json: decode_array fix

vlib/v/checker/checker.v

@@ -735,7 +735,8 @@ pub fn (mut c Checker) call_fn(call_expr mut ast.CallExpr) table.Type {
 	} else if fn_name == 'json.decode' {
 		expr := call_expr.args[0].expr
 		if !(expr is ast.Type) {
-			c.error('json.decode: first argument needs to be a type', call_expr.pos)
+			typ := typeof(expr)
+			c.error('json.decode: first argument needs to be a type, got `$typ`', call_expr.pos)
 			return table.void_type
 		}
 		typ := expr as ast.Type

vlib/v/gen/json.v

@@ -124,7 +124,7 @@ fn (mut g Gen) decode_array(value_type table.Type) string {
 	if is_js_prim(styp) {
 		s = '$styp val = ${fn_name}(jsval); '
 	} else {
-		s = '\t$styp val; ${fn_name}(jsval, &val); '
+		s = '\t$styp val = *($styp*) ${fn_name}(jsval).data; '
 	}
 	return '
 res = __new_array(0, 0, sizeof($styp));

vlib/v/parser/fn.v

@@ -22,7 +22,7 @@ pub fn (mut p Parser) call_expr(is_c, is_js bool, mod string) ast.CallExpr {
 	}
 	if fn_name == 'json.decode' {
 		// Makes name_expr() parse the type (`User` in `json.decode(User, txt)`)`
-		p.inside_is = true
+		p.expecting_type = true
 		p.expr_mod = ''
 	}
 	p.check(.lpar)

vlib/v/parser/parser.v

@@ -42,7 +42,7 @@ mut:
 	inside_match      bool // to separate `match A { }` from `Struct{}`
 	inside_match_case bool // to separate `match_expr { }` from `Struct{}`
 	is_stmt_ident     bool // true while the beginning of a statement is an ident/selector
-	inside_is         bool // `is Type`, expecting type
+	expecting_type    bool // `is Type`, expecting type
 }
 
 // for tests
@@ -584,8 +584,8 @@ pub fn (mut p Parser) parse_ident(is_c, is_js bool) ast.Ident {
 
 pub fn (mut p Parser) name_expr() ast.Expr {
 	mut node := ast.Expr{}
-	if p.inside_is {
+	if p.expecting_type {
-		p.inside_is = false
+		p.expecting_type = false
 		// get type position before moving to next
 		type_pos := p.tok.position()
 		typ := p.parse_type()

vlib/v/parser/pratt.v

@@ -62,8 +62,13 @@ pub fn (mut p Parser) expr(precedence int) ast.Expr {
 			node = p.if_expr()
 		}
 		.lsbr {
+			if p.expecting_type {
+				// parse json.decode type (`json.decode([]User, s)`)
+				node = p.name_expr()
+			} else {
 				node = p.array_init()
 			}
+		}
 		.key_none {
 			p.next()
 			node = ast.None{}
@@ -190,7 +195,7 @@ fn (mut p Parser) infix_expr(left ast.Expr) ast.Expr {
 	p.next()
 	mut right := ast.Expr{}
 	if op == .key_is {
-		p.inside_is = true
+		p.expecting_type = true
 	}
 	right = p.expr(precedence)
 	return ast.InfixExpr{