scallywag mingw64 complain cross-tools not installed before installs decided

[Jon Turney]

On 16/05/2023 05:58, Brian Inglis via Cygwin-apps wrote:
> Just recently noticed this has been happening as builds succeeded; see:
> 
> https://cygwin.com/cgi-bin2/jobs.cgi?srcpkg=mingw64-x86_64-nghttp2&status=build+succeeded&user=Brian+Inglis&id=6354
> https://github.com/cygwin/scallywag/actions/runs/4968984196
> 
> https://cygwin.com/cgi-bin2/jobs.cgi?srcpkg=mingw64-x86_64-nghttp2&status=build+succeeded&user=Brian+Inglis&id=5367
> https://github.com/cygwin/scallywag/actions/runs/4225550616
> 
> scallywag: repository contains cygport mingw64-x86_64-nghttp2.cygport
> scallywag: cygport vars failed, exit status 1
> scallywag: /usr/share/cygport/cygclass/cross.cygclass: line 142: 
> x86_64-w64-mingw32-gcc: command not found
> *** ERROR: This package requires x86_64-w64-mingw32 binutils and gcc
> 
> scallywag:
> scallywag: parsing cygport 
> /cygdrive/d/a/scallywag/mingw64-x86_64-nghttp2/mingw64-x86_64-nghttp2.cygport

This isn't actually a new problem, although it's probably more clearly 
reported now.

The problem is that some cygport classes perform environment checks in 
free code (not as part of any function) e.g. 'inherit cross' immediately 
checks for the CROSS_HOST complier.

This interacts badly with cygport commands which aren't actually one of 
the build steps, and particularly with 'cygport vars BUILD_REQUIRES' 
(which scallywag wants to use to determine what packages need to be 
installed)

To make things (usually) work in this situation, scallywag falls back to 
trying to parse the cygport file to extract variables (as we did before 
'cygport vars' was implemented) - which succeeds because it doesn't try 
to execute the cygport, but is much less reliable in terms of giving 
correct answers, since it only understands literal string assignments, 
and can't understand e.g. shell variable expansions etc.

The real fix is for someone to rearrange things in cygport, so that 
these checks only occur before the build-steps which they are actually 
prerequisites for, but that hasn't happened yet...