checker: do not allow nil sum types init

vlib/builtin/bare/builtin.v

@@ -0,0 +1,5 @@
+module builtin
+
+struct string {
+	len int
+}

vlib/v/ast/ast.v

@@ -12,25 +12,25 @@ pub type TypeDecl = AliasTypeDecl | FnTypeDecl | SumTypeDecl
 
 pub type Expr = AnonFn | ArrayDecompose | ArrayInit | AsCast | Assoc | AtExpr | BoolLiteral |
 	CTempVar | CallExpr | CastExpr | ChanInit | CharLiteral | Comment | ComptimeCall |
-	ComptimeSelector | ConcatExpr | DumpExpr | EnumVal | FloatLiteral | GoExpr | Ident |
-	IfExpr | IfGuardExpr | IndexExpr | InfixExpr | IntegerLiteral | Likely | LockExpr |
+	ComptimeSelector | ConcatExpr | DumpExpr | EmptyExpr | EnumVal | FloatLiteral | GoExpr |
+	Ident | IfExpr | IfGuardExpr | IndexExpr | InfixExpr | IntegerLiteral | Likely | LockExpr |
 	MapInit | MatchExpr | NodeError | None | OffsetOf | OrExpr | ParExpr | PostfixExpr |
 	PrefixExpr | RangeExpr | SelectExpr | SelectorExpr | SizeOf | SqlExpr | StringInterLiteral |
 	StringLiteral | StructInit | Type | TypeOf | UnsafeExpr
 
 pub type Stmt = AsmStmt | AssertStmt | AssignStmt | Block | BranchStmt | CompFor | ConstDecl |
-	DeferStmt | EnumDecl | ExprStmt | FnDecl | ForCStmt | ForInStmt | ForStmt | GlobalDecl |
-	GoStmt | GotoLabel | GotoStmt | HashStmt | Import | InterfaceDecl | Module | NodeError |
-	Return | SqlStmt | StructDecl | TypeDecl
+	DeferStmt | EmptyStmt | EnumDecl | ExprStmt | FnDecl | ForCStmt | ForInStmt | ForStmt |
+	GlobalDecl | GoStmt | GotoLabel | GotoStmt | HashStmt | Import | InterfaceDecl | Module |
+	NodeError | Return | SqlStmt | StructDecl | TypeDecl
 
 // NB: when you add a new Expr or Stmt type with a .pos field, remember to update
 // the .position() token.Position methods too.
 pub type ScopeObject = AsmRegister | ConstField | GlobalField | Var
 
-// TOOD: replace table.Param
+// TODO: replace table.Param
 pub type Node = CallArg | ConstField | EnumField | Expr | Field | File | GlobalField |
-	IfBranch | MatchBranch | ScopeObject | SelectBranch | Stmt | StructField | StructInitField |
-	table.Param
+	IfBranch | MatchBranch | NodeError | ScopeObject | SelectBranch | Stmt | StructField |
+	StructInitField | table.Param
 
 pub struct Type {
 pub:
@@ -38,6 +38,21 @@ pub:
 	pos token.Position
 }
 
+pub struct EmptyExpr {}
+
+pub fn empty_expr() Expr {
+	return EmptyExpr{}
+}
+
+pub struct EmptyStmt {
+pub:
+	pos token.Position
+}
+
+pub fn empty_stmt() Stmt {
+	return EmptyStmt{}
+}
+
 // `{stmts}` or `unsafe {stmts}`
 pub struct Block {
 pub:
@@ -1431,6 +1446,10 @@ pub fn (expr Expr) position() token.Position {
 		AnonFn {
 			return expr.decl.pos
 		}
+		EmptyExpr {
+			println('compiler bug, unhandled EmptyExpr position()')
+			return token.Position{}
+		}
 		NodeError, ArrayDecompose, ArrayInit, AsCast, Assoc, AtExpr, BoolLiteral, CallExpr, CastExpr,
 		ChanInit, CharLiteral, ConcatExpr, Comment, ComptimeCall, ComptimeSelector, EnumVal, DumpExpr,
 		FloatLiteral, GoExpr, Ident, IfExpr, IndexExpr, IntegerLiteral, Likely, LockExpr, MapInit,
@@ -1540,6 +1559,9 @@ pub:
 
