Cannot turn off checking of pragma(s) suppressing important diagnostics when including external headers

[carldelfin]

I am developing an R package that uses JSON for Modern C++ (placed in src/include/json.hpp and included with #include "include/json.hpp".) My issue is that devtools::check() warns about pragma(s) suppressing important diagnostics:

── R CMD check results ──────────────────── cppheader 0.0.0.9000 ────
Duration: 8.1s

❯ checking pragmas in C/C++ headers and code ... WARNING
  File which contains pragma(s) suppressing important diagnostics
    ‘src/include/json.hpp’

From what I can gather from Section 8 in R Internals, this is controlled by the environment variable _R_CHECK_PRAGMAS_, which defaults to FALSE for non-CRAN checks but TRUE for CRAN checks.

I get the warning even though NOT_CRAN is true when testing locally. I also get the warning even when I explicitly set this environment variable to FALSE, and also set NOT_CRAN to true, like so:

devtools::check(
  document = TRUE,
  env_vars = c(
    "_R_CHECK_PRAGMAS_" = "FALSE",
    "NOT_CRAN" = "true"
  )
)

The environment variables are picked up, but I still get the warning:

══ Checking════════════════════════════════════════════════
Setting env vars:
• _R_CHECK_CRAN_INCOMING_REMOTE_               : FALSE
• _R_CHECK_CRAN_INCOMING_                      : FALSE
• _R_CHECK_FORCE_SUGGESTS_                     : FALSE
• _R_CHECK_PACKAGES_USED_IGNORE_UNUSED_IMPORTS_: FALSE
• _R_CHECK_PRAGMAS_                            : FALSE
• NOT_CRAN                                     : true

...

── R CMD check results ──────────────────── cppheader 0.0.0.9000 ────
Duration: 8.3s

❯ checking pragmas in C/C++ headers and code ... WARNING
  File which contains pragma(s) suppressing important diagnostics
    ‘src/include/json.hpp’

I raised this issue on Posit's forum, and was re-directed here; hope it's the right place.

[DavisVaughan]

CRAN / R CMD check warns about any #pragmas included in your package. Yours seem to come from json.hpp here:

https://github.com/nlohmann/json/blob/ad2ee18539aa53df0908ada2a075d381a55138d8/include/nlohmann/json.hpp#L774

That doesn't have anything to do with cpp11 FWIW, so there is nothing for us to do on our end.

The "right" thing to do (even though it stinks) is to go in and hand modify json.hpp to remove those pragmas if possible. But there are 9 of them and that sounds super annoying for you. You didn't hear it from me, but you can probably change them from #pragma to # pragma (note the space) and that might turn the warning off...

[carldelfin]

Thanks a lot for the quick reply - a swift %s/#pragma/# pragma/ may or may not have resolved the issue...