checker, cgen: fix closure with fn variables (fix #15286) (#15427)

vlib/v/checker/fn.v

@@ -674,7 +674,15 @@ pub fn (mut c Checker) fn_call(mut node ast.CallExpr, mut continue_check &bool)
 					node.fn_var_type = typ
 				}
 				ast.Var {
-					typ = if obj.smartcasts.len != 0 { obj.smartcasts.last() } else { obj.typ }
+					if obj.smartcasts.len != 0 {
+						typ = obj.smartcasts.last()
+					} else {
+						if obj.typ == 0 {
+							typ = c.expr(obj.expr)
+						} else {
+							typ = obj.typ
+						}
+					}
 					node.is_fn_var = true
 					node.fn_var_type = typ
 				}

vlib/v/gen/c/fn.v

@@ -473,8 +473,23 @@ fn (mut g Gen) gen_anon_fn_decl(mut node ast.AnonFn) {
 		ctx_struct := closure_ctx(node.decl)
 		builder.writeln('$ctx_struct {')
 		for var in node.inherited_vars {
-			styp := g.typ(var.typ)
-			builder.writeln('\t$styp $var.name;')
+			var_sym := g.table.sym(var.typ)
+			if var_sym.info is ast.FnType {
+				ret_styp := g.typ(var_sym.info.func.return_type)
+				builder.write_string('\t$ret_styp (*$var.name) (')
+				arg_len := var_sym.info.func.params.len
+				for j, arg in var_sym.info.func.params {
+					arg_styp := g.typ(arg.typ)
+					builder.write_string('$arg_styp $arg.name')
+					if j < arg_len - 1 {
+						builder.write_string(', ')
+					}
+				}
+				builder.writeln(');')
+			} else {
+				styp := g.typ(var.typ)
+				builder.writeln('\t$styp $var.name;')
+			}
 		}
 		builder.writeln('};\n')
 	}
@@ -1322,6 +1337,9 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 								g.write(')')
 							}
 							is_fn_var = true
+						} else if obj.is_inherited {
+							g.write(c.closure_ctx + '->' + node.name)
+							is_fn_var = true
 						}
 					}
 					else {}

vlib/v/tests/inout/closure_with_fn_variables.out

@@ -0,0 +1,2 @@
+test1
+test2

vlib/v/tests/inout/closure_with_fn_variables.vv

@@ -0,0 +1,19 @@
+module main
+
+fn test1() {
+	println('test1')
+}
+
+fn test2() {
+	println('test2')
+}
+
+fn main() {
+	t1 := test1
+	t2 := test2
+	anon := fn [t1, t2] () {
+		t1()
+		t2()
+	}
+	anon()
+}