それを最初に出していれば…

gem install rdiscount --platform=ruby -- (スペース、マイナス2つ、スペース)
のあとに、
Provided configuration options: から始まる箇所のオプションのどれかに適切な値(*)を指定してください。

知っている範囲で、似たような例だと、
gem install mysql -- --with-mysql-config=/opt/local/bin/mysql_config5
のようなケースがありました。


* 北村さんの環境で何を指定すべきなのかまでは分かりません。

2010/11/19 北村  丈 <jyo555@w...>:
> C:\hoge\Ruby192>gem install rdiscount --platform=ruby
> Building native extensions.  This could take a while...
> ERROR:  Error installing rdiscount:
>       ERROR: Failed to build gem native extension.
>
> C:/Ruby192/bin/ruby.exe extconf.rb
> checking for random()... *** 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.
>
> Provided configuration options:
>       --with-opt-dir
>       --without-opt-dir
>       --with-opt-include
>       --without-opt-include=${opt-dir}/include
>       --with-opt-lib
>       --without-opt-lib=${opt-dir}/lib
>       --with-make-prog
>       --without-make-prog
>       --srcdir=.
>       --curdir
>       --ruby=C:/Ruby192/bin/ruby
>       --with-rdiscount-dir
>       --without-rdiscount-dir
>       --with-rdiscount-include
>       --without-rdiscount-include=${rdiscount-dir}/include
>       --with-rdiscount-lib
>       --without-rdiscount-lib=${rdiscount-dir}/lib
> C:/Ruby192/lib/ruby/1.9.1/mkmf.rb:368:in `try_do': The complier failed to
> genera
> te an executable file. (RuntimeError)
> You have to install development tools first.
>       from C:/Ruby192/lib/ruby/1.9.1/mkmf.rb:435:in `try_link0'

-- 
OZAWA Sakuro

"I think we can agree, the past is over." - George W. Bush

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