 pub fn (node Node) position() token.Position {
 	match node {
+		NodeError {
+			return token.Position{}
+		}
 		Stmt {
 			mut pos := node.pos
 			if node is Import {
@@ -1736,15 +1758,19 @@ pub fn (node Node) children() []Node {
 // a dependency cycle between v.ast and v.table, for the single
 // field table.Field.default_expr, which should be ast.Expr
 pub fn fe2ex(x table.FExpr) Expr {
-	res := Expr{}
-	unsafe { C.memcpy(&res, &x, sizeof(Expr)) }
-	return res
+	unsafe {
+		res := Expr{}
+		C.memcpy(&res, &x, sizeof(Expr))
+		return res
+	}
 }
 
 pub fn ex2fe(x Expr) table.FExpr {
-	res := table.FExpr{}
-	unsafe { C.memcpy(&res, &x, sizeof(table.FExpr)) }
-	return res
+	unsafe {
+		res := table.FExpr{}
+		C.memcpy(&res, &x, sizeof(table.FExpr))
+		return res
+	}
 }
 
 // helper for dealing with `m[k1][k2][k3][k3] = value`

vlib/v/ast/init.v

@@ -9,9 +9,9 @@ pub fn resolve_init(node StructInit, typ table.Type, t &table.Table) Expr {
 		mut has_len := false
 		mut has_cap := false
 		mut has_default := false
-		mut len_expr := Expr{}
-		mut cap_expr := Expr{}
-		mut default_expr := Expr{}
+		mut len_expr := empty_expr()
+		mut cap_expr := empty_expr()
+		mut default_expr := empty_expr()
 		mut exprs := []Expr{}
 		for field in node.fields {
 			match field.name {

vlib/v/checker/checker.v

@@ -469,6 +469,9 @@ pub fn (mut c Checker) struct_init(mut struct_init ast.StructInit) table.Type {
 	utyp := c.unwrap_generic(struct_init.typ)
 	c.ensure_type_exists(utyp, struct_init.pos) or {}
 	type_sym := c.table.get_type_symbol(utyp)
+	if !c.inside_unsafe && type_sym.kind == .sum_type {
+		c.warn('direct sum type init (`x := SumType{}`) will be removed soon', struct_init.pos)
+	}
 	// Make sure the first letter is capital, do not allow e.g. `x := string{}`,
 	// but `x := T{}` is ok.
 	if !c.is_builtin_mod && !c.inside_unsafe && type_sym.language == .v
@@ -3386,6 +3389,10 @@ fn (mut c Checker) stmt(node ast.Stmt) {
 	}
 	// c.expected_type = table.void_type
 	match mut node {
+		ast.EmptyStmt {
+			print_backtrace()
+			eprintln('Checker.stmt() EmptyStmt')
+		}
 		ast.NodeError {}
 		ast.AsmStmt {
 			c.asm_stmt(mut node)
@@ -3532,9 +3539,13 @@ fn (mut c Checker) branch_stmt(node ast.BranchStmt) {
 fn (mut c Checker) for_c_stmt(node ast.ForCStmt) {
 	c.in_for_count++
 	prev_loop_label := c.loop_label
-	c.stmt(node.init)
+	if node.has_init {
+		c.stmt(node.init)
+	}
 	c.expr(node.cond)
-	c.stmt(node.inc)
+	if node.has_inc {
+		c.stmt(node.inc)
+	}
 	c.check_loop_label(node.label, node.pos)
 	c.stmts(node.stmts)
 	c.loop_label = prev_loop_label
@@ -3975,6 +3986,10 @@ pub fn (mut c Checker) expr(node ast.Expr) table.Type {
 	}
 	match mut node {
 		ast.NodeError {}
+		ast.EmptyExpr {
+			print_backtrace()
+			c.error('checker.expr(): unhandled EmptyExpr', token.Position{})
+		}
 		ast.CTempVar {
 			return node.typ
 		}
@@ -5567,7 +5582,7 @@ fn (mut c Checker) find_obj_definition(obj ast.ScopeObject) ?ast.Expr {
 	match obj {
 		ast.Var, ast.ConstField, ast.GlobalField, ast.AsmRegister { name = obj.name }
 	}
-	mut expr := ast.Expr{}
+	mut expr := ast.empty_expr()
 	if obj is ast.Var {
 		if obj.is_mut {
 			return error('`$name` is mut and may have changed since its definition')
@@ -6202,7 +6217,9 @@ fn (mut c Checker) sql_stmt(mut node ast.SqlStmt) table.Type {
 			c.expr(expr)
 		}
 	}
-	c.expr(node.where_expr)
+	if node.where_expr !is ast.EmptyExpr {
+		c.expr(node.where_expr)
+	}
 
