From 2a0ee408afeeae0f1a0d354ac36c400a361f6767 Mon Sep 17 00:00:00 2001
From: Luke Gruber <luke.gru@gmail.com>
Date: Tue, 17 Sep 2024 08:34:29 -0400
Subject: [PATCH] [ruby/error_highlight] Fix error with prism when method given
 no arguments

such as:

  p = Proc.new

This now matches the RubyVM::AbstractSyntaxTree behavior, which is
not to highlight anything.

https://github.com/ruby/error_highlight/commit/d5c592a1ba
---
 lib/error_highlight/base.rb                  | 3 +++
 test/error_highlight/test_error_highlight.rb | 9 +++++++++
 2 files changed, 12 insertions(+)

diff --git a/lib/error_highlight/base.rb b/lib/error_highlight/base.rb
index 4669727c65..e2077fa5a6 100644
--- a/lib/error_highlight/base.rb
+++ b/lib/error_highlight/base.rb
@@ -700,6 +700,9 @@ module ErrorHighlight
     #   foo 42
     #       ^^
     def prism_spot_call_for_args
+      # Disallow highlighting arguments if there are no arguments.
+      return if @node.arguments.nil?
+
       # Explicitly turn off foo.() syntax because error_highlight expects this
       # to not work.
       return nil if @node.name == :call && @node.message_loc.nil?
diff --git a/test/error_highlight/test_error_highlight.rb b/test/error_highlight/test_error_highlight.rb
index 5f4c386990..63e7032eda 100644
--- a/test/error_highlight/test_error_highlight.rb
+++ b/test/error_highlight/test_error_highlight.rb
@@ -197,6 +197,15 @@ undefined method `foo' for #{ NIL_RECV_MESSAGE }
     end
   end
 
+  def test_CALL_arg_7
+    assert_error_message(ArgumentError, <<~END) do
+tried to create Proc object without a block (ArgumentError)
+    END
+
+      Proc.new
+    end
+  end
+
   def test_QCALL_1
     assert_error_message(NoMethodError, <<~END) do
 undefined method `foo' for #{ ONE_RECV_MESSAGE }