parser: simplify unused vars & add loop/if vars etc

vlib/builtin/string.v

@@ -832,7 +832,7 @@ fn (ar []string) contains(val string) bool {
 
 // TODO generic
 fn (ar []int) contains(val int) bool {
-	for i, s in ar {
+	for s in ar {
 		if s == val {
 			return true
 		}
@@ -1206,7 +1206,7 @@ pub fn (a []string) join(del string) string {
 		return ''
 	}
 	mut len := 0
-	for i, val in a {
+	for val in a {
 		len += val.len + del.len
 	}
 	len -= del.len

vlib/os/os.v

@@ -1061,7 +1061,7 @@ pub fn walk_ext(path, ext string) []string {
 	}
 	mut res := []string{}
 	separator := if path.ends_with(os.path_separator) { '' } else { os.path_separator }
-	for i, file in files {
+	for file in files {
 		if file.starts_with('.') {
 			continue
 		}

vlib/v/ast/ast.v

@@ -270,12 +270,13 @@ pub struct Stmt {
 */
 pub struct Var {
 pub:
-	name   string
+	name    string
-	expr   Expr
+	expr    Expr
-	is_mut bool
+	is_mut  bool
 mut:
-	typ    table.Type
+	typ     table.Type
-	pos    token.Position
+	pos     token.Position
+	is_used bool
 }
 
 pub struct GlobalDecl {

vlib/v/ast/scope.v

@@ -12,15 +12,9 @@ mut:
 	children  []&Scope
 	start_pos int
 	end_pos   int
-	unused_vars map[string]UnusedVar
 	objects   map[string]ScopeObject
 }
 
-pub struct UnusedVar {
-	name string
-	pos token.Position
-}
-
 pub fn new_scope(parent &Scope, start_pos int) &Scope {
 	return &ast.Scope{
 		parent: parent
@@ -63,12 +57,12 @@ pub fn (s &Scope) is_known(name string) bool {
 	return false
 }
 
-pub fn (s &Scope) find_var(name string) ?Var {
+pub fn (s &Scope) find_var(name string) ?&Var {
 	if obj := s.find(name) {
 		v := ScopeObject(obj)
 		match v {
 			Var {
-				return *it
+				return it
 			}
 			else {}
 		}
@@ -76,12 +70,12 @@ pub fn (s &Scope) find_var(name string) ?Var {
 	return none
 }
 
-pub fn (s &Scope) find_const(name string) ?ConstField {
+pub fn (s &Scope) find_const(name string) ?&ConstField {
 	if obj := s.find(name) {
 		cf := ScopeObject(obj)
 		match cf {
 			ConstField {
-				return *it
+				return it
 			}
 			else {}
 		}
@@ -112,37 +106,13 @@ pub fn (s mut Scope) register(name string, obj ScopeObject) {
 	if name == '_' {
 		return
 	}
-	if x := s.find(name) {
+	if _ := s.find(name) {
 		// println('existing obect: $name')
 		return
 	}
 	s.objects[name] = obj
 }
 
-pub fn (s mut Scope) register_unused_var(name string, pos token.Position) {
-	s.unused_vars[name] = UnusedVar{name, pos}
-}
-
-pub fn (s mut Scope) remove_unused_var(name string) {
-	mut sc := s
-	for !isnil(sc) {
-		sc.unused_vars.delete(name)
-		sc = sc.parent
-	}
-}
-
-pub fn (s mut Scope) unused_vars() []UnusedVar {
-	ret := []UnusedVar{}
-	for _, v in s.unused_vars {
-		ret << v
-	}
-	return ret
-}
-
-pub fn (s mut Scope) clear_unused_vars() {
-	s.unused_vars = map[string]UnusedVar
-}
-
 pub fn (s &Scope) outermost() &Scope {
 	mut sc := s
 	for !isnil(sc.parent) {