 	return table.void_type
 }

vlib/v/checker/tests/sum_type_assign_non_variant_err.out

@@ -1,6 +1,6 @@
 vlib/v/checker/tests/sum_type_assign_non_variant_err.vv:11:6: error: cannot assign to `w`: expected `Stmt`, not `IfExpr`
     9 | fn main() {
-   10 |     mut w := Stmt{}
+   10 |     mut w := Stmt(AnotherThing{})
    11 |     w = IfExpr{}
       |         ~~~~~~~~
    12 | }

vlib/v/checker/tests/sum_type_assign_non_variant_err.vv

@@ -7,6 +7,6 @@ type Stmt = Expr | AnotherThing
 struct AnotherThing {}
 
 fn main() {
-    mut w := Stmt{}
+    mut w := Stmt(AnotherThing{})
 	w = IfExpr{}
 }

vlib/v/fmt/fmt.v

@@ -365,7 +365,7 @@ pub fn (mut f Fmt) node_str(node ast.Node) string {
 //=== General Stmt-related methods and helpers ===//
 
 pub fn (mut f Fmt) stmts(stmts []ast.Stmt) {
-	mut prev_stmt := if stmts.len > 0 { stmts[0] } else { ast.Stmt{} }
+	mut prev_stmt := if stmts.len > 0 { stmts[0] } else { ast.empty_stmt() }
 	f.indent++
 	for stmt in stmts {
 		if !f.pref.building_v && f.should_insert_newline_before_node(stmt, prev_stmt) {
@@ -383,6 +383,7 @@ pub fn (mut f Fmt) stmt(node ast.Stmt) {
 	}
 	match node {
 		ast.NodeError {}
+		ast.EmptyStmt {}
 		ast.AsmStmt {
 			f.asm_stmt(node)
 		}
@@ -482,6 +483,7 @@ pub fn (mut f Fmt) expr(node ast.Expr) {
 	}
 	match mut node {
 		ast.NodeError {}
+		ast.EmptyExpr {}
 		ast.AnonFn {
 			f.fn_decl(node.decl)
 		}
@@ -897,7 +899,11 @@ pub fn (mut f Fmt) const_decl(node ast.ConstDecl) {
 		}
 		f.indent++
 	}
-	mut prev_field := if node.fields.len > 0 { ast.Node(node.fields[0]) } else { ast.Node{} }
+	mut prev_field := if node.fields.len > 0 {
+		ast.Node(node.fields[0])
+	} else {
+		ast.Node(ast.NodeError{})
+	}
 	for field in node.fields {
 		if field.comments.len > 0 {
 			if f.should_insert_newline_before_node(ast.Expr(field.comments[0]), prev_field) {

