From 7754d5aef57134fd9fe6c36a40f9a5514ecf2874 Mon Sep 17 00:00:00 2001
From: Dylan Thacker-Smith <dylan.smith@shopify.com>
Date: Wed, 28 Oct 2020 10:37:00 -0400
Subject: [PATCH] Attempt to strict parse variables before lax parsing in lax
 error mode (#1338)

---
 lib/liquid/parser_switching.rb    | 12 ++++++++++++
 lib/liquid/variable.rb            |  2 +-
 test/integration/assign_test.rb   |  5 +++++
 test/integration/variable_test.rb |  5 +++++
 4 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/lib/liquid/parser_switching.rb b/lib/liquid/parser_switching.rb
index 1a8d4ff..78afd58 100644
--- a/lib/liquid/parser_switching.rb
+++ b/lib/liquid/parser_switching.rb
@@ -2,6 +2,18 @@
 
 module Liquid
   module ParserSwitching
+    def strict_parse_with_error_mode_fallback(markup)
+      strict_parse_with_error_context(markup)
+    rescue SyntaxError => e
+      case parse_context.error_mode
+      when :strict
+        raise
+      when :warn
+        parse_context.warnings << e
+      end
+      lax_parse(markup)
+    end
+
     def parse_with_selected_parser(markup)
       case parse_context.error_mode
       when :strict then strict_parse_with_error_context(markup)
diff --git a/lib/liquid/variable.rb b/lib/liquid/variable.rb
index 77d6b0c..891425c 100644
--- a/lib/liquid/variable.rb
+++ b/lib/liquid/variable.rb
@@ -30,7 +30,7 @@ module Liquid
       @parse_context = parse_context
       @line_number   = parse_context.line_number
 
-      parse_with_selected_parser(markup)
+      strict_parse_with_error_mode_fallback(markup)
     end
 
     def raw
diff --git a/test/integration/assign_test.rb b/test/integration/assign_test.rb
index b956fd1..c5a8dd9 100644
--- a/test/integration/assign_test.rb
+++ b/test/integration/assign_test.rb
@@ -48,6 +48,11 @@ class AssignTest < Minitest::Test
     end
   end
 
+  def test_expression_with_whitespace_in_square_brackets
+    source = "{% assign r = a[ 'b' ] %}{{ r }}"
+    assert_template_result('result', source, 'a' => { 'b' => 'result' })
+  end
+
   def test_assign_score_exceeding_resource_limit
     t = Template.parse("{% assign foo = 42 %}{% assign bar = 23 %}")
     t.resource_limits.assign_score_limit = 1
diff --git a/test/integration/variable_test.rb b/test/integration/variable_test.rb
index 168f43a..ad1b28e 100644
--- a/test/integration/variable_test.rb
+++ b/test/integration/variable_test.rb
@@ -21,6 +21,11 @@ class VariableTest < Minitest::Test
     assert_equal('  worked wonderfully  ', template.render!('test' => 'worked wonderfully'))
   end
 
+  def test_expression_with_whitespace_in_square_brackets
+    assert_template_result('result', "{{ a[ 'b' ] }}", 'a' => { 'b' => 'result' })
+    assert_template_result('result', "{{ a[ [ 'b' ] ] }}", 'b' => 'c', 'a' => { 'c' => 'result' })
+  end
+
   def test_ignore_unknown
     template = Template.parse(%({{ test }}))
     assert_equal('', template.render!)