Fix #4238 - if should match undef as ''

The comparisons operator (and more particularly == and !=) were not treating
the undef value as '', like case and selector did since #2818.

This patch makes sure comparison operator uses AST leaf matching.

Unfortunately, doing this introduces a behavior change compared to
the previous versions:
Numbers embedded in strings will now be matched as numbers in case and
selector statements instead of string matching.

Signed-off-by: Brice Figureau <brice-puppet@daysofwonder.com>

2 files changed, 10 insertions, 8 deletions

diff --git a/lib/puppet/parser/ast/comparison_operator.rb b/lib/puppet/parser/ast/comparison_operator.rb
index c8694bbff..039c81df8 100644
--- a/lib/puppet/parser/ast/comparison_operator.rb
+++ b/lib/puppet/parser/ast/comparison_operator.rb
@@ -16,17 +16,16 @@ class Puppet::Parser::AST
     def evaluate(scope)
       # evaluate the operands, should return a boolean value
       lval = @lval.safeevaluate(scope)
-      rval = @rval.safeevaluate(scope)
 
-      # convert to number if operands are number
-      lval = Puppet::Parser::Scope.number?(lval) || lval
-      rval = Puppet::Parser::Scope.number?(rval) || rval
+      case @operator
+      when "==","!="
+        @rval.evaluate_match(lval, scope) ? @operator == '==' : @operator == '!='
+      else
+        rval = @rval.safeevaluate(scope)
+        rval = Puppet::Parser::Scope.number?(rval) || rval
+        lval = Puppet::Parser::Scope.number?(lval) || lval
 
-      # return result
-      unless @operator == '!='
         lval.send(@operator,rval)
-      else
-        lval != rval
       end
     end
 
diff --git a/lib/puppet/parser/ast/leaf.rb b/lib/puppet/parser/ast/leaf.rb
index 3b9163d9c..49f430278 100644
--- a/lib/puppet/parser/ast/leaf.rb
+++ b/lib/puppet/parser/ast/leaf.rb
@@ -17,6 +17,9 @@ class Puppet::Parser::AST
       obj   = obj.downcase   if obj.respond_to?(:downcase)
       value = value.downcase if value.respond_to?(:downcase)
 
+      obj   = Puppet::Parser::Scope.number?(obj)   || obj
+      value = Puppet::Parser::Scope.number?(value) || value
+
       # "" == undef for case/selector/if
       obj == value or (obj == "" and value == :undef)
     end