Fix name locations of FunDef and External nodes (#14267)

spec/compiler/parser/parser_spec.cr

@@ -2505,6 +2505,24 @@ module Crystal
         name_location.column_number.should eq(12)
       end
 
+      it "sets location of top-level fun name" do
+        parser = Parser.new("fun foo; end")
+        node = parser.parse.as(FunDef)
+
+        name_location = node.name_location.should_not be_nil
+        name_location.line_number.should eq(1)
+        name_location.column_number.should eq(5)
+      end
+
+      it "sets location of lib fun name" do
+        parser = Parser.new("lib Foo; fun foo; end")
+        node = parser.parse.as(LibDef).body.as(FunDef)
+
+        name_location = node.name_location.should_not be_nil
+        name_location.line_number.should eq(1)
+        name_location.column_number.should eq(14)
+      end
+
       it "sets correct location of proc literal" do
         parser = Parser.new("->(\n  x : Int32,\n  y : String\n) { }")
         node = parser.parse.as(ProcLiteral)

src/compiler/crystal/semantic/top_level_visitor.cr

@@ -918,6 +918,7 @@ class Crystal::TopLevelVisitor < Crystal::SemanticVisitor
     end
 
     external = External.new(node.name, external_args, node.body, node.real_name).at(node)
+    external.name_location = node.name_location
 
     call_convention = nil
     process_def_annotations(external, annotations) do |annotation_type, ann|

src/compiler/crystal/syntax/ast.cr

@@ -1954,6 +1954,7 @@ module Crystal
     property real_name : String
     property doc : String?
     property? varargs : Bool
+    property name_location : Location?
 
     def initialize(@name, @args = [] of Arg, @return_type = nil, @varargs = false, @body = nil, @real_name = name)
     end
@@ -1965,7 +1966,13 @@ module Crystal
     end
 
     def clone_without_location
-      FunDef.new(@name, @args.clone, @return_type.clone, @varargs, @body.clone, @real_name)
+      clone = FunDef.new(@name, @args.clone, @return_type.clone, @varargs, @body.clone, @real_name)
+      clone.name_location = name_location
+      clone
+    end
+
+    def name_size
+      @name.size
     end
 
     def_equals_and_hash @name, @args, @return_type, @varargs, @body, @real_name

src/compiler/crystal/syntax/parser.cr

@@ -5732,6 +5732,7 @@ module Crystal
       with_isolated_var_scope(require_body) do
         next_token_skip_space_or_newline
 
+        name_location = @token.location
         name = if top_level
                  check_ident
                else
@@ -5835,6 +5836,7 @@ module Crystal
         end
 
         fun_def = FunDef.new name, params, return_type, varargs, body, real_name
+        fun_def.name_location = name_location
         fun_def.doc = doc
         fun_def.at(location).at_end(end_location)
       end