vlib/v/gen/c/cgen.v

@@ -1010,6 +1010,7 @@ fn (mut g Gen) stmt(node ast.Stmt) {
 	// println('g.stmt()')
 	// g.writeln('//// stmt start')
 	match node {
+		ast.EmptyStmt {}
 		ast.AsmStmt {
 			g.write_v_source_line_info(node.pos)
 			g.gen_asm_stmt(node)
@@ -2789,6 +2790,9 @@ fn (mut g Gen) expr(node ast.Expr) {
 	}
 	// NB: please keep the type names in the match here in alphabetical order:
 	match mut node {
+		ast.EmptyExpr {
+			g.error('g.expr(): unhandled EmptyExpr', token.Position{})
+		}
 		ast.AnonFn {
 			// TODO: dont fiddle with buffers
 			g.gen_anon_fn_decl(mut node)
@@ -4158,7 +4162,7 @@ fn (mut g Gen) select_expr(node ast.SelectExpr) {
 	mut is_push := []bool{cap: n_channels}
 	mut has_else := false
 	mut has_timeout := false
-	mut timeout_expr := ast.Expr{}
+	mut timeout_expr := ast.empty_expr()
 	mut exception_branch := -1
 	for j, branch in node.branches {
 		if branch.is_else {
@@ -4182,7 +4186,7 @@ fn (mut g Gen) select_expr(node ast.SelectExpr) {
 						elem_types << ''
 					} else {
 						// must be evaluated to tmp var before real `select` is performed
-						objs << ast.Expr{}
+						objs << ast.empty_expr()
 						tmp_obj := g.new_tmp_var()
 						tmp_objs << tmp_obj
 						el_stype := g.typ(g.table.mktyp(expr.right_type))
@@ -5283,6 +5287,14 @@ fn (mut g Gen) write_builtin_types() {
 	for builtin_name in c.builtins {
 		sym := g.table.type_symbols[g.table.type_idxs[builtin_name]]
 		if sym.kind == .interface_ {
+			if g.pref.is_verbose {
+				println('XAXAXA $sym.name')
+				if isnil(sym.info) {
+					println('FFF')
+				}
+				println(sym.info)
+				println(sym.kind)
+			}
 			g.write_interface_typesymbol_declaration(sym)
 		} else {
 			builtin_types << sym

vlib/v/gen/js/js.v

@@ -356,6 +356,7 @@ fn (mut g JsGen) stmts(stmts []ast.Stmt) {
 fn (mut g JsGen) stmt(node ast.Stmt) {
 	g.stmt_start_pos = g.ns.out.len
 	match node {
+		ast.EmptyStmt{}
 		ast.AsmStmt {
 			panic('inline asm is not supported by js')
 		}
@@ -447,6 +448,7 @@ fn (mut g JsGen) stmt(node ast.Stmt) {
 fn (mut g JsGen) expr(node ast.Expr) {
 	match node {
 		ast.NodeError {}
+		ast.EmptyExpr {}
 		ast.CTempVar {
 			g.write('/* ast.CTempVar: node.name */')
 		}

vlib/v/markused/walker.v

@@ -49,6 +49,7 @@ pub fn (mut w Walker) mark_root_fns(all_fn_root_names []string) {
 
 pub fn (mut w Walker) stmt(node ast.Stmt) {
 	match mut node {
+		ast.EmptyStmt {}
 		ast.AsmStmt {
 			w.asm_io(node.output)
 			w.asm_io(node.input)
@@ -153,6 +154,9 @@ fn (mut w Walker) exprs(exprs []ast.Expr) {
 
 fn (mut w Walker) expr(node ast.Expr) {
 	match mut node {
+		ast.EmptyExpr {
+			panic('Walker: EmptyExpr')
+		}
 		ast.AnonFn {
 			w.fn_decl(mut node.decl)
 		}

