parser, fmt: fix fmt in struct declarations with a fields, declared to be arrays of anonymous structs (fix #16947) (#16952)

vlib/v/fmt/struct.v

@@ -132,18 +132,7 @@ pub fn (mut f Fmt) struct_decl(node ast.StructDecl, is_anon bool) {
 		}
 		f.write(strings.repeat(` `, field_align.max_len - field.name.len - comments_len))
 		// Handle anon structs recursively
-		mut field_is_anon := false
-		sym := f.table.sym(field.typ)
-		if sym.kind == .struct_ {
-			info := sym.info as ast.Struct
-			field_is_anon = info.is_anon
-		}
-		if field_is_anon {
-			f.indent++
-			f.struct_decl(field.anon_struct_decl, true)
-			f.indent--
-		} else {
-			// If it's not an anon struct, just write the type of the field
+		if !f.write_anon_struct_field_decl(field.typ, field.anon_struct_decl) {
 			f.write(field_types[i])
 		}
 		f.mark_types_import_as_used(field.typ)
@@ -201,6 +190,47 @@ pub fn (mut f Fmt) struct_decl(node ast.StructDecl, is_anon bool) {
 	}
 }
 
+fn (mut f Fmt) write_anon_struct_field_decl(field_typ ast.Type, field_anon_decl ast.StructDecl) bool {
+	sym := f.table.sym(field_typ)
+	match sym.kind {
+		.struct_ {
+			info := sym.info as ast.Struct
+			if info.is_anon {
+				f.indent++
+				f.struct_decl(field_anon_decl, true)
+				f.indent--
+				return true
+			}
+		}
+		.array {
+			if sym.info is ast.Array {
+				elem_sym := f.table.sym(sym.info.elem_type)
+				if elem_sym.info is ast.Struct {
+					if elem_sym.info.is_anon {
+						f.write('[]'.repeat(sym.info.nr_dims))
+						f.write_anon_struct_field_decl(sym.info.elem_type, field_anon_decl)
+						return true
+					}
+				}
+			}
+		}
+		.array_fixed {
+			if sym.info is ast.ArrayFixed {
+				elem_sym := f.table.sym(sym.info.elem_type)
+				if elem_sym.info is ast.Struct {
+					if elem_sym.info.is_anon {
+						f.write('[${sym.info.size}]')
+						f.write_anon_struct_field_decl(sym.info.elem_type, field_anon_decl)
+						return true
+					}
+				}
+			}
+		}
+		else {}
+	}
+	return false
+}
+
 pub fn (mut f Fmt) struct_init(node ast.StructInit) {
 	struct_init_save := f.is_struct_init
 	f.is_struct_init = true

vlib/v/fmt/tests/struct_with_array_of_anon_struct_field_decl_keep.vv

@@ -0,0 +1,13 @@
+struct Abc {
+	a []struct {
+		b string
+	}
+}
+
+fn main() {
+	abc := Abc{
+		a: [struct {'this is b'}]
+	}
+
+	dump(abc)
+}

vlib/v/parser/parse_type.v

@@ -434,9 +434,9 @@ pub fn (mut p Parser) parse_type() ast.Type {
 	}
 	// Anon structs
 	if p.tok.kind == .key_struct {
-		struct_decl := p.struct_decl(true)
+		p.anon_struct_decl = p.struct_decl(true)
 		// Find the registered anon struct type, it was registered above in `p.struct_decl()`
-		return p.table.find_type_idx(struct_decl.name)
+		return p.table.find_type_idx(p.anon_struct_decl.name)
 	}
 
 	language := p.parse_language()

vlib/v/parser/parser.v

@@ -89,6 +89,7 @@ mut:
 	defer_vars                []ast.Ident
 	should_abort              bool // when too many errors/warnings/notices are accumulated, should_abort becomes true, and the parser should stop
 	codegen_text              string
+	anon_struct_decl          ast.StructDecl
 	struct_init_generic_types []ast.Type
 	if_cond_comments          []ast.Comment
 	script_mode               bool

vlib/v/parser/struct.v

@@ -202,7 +202,6 @@ fn (mut p Parser) struct_decl(is_anon bool) ast.StructDecl {
 			mut type_pos := token.Pos{}
 			mut field_pos := token.Pos{}
 			mut option_pos := token.Pos{}
-			mut anon_struct_decl := ast.StructDecl{}
 			if is_embed {
 				// struct embedding
 				type_pos = p.tok.pos()
@@ -247,9 +246,9 @@ fn (mut p Parser) struct_decl(is_anon bool) ast.StructDecl {
 				if p.tok.kind == .key_struct {
 					// Anon structs
 					if p.tok.kind == .key_struct {
-						anon_struct_decl = p.struct_decl(true)
+						p.anon_struct_decl = p.struct_decl(true)
 						// Find the registered anon struct type, it was registered above in `p.struct_decl()`
-						typ = p.table.find_type_idx(anon_struct_decl.name)
+						typ = p.table.find_type_idx(p.anon_struct_decl.name)
 					}
 				} else {
 					start_type_pos := p.tok.pos()
@@ -308,8 +307,9 @@ fn (mut p Parser) struct_decl(is_anon bool) ast.StructDecl {
 					is_global: is_field_global
 					is_volatile: is_field_volatile
 					is_deprecated: is_field_deprecated
-					anon_struct_decl: anon_struct_decl
+					anon_struct_decl: p.anon_struct_decl
 				}
+				p.anon_struct_decl = ast.StructDecl{}
 			}
 			// save embeds as table fields too, it will be used in generation phase
 			fields << ast.StructField{