Show a dedicated snippet for "wrong number of arguments" error

lib/error_highlight/base.rb

@@ -239,6 +239,20 @@ def spot
       when :OP_CDECL
         spot_op_cdecl
 
+      when :DEFN
+        raise NotImplementedError if @point_type != :name
+        spot_defn
+
+      when :DEFS
+        raise NotImplementedError if @point_type != :name
+        spot_defs
+
+      when :LAMBDA
+        spot_lambda
+
+      when :ITER
+        spot_iter
+
       when :call_node
         case @point_type
         when :name
@@ -280,6 +294,30 @@ def spot
       when :constant_path_operator_write_node
         prism_spot_constant_path_operator_write
 
+      when :def_node
+        case @point_type
+        when :name
+          prism_spot_def_for_name
+        when :args
+          raise NotImplementedError
+        end
+
+      when :lambda_node
+        case @point_type
+        when :name
+          prism_spot_lambda_for_name
+        when :args
+          raise NotImplementedError
+        end
+
+      when :block_node
+        case @point_type
+        when :name
+          prism_spot_block_for_name
+        when :args
+          raise NotImplementedError
+        end
+
       end
 
       if @snippet && @beg_column && @end_column && @beg_column < @end_column
@@ -621,6 +659,55 @@ def spot_op_cdecl
       end
     end
 
+    # Example:
+    #   def bar; end
+    #       ^^^
+    def spot_defn
+      mid, = @node.children
+      fetch_line(@node.first_lineno)
+      if @snippet.match(/\Gdef\s+(#{ Regexp.quote(mid) }\b)/, @node.first_column)
+        @beg_column = $~.begin(1)
+        @end_column = $~.end(1)
+      end
+    end
+
+    # Example:
+    #   def Foo.bar; end
+    #          ^^^^
+    def spot_defs
+      nd_recv, mid, = @node.children
+      fetch_line(nd_recv.last_lineno)
+      if @snippet.match(/\G\s*(\.\s*#{ Regexp.quote(mid) }\b)/, nd_recv.last_column)
+        @beg_column = $~.begin(1)
+        @end_column = $~.end(1)
+      end
+    end
+
+    # Example:
+    #   -> { ... }
+    #   ^^
+    def spot_lambda
+      fetch_line(@node.first_lineno)
+      if @snippet.match(/\G->/, @node.first_column)
+        @beg_column = $~.begin(0)
+        @end_column = $~.end(0)
+      end
+    end
+
+    # Example:
+    #   lambda { ... }
+    #          ^
+    #   define_method :foo do
+    #                      ^^
+    def spot_iter
+      _nd_fcall, nd_scope = @node.children
+      fetch_line(nd_scope.first_lineno)
+      if @snippet.match(/\G(?:do\b|\{)/, nd_scope.first_column)
+        @beg_column = $~.begin(0)
+        @end_column = $~.end(0)
+      end
+    end
+
     def fetch_line(lineno)
       @beg_lineno = @end_lineno = lineno
       @snippet = @fetch[lineno]
@@ -826,6 +913,31 @@ def prism_spot_constant_path_operator_write
         prism_location(@node.binary_operator_loc.chop)
       end
     end
+
+    # Example:
+    #   def foo()
+    #       ^^^
+    def prism_spot_def_for_name
+      location = @node.name_loc
+      location = location.join(@node.operator_loc) if @node.operator_loc
+      prism_location(location)
+    end
+
+    # Example:
+    #   -> x, y { }
+    #   ^^
+    def prism_spot_lambda_for_name
+      prism_location(@node.operator_loc)
+    end
+
+    # Example:
+    #   lambda { }
+    #          ^
+    #   define_method :foo do |x, y|
+    #                      ^
+    def prism_spot_block_for_name
+      prism_location(@node.opening_loc)
+    end
   end
 
   private_constant :Spotter

lib/error_highlight/core_ext.rb

@@ -3,9 +3,38 @@
 module ErrorHighlight
   module CoreExt
     private def generate_snippet
-      spot = ErrorHighlight.spot(self)
-      return "" unless spot
-      return ErrorHighlight.formatter.message_for(spot)
+      if ArgumentError === self && message =~ /\A(?:wrong number of arguments|missing keyword|unknown keyword|no keywords accepted)\b/
+        locs = self.backtrace_locations
+        return "" if locs.size < 2
+        callee_loc, caller_loc = locs
+        callee_spot = ErrorHighlight.spot(self, backtrace_location: callee_loc, point_type: :name)
+        caller_spot = ErrorHighlight.spot(self, backtrace_location: caller_loc, point_type: :name)
+        if caller_spot && callee_spot &&
+            caller_loc.path == callee_loc.path &&
+            caller_loc.lineno == callee_loc.lineno &&
+            caller_spot == callee_spot
+          callee_loc = callee_spot = nil
+        end
+        ret = +"\n"
+        [["caller", caller_loc, caller_spot], ["callee", callee_loc, callee_spot]].each do |header, loc, spot|
+          out = nil
+          if loc
+            out = "    #{ header }: #{ loc.path }:#{ loc.lineno }"
+            if spot
+              _, _, snippet, highlight = ErrorHighlight.formatter.message_for(spot).lines
+              out += "\n    | #{ snippet }      #{ highlight }"
+            else
+              out += "\n    (cannot create a snippet of the method definition; use Ruby 3.5 or later)"
+            end
+          end
+          ret << "\n" + out if out
+        end
+        ret
+      else
+        spot = ErrorHighlight.spot(self)
+        return "" unless spot
+        return ErrorHighlight.formatter.message_for(spot)
+      end
     end
 
     if Exception.method_defined?(:detailed_message)