From 327790cdce43b30411635583f0bd841e33379b68 Mon Sep 17 00:00:00 2001
From: Guilherme Carreiro <guilherme.carreiro@shopify.com>
Date: Thu, 2 Oct 2025 11:29:49 +0200
Subject: [PATCH] Fix an int the `cycle` tag, add extra unit tests, and updated
 parser switcher:   - Fixed NoMethod error with .peek (using look instead)   -
 Add friendlier error message when {% cycle %}

---
 lib/liquid/parser_switching.rb          | 13 ++++++++-----
 lib/liquid/tags/cycle.rb                | 15 +++++++++++----
 lib/liquid/tags/for.rb                  |  4 ++++
 lib/liquid/tags/if.rb                   |  4 ++++
 test/integration/tags/cycle_tag_test.rb | 24 ++++++++++++++++++++----
 5 files changed, 47 insertions(+), 13 deletions(-)

diff --git a/lib/liquid/parser_switching.rb b/lib/liquid/parser_switching.rb
index a978dc43..78b86b23 100644
--- a/lib/liquid/parser_switching.rb
+++ b/lib/liquid/parser_switching.rb
@@ -2,9 +2,12 @@
 
 module Liquid
   module ParserSwitching
-    # Do not use this. Use parse_with_selected_parser instead.
-    # It's basically doing the same thing, except this will use strict_parse regardless
-    # of the error mode and fallback only if strict throws.
+    # Do not use this.
+    #
+    # It's basically doing the same thing the {#parse_with_selected_parser},
+    # except this will use the strict parser, instead of the rigid parser.
+    #
+    # @deprecated Use {#parse_with_selected_parser} instead.
     def strict_parse_with_error_mode_fallback(markup)
       strict_parse_with_error_context(markup)
     rescue SyntaxError => e
@@ -26,7 +29,7 @@ module Liquid
       when :lax    then lax_parse(markup)
       when :warn
         begin
-          strict_parse_with_error_context(markup)
+          rigid_parse_with_error_context(markup)
         rescue SyntaxError => e
           parse_context.warnings << e
           lax_parse(markup)
@@ -37,7 +40,7 @@ module Liquid
     private
 
     def rigid_parse_with_error_context(markup)
-      respond_to?(:rigid_parse) ? rigid_parse(markup) : strict_parse(markup)
+      rigid_parse(markup)
     rescue SyntaxError => e
       e.line_number    = line_number
       e.markup_context = markup_context(markup)
diff --git a/lib/liquid/tags/cycle.rb b/lib/liquid/tags/cycle.rb
index 2df55bfb..d4f7166a 100644
--- a/lib/liquid/tags/cycle.rb
+++ b/lib/liquid/tags/cycle.rb
@@ -52,27 +52,34 @@ module Liquid
       output
     end
 
+    private
+
     # cycle [name:] expression(, expression)*
     def rigid_parse(markup)
       p = @parse_context.new_parser(markup)
 
-      if p.look(:id) && p.peek(1) == :colon
+      if p.look(:id) && p.look(:colon, 1)
         @name = p.consume(:id)
         @is_named = true
         p.consume(:colon)
       end
 
       @variables = []
+
+      raise SyntaxError, options[:locale].t("errors.syntax.cycle") if p.look(:end_of_string)
+
       while (var = p.expression)
+        var = parse_expression(var)
         @variables << var
         break unless p.consume?(:comma)
       end
 
-      raise_syntax_error(options) if @variables.empty?
+      unless @is_named
+        @name = @variables.to_s
+        @is_named = !@name.match?(/\w+:0x\h{8}/)
+      end
     end
 
-    private
-
     # Temporarily until we migrate
     def strict_parse(markup)
       lax_parse(markup)
diff --git a/lib/liquid/tags/for.rb b/lib/liquid/tags/for.rb
index 6aa308f1..c2be5db1 100644
--- a/lib/liquid/tags/for.rb
+++ b/lib/liquid/tags/for.rb
@@ -111,6 +111,10 @@ module Liquid
 
     private
 
+    def rigid_parse(markup)
+      strict_parse(markup)
+    end
+
     def collection_segment(context)
       offsets = context.registers[:for] ||= {}
 
diff --git a/lib/liquid/tags/if.rb b/lib/liquid/tags/if.rb
index 040fecb8..342374f1 100644
--- a/lib/liquid/tags/if.rb
+++ b/lib/liquid/tags/if.rb
@@ -66,6 +66,10 @@ module Liquid
 
     private
 
+    def rigid_parse(markup)
+      strict_parse(markup)
+    end
+
     def push_block(tag, markup)
       block = if tag == 'else'
         ElseCondition.new
diff --git a/test/integration/tags/cycle_tag_test.rb b/test/integration/tags/cycle_tag_test.rb
index 8cd6daac..a4042479 100644
--- a/test/integration/tags/cycle_tag_test.rb
+++ b/test/integration/tags/cycle_tag_test.rb
@@ -46,18 +46,34 @@ class CycleTagTest < Minitest::Test
     assert_template_result("11", template)
   end
 
+  def test_cycle_tag_without_arguments
+    error = assert_raises(Liquid::SyntaxError) do
+      Template.parse("{% cycle %}")
+    end
+
+    assert_match(/Syntax Error in 'cycle' - Valid syntax: cycle \[name :\] var/, error.message)
+  end
+
   def test_cycle_tag_with_error_mode
     # QuotedFragment is more permissive than what Parser#expression allows.
+    temlate1 = "{% assign 5 = 'b' %}{% cycle .5, .4 %}"
+    temlate2 = "{% cycle .5: 'a', 'b' %}"
+
     [:lax, :strict].each do |mode|
       with_error_mode(mode) do
-        assert_template_result("a", "{% cycle .5: 'a', 'b' %}")
-        assert_template_result("b", "{% assign 5 = 'b' %}{% cycle .5, .4 %}")
+        assert_template_result("b", temlate1)
+        assert_template_result("a", temlate2)
       end
     end
 
     with_error_mode(:rigid) do
-      assert_raises(Liquid::SyntaxError) { Template.parse("{% cycle .5: 'a', 'b' %}") }
-      assert_raises(Liquid::SyntaxError) { Template.parse("{% cycle .5, .4 %}") }
+      error1 = assert_raises(Liquid::SyntaxError) { Template.parse(temlate1) }
+      error2 = assert_raises(Liquid::SyntaxError) { Template.parse(temlate2) }
+
+      expected_error = /Liquid syntax error: \[:dot, "."\] is not a valid expression/
+
+      assert_match(expected_error, error1.message)
+      assert_match(expected_error, error2.message)
     end
   end
 end