parser: handle mut & receivers; fix checker_error_test

vlib/v/checker/checker.v

@@ -64,12 +64,17 @@ pub fn (c mut Checker) check_files(ast_files []ast.File) {
 	if c.pref.build_mode == .build_module || c.pref.is_test {
 		return
 	}
+	if ast_files.len > 1 && ast_files[0].mod.name == 'builtin' {
+		// TODO hack to fix vv tests
+		return
+	}
 	for i, f in c.table.fns {
 		if f.name == 'main' {
 			return
 		}
 	}
 	eprintln('function `main` is undeclared in the main module')
+	//eprintln(ast_files[0].mod.name)
 	exit(1)
 }
 
@@ -531,7 +536,7 @@ pub fn (c mut Checker) selector_expr(selector_expr mut ast.SelectorExpr) table.T
 pub fn (c mut Checker) return_stmt(return_stmt mut ast.Return) {
 	c.expected_type = c.fn_return_type
 	if return_stmt.exprs.len > 0 && c.fn_return_type == table.void_type {
-		c.error('1too many arguments to return, current function does not return anything',
+		c.error('too many arguments to return, current function does not return anything',
 			return_stmt.pos)
 		return
 	}

vlib/v/parser/fn.v

@@ -107,12 +107,16 @@ fn (p mut Parser) fn_decl() ast.FnDecl {
 		p.next()
 		rec_name = p.check_name()
 		rec_mut = p.tok.kind == .key_mut
+		is_amp := p.peek_tok.kind == .amp
 		// if rec_mut {
 		// p.check(.key_mut)
 		// }
 		// TODO: talk to alex, should mut be parsed with the type like this?
 		// or should it be a property of the arg, like this ptr/mut becomes indistinguishable
 		rec_type = p.parse_type()
+		if is_amp && rec_mut {
+			p.error('use `(f mut Foo)` or `(f &Foo)` instead of `(f mut &Foo)`')
+		}
 		args << table.Arg{
 			name: rec_name
 			is_mut: rec_mut

vlib/v/pref/default.v

@@ -3,8 +3,10 @@
 // that can be found in the LICENSE file.
 module pref
 
-import os
-import term
+import (
+	os
+	term
+)
 
 pub const (
 	default_module_path = mpath()
@@ -42,7 +44,6 @@ pub fn (p mut Preferences) fill_with_defaults() {
 		}
 		target_dir := if os.is_dir(rpath) { rpath } else { os.dir(rpath) }
 		p.out_name = os.join_path(target_dir, base)
-
 		if rpath == '$p.vroot/cmd/v' && os.is_dir('vlib/compiler') {
 			// Building V? Use v2, since we can't overwrite a running
 			// executable on Windows + the precompiled V is more
@@ -61,7 +62,7 @@ pub fn (p mut Preferences) fill_with_defaults() {
 	if p.ccompiler == '' {
 		p.ccompiler = default_c_compiler()
 	}
-	p.is_test = p.path.ends_with('_test.v')
+	p.is_test = p.path.ends_with('_test.v') || p.path.ends_with('.vv')
 	p.is_script = p.path.ends_with('.v') || p.path.ends_with('.vsh')
 	if p.third_party_option == '' {
 		p.third_party_option = p.cflags