From d236d6a47350eb602e6360adeb01aa4c4e013fb3 Mon Sep 17 00:00:00 2001
From: yuyi <yuyi98@163.com>
Date: Fri, 30 Apr 2021 18:40:36 +0800
Subject: [PATCH] parser, cgen: fix generics fn typeof name (fix #7357) (#9939)

---
 vlib/v/gen/c/auto_str_methods.v            |  7 +++++--
 vlib/v/gen/c/cgen.v                        | 16 +++++++++++-----
 vlib/v/parser/fn.v                         |  2 ++
 vlib/v/parser/parse_type.v                 | 13 +++++++++++++
 vlib/v/tests/generic_fn_typeof_name_test.v | 15 +++++++++++++++
 5 files changed, 46 insertions(+), 7 deletions(-)
 create mode 100644 vlib/v/tests/generic_fn_typeof_name_test.v

diff --git a/vlib/v/gen/c/auto_str_methods.v b/vlib/v/gen/c/auto_str_methods.v
index 3e8f71c3ec..c3d76fd5dd 100644
--- a/vlib/v/gen/c/auto_str_methods.v
+++ b/vlib/v/gen/c/auto_str_methods.v
@@ -724,14 +724,17 @@ fn (mut g Gen) gen_str_for_union_sum_type(info ast.SumType, styp string, str_fn_
 fn (mut g Gen) fn_decl_str(info ast.FnType) string {
 	mut fn_str := 'fn ('
 	for i, arg in info.func.params {
+		if arg.is_mut {
+			fn_str += 'mut '
+		}
 		if i > 0 {
 			fn_str += ', '
 		}
-		fn_str += util.strip_main_name(g.table.get_type_name(arg.typ))
+		fn_str += util.strip_main_name(g.table.get_type_name(g.unwrap_generic(arg.typ)))
 	}
 	fn_str += ')'
 	if info.func.return_type != ast.void_type {
-		fn_str += ' ${util.strip_main_name(g.table.get_type_name(info.func.return_type))}'
+		fn_str += ' ${util.strip_main_name(g.table.get_type_name(g.unwrap_generic(info.func.return_type)))}'
 	}
 	return fn_str
 }
diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index d6a10155ea..fcb9374f65 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -3229,12 +3229,18 @@ fn (mut g Gen) expr(node ast.Expr) {
 }
 
 // T.name, typeof(expr).name
-fn (mut g Gen) type_name(type_ ast.Type) {
-	mut typ := type_
-	if typ.has_flag(.generic) {
-		typ = g.cur_concrete_types[0]
+fn (mut g Gen) type_name(typ ast.Type) {
+	sym := g.table.get_type_symbol(typ)
+	mut s := ''
+	if sym.kind == .function {
+		if typ.is_ptr() {
+			s = '&' + g.fn_decl_str(sym.info as ast.FnType)
+		} else {
+			s = g.fn_decl_str(sym.info as ast.FnType)
+		}
+	} else {
+		s = g.table.type_to_str(g.unwrap_generic(typ))
 	}
-	s := g.table.type_to_str(typ)
 	g.write('_SLIT("${util.strip_main_name(s)}")')
 }
 
diff --git a/vlib/v/parser/fn.v b/vlib/v/parser/fn.v
index 21ab9cdd2d..77c318a771 100644
--- a/vlib/v/parser/fn.v
+++ b/vlib/v/parser/fn.v
@@ -703,6 +703,8 @@ fn (mut p Parser) fn_args() ([]ast.Param, bool, bool) {
 	types_only := p.tok.kind in [.amp, .ellipsis, .key_fn, .lsbr]
 		|| (p.peek_tok.kind == .comma && p.table.known_type(argname))
 		|| p.peek_tok.kind == .dot || p.peek_tok.kind == .rpar
+		|| (p.tok.kind == .key_mut && (p.peek_token(2).kind == .comma
+		|| p.peek_token(2).kind == .rpar))
 	// TODO copy pasta, merge 2 branches
 	if types_only {
 		mut arg_no := 1
diff --git a/vlib/v/parser/parse_type.v b/vlib/v/parser/parse_type.v
index 42fe40889d..30c70003fe 100644
--- a/vlib/v/parser/parse_type.v
+++ b/vlib/v/parser/parse_type.v
@@ -193,11 +193,21 @@ pub fn (mut p Parser) parse_multi_return_type() ast.Type {
 pub fn (mut p Parser) parse_fn_type(name string) ast.Type {
 	// p.warn('parse fn')
 	p.check(.key_fn)
+	mut has_generic := false
 	line_nr := p.tok.line_nr
 	args, _, is_variadic := p.fn_args()
+	for arg in args {
+		if arg.typ.has_flag(.generic) {
+			has_generic = true
+			break
+		}
+	}
 	mut return_type := ast.void_type
 	if p.tok.line_nr == line_nr && p.tok.kind.is_start_of_type() {
 		return_type = p.parse_type()
+		if return_type.has_flag(.generic) {
+			has_generic = true
+		}
 	}
 	func := ast.Fn{
 		name: name
@@ -209,6 +219,9 @@ pub fn (mut p Parser) parse_fn_type(name string) ast.Type {
 	// because typedefs get generated after the map struct is generated
 	has_decl := p.builtin_mod && name.starts_with('Map') && name.ends_with('Fn')
 	idx := p.table.find_or_register_fn_type(p.mod, func, false, has_decl)
+	if has_generic {
+		return ast.new_type(idx).set_flag(.generic)
+	}
 	return ast.new_type(idx)
 }
 
diff --git a/vlib/v/tests/generic_fn_typeof_name_test.v b/vlib/v/tests/generic_fn_typeof_name_test.v
new file mode 100644
index 0000000000..413553bb25
--- /dev/null
+++ b/vlib/v/tests/generic_fn_typeof_name_test.v
@@ -0,0 +1,15 @@
+struct Client {}
+
+fn add_handler<T>(handler fn (mut Client, T)) string {
+	return typeof(handler).name
+}
+
+fn on_message(mut client Client, event string) {
+	println(event)
+}
+
+fn test_generics_fn_typeof_name() {
+	ret := add_handler<string>(on_message)
+	println(ret)
+	assert ret == 'fn (mut Client, string)'
+}