diff --git a/vlib/v/builder/compile.v b/vlib/v/builder/compile.v
index e9a7e34f95..b299a62ade 100644
--- a/vlib/v/builder/compile.v
+++ b/vlib/v/builder/compile.v
@@ -11,59 +11,6 @@ import (
 	strings
 )
 
-/*
-pub struct V {
-pub mut:
-        mod_file_cacher     &builder.ModFileCacher // used during lookup for v.mod to support @VROOT
-        out_name_c          string // name of the temporary C file
-        files               []string // all V files that need to be parsed and compiled
-        compiled_dir        string // contains os.real_path() of the dir of the final file beeing compiled, or the dir itself when doing `v .`
-        pref                &pref.Preferences // all the preferences and settings extracted to a struct for reusability
-        vgen_buf            strings.Builder // temporary buffer for generated V code (.str() etc)
-        file_parser_idx     map[string]int // map absolute file path to v.parsers index
-        gen_parser_idx      map[string]int
-        cached_mods         []string
-        module_lookup_paths []string
-
-        v_fmt_all           bool   // << input set by cmd/tools/vfmt.v
-        v_fmt_file          string // << file given by the user from cmd/tools/vfmt.v
-        v_fmt_file_result   string // >> file with formatted output generated by vlib/compiler/vfmt.v
-}
-
-pub fn new_v(pref &pref.Preferences) &V {
-        rdir := os.real_path(pref.path)
-
-        mut out_name_c := get_vtmp_filename(pref.out_name, '.tmp.c')
-        if pref.is_so {
-                out_name_c = get_vtmp_filename(pref.out_name, '.tmp.so.c')
-        }
-
-        mut vgen_buf := strings.new_builder(1000)
-        vgen_buf.writeln('module vgen\nimport strings')
-        compiled_dir:=if os.is_dir(rdir) { rdir } else { os.dir(rdir) }
-
-        return &V{
-                mod_file_cacher: builder.new_mod_file_cacher()
-                compiled_dir:compiled_dir// if os.is_dir(rdir) { rdir } else { os.dir(rdir) }
-                out_name_c: out_name_c
-                pref: pref
-                vgen_buf: vgen_buf
-        }
-}
-*/
-/*
-// make v2 from v1
-fn (v &V) new_v2() builder.Builder {
-        mut b := builder.new_builder(v.pref)
-        b = { b|
-                os: v.pref.os,
-                module_path: pref.default_module_path,
-                compiled_dir: v.compiled_dir,
-                module_search_paths: v.module_lookup_paths
-        }
-        return b
-}
-*/
 fn get_vtmp_folder() string {
 	vtmp := os.join_path(os.temp_dir(), 'v')
 	if !os.is_dir(vtmp) {
@@ -76,8 +23,7 @@ fn get_vtmp_folder() string {
 
 fn get_vtmp_filename(base_file_name, postfix string) string {
 	vtmp := get_vtmp_folder()
-	return os.real_path(os.join_path(vtmp, os.file_name(os.real_path(base_file_name)) +
-		postfix))
+	return os.real_path(os.join_path(vtmp, os.file_name(os.real_path(base_file_name)) + postfix))
 }
 
 pub fn compile(command string, pref &pref.Preferences) {
@@ -109,7 +55,7 @@ pub fn compile(command string, pref &pref.Preferences) {
 		// v.add_v_files_to_compile()
 		// v.files << v.dir
 		// v2 compiler
-		//b.set_module_lookup_paths()
+		// b.set_module_lookup_paths()
 		files << b.get_builtin_files()
 		files << b.get_user_files()
 		b.set_module_lookup_paths()
@@ -117,7 +63,7 @@ pub fn compile(command string, pref &pref.Preferences) {
 			println('all .v files:')
 			println(files)
 		}
-		//b.build_c(files, b.out_name_c)	// v.pref.out_name + '.c')
+		// b.build_c(files, b.out_name_c)	// v.pref.out_name + '.c')
 		b.build_c(files, pref.out_name + '.c')
 		b.cc()
 	}
@@ -196,9 +142,9 @@ fn (v mut Builder) set_module_lookup_paths() {
 	}
 }
 
-pub fn (v &Builder) get_builtin_files() []string {
-	//println('get_builtin_files() lookuppath:')
-	//println(v.pref.lookup_path)
+pub fn (v Builder) get_builtin_files() []string {
+	// println('get_builtin_files() lookuppath:')
+	// println(v.pref.lookup_path)
 	// Lookup for built-in folder in lookup path.
 	// Assumption: `builtin/` folder implies usable implementation of builtin
 	for location in v.pref.lookup_path {
@@ -219,7 +165,7 @@ Did you forget to add vlib to the path? (Use @vlib for default vlib)')
 	panic('Unreachable code reached.')
 }
 