vlib/v/parser/assign.v

@@ -149,7 +149,7 @@ fn (mut p Parser) partial_assign_stmt(left []ast.Expr, left_comments []ast.Comme
 					r0 := right[0]
 					mut v := ast.Var{
 						name: lx.name
-						expr: if left.len == right.len { right[i] } else { ast.Expr{} }
+						expr: if left.len == right.len { right[i] } else { ast.empty_expr() }
 						share: share
 						is_mut: lx.is_mut || p.inside_for
 						pos: lx.pos

vlib/v/parser/containers.v

@@ -21,7 +21,7 @@ fn (mut p Parser) array_init() ast.ArrayInit {
 	mut has_val := false
 	mut has_type := false
 	mut has_default := false
-	mut default_expr := ast.Expr{}
+	mut default_expr := ast.empty_expr()
 	if p.tok.kind == .rsbr {
 		last_pos = p.tok.position()
 		// []typ => `[]` and `typ` must be on the same line
@@ -103,8 +103,8 @@ fn (mut p Parser) array_init() ast.ArrayInit {
 	}
 	mut has_len := false
 	mut has_cap := false
-	mut len_expr := ast.Expr{}
-	mut cap_expr := ast.Expr{}
+	mut len_expr := ast.empty_expr()
+	mut cap_expr := ast.empty_expr()
 	if p.tok.kind == .lcbr && exprs.len == 0 && array_type != table.void_type {
 		// `[]int{ len: 10, cap: 100}` syntax
 		p.next()

vlib/v/parser/fn.v

@@ -129,7 +129,7 @@ pub fn (mut p Parser) call_args() []ast.CallArg {
 			p.next()
 			array_decompose = true
 		}
-		mut expr := ast.Expr{}
+		mut expr := ast.empty_expr()
 		if p.tok.kind == .name && p.peek_tok.kind == .colon {
 			// `foo(key:val, key2:val2)`
 			expr = p.struct_init(true) // short_syntax:true

vlib/v/parser/for.v

@@ -35,9 +35,9 @@ fn (mut p Parser) for_stmt() ast.Stmt {
 		if p.tok.kind == .key_mut {
 			return p.error('`mut` is not needed in `for ;;` loops: use `for i := 0; i < n; i ++ {`')
 		}
-		mut init := ast.Stmt{}
+		mut init := ast.empty_stmt()
 		mut cond := p.new_true_expr()
-		mut inc := ast.Stmt{}
+		mut inc := ast.empty_stmt()
 		mut has_init := false
 		mut has_cond := false
 		mut has_inc := false
@@ -136,7 +136,7 @@ fn (mut p Parser) for_stmt() ast.Stmt {
 		// 0 .. 10
 		// start := p.tok.lit.int()
 		// TODO use RangeExpr
-		mut high_expr := ast.Expr{}
+		mut high_expr := ast.empty_expr()
 		mut is_range := false
 		if p.tok.kind == .dotdot {
 			is_range = true

vlib/v/parser/if_match.v

@@ -79,7 +79,7 @@ fn (mut p Parser) if_expr(is_comptime bool) ast.IfExpr {
 			return ast.IfExpr{}
 		}
 		comments << p.eat_comments({})
-		mut cond := ast.Expr{}
+		mut cond := ast.empty_expr()
 		mut is_guard := false
 		// `if x := opt() {`
 		if !is_comptime && p.peek_tok.kind == .decl_assign {
@@ -290,7 +290,7 @@ fn (mut p Parser) select_expr() ast.SelectExpr {
 		// final else
 		mut is_else := false
 		mut is_timeout := false
-		mut stmt := ast.Stmt{}
+		mut stmt := ast.empty_stmt()
 		if p.tok.kind == .key_else {
 			if has_timeout {
 				p.error_with_pos('timeout `> t` and `else` are mutually exclusive `select` keys',

vlib/v/parser/parser.v

@@ -597,7 +597,7 @@ pub fn (mut p Parser) top_stmt() ast.Stmt {
 	}
 	// TODO remove dummy return statement
 	// the compiler complains if it's not there
-	return ast.Stmt{}
+	return ast.empty_stmt()
 }
 
