Rename error_squiggle to error_highlight

Merged: https://github.com/ruby/ruby/pull/4586

lib/error_highlight/core_ext.rb

@@ -0,0 +1,48 @@
+module ErrorHighlight
+  module CoreExt
+    SKIP_TO_S_FOR_SUPER_LOOKUP = true
+    private_constant :SKIP_TO_S_FOR_SUPER_LOOKUP
+
+    def to_s
+      msg = super.dup
+
+      locs = backtrace_locations
+      return msg unless locs
+
+      loc = locs.first
+      begin
+        node = RubyVM::AbstractSyntaxTree.of(loc, save_script_lines: true)
+        opts = {}
+
+        case self
+        when NoMethodError, NameError
+          point = :name
+          opts[:name] = name
+        when TypeError, ArgumentError
+          point = :args
+        end
+
+        spot = ErrorHighlight.spot(node, point, **opts) do |lineno, last_lineno|
+          last_lineno ||= lineno
+          node.script_lines[lineno - 1 .. last_lineno - 1].join("")
+        end
+
+      rescue Errno::ENOENT
+      end
+
+      if spot
+        marker = " " * spot[:first_column] + "^" * (spot[:last_column] - spot[:first_column])
+        points = "\n\n#{ spot[:line] }#{ marker }"
+        msg << points if !msg.include?(points)
+      end
+
+      msg
+    end
+  end
+
+  NameError.prepend(CoreExt)
+
+  # temporarily disabled
+  #TypeError.prepend(CoreExt)
+  #ArgumentError.prepend(CoreExt)
+end