Better error when linking fails

Refs http://stackoverflow.com/questions/9762943

The system ln no longer outputs anything. Though the user can force its output with a --verbose of course. So in cases where it's not the usual of: not writable or existing file, we can ask the user to run with --verbose. I don't particularly like hiding its output, but it just confused the error IMO since it is creating a relative symlink the output was weird every time I've seen it in tickets.

I made a print wrapper so that the brew-link output doesn't get mucked up if an exception is thrown.

1 files changed, 8 insertions, 3 deletions

diff --git a/Library/Homebrew/extend/pathname.rb b/Library/Homebrew/extend/pathname.rb
index 1ccbff51c..7412fd157 100644
--- a/Library/Homebrew/extend/pathname.rb
+++ b/Library/Homebrew/extend/pathname.rb
@@ -283,9 +283,14 @@ class Pathname
     self.dirname.mkpath
     Dir.chdir self.dirname do
       # NOTE only system ln -s will create RELATIVE symlinks
-      system 'ln', '-s', src.relative_path_from(self.dirname), self.basename
-      # ln outputs useful error message for us
-      raise "Could not create symlink: #{to_s}." unless $?.success?
+      quiet_system 'ln', '-s', src.relative_path_from(self.dirname), self.basename
+      if not $?.success?
+        raise <<-EOS.undent
+          Could not symlink file: #{src.expand_path}
+          Check #{self} does not already exist.
+          Check #{dirname} is writable.
+        EOS
+      end
     end
   end