 // TODO [if vfmt]
@@ -1757,7 +1757,7 @@ fn (p &Parser) is_generic_call() bool {
 
 pub fn (mut p Parser) name_expr() ast.Expr {
 	prev_tok_kind := p.prev_tok.kind
-	mut node := ast.Expr{}
+	mut node := ast.empty_expr()
 	if p.expecting_type {
 		p.expecting_type = false
 		// get type position before moving to next
@@ -1801,7 +1801,7 @@ pub fn (mut p Parser) name_expr() ast.Expr {
 		mut last_pos := first_pos
 		chan_type := p.parse_chan_type()
 		mut has_cap := false
-		mut cap_expr := ast.Expr{}
+		mut cap_expr := ast.empty_expr()
 		p.check(.lcbr)
 		if p.tok.kind == .rcbr {
 			last_pos = p.tok.position()
@@ -1910,8 +1910,8 @@ pub fn (mut p Parser) name_expr() ast.Expr {
 			// without the next line int would result in int*
 			p.is_amp = false
 			p.check(.lpar)
-			mut expr := ast.Expr{}
-			mut arg := ast.Expr{}
+			mut expr := ast.empty_expr()
+			mut arg := ast.empty_expr()
 			mut has_arg := false
 			expr = p.expr(0)
 			// TODO, string(b, len)
@@ -2013,7 +2013,7 @@ fn (mut p Parser) index_expr(left ast.Expr) ast.IndexExpr {
 			left: left
 			pos: pos
 			index: ast.RangeExpr{
-				low: ast.Expr{}
+				low: ast.empty_expr()
 				high: high
 				has_high: true
 				pos: pos
@@ -2025,7 +2025,7 @@ fn (mut p Parser) index_expr(left ast.Expr) ast.IndexExpr {
 	if p.tok.kind == .dotdot {
 		// [start..end] or [start..]
 		p.next()
-		mut high := ast.Expr{}
+		mut high := ast.empty_expr()
 		if p.tok.kind != .rsbr {
 			has_high = true
 			high = p.expr(0)
@@ -2263,7 +2263,7 @@ fn (mut p Parser) string_expr() ast.Expr {
 	if is_raw || is_cstr {
 		p.next()
 	}
-	mut node := ast.Expr{}
+	mut node := ast.empty_expr()
 	val := p.tok.lit
 	pos := p.tok.position()
 	if p.peek_tok.kind != .str_dollar {
@@ -2372,7 +2372,7 @@ fn (mut p Parser) parse_number_literal() ast.Expr {
 	}
 	lit := p.tok.lit
 	full_lit := if is_neg { '-' + lit } else { lit }
-	mut node := ast.Expr{}
+	mut node := ast.empty_expr()
 	if lit.index_any('.eE') >= 0 && lit[..2] !in ['0x', '0X', '0o', '0O', '0b', '0B'] {
 		node = ast.FloatLiteral{
 			val: full_lit
@@ -2714,7 +2714,7 @@ fn (mut p Parser) global_decl() ast.GlobalDecl {
 			p.error('global assign must have the type around the value, use `__global ( name = type(value) )`')
 			return ast.GlobalDecl{}
 		}
-		mut expr := ast.Expr{}
+		mut expr := ast.empty_expr()
 		if has_expr {
 			if p.tok.kind != .lpar {
 				p.error('global assign must have a type and value, use `__global ( name = type(value) )` or `__global ( name type )`')
@@ -2769,7 +2769,7 @@ fn (mut p Parser) enum_decl() ast.EnumDecl {
 		pos := p.tok.position()
 		val := p.check_name()
 		vals << val
-		mut expr := ast.Expr{}
+		mut expr := ast.empty_expr()
 		mut has_expr := false
 		// p.warn('enum val $val')
 		if p.tok.kind == .assign {
@@ -2854,7 +2854,7 @@ fn (mut p Parser) type_decl() ast.TypeDecl {
 	if name.len == 1 && name[0].is_capital() {
 		p.error_with_pos('single letter capital names are reserved for generic template types.',
 			decl_pos)
-		return ast.TypeDecl{}
+		return ast.FnTypeDecl{}
 	}
 	mut sum_variants := []ast.SumTypeVariant{}
 	p.check(.assign)