-pub fn (v &Builder) get_user_files() []string {
+pub fn (v Builder) get_user_files() []string {
 	mut dir := v.pref.path
 	v.log('get_v_files($dir)')
 	// Need to store user files separately, because they have to be added after
@@ -297,4 +243,3 @@ pub fn (v &Builder) get_user_files() []string {
 	}
 	return user_files
 }
-
diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index c1576285be..f59f1f7c9c 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -652,6 +652,12 @@ fn (c mut Checker) stmt(node ast.Stmt) {
 			c.expected_type = table.void_type
 		}
 		ast.FnDecl {
+			//if it.is_method {
+				//sym := c.table.get_type_symbol(it.receiver.typ)
+				//if sym.has_method(it.name) {
+					//c.warn('duplicate method `$it.name`', it.pos)
+				//}
+			//}
 			c.expected_type = table.void_type
 			c.fn_return_type = it.return_type
 			c.stmts(it.stmts)
diff --git a/vlib/v/parser/fn.v b/vlib/v/parser/fn.v
index a0c702ab8c..c2f22957db 100644
--- a/vlib/v/parser/fn.v
+++ b/vlib/v/parser/fn.v
@@ -12,7 +12,13 @@ import (
 pub fn (p mut Parser) call_expr(is_c bool, mod string) ast.CallExpr {
 	tok := p.tok
 	name := p.check_name()
-	fn_name := if is_c { 'C.$name' } else if mod.len > 0 { '${mod}.$name' } else { name }
+	fn_name := if is_c {
+		'C.$name'
+	} else if mod.len > 0 {
+		'${mod}.$name'
+	} else {
+		name
+	}
 	p.check(.lpar)
 	args := p.call_args()
 	mut or_stmts := []ast.Stmt
@@ -33,13 +39,12 @@ pub fn (p mut Parser) call_expr(is_c bool, mod string) ast.CallExpr {
 	node := ast.CallExpr{
 		name: fn_name
 		args: args
-		// tok: tok
 		mod: p.mod
 		pos: tok.position()
 		is_c: is_c
 		or_block: ast.OrExpr{
-			stmts: or_stmts
-		}
+		stmts: or_stmts
+	}
 	}
 	return node
 }
@@ -111,9 +116,12 @@ fn (p mut Parser) fn_decl() ast.FnDecl {
 		if !is_c && !p.pref.translated && scanner.contains_capital(name) {
 			p.error('function names cannot contain uppercase letters, use snake_case instead')
 		}
+		if is_method && p.table.get_type_symbol(rec_type).has_method(name) {
+			p.warn('duplicate method `$name`')
+		}
 	}
 	if p.tok.kind in [.plus, .minus, .mul, .div, .mod] {
-		name = p.tok.kind.str() // op_to_fn_name()
+		name = p.tok.kind.str()		// op_to_fn_name()
 		p.next()
 	}
 	// <T>
@@ -123,7 +131,7 @@ fn (p mut Parser) fn_decl() ast.FnDecl {
 		p.check(.gt)
 	}
 	// Args
-	args2,is_variadic := p.fn_args()
+	args2, is_variadic := p.fn_args()
 	args << args2
 	for arg in args {
 		p.scope.register(arg.name, ast.Var{
@@ -146,12 +154,10 @@ fn (p mut Parser) fn_decl() ast.FnDecl {
 			return_type: return_type
 			is_variadic: is_variadic
 		})
-	}
-	else {
+	} else {
 		if is_c {
 			name = 'C.$name'
-		}
-		else {
+		} else {
 			name = p.prepend_mod(name)
 		}
 		p.table.register_fn(table.Fn{
@@ -178,9 +184,9 @@ fn (p mut Parser) fn_decl() ast.FnDecl {
 		is_pub: is_pub
 		is_variadic: is_variadic
 		receiver: ast.Field{
-			name: rec_name
-			typ: rec_type
-		}
+		name: rec_name
+		typ: rec_type
+	}
 		is_method: is_method
 		rec_mut: rec_mut
 		is_c: is_c
@@ -189,14 +195,15 @@ fn (p mut Parser) fn_decl() ast.FnDecl {
 	}
 }
 
-fn (p mut Parser) fn_args() ([]table.Arg,bool) {
+fn (p mut Parser) fn_args() ([]table.Arg, bool) {
 	p.check(.lpar)
 	mut args := []table.Arg
 	mut is_variadic := false
 	// `int, int, string` (no names, just types)
-	types_only := p.tok.kind in [.amp, .and] || (p.peek_tok.kind == .comma && p.table.known_type(p.tok.lit)) || p.peek_tok.kind == .rpar
+	types_only := p.tok.kind in [.amp, .and] || (p.peek_tok.kind == .comma && p.table.known_type(p.tok.lit)) || 
+		p.peek_tok.kind == .rpar
 	if types_only {
-		//p.warn('types only')
+		// p.warn('types only')
 		mut arg_no := 1
 		for p.tok.kind != .rpar {
 			arg_name := 'arg_$arg_no'
@@ -225,8 +232,7 @@ fn (p mut Parser) fn_args() ([]table.Arg,bool) {
 			}
 			arg_no++
 		}
-	}
-	else {
+	} else {
 		for p.tok.kind != .rpar {
 			mut arg_names := [p.check_name()]
 			// `a, b, c int`
@@ -263,9 +269,9 @@ fn (p mut Parser) fn_args() ([]table.Arg,bool) {
 		}
 	}
 	p.check(.rpar)
-	return args,is_variadic
+	return args, is_variadic
 }
 
-fn (p &Parser) fileis(s string) bool {
+fn (p Parser) fileis(s string) bool {
 	return p.file_name.contains(s)
 }