checker: fix nested struct ref field init check for embedded structs (fix #15768) (#15785)

vlib/v/checker/struct.v

@@ -482,12 +482,23 @@ pub fn (mut c Checker) struct_init(mut node ast.StructInit) ast.Type {
 				}
 			}
 			// Check uninitialized refs/sum types
-			for i, field in info.fields {
+			// The variable `fields` contains two parts, the first part is the same as info.fields,
+			// and the second part is all fields embedded in the structure
+			// If the return value data composition form in `c.table.struct_fields()` is modified,
+			// need to modify here accordingly.
+			fields := c.table.struct_fields(type_sym)
+			mut checked_structs := []ast.Type{}
+			for i, field in fields {
 				if field.name in inited_fields {
 					continue
 				}
+				sym := c.table.sym(field.typ)
+				if field.name.len > 0 && field.name[0].is_capital() && sym.info is ast.Struct
+					&& sym.language == .v {
+					continue
+				}
 				if field.has_default_expr {
-					if field.default_expr_typ == 0 {
+					if i < info.fields.len && field.default_expr_typ == 0 {
 						if field.default_expr is ast.StructInit {
 							idx := c.table.find_type_idx(field.default_expr.typ_str)
 							if idx != 0 {
@@ -503,11 +514,15 @@ pub fn (mut c Checker) struct_init(mut node ast.StructInit) ast.Type {
 				}
 				if field.typ.is_ptr() && !field.typ.has_flag(.shared_f) && !node.has_update_expr
 					&& !c.pref.translated && !c.file.is_translated {
-					c.error('reference field `${type_sym.name}.$field.name` must be initialized',
+					c.warn('reference field `${type_sym.name}.$field.name` must be initialized',
 						node.pos)
+					continue
+				}
+				if sym.kind == .struct_ && !(sym.info as ast.Struct).is_typedef {
+					c.check_ref_fields_initialized(sym, mut checked_structs, '${type_sym.name}.$field.name',
+						node)
 				}
 				// Do not allow empty uninitialized interfaces
-				sym := c.table.sym(field.typ)
 				mut has_noinit := false
 				for attr in field.attrs {
 					if attr.name == 'noinit' {
@@ -542,13 +557,6 @@ pub fn (mut c Checker) struct_init(mut node ast.StructInit) ast.Type {
 							node.pos)
 					}
 				}
-				// Check for struct type
-				if sym.kind == .struct_ && !(sym.info as ast.Struct).is_typedef {
-					mut checked_structs := []ast.Type{}
-					checked_structs << field.typ
-					c.check_ref_fields_initialized(sym.info as ast.Struct, mut checked_structs,
-						'${node.typ_str}.$field.name', node)
-				}
 			}
 		}
 		else {}
@@ -575,24 +583,29 @@ pub fn (mut c Checker) struct_init(mut node ast.StructInit) ast.Type {
 }
 
 // Recursively check whether the struct type field is initialized
-fn (mut c Checker) check_ref_fields_initialized(struct_ &ast.Struct, mut checked_structs []ast.Type, linked_name string, node &ast.StructInit) {
+fn (mut c Checker) check_ref_fields_initialized(struct_sym &ast.TypeSymbol, mut checked_structs []ast.Type, linked_name string, node &ast.StructInit) {
 	if c.pref.translated || c.file.is_translated {
 		return
 	}
-	for field in struct_.fields {
+	fields := c.table.struct_fields(struct_sym)
+	for field in fields {
+		sym := c.table.sym(field.typ)
+		if field.name.len > 0 && field.name[0].is_capital() && sym.info is ast.Struct
+			&& sym.language == .v {
+			continue
+		}
 		if field.typ.is_ptr() && !field.typ.has_flag(.shared_f) && !field.has_default_expr {
 			c.warn('reference field `${linked_name}.$field.name` must be initialized',
 				node.pos)
 			continue
 		}
-		sym := c.table.sym(field.typ)
 		if sym.kind == .struct_ {
 			info := sym.info as ast.Struct
 			if info.is_typedef || field.typ in checked_structs {
 				continue
 			}
 			checked_structs << field.typ
-			c.check_ref_fields_initialized(info, mut checked_structs, '${linked_name}.$field.name',
+			c.check_ref_fields_initialized(sym, mut checked_structs, '${linked_name}.$field.name',
 				node)
 		}
 	}

vlib/v/checker/tests/reference_field_must_be_initialized.out

@@ -1,11 +1,4 @@
-vlib/v/checker/tests/reference_field_must_be_initialized.vv:8:7: warning: reference field `Node.next.next` must be initialized
+vlib/v/checker/tests/reference_field_must_be_initialized.vv:8:7: warning: reference field `Node.next` must be initialized
-    6 | 
-    7 | fn main(){
-    8 |     n := Node{ data: 123 }
-      |          ~~~~~~~~~~~~~~~~~
-    9 |     eprintln('n.data: $n.data')
-   10 | }
-vlib/v/checker/tests/reference_field_must_be_initialized.vv:8:7: error: reference field `Node.next` must be initialized
     6 | 
     7 | fn main(){
     8 |     n := Node{ data: 123 }

vlib/v/checker/tests/struct_ref_fields_uninitialized_err.out

@@ -1,7 +1,13 @@
-vlib/v/checker/tests/struct_ref_fields_uninitialized_err.vv:11:7: warning: reference field `Outer.c.b` must be initialized
+vlib/v/checker/tests/struct_ref_fields_uninitialized_err.vv:22:7: warning: reference field `Outer.c.b` must be initialized
-    9 | 
+   20 | 
-   10 | fn main() {
+   21 | fn main() {
-   11 |     o := Outer{}
+   22 |     _ := Outer{}
       |          ~~~~~~~
-   12 |     dump(o)
+   23 |     _ := Struct{}
-   13 | }
+   24 | }
+vlib/v/checker/tests/struct_ref_fields_uninitialized_err.vv:23:7: warning: reference field `Struct.ref2` must be initialized
+   21 | fn main() {
+   22 |     _ := Outer{}
+   23 |     _ := Struct{}
+      |          ~~~~~~~~
+   24 | }

vlib/v/checker/tests/struct_ref_fields_uninitialized_err.vv

@@ -7,7 +7,18 @@ struct Outer {
 	c ContainsRef
 }
 
-fn main() {
+struct Ref {}
-	o := Outer{}
+
-	dump(o)
+struct EmbedStruct {
+	ref1 &Ref = unsafe { nil }
+	ref2 &Ref
+}
+
+struct Struct {
+	EmbedStruct
+}
+
+fn main() {
+	_ := Outer{}
+	_ := Struct{}
 }