cgen: fix struct init for anon struct field on C structs

vlib/v/ast/ast.v

@@ -424,22 +424,21 @@ pub:
 	generic_types []Type
 	is_pub        bool
 	// _pos fields for vfmt
-	mut_pos      int = -1 // mut:
-	pub_pos      int = -1 // pub:
-	pub_mut_pos  int = -1 // pub mut:
-	global_pos   int = -1 // __global:
-	module_pos   int = -1 // module:
-	language     Language
-	is_union     bool
-	attrs        []Attr
-	pre_comments []Comment
-	end_comments []Comment
-	embeds       []Embed
-
+	mut_pos          int = -1 // mut:
+	pub_pos          int = -1 // pub:
+	pub_mut_pos      int = -1 // pub mut:
+	global_pos       int = -1 // __global:
+	module_pos       int = -1 // module:
+	is_union         bool
+	attrs            []Attr
+	pre_comments     []Comment
+	end_comments     []Comment
+	embeds           []Embed
 	is_implements    bool
 	implements_types []TypeNode
 pub mut:
-	fields []StructField
+	language Language
+	fields   []StructField
 }
 
 pub struct Embed {
@@ -522,6 +521,7 @@ pub mut:
 	has_update_expr      bool // has `...a`
 	init_fields          []StructInitField
 	generic_types        []Type
+	language             Language
 }
 
 pub enum StructInitKind {

vlib/v/gen/c/struct.v

@@ -78,7 +78,10 @@ fn (mut g Gen) struct_init(node ast.StructInit) {
 		}
 	}
 	if is_anon {
-		g.writeln('(${styp}){')
+		if node.language == .v {
+			g.write('(${styp})')
+		}
+		g.writeln('{')
 	} else if g.is_shared && !g.inside_opt_data && !g.is_arraymap_set {
 		mut shared_typ := node.typ.set_flag(.shared_f)
 		shared_styp = g.styp(shared_typ)
@@ -433,7 +436,8 @@ fn (mut g Gen) zero_struct_field(field ast.StructField) bool {
 			}
 			if has_option_field || field.anon_struct_decl.fields.len > 0 {
 				default_init := ast.StructInit{
-					typ: field.typ
+					typ:      field.typ
+					language: field.anon_struct_decl.language
 				}
 				g.write('.${field_name} = ')
 				if field.typ.has_flag(.option) {

vlib/v/parser/struct.v

@@ -239,6 +239,7 @@ fn (mut p Parser) struct_decl(is_anon bool) ast.StructDecl {
 				if p.tok.kind == .key_struct {
 					// Anon structs
 					p.anon_struct_decl = p.struct_decl(true)
+					p.anon_struct_decl.language = language
 					// Find the registered anon struct type, it was registered above in `p.struct_decl()`
 					typ = p.table.find_type_idx(p.anon_struct_decl.name)
 				} else {

vlib/v/tests/c_structs/anon.h

@@ -0,0 +1,11 @@
+// anon.h
+#ifndef TEST_H
+#define TEST_H
+
+typedef struct {
+      struct {
+               int x;
+       } inner;
+} outer;
+
+#endif

vlib/v/tests/c_structs/cstruct_anon_test.c.v

@@ -0,0 +1,19 @@
+#insert "@VMODROOT/anon.h"
+
+@[typedef]
+struct C.outer {
+	inner struct {
+		x int
+	}
+}
+
+struct Outer {
+	inner struct {
+		val int
+	}
+}
+
+fn test_main() {
+	_ = Outer{}
+	_ = C.outer{}
+}