json: fix encode/decode support for generic structs (#6489)

vlib/json/json_test.v

@@ -218,7 +218,7 @@ fn test_nested_type() {
 			assert data2.countries[i].cities[j].name == data.countries[i].cities[j].name
 		}
 	}
-	
+
 	for key, user in data.users {
 		assert data2.users[key].age == user.age
 		assert data2.users[key].nums == user.nums
@@ -235,6 +235,25 @@ fn test_nested_type() {
 	}
 }
 
+struct Foo<T> {
+pub:
+	name string
+	data T
+}
+
+fn test_generic_struct() {
+	foo_int := Foo<int>{'bar', 12}
+	foo_enc := json.encode(foo_int)
+	assert foo_enc == '{"name":"bar","data":12}'
+
+	foo_dec := json.decode(Foo<int>, foo_enc) or {
+		exit(1)
+	}
+
+	assert foo_dec.name == 'bar'
+	assert foo_dec.data == 12
+}
+
 fn test_errors() {
 	invalid_array := fn () {
 		data := '{"countries":[{"cities":[{"name":"London"},{"name":"Manchester"}],"name":"UK"},{"cities":{"name":"Donlon"},"name":"KU"}],"users":{"Foo":{"age":10,"nums":[1,2,3],"lastName":"Johnson","IsRegistered":true,"type":0,"pet_animals":"little foo"},"Boo":{"age":20,"nums":[5,3,1],"lastName":"Smith","IsRegistered":false,"type":4,"pet_animals":"little boo"}},"extra":{"2":{"n1":2,"n2":4,"n3":8,"n4":16},"3":{"n1":3,"n2":9,"n3":27,"n4":81}}}'

vlib/v/gen/cgen.v

@@ -482,9 +482,9 @@ static inline $opt_el_type __Option_${styp}_popval($styp ch) {
 	}
 }
 
-// cc_type returns the Cleaned Concrete Type name, *without ptr*,
+// TODO: merge cc_type and cc_type2
-// i.e. it's always just Cat, not Cat_ptr:
+// cc_type but without the `struct` prefix
-fn (g &Gen) cc_type(t table.Type) string {
+fn (g &Gen) cc_type2(t table.Type) string {
 	sym := g.table.get_type_symbol(g.unwrap_generic(t))
 	mut styp := util.no_dots(sym.name)
 	if sym.kind == .struct_ {
@@ -501,6 +501,14 @@ fn (g &Gen) cc_type(t table.Type) string {
 			styp = styp.replace('<', '_T_').replace('>', '').replace(',', '_')
 		}
 	}
+	return styp
+}
+
+// cc_type returns the Cleaned Concrete Type name, *without ptr*,
+// i.e. it's always just Cat, not Cat_ptr:
+fn (g &Gen) cc_type(t table.Type) string {
+	sym := g.table.get_type_symbol(g.unwrap_generic(t))
+	mut styp := g.cc_type2(t)
 	if styp.starts_with('C__') {
 		styp = styp[3..]
 		if sym.kind == .struct_ {

vlib/v/gen/fn.v

@@ -50,7 +50,8 @@ fn (mut g Gen) gen_fn_decl(it ast.FnDecl, skip bool) {
 		name = util.replace_op(name)
 	}
 	if it.is_method {
-		name = g.table.get_type_symbol(it.receiver.typ).name + '_' + name
+		name = g.cc_type2(it.receiver.typ) + '_' + name
+		// name = g.table.get_type_symbol(it.receiver.typ).name + '_' + name
 	}
 	if it.language == .c {
 		name = util.no_dots(name)
@@ -336,7 +337,8 @@ fn (mut g Gen) method_call(node ast.CallExpr) {
 	// mut receiver_type_name := g.cc_type(node.receiver_type)
 	// mut receiver_type_name := g.typ(node.receiver_type)
 	typ_sym := g.table.get_type_symbol(g.unwrap_generic(node.receiver_type))
-	mut receiver_type_name := util.no_dots(typ_sym.name)
+	// mut receiver_type_name := util.no_dots(typ_sym.name)
+	mut receiver_type_name := util.no_dots(g.cc_type2(g.unwrap_generic(node.receiver_type)))
 	if typ_sym.kind == .interface_ {
 		// Speaker_name_table[s._interface_idx].speak(s._object)
 		g.write('${c_name(receiver_type_name)}_name_table[')
@@ -494,7 +496,7 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 		cur_line := g.go_before_stmt(0)
 		if is_json_encode {
 			g.gen_json_for_type(node.args[0].typ)
-			json_type_str = g.table.get_type_symbol(node.args[0].typ).name
+			json_type_str = g.typ(node.args[0].typ)
 			// `json__encode` => `json__encode_User`
 			encode_name := c_name(name) + '_' + util.no_dots(json_type_str)
 			g.writeln('// json.encode')
@@ -507,7 +509,7 @@ fn (mut g Gen) fn_call(node ast.CallExpr) {
 		} else {
 			ast_type := node.args[0].expr as ast.Type
 			// `json.decode(User, s)` => json.decode_User(s)
-			typ := c_name(g.table.get_type_symbol(ast_type.typ).name)
+			typ := c_name(g.typ(ast_type.typ))
 			fn_name := c_name(name) + '_' + typ
 			g.gen_json_for_type(ast_type.typ)
 			g.writeln('// json.decode')

vlib/v/gen/json.v

@@ -37,7 +37,7 @@ fn (mut g Gen) gen_json_for_type(typ table.Type) {
 	// decode_TYPE funcs receive an actual cJSON* object to decode
 	// cJSON_Parse(str) call is added by the compiler
 	// Code gen decoder
-	dec_fn_name := js_dec_name(sym.name)
+	dec_fn_name := js_dec_name(styp)
 	// Make sure that this optional type actually exists
 	g.register_optional(typ)
 	dec_fn_dec := 'Option_$styp ${dec_fn_name}(cJSON* root)'
@@ -58,7 +58,7 @@ $dec_fn_dec {
 	g.json_forward_decls.writeln('$dec_fn_dec;')
 	// Code gen encoder
 	// encode_TYPE funcs receive an object to encode
-	enc_fn_name := js_enc_name(sym.name)
+	enc_fn_name := js_enc_name(styp)
 	enc_fn_dec := 'cJSON* ${enc_fn_name}($styp val)'
 	g.json_forward_decls.writeln('$enc_fn_dec;\n')
 	enc.writeln('

vlib/v/tests/generics_test.v

@@ -237,6 +237,20 @@ fn test_generic_struct() {
 	// println(x.model.name)
 }
 
+struct Foo<T> {
+pub:
+	data T
+}
+
+fn (f Foo<int>) value() string {
+	return f.data.str()
+}
+
+fn test_generic_struct_method() {
+	foo_int := Foo<int>{2}
+	assert foo_int.value() == '2'
+}
+
 /*
 struct Abc{ x int y int z int }
 

vlib/x/json2/json2.v

@@ -122,3 +122,12 @@ pub fn (f Any) arr() []Any {
 
 	return [f]
 }
+
+// Use `Any` as a bool
+pub fn (f Any) bool() bool {
+	match f {
+		bool { return *f }
+		string { return (*f).bool() }
+		else { return false }
+	}
+}