fmt: handle anon structs; tests: bring back anon struct test

vlib/v/ast/ast.v

@@ -316,6 +316,7 @@ pub mut:
 	default_expr_typ Type
 	name             string
 	typ              Type
+	anon_struct_decl StructDecl // only if the field is an anonymous struct
 }
 
 pub fn (f &StructField) equals(o &StructField) bool {

vlib/v/ast/types.v

@@ -1121,7 +1121,7 @@ pub mut:
 	parent_type    Type
 }
 
-// human readable type name
+// human readable type name, also used by vfmt
 pub fn (t &Table) type_to_str(typ Type) string {
 	return t.type_to_str_using_aliases(typ, map[string]string{})
 }

vlib/v/fmt/fmt.v

@@ -500,7 +500,7 @@ pub fn (mut f Fmt) stmt(node ast.Stmt) {
 			f.sql_stmt(node)
 		}
 		ast.StructDecl {
-			f.struct_decl(node)
+			f.struct_decl(node, false)
 		}
 		ast.TypeDecl {
 			f.type_decl(node)

vlib/v/fmt/struct.v

@@ -6,7 +6,7 @@ module fmt
 import strings
 import v.ast
 
-pub fn (mut f Fmt) struct_decl(node ast.StructDecl) {
+pub fn (mut f Fmt) struct_decl(node ast.StructDecl, is_anon bool) {
 	f.attrs(node.attrs)
 	if node.is_pub {
 		f.write('pub ')
@@ -18,7 +18,9 @@ pub fn (mut f Fmt) struct_decl(node ast.StructDecl) {
 	}
 	f.write_language_prefix(node.language)
 	name := node.name.after('.') // strip prepended module
-	f.write(name)
+	if !is_anon {
+		f.write(name)
+	}
 	f.write_generic_types(node.generic_types)
 	if node.fields.len == 0 && node.embeds.len == 0 && node.pos.line_nr == node.pos.last_line {
 		f.writeln(' {}')
@@ -28,8 +30,11 @@ pub fn (mut f Fmt) struct_decl(node ast.StructDecl) {
 	mut comment_aligns := []AlignInfo{}
 	mut default_expr_aligns := []AlignInfo{}
 	mut field_types := []string{cap: node.fields.len}
+	// Calculate the alignments first
 	for i, field in node.fields {
 		ft := f.no_cur_mod(f.table.type_to_str_using_aliases(field.typ, f.mod2alias))
+		// Handle anon structs recursively
+		sym := f.table.sym(field.typ)
 		field_types << ft
 		attrs_len := inline_attrs_len(field.attrs)
 		end_pos := field.pos.pos + field.pos.len
@@ -68,6 +73,7 @@ pub fn (mut f Fmt) struct_decl(node ast.StructDecl) {
 			f.comments(comments, level: .indent)
 		}
 	}
+	// Now handle each field
 	mut field_align_i := 0
 	mut comment_align_i := 0
 	mut default_expr_align_i := 0
@@ -125,7 +131,21 @@ pub fn (mut f Fmt) struct_decl(node ast.StructDecl) {
 			field_align = field_aligns[field_align_i]
 		}
 		f.write(strings.repeat(` `, field_align.max_len - field.name.len - comments_len))
-		f.write(field_types[i])
+		// 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
+			f.write(field_types[i])
+		}
 		f.mark_types_import_as_used(field.typ)
 		attrs_len := inline_attrs_len(field.attrs)
 		has_attrs := field.attrs.len > 0
@@ -174,7 +194,11 @@ pub fn (mut f Fmt) struct_decl(node ast.StructDecl) {
 		}
 	}
 	f.comments_after_last_field(node.end_comments)
-	f.writeln('}\n')
+	if is_anon {
+		f.write('}')
+	} else {
+		f.writeln('}\n')
+	}
 }
 
 pub fn (mut f Fmt) struct_init(node ast.StructInit) {

vlib/v/gen/c/struct.v

@@ -26,7 +26,17 @@ fn (mut g Gen) struct_init(node ast.StructInit) {
 	defer {
 		g.write(')')
 	}
-	if g.is_shared && !g.inside_opt_data && !g.is_arraymap_set {
+
+	mut is_anon := false
+	if sym.kind == .struct_ {
+		mut info := sym.info as ast.Struct
+
+		is_anon = info.is_anon
+	}
+	if is_anon {
+		// No name needed for anon structs, C figures it out on its own.
+		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.typ(shared_typ)
 		g.writeln('($shared_styp*)__dup${shared_styp}(&($shared_styp){.mtx = {0}, .val =($styp){')

vlib/v/parser/struct.v

@@ -199,6 +199,7 @@ fn (mut p Parser) struct_decl(is_anon bool) ast.StructDecl {
 			mut typ := ast.Type(0)
 			mut type_pos := token.Pos{}
 			mut field_pos := token.Pos{}
+			mut anon_struct_decl := ast.StructDecl{}
 			if is_embed {
 				// struct embedding
 				type_pos = p.tok.pos()
@@ -237,7 +238,16 @@ fn (mut p Parser) struct_decl(is_anon bool) ast.StructDecl {
 					}
 				}
 				p.inside_struct_field_decl = true
-				typ = p.parse_type()
+				if p.tok.kind == .key_struct {
+					// Anon structs
+					if p.tok.kind == .key_struct {
+						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)
+					}
+				} else {
+					typ = p.parse_type()
+				}
 				p.inside_struct_field_decl = false
 				if typ.idx() == 0 {
 					// error is set in parse_type
@@ -287,6 +297,7 @@ 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
 				}
 			}
 			// save embeds as table fields too, it will be used in generation phase

vlib/v/tests/struct_test.v

@@ -413,16 +413,18 @@ fn test_struct_update() {
 	assert c2.name == 'test'
 }
 
-/*
 // Test anon structs
 struct Book {
-	x Foo
-	title string
-	author struct {
+	x      Foo
+	author struct  {
 		name string
-		age int
+		age  int
 	}
+
+	title string
 }
 
-fn test_anon() {}
-*/
+fn test_anon() {
+	// book := Book{author:struct{'sdf', 23}}
+	// println(book.author.age)
+}