[cmake-developers] Ninja generator on Windows

[Peter Collingbourne]

On Tue, Jan 31, 2012 at 10:32:23PM +0100, Peter Kümmel wrote:
> On 31.01.2012 16:19, Peter Collingbourne wrote:
>> On Tue, Jan 31, 2012 at 12:15:59AM +0100, Peter Kümmel wrote:
>>> - Paths like 'c:\' - Ninja now supports colon escaping "c:" ->  "c$:"
>>>    Is there a single place where the escaping could be done?
>>
>> ':' only needs to be escaped in identifiers.  So
>> cmGlobalNinjaGenerator::EncodeIdent is the correct place.
>
> Also the colons in drive names must be "escaped". For instance,
> when you wanna configure ninja to build the tests with gtest
> at C:\gtest-1.6.0, you have to call
>
>      python configure.py --with-gtest=c$:\gtest-1.6.0
>
> this generates the rule:
>
> build $builddir\gtest_main.o: cxx $
>      c$:\gtest-1.6.0\src/gtest_main.cc
>
> Without the $: the build script does not work.

Sorry if I wasn't clear here.  When I wrote "identifiers" I was
referring to lexicographical identifiers in the Ninja grammar.
Path names in build statements are lexed as identifiers, and so must
be escaped.  But variable values (including those containing paths)
are not lexed as identifiers so there is no need to escape anything
other than '$'.  All path names destined to be output as identifiers
should already be going through cmGlobalNinjaGenerator::EncodeIdent.

Probably the lack of correct identifier escaping for Ninja's configure
script is a bug in ninja_syntax.py.

>>> - Finding the msvc compiler fails because TARGET_IMPLIB is empty
>>>    and to the linker /implib: is passed without an argument.
>>>    Why is TARGET_IMPLIB empty?
>>
>> Probably because cmLocalGenerator::TargetImplib is not being
>> set.  Look at how the makefile generator does it.
>>
>
> Do you think much win32 stuff is missing? I ask, because you've based
> the ninja generator on a Makefile generator, or I'm wrong?

No idea.  I've never tried the generator on Windows.  We're probably
at least 3/4 of the way there though.

>>> - Some targets have the .exe extension, but the rule misses the .exe.
>>
>> Can you show an example of what you mean?  The generator should be
>> using cmTarget::GetFullPath to build paths to targets which seems
>> to append CMAKE_EXECUTABLE_SUFFIX (i.e. ".exe" on Windows) where
>> necessary.
>
> Is was a bug in my CMakeLists.txt because MSVC_IDE was set, even when I use
> the Ninja generator.
>
> Currently I use "CMAKE_GENERATOR STREQUAL Ninja" the check for the ninja generator.
> Is there a simpler way? Couldn't we set NINJA or CMAKE_NINJA?

I don't see any reason to be inconsistent with the other generators.

>>> - When&&  is used for calling multiple command a 'cmd.exe /c' call is necessary.
>>
>> Correct.  That will need to be prepended in
>> cmLocalNinjaGenerator::BuildCommandLine if the vector contains more
>> than one command.
>
> When there are no PRE and POST steps the cmd and && could be dropped completely
> (also the "cd ." nop, which I've used instead of ":")

Yes.

I've reminded myself of something.  Remember that BuildCommandLine
is used to build both "full" command lines and sub-command lines
(such as lists of PRE and POST commands) and consider the case where
the sub command line contains more than one command.

COMMAND = cmd /c $PRE && foo && $POST
[...]
PRE = cmd /c foo && bar
POST = cmd /c foo && bar

Note the multiple "cmd /c"s.  I don't know what Windows will think
of that but it makes me nervous and in any case will probably slow
the build down.  We might need a pair of functions, one for building
full command lines and one for sub command lines.

Thanks,
-- 
Peter