Implement regexp variables

What does this MR do and why?

Related #35438 (closed)

TODO:

1. Persistent yaml variable types to database

2. Treat regexp variables differently when evaluating variables

diff --git a/lib/gitlab/ci/build/rules/rule/clause/if.rb b/lib/gitlab/ci/build/rules/rule/clause/if.rb
index 499a265a1e2..d01a4de078f 100644
--- a/lib/gitlab/ci/build/rules/rule/clause/if.rb
+++ b/lib/gitlab/ci/build/rules/rule/clause/if.rb
@@ -9,6 +9,7 @@ def initialize(expression)
         end
 
         def satisfied_by?(pipeline, context)
+          # TODO :We need to know variable types in the variables hash here
           ::Gitlab::Ci::Pipeline::Expression::Statement.new(
             @expression, context.variables_hash).truthful?
         end
diff --git a/lib/gitlab/ci/pipeline/expression/lexeme/matches.rb b/lib/gitlab/ci/pipeline/expression/lexeme/matches.rb
index 4d65b914d8d..12c8345c518 100644
--- a/lib/gitlab/ci/pipeline/expression/lexeme/matches.rb
+++ b/lib/gitlab/ci/pipeline/expression/lexeme/matches.rb
@@ -9,6 +9,9 @@ class Matches < Lexeme::LogicalOperator
             PATTERN = /=~/.freeze
 
             def evaluate(variables = {})
+              # TODO: If the variables here aren't just a hash and have the
+              # type, we can switch the behavior here if the variable is a
+              # regexp type or not
               text = @left.evaluate(variables)
               regexp = @right.evaluate(variables)
               return false unless regexp

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