER is already given with forward slashes.

How to Verify:

make STANCFLAGS=--allow-undefined USER_HEADER=C:\path\to\user_header.hpp C:/path/to/model.exe

Before: fatal error: '...' file not found, with the separators stripped from the path. After: compiles and links.

Verified on Windows ARM64 with RTools 4.5 aarch64 (clang 19.1.7, GNU Make 4.4.1) against CmdStan 2.40.0, using external.stan / return_one.hpp from cmdstanpy's test data: the build fails before the change and succeeds after it, with the
emitted flag going from -include C:\Users\...\return_one.hpp to -include C:/Users/.../return_one.hpp.

Side Effects:

None expected. $(subst ...) is a literal separator swap, so it is a no-op for paths that contain no backslashes.

The remaining bare uses of $(USER_HEADER) in this file are deliberate: the prerequisite on line 80 and the missing-header diagnostic on lines 51-57, which should echo the path as the user supplied it.

Documentation:

No documentation changes needed.

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):

Nikhil Dabas

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 )
stat_comp_benchmarks/benchmarks/low_dim_corr_gauss/low_dim_corr_gauss.stan	0.01	0.01	0.98	-1.79% slower
stat_comp_benchmarks/benchmarks/irt_2pl/irt_2pl.stan	4.11	3.9	1.05	5.16% faster
stat_comp_benchmarks/benchmarks/pkpd/one_comp_mm_elim_abs.stan	18.8	17.71	1.06	5.81% faster
stat_comp_benchmarks/benchmarks/pkpd/sim_one_comp_mm_elim_abs.stan	0.24	0.23	1.06	5.8% faster
stat_comp_benchmarks/benchmarks/low_dim_gauss_mix_collapse/low_dim_gauss_mix_collapse.stan	8.21	7.8	1.05	5.05% faster
stat_comp_benchmarks/benchmarks/gp_regr/gp_regr.stan	0.1	0.1	1.03	2.51% faster
stat_comp_benchmarks/benchmarks/gp_regr/gen_gp_data.stan	0.02	0.02	1.06	5.26% faster
stat_comp_benchmarks/benchmarks/eight_schools/eight_schools.stan	0.06	0.05	1.09	7.98% faster
stat_comp_benchmarks/benchmarks/low_dim_gauss_mix/low_dim_gauss_mix.stan	2.66	2.52	1.06	5.35% faster
stat_comp_benchmarks/benchmarks/arK/arK.stan	1.53	1.45	1.06	5.6% faster
stat_comp_benchmarks/benchmarks/sir/sir.stan	65.24	63.63	1.03	2.46% faster
stat_comp_benchmarks/benchmarks/garch/garch.stan	0.4	0.4	1.0	0.18% faster
stat_comp_benchmarks/benchmarks/gp_pois_regr/gp_pois_regr.stan	2.1	2.08	1.01	1.14% faster
stat_comp_benchmarks/benchmarks/arma/arma.stan	0.27	0.27	0.98	-1.76% slower
performance.compilation	248.16	225.96	1.1	8.95% faster
Mean result: 1.0411051223537444

Jenkins Console Log
Jenkins Build Stages
Commit hash: c865b6f141c9d526e21e2f2e20a3edf2aa0e1fe0

Machine information

Distributor ID:	Ubuntu
Description:	Ubuntu 20.04.3 LTS
Release:	20.04
Codename:	focal

CPU:

Architecture:                            x86_64
CPU op-mode(s):                          32-bit, 64-bit
Byte Order:                              Little Endian
Address sizes:                           46 bits physical, 48 bits virtual
CPU(s):                                  80
On-line CPU(s) list:                     0-79
Thread(s) per core:                      2
Core(s) per socket:                      20
Socket(s):                               2
NUMA node(s):                            2
Vendor ID:                               GenuineIntel
CPU family:                              6
Model:                                   85
Model name:                              Intel(R) Xeon(R) Gold 6248 CPU @ 2.50GHz
Stepping:                                7
CPU MHz:                                 1000.091
CPU max MHz:                             3900.0000
CPU min MHz:                             1000.0000
BogoMIPS:                                5000.00
L1d cache:                               1.3 MiB
L1i cache:                               1.3 MiB
L2 cache:                                40 MiB
L3 cache:                                55 MiB
NUMA node0 CPU(s):                       0,2,4,6,8,10,12,14,16,18,20,22,24,26,28,30,32,34,36,38,40,42,44,46,48,50,52,54,56,58,60,62,64,66,68,70,72,74,76,78
NUMA node1 CPU(s):                       1,3,5,7,9,11,13,15,17,19,21,23,25,27,29,31,33,35,37,39,41,43,45,47,49,51,53,55,57,59,61,63,65,67,69,71,73,75,77,79
Vulnerability Gather data sampling:      Mitigation; Microcode
Vulnerability Indirect target selection: Mitigation; Aligned branch/return thunks
Vulnerability Itlb multihit:             KVM: Mitigation: VMX unsupported
Vulnerability L1tf:                      Not affected
Vulnerability Mds:                       Not affected
Vulnerability Meltdown:                  Not affected
Vulnerability Mmio stale data:           Mitigation; Clear CPU buffers; SMT vulnerable
Vulnerability Old microcode:             Not affected
Vulnerability Reg file data sampling:    Not affected
Vulnerability Retbleed:                  Mitigation; Enhanced IBRS
Vulnerability Spec rstack overflow:      Not affected
Vulnerability Spec store bypass:         Mitigation; Speculative Store Bypass disabled via prctl
Vulnerability Spectre v1:                Mitigation; usercopy/swapgs barriers and __user pointer sanitization
Vulnerability Spectre v2:                Mitigation; Enhanced / Automatic IBRS; IBPB conditional; PBRSB-eIBRS SW sequence; BHI SW loop, KVM SW loop
Vulnerability Srbds:                     Not affected
Vulnerability Tsa:                       Not affected
Vulnerability Tsx async abort:           Mitigation; TSX disabled
Vulnerability Vmscape:                   Mitigation; IBPB before exit to userspace
Flags:                                   fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc art arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc cpuid aperfmperf pni pclmulqdq dtes64 monitor ds_cpl smx est tm2 ssse3 sdbg fma cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic movbe popcnt tsc_deadline_timer aes xsave avx f16c rdrand lahf_lm abm 3dnowprefetch cpuid_fault epb cat_l3 cdp_l3 intel_ppin ssbd mba ibrs ibpb stibp ibrs_enhanced fsgsbase tsc_adjust bmi1 avx2 smep bmi2 erms invpcid cqm mpx rdt_a avx512f avx512dq rdseed adx smap clflushopt clwb intel_pt avx512cd avx512bw avx512vl xsaveopt xsavec xgetbv1 xsaves cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local dtherm ida arat pln pts hwp hwp_act_window hwp_epp hwp_pkg_req pku ospke avx512_vnni md_clear flush_l1d arch_capabilities

G++:

g++ (Ubuntu 9.4.0-1ubuntu1~20.04) 9.4.0
Copyright (C) 2019 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

Clang:

clang version 10.0.0-4ubuntu1 
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

[WardBrian]

Thanks!