[cmake-developers] Questions concerning using "MinGW Makefiles" when MSYS (without sh.exe) is on the PATH

[Alan W. Irwin]

My "build_projects" CMake project now contains ExternalProject_Add
build configurations for 5 different software projects which build
cleanly on Linux using the default "Unix Makefiles" generator on
that platform and which build cleanly on the MinGW/MSYS/Wine
platform using the "MSYS Makefiles" generator.

I have now tried running the build_projects cmake configuration using
the "MinGW Makefiles" generator, but those builds need many
executables from MSYS (such as mkdir.exe, cat.exe, tr.exe, unzip.exe,
etc.,) in order for them to work properly. So most of MSYS needs to be
on the PATH.

For this case "MinGW Makefiles" complains that sh.exe is on the PATH
so I worked around that issue by making a special copy of msys/1.0/bin
called msys/1.0/bin_without_sh that has sh.exe removed and putting
msys/1.0/bin_without_sh on the PATH rarther than msys/1.0/bin.  I also
take care to always use mingw32-make.exe (the MinGW version of make)
rather than make.exe (the MSYS version of make) for this case.

This trick to get "MinGW Makefiles" to work with most of MSYS on the
PATH has worked perfectly in the past for PLplot builds so I expected
it to work also for the present case (where the 5 projects being built
so far with build_projects do not include PLplot yet and are each
smaller than PLplot.) That expectation was correct for 4 of the 5
projects, but the fifth one (a libharu build) has an error concerning
the "mkdir.exe -p" command that fails for some unknown reason with an
error message of "Path not found.").

Some questions:

1. Is that demand from the "MinGW Makefiles" generator that sh.exe not
be on the PATH necessary any more?  The reason I ask this is the
strings command does indicate that mingw32-make.exe contains a
reference to sh.exe, but all the Makefiles generated by "MinGW
Makefiles" specify

SHELL = cmd.exe

so it seems unlikely that mingw32-make.exe would get confused by those
Makefiles if sh.exe were on the PATH.

2. In light of the fact that SHELL is set to cmd.exe in the Makefiles,
is it possible the above trick to get "MinGW Makefiles" to work may
simply be a workaround for a "MinGW Makefiles" generator issue and is
otherwise not necessary from the mingw32-make.exe perspective?  The
four good builds I have now with this trick and the good build of
PLplot I had in the past with this trick would support that idea.  Of
course, there is one build (libharu) that currently has an issue for
"MinGW Makefiles" that does not occur for "MSYS Makefiles" (or "Unix
Makefiles" on Linux).  Of course, that issue could be due to something
else other than MSYS (without sh.exe) being on the PATH so I am
continuing to investigate.

But to eliminate or confirm that MSYS (without sh.exe) is the issue
for the bad "MinGW Makefiles" libharu build, your comments on the
above two questions would be most appreciated.

Alan
__________________________
Alan W. Irwin

Astronomical research affiliation with Department of Physics and Astronomy,
University of Victoria (astrowww.phys.uvic.ca).

Programming affiliations with the FreeEOS equation-of-state
implementation for stellar interiors (freeeos.sf.net); the Time
Ephemerides project (timeephem.sf.net); PLplot scientific plotting
software package (plplot.sf.net); the libLASi project
(unifont.org/lasi); the Loads of Linux Links project (loll.sf.net);
and the Linux Brochure Project (lbproject.sf.net).
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Linux-powered Science
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