Refine error message

Highlight failed command and suggest installing the command.
[Bug #16042]

1 files changed, 6 insertions, 1 deletions

diff --git a/tool/pure_parser.rb b/tool/pure_parser.rb
index 4d5e86e543..9ab663830e 100755
--- a/tool/pure_parser.rb
+++ b/tool/pure_parser.rb
@@ -4,7 +4,12 @@ BEGIN {
 
   colorize = Colorize.new
   file = ARGV.shift
-  unless /\Abison .* (\d+)\.\d+/ =~ IO.popen(ARGV+%w[--version], &:read)
+  begin
+    version = IO.popen(ARGV+%w[--version], &:read)
+  rescue Errno::ENOENT
+    abort "Failed to run `#{colorize.fail ARGV.join(' ')}'; You may have to install it."
+  end
+  unless /\Abison .* (\d+)\.\d+/ =~ version
     puts colorize.fail("not bison")
     exit
   end