json: allow i32 decoding and encoding (#21162)

vlib/json/json_i32_test.v

@@ -0,0 +1,16 @@
+import json
+
+pub struct StructB {
+	kind  string
+	value i32
+}
+
+fn test_json_i32() {
+	struct_b := json.decode(StructB, '{"kind": "Int32", "value": 100}')!
+	assert struct_b == StructB{
+		kind: 'Int32'
+		value: 100
+	}
+
+	assert json.encode(struct_b) == '{"kind":"Int32","value":100}'
+}

vlib/v/gen/c/json.v

@@ -902,20 +902,26 @@ fn gen_js_get_opt(dec_name string, field_type string, styp string, tmp string, n
 }
 
 fn js_enc_name(typ string) string {
-	suffix := typ.replace('*', '_ptr')
+	mut suffix := typ.replace('*', '_ptr')
+	if typ == 'i32' {
+		suffix = typ.replace('i32', 'int')
+	}
 	name := 'json__encode_${suffix}'
 	return util.no_dots(name)
 }
 
 fn js_dec_name(typ string) string {
-	suffix := typ.replace('*', '_ptr')
+	mut suffix := typ.replace('*', '_ptr')
+	if typ == 'i32' {
+		suffix = typ.replace('i32', 'int')
+	}
 	name := 'json__decode_${suffix}'
 	return util.no_dots(name)
 }
 
 fn is_js_prim(typ string) bool {
-	return typ in ['int', 'rune', 'string', 'bool', 'f32', 'f64', 'i8', 'i16', 'i64', 'u8', 'u16',
-		'u32', 'u64', 'byte']
+	return typ in ['int', 'rune', 'string', 'bool', 'f32', 'f64', 'i8', 'i16', 'i32', 'i64', 'u8',
+		'u16', 'u32', 'u64', 'byte']
 }
 
 fn (mut g Gen) decode_array(utyp ast.Type, value_type ast.Type, fixed_array_size int, ret_styp string) string {