cgen: fix the alias of fixed_array (fix #9537) (#9544)

vlib/v/gen/c/cgen.v

@@ -760,6 +760,32 @@ pub fn (mut g Gen) write_typedef_types() {
 			.array {
 				g.type_definitions.writeln('typedef array $typ.cname;')
 			}
+			.array_fixed {
+				info := typ.info as table.ArrayFixed
+				elem_sym := g.table.get_type_symbol(info.elem_type)
+				if elem_sym.is_builtin() {
+					// .array_fixed {
+					styp := typ.cname
+					// array_fixed_char_300 => char x[300]
+					mut fixed := styp[12..]
+					len := styp.after('_')
+					fixed = fixed[..fixed.len - len.len - 1]
+					if fixed.starts_with('C__') {
+						fixed = fixed[3..]
+					}
+					if elem_sym.info is table.FnType {
+						pos := g.out.len
+						g.write_fn_ptr_decl(&elem_sym.info, '')
+						fixed = g.out.after(pos)
+						g.out.go_back(fixed.len)
+						mut def_str := 'typedef $fixed;'
+						def_str = def_str.replace_once('(*)', '(*$styp[$len])')
+						g.type_definitions.writeln(def_str)
+					} else {
+						g.type_definitions.writeln('typedef $fixed $styp [$len];')
+					}
+				}
+			}
 			.interface_ {
 				g.write_interface_typesymbol_declaration(typ)
 			}
@@ -5419,6 +5445,8 @@ fn (mut g Gen) write_types(types []table.TypeSymbol) {
 				g.type_definitions.writeln('')
 			}
 			table.ArrayFixed {
+				elem_sym := g.table.get_type_symbol(typ.info.elem_type)
+				if !elem_sym.is_builtin() {
 					// .array_fixed {
 					styp := typ.cname
 					// array_fixed_char_300 => char x[300]
@@ -5428,8 +5456,6 @@ fn (mut g Gen) write_types(types []table.TypeSymbol) {
 					if fixed.starts_with('C__') {
 						fixed = fixed[3..]
 					}
-				elem_type := typ.info.elem_type
-				elem_sym := g.table.get_type_symbol(elem_type)
 					if elem_sym.info is table.FnType {
 						pos := g.out.len
 						g.write_fn_ptr_decl(&elem_sym.info, '')
@@ -5442,6 +5468,7 @@ fn (mut g Gen) write_types(types []table.TypeSymbol) {
 						g.type_definitions.writeln('typedef $fixed $styp [$len];')
 					}
 				}
+			}
 			else {}
 		}
 	}

vlib/v/tests/alias_fixed_array_test.v

@@ -0,0 +1,12 @@
+type Block = [8]byte
+
+fn test_alias_fixed_array() {
+	a := [8]byte{init: 22}
+	ret := get(Block(a))
+	println(ret)
+	assert ret == 'Block([22, 22, 22, 22, 22, 22, 22, 22])'
+}
+
+fn get(b Block) string {
+	return '$b'
+}