I got around this issue by manually installing rjb 1.1.2:

gem install rjb -v 1.1.2

then

gem install buildr --ignore-dependencies



On Mon, May 12, 2008 at 10:38 AM, Shane Witbeck
<shane / digitalsanctum.com> wrote:
> I'm running into the same issue. Are there any other better
> suggestions for a workaround?
>
> It seems this should be a pretty high priority since it prevents an
> install of buildr on windows machines.
>
> Thanks,
> Shane
>
>
> On Thu, May 1, 2008 at 1:10 AM, Phillip Gawlowski
> <cmdjackryan / googlemail.com> wrote:
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>> BWACJay wrote:
>> | I've spent two good(bad, actually) days on this already, and searched
>> | through all the archives and anywhere else that the Google might take
>> | me...
>> |
>> | I'm simply trying to install the rjb gem using "gem install rjb". I
>> | get this response:
>> | ------
>> | Building native extensions.  This could take a while...
>> | ERROR:  Error installing rjb:
>> |       ERROR: Failed to build gem native extension.
>> |
>> | c:/ruby/bin/ruby.exe extconf.rb install rjb
>> | checking for jni.h... no
>> | *** extconf.rb failed ***
>> | Could not create Makefile due to some reason, probably lack of
>> | necessary libraries and/or headers.  Check the mkmf.log file for more
>> | details.  You may need configuration options.
>> | ...
>> | ------
>> |
>> | I've seen posts about this exact problem, but none of the solutions
>> | work for me (or I'm not executing them correctly, but I've gone
>> | through them all at least 10 times so far).  The proposed solutions
>> | that I've seen are:
>> | 1) make sure path environment variable includes JDK root directory.
>> | My path variable includes the JDK root directory, the /bin directory,
>> | and the /include directory (I've tried each individually as well)
>> | 2) the JAVA_HOME environment variable not set.  My command "c:\>echo
>> | %JAVA_HOME%" returns "C:\j2sdk1.4.2_17"
>> | 3) copy the jni.h (and a few other) files to the rjb-1.1.3/ext folder,
>> | which I have done.
>> | 4) run a specific version of the install gem.  I've tried the default
>> | 'gem install rjb' as well as 'gem install -platform mswin32' (even
>> | tried 'gem install -platform ruby') and no progress.
>> |
>> | Here is some other helpful? info:
>> | OS = WinXP SP2
>> | Ruby = ruby 1.8.6 (2007-09-24 patchlevel 111) [i386-mswin32]
>> | Rails = Rails 2.0.2
>> | Java SDK = J2SE 1.4.2_17
>> | RJB = 1.1.3
>> |
>> | Any direction would be greatly appreciated.
>>
>> Well, unless you have Visual C++ 6.0 installed, you won't be able to
>> compile C extensions.
>>
>> One option would be to use the (highly experimental) Windows installer3
>> recipe, which downloads all you need to compile Ruby (including the
>> MinGW32 GCC compiler), compiles Ruby, and puts it into a sandbox, so
>> that you current installation doesn't get mixed up. With any luck, you
>> should be able to just do a 'gem install rjb' in the compiled Ruby's bin
>> directory, and the gem should install successfully.
>>
>> A quick and dirty guide to getting the installer3 recipe:
>> <http://groups.google.com/group/comp.lang.ruby/browse_frm/thread/1e2f1b9a3d611e3b?tvc=1>
>>
>> - --
>> Phillip Gawlowski
>> Twitter: twitter.com/cynicalryan
>> Blog: http://justarubyist.blogspot.com
>>
>> Dulce bellum inexpertis.
>> (War is sweet to those who do not fight.)
>> ~ -- Gerard Didier Erasmus (c. 1465-1536)
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>
>
>
> --
> -Shane
>
>



-- 
-Shane