Unexpected/Incorrect Path Conversion when Exporting Environment Variables

[cariad-robert-abel]

I recently updated my msys and noticed that some Makefile recipes started failing. Basically, whenever more than one path-like string is exported, a weird conversion kicks in that tries to split each single path as if it were a list of paths and then replaces the first forward slash /.

As far as I understand, make exports variables through the environment for subsequent invocations of tools using the export command, so this isn't the usual path mangling when using command-line arguments or at least I assume that make does not invoke a second executable and passes the exported data via command-line arguments to achieve this.

I reduced this down to the following minimal example:

ex
│   Makefile
└───dir
        Makefile

The Makefile contents are simple:

##########################################################################
# Makefile

.PHONY: foo
foo: export SINGLE += $(abspath file1)
foo: export DOUBLE += $(abspath file2) $(abspath file3)
foo:
	@echo "SHELL = $(SHELL)"
	@echo "SINGLE = $(SINGLE)"
	@echo "DOUBLE = $(DOUBLE)"
	+@cd dir && $(MAKE) bar && cd ..

##########################################################################
# dir/Makefile

.PHONY: bar
bar:
	@echo "SHELL = $(SHELL)"
	@echo "SINGLE = $(SINGLE)"
	@echo "DOUBLE = $(DOUBLE)"

The output with msys-2.0.dll version 3004.3.0.0 used to be:

$ mingw32-make foo
SHELL = C:/msys2/usr/bin/sh.exe
SINGLE = C:/tmp/ex/file1
DOUBLE = C:/tmp/ex/file2 C:/tmp/ex/file3
mingw32-make[1]: Entering directory 'C:/tmp/ex/dir'
SHELL = C:/msys2/usr/bin/sh.exe
SINGLE = C:/tmp/ex/file1
DOUBLE = C:/tmp/ex/file2 C:/tmp/ex/file3
mingw32-make[1]: Leaving directory 'C:/tmp/ex/dir'

However with msys-2.0.dll version 3004.6.0.0 the output is:

$ mingw32-make foo
SHELL = C:/msys2/usr/bin/sh.exe
SINGLE = C:/tmp/ex/file1
DOUBLE = C:/tmp/ex/file2 C:/tmp/ex/file3
mingw32-make[1]: Entering directory 'C:/tmp/ex/dir'
SHELL = C:/msys2/usr/bin/sh.exe
SINGLE = C:/tmp/ex/file1
DOUBLE = C;C:\msys2\ex\file2 C;C:\msys2\ex\file3        # <-- error on this line
mingw32-make[1]: Leaving directory 'C:/tmp/ex/dir'

Basically, the each path is treated as if the first colon : was actually a separator within a list of paths, then the first forward slash / is replaced by the msys2 base directory and then the paths are concatenated again using the windows separator for lists of paths, semicolon ;.

I strongly suspect this is related to #150, because as one can see, it does not happen with just a single path.
However, curiously this error does not occur when the exported list itself starts with a space, so using foo: export DOUBLE := $(DOUBLE) $(abspath file2) $(abspath file3) (DOUBLE is initially empty) does not trigger this behavior. This leads me to believe this might be a slightly different case.

I also noticed that the behavior does not occur when using SHELL = cmd, so it's definitely the invocation of sh.exe in line 3 of the foo recipe that's causing the issue. Unfortunately, MSYS2_ARG_CONV_EXCL does not have any effect on this.

I apologize for the somewhat lengthy issue ;)

[dscho]

I think you're correct, and this is due to the change where spaces are now considered to be perfectly fine in file/directory names.

I'm not quite sure how we can address your scenario without re-breaking the fix where, say, /c/Program Files was considered not to be a path.

Could you elaborate a bit why the path list in the Makefile has to be in mixed format (i.e. DOS drive but no backslashes) and with a space instead of the usual semicolon as separator?

[cariad-robert-abel]

Could you elaborate a bit why the path list in the Makefile has to be in mixed format (i.e. DOS drive but no backslashes) and with a space instead of the usual semicolon as separator?

The reason I use paths with forward slashes— C:/Project/src instead of C:\Project\src—is that

1. that's the style returned by $(abspath <relative-path>), and
2. sh.exe is in the path and make uses that to invoke recipes, so all backslashes would have to be escaped, which is a nightmare especially when appending to already-escaped variables' contents, and
3. I call native and msys/unixy programs alike and now the translation/escaping of paths would have to be program-specific, which is another headache. Hence the use of mingw32-make instead of regular make.

Why is this list not separated by semi-colons? Because it's actually my INCLUDES variable that is then processed using $(INCLUDES:%=-I%) in the sub-Makefile. It's a regular list of strings separated by whitespace, which is very common in Makefiles. The paths are actually also quoted ("C:/Project/Name/src"), but that does not make a difference to this bug and I left it out for brevity.

I'm not quite sure how we can address your scenario without re-breaking the fix where, say, /c/Program Files was considered not to be a path.

I'm not sure I follow, because wouldn't it have to be /c/Program\ Files anyway in a unixy list of paths, e.g. /c/Program\ Files/Git/bin:/c/Program\ Files/GnuPG/bin? In any case, my use case is really a very common use case when using hierarchical Makefiles, so this will break a lot of use cases, I'm afraid.

I'd be happy if there was a (possibly separate) environment variable that disables this behavior, seeing as even MSYS2_ARG_CONV_EXCL has no effect.

[jeremyd2019]

I'd be happy if there was a (possibly separate) environment variable that disables this behavior, seeing as even MSYS2_ARG_CONV_EXCL has no effect.

I think MSYS2_ENV_CONV_EXCL is what you are looking for here: https://www.msys2.org/docs/filesystem-paths/#environment-variables

That doesn't negate this issue though, this does seem like a common case to me, at least for a user of mingw32-make.

[cariad-robert-abel]

I think MSYS2_ENV_CONV_EXCL is what you are looking for

Wow, I wasn't even aware that msys2 did that. Thanks for pointing this out :)