Ruby-build: 2.6.1 w/jemalloc, Ubuntu 16.04

[jsimpson]

I've been trying to install ruby-2.6.1 with support for jemalloc but I believe that I'm having some trouble. I've been issuing the following to rbenv install without success:

$ RUBY_CONFIGURE_OPTS=--with-jemalloc rbenv install 2.6.1
$ irb
>> RbConfig::CONFIG['LIBS']
=> "-lm "

However, I was able to successfully compile ruby-2.5.1 with jemalloc support:

$ RUBY_CONFIGURE_OPTS=--with-jemalloc rbenv install 2.5.1
$ irb
>> RbConfig::CONFIG['LIBS']
=> "-lpthread -ljemalloc -lgmp -ldl -lcrypt -lm "

I'm not sure what's going on. Maybe something has changed between 2.5.x and 2.6.x that I'm just unaware of, and my ability to Google for it is letting me down? Thanks for any assistance or advice you can offer!

[jsimpson]

For any others that may come along:

$ irb
>> RbConfig::CONFIG['MAINLIBS']
=> "-lz -lpthread -lrt -lrt -ljemalloc -lgmp -ldl -lcrypt -lm "

It appears that library support is now in CONFIG['MAINLIBS'] in 2.6.x, previously it was in CONFIG['LIBS'].

See here for more discussion.