Cran build issue for package release

[DyfanJones]

Hi All,

Not sure where to ask this. I am currently getting a Cran build error for the 2 rust package wrappers I maintain: heck and llmjson. I just wanted to confirm if this is down to a possible issue with the cran windows machine or my src/Makevars.win.in.

Log Error:

error: failed to run custom build command for `proc-macro2 v1.0.107`

Caused by:
  could not execute process `d:\temp\2026_08_20_21_45_17_16432\Rtmp2bHG0Y\R.INSTALL4b78126f6e74\llmjson\src\./rust/target\debug\build\proc-macro2-38a6c09e3f38de23\build-script-build` (never executed)

Caused by:
  %1 ist keine zulässige Win32-Anwendung. (os error 193)
warning: build failed, waiting for other jobs to finish...
error: failed to run custom build command for `quote v1.0.47`

DyfanJones/heck#18
DyfanJones/llmjson#2

[JosiahParry]

@kbvernon recently ran into this i think and patched the makevars for it. Blake, what was the fix?

[JosiahParry]

#541