vlib/v/parser/pratt.v

@@ -14,7 +14,7 @@ pub fn (mut p Parser) expr(precedence int) ast.Expr {
 		eprintln('parsing file: ${p.file_name:-30} | tok.kind: ${p.tok.kind:-10} | tok.lit: ${p.tok.lit:-10} | tok_pos: ${tok_pos.str():-45} | expr($precedence)')
 	}
 	// println('\n\nparser.expr()')
-	mut node := ast.Expr{}
+	mut node := ast.empty_expr()
 	is_stmt_ident := p.is_stmt_ident
 	p.is_stmt_ident = false
 	if !p.pref.is_fmt {
@@ -439,7 +439,7 @@ fn (mut p Parser) infix_expr(left ast.Expr) ast.Expr {
 	precedence := p.tok.precedence()
 	mut pos := p.tok.position()
 	p.next()
-	mut right := ast.Expr{}
+	mut right := ast.empty_expr()
 	prev_expecting_type := p.expecting_type
 	if op in [.key_is, .not_is] {
 		p.expecting_type = true

vlib/v/parser/sql.v

@@ -22,7 +22,7 @@ fn (mut p Parser) sql_expr() ast.Expr {
 	}
 	table_pos := p.tok.position()
 	table_type := p.parse_type() // `User`
-	mut where_expr := ast.Expr{}
+	mut where_expr := ast.empty_expr()
 	has_where := p.tok.kind == .name && p.tok.lit == 'where'
 	mut query_one := false // one object is returned, not an array
 	if has_where {
@@ -40,11 +40,11 @@ fn (mut p Parser) sql_expr() ast.Expr {
 		}
 	}
 	mut has_limit := false
-	mut limit_expr := ast.Expr{}
+	mut limit_expr := ast.empty_expr()
 	mut has_offset := false
-	mut offset_expr := ast.Expr{}
+	mut offset_expr := ast.empty_expr()
 	mut has_order := false
-	mut order_expr := ast.Expr{}
+	mut order_expr := ast.empty_expr()
 	mut has_desc := false
 	if p.tok.kind == .name && p.tok.lit == 'order' {
 		p.check_name() // `order`
@@ -172,7 +172,7 @@ fn (mut p Parser) sql_stmt() ast.SqlStmt {
 	}
 
 	mut table_pos := p.tok.position()
-	mut where_expr := ast.Expr{}
+	mut where_expr := ast.empty_expr()
 	if kind == .insert {
 		table_pos = p.tok.position()
 		table_type = p.parse_type()

vlib/v/parser/struct.v

@@ -239,7 +239,7 @@ fn (mut p Parser) struct_decl() ast.StructDecl {
 				// attrs are stored in `p.attrs`
 				p.attributes()
 			}
-			mut default_expr := ast.Expr{}
+			mut default_expr := ast.empty_expr()
 			mut has_default_expr := false
 			if !is_embed {
 				if p.tok.kind == .assign {
@@ -352,12 +352,12 @@ fn (mut p Parser) struct_init(short_syntax bool) ast.StructInit {
 	// p.warn(is_short_syntax.str())
 	saved_is_amp := p.is_amp
 	p.is_amp = false
-	mut update_expr := ast.Expr{}
+	mut update_expr := ast.empty_expr()
 	mut update_expr_comments := []ast.Comment{}
 	mut has_update_expr := false
 	for p.tok.kind !in [.rcbr, .rpar, .eof] {
 		mut field_name := ''
-		mut expr := ast.Expr{}
+		mut expr := ast.empty_expr()
 		mut field_pos := token.Position{}
 		mut first_field_pos := token.Position{}
 		mut comments := []ast.Comment{}