Homebrew: Ignoring bigdecimal-1.3.2 because its extensions are not built

Question

Always when I run brew update the Ignoring bigdecimal-1.3.2 because its extensions are not built. Try: gem pristine bigdecimal --version 1.3.2 warning shows up:

> brew update
Ignoring bigdecimal-1.3.2 because its extensions are not built.  Try: gem pristine bigdecimal --version 1.3.2
Ignoring bigdecimal-1.3.2 because its extensions are not built.  Try: gem pristine bigdecimal --version 1.3.2
Already up-to-date.

I'm using Homebrew v1.7.7 (Homebrew/homebrew-core (git revision 77cae; last commit 2018-10-19), Homebrew/homebrew-cask (git revision c95843; last commit 2018-10-19)) and rbenv v1.1.1.

I already did gem pristine bigdecimal --version 1.3.2 and it says:

> gem pristine bigdecimal --version 1.3.2
ERROR:  While executing gem ... (Gem::Exception)
    Failed to find gems ["bigdecimal"] = 1.3.2

Even gem pristine --all doesn't fixed it.

The gem environment is showing me 2 gem paths. Is that fine?

> gem environment
RubyGems Environment:
  - RUBYGEMS VERSION: 2.6.11
  - RUBY VERSION: 2.4.1 (2017-03-22 patchlevel 111) [x86_64-darwin16]
  - INSTALLATION DIRECTORY: /Users/ricardo/.rbenv/versions/2.4.1/lib/ruby/gems/2.4.0
  - USER INSTALLATION DIRECTORY: /Users/ricardo/.gem/ruby/2.4.0
  - RUBY EXECUTABLE: /Users/ricardo/.rbenv/versions/2.4.1/bin/ruby
  - EXECUTABLE DIRECTORY: /Users/ricardo/.rbenv/versions/2.4.1/bin
  - SPEC CACHE DIRECTORY: /Users/ricardo/.gem/specs
  - SYSTEM CONFIGURATION DIRECTORY: /Users/ricardo/.rbenv/versions/2.4.1/etc
  - RUBYGEMS PLATFORMS:
    - ruby
    - x86_64-darwin-16
  - GEM PATHS:
     - /Users/ricardo/.rbenv/versions/2.4.1/lib/ruby/gems/2.4.0
     - /Users/ricardo/.gem/ruby/2.4.0
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :backtrace => false
     - :bulk_threshold => 1000
     - "gem" => "--no-rdoc --no-ri --user-install"
  - REMOTE SOURCES:
     - https://rubygems.org/
  - SHELL PATH:
     - /Users/ricardo/.rbenv/versions/2.4.1/bin
     - /usr/local/Cellar/rbenv/1.1.1/libexec
     - /Users/ricardo/.gem/ruby/2.4.0/bin
     - /Users/ricardo/.rbenv/shims
     - /usr/local/bin
     - /usr/bin
     - /bin
     - /usr/sbin
     - /sbin

Answer 1

Make sure you're using the right gem. The following fixed it for me:

$ which ruby
/usr/local/bin/ruby
$ /usr/bin/gem uninstall bigdecimal --all --force

(edit: fixed "remove" to "uninstall")