From 3dfbd2351b1e123e035269c94919cf796b7bf177 Mon Sep 17 00:00:00 2001
From: yuyi <yuyi98@163.com>
Date: Sat, 8 May 2021 19:06:56 +0800
Subject: [PATCH] checker,cgen: fix generics with generic_fn type parameter
 (#10022)

---
 vlib/v/checker/checker.v                      |  2 +-
 vlib/v/gen/c/fn.v                             | 17 +++-------
 ...ics_with_generics_fn_type_parameter_test.v | 34 +++++++++++++++++++
 3 files changed, 40 insertions(+), 13 deletions(-)
 create mode 100644 vlib/v/tests/generics_with_generics_fn_type_parameter_test.v

diff --git a/vlib/v/checker/checker.v b/vlib/v/checker/checker.v
index b6cc5cfeaa..0197c199c7 100644
--- a/vlib/v/checker/checker.v
+++ b/vlib/v/checker/checker.v
@@ -2276,7 +2276,7 @@ pub fn (mut c Checker) fn_call(mut call_expr ast.CallExpr) ast.Type {
 	if !found {
 		if v := call_expr.scope.find_var(fn_name) {
 			if v.typ != 0 {
-				vts := c.table.get_type_symbol(v.typ)
+				vts := c.table.get_type_symbol(c.unwrap_generic(v.typ))
 				if vts.kind == .function {
 					info := vts.info as ast.FnType
 					func = info.func
diff --git a/vlib/v/gen/c/fn.v b/vlib/v/gen/c/fn.v
index 057a8c3b0a..69a3812295 100644
--- a/vlib/v/gen/c/fn.v
+++ b/vlib/v/gen/c/fn.v
@@ -371,18 +371,11 @@ fn (mut g Gen) fn_args(args []ast.Param, is_variadic bool) ([]string, []string)
 		if arg_type_sym.kind == .function {
 			info := arg_type_sym.info as ast.FnType
 			func := info.func
-			if !info.is_anon {
-				g.write(arg_type_name + ' ' + caname)
-				g.definitions.write_string(arg_type_name + ' ' + caname)
-				fargs << caname
-				fargtypes << arg_type_name
-			} else {
-				g.write('${g.typ(func.return_type)} (*$caname)(')
-				g.definitions.write_string('${g.typ(func.return_type)} (*$caname)(')
-				g.fn_args(func.params, func.is_variadic)
-				g.write(')')
-				g.definitions.write_string(')')
-			}
+			g.write('${g.typ(func.return_type)} (*$caname)(')
+			g.definitions.write_string('${g.typ(func.return_type)} (*$caname)(')
+			g.fn_args(func.params, func.is_variadic)
+			g.write(')')
+			g.definitions.write_string(')')
 		} else {
 			s := '$arg_type_name $caname'
 			g.write(s)
diff --git a/vlib/v/tests/generics_with_generics_fn_type_parameter_test.v b/vlib/v/tests/generics_with_generics_fn_type_parameter_test.v
new file mode 100644
index 0000000000..d5a0267187
--- /dev/null
+++ b/vlib/v/tests/generics_with_generics_fn_type_parameter_test.v
@@ -0,0 +1,34 @@
+fn neg(a int) int {
+	return -a
+}
+
+fn indirect_call(func fn (int) int, a int) int {
+	println(typeof(func).name)
+	return func(a)
+}
+
+fn generic_call<T>(func T, a int) int {
+	println(T.name)
+	return func(a)
+}
+
+fn generic_indirect_call<T>(func T, a int) int {
+	println(T.name)
+	return indirect_call(func, a)
+}
+
+fn test_generics_with_generics_fn_type_parameter() {
+	mut ret := 0
+
+	ret = indirect_call(neg, 2)
+	println(ret)
+	assert ret == -2
+
+	ret = generic_call(neg, 3)
+	println(ret)
+	assert ret == -3
+
+	ret = generic_indirect_call(neg, 4)
+	println(ret)
+	assert ret == -4
+}