vlib/v/checker/checker.v

@@ -203,7 +203,7 @@ pub fn (mut c Checker) struct_decl(decl ast.StructDecl) {
 		}
 		c.error('struct name must begin with capital letter', pos)
 	}
-	for fi, field in decl.fields {
+	for field in decl.fields {
 		sym := c.table.get_type_symbol(field.typ)
 		if sym.kind == .placeholder && !decl.is_c && !sym.name.starts_with('C.') {
 			c.error('unknown type `$sym.name`', field.pos)
@@ -554,7 +554,7 @@ pub fn (mut c Checker) call_method(call_expr mut ast.CallExpr) table.Type {
 			mut scope := c.file.scope.innermost(call_expr.pos.pos)
 			scope.update_var_type('it', array_info.elem_type)
 		}
-		for i, arg in call_expr.args {
+		for arg in call_expr.args {
 			c.expr(arg.expr)
 		}
 		// need to return `array_xxx` instead of `array`

vlib/v/gen/cgen.v

@@ -480,7 +480,7 @@ fn (mut g Gen) stmt(node ast.Stmt) {
 			g.typedefs.writeln('typedef enum {')
 			mut cur_enum_expr := ''
 			mut cur_enum_offset := 0
-			for j, field in it.fields {
+			for field in it.fields {
 				g.typedefs.write('\t${enum_name}_${field.name}')
 				if field.has_expr {
 					g.typedefs.write(' = ')
@@ -1918,7 +1918,7 @@ fn (mut g Gen) return_statement(node ast.Return) {
 }
 
 fn (mut g Gen) const_decl(node ast.ConstDecl) {
-	for i, field in node.fields {
+	for field in node.fields {
 		name := c_name(field.name)
 		// TODO hack. Cut the generated value and paste it into definitions.
 		pos := g.out.len
@@ -3061,7 +3061,7 @@ fn (mut g Gen) gen_str_for_enum(info table.Enum, styp, str_fn_name string) {
 	g.definitions.writeln('string ${str_fn_name}($styp it); // auto')
 	g.auto_str_funcs.writeln('string ${str_fn_name}($styp it) { /* gen_str_for_enum */')
 	g.auto_str_funcs.writeln('\tswitch(it) {')
-	for i, val in info.vals {
+	for val in info.vals {
 		g.auto_str_funcs.writeln('\t\tcase ${s}_$val: return tos3("$val");')
 	}
 	g.auto_str_funcs.writeln('\t\tdefault: return tos3("unknown enum value");')
@@ -3075,7 +3075,7 @@ fn (mut g Gen) gen_str_for_struct(info table.Struct, styp, str_fn_name string) {
 	mut fnames2strfunc := {
 		'': ''
 	} // map[string]string // TODO vfmt bug
-	for i, field in info.fields {
+	for field in info.fields {
 		sym := g.table.get_type_symbol(field.typ)
 		if sym.kind in [.struct_, .array, .array_fixed, .map, .enum_] {
 			field_styp := g.typ(field.typ)

vlib/v/gen/fn.v

@@ -426,7 +426,7 @@ fn (mut g Gen) call_args(args []ast.CallArg, expected_types []table.Type) {
 	is_forwarding_varg := args.len > 0 && args[args.len - 1].typ.flag_is(.variadic)
 	gen_vargs := is_variadic && !is_forwarding_varg
 	mut arg_no := 0
-	for i, arg in args {
+	for arg in args {
 		if gen_vargs && arg_no == expected_types.len - 1 {
 			break
 		}

vlib/v/gen/x64/gen.v

@@ -600,7 +600,7 @@ fn (mut g Gen) allocate_var(name string, size, initial_val int) {
 
 fn (mut g Gen) assign_stmt(node ast.AssignStmt) {
 	// `a := 1` | `a,b := 1,2`
-	for i, ident in node.left {
+	for ident in node.left {
 		match node.right[0] {
 			ast.IntegerLiteral {
 				g.allocate_var(ident.name, 4, it.val.int())

vlib/v/parser/assign.v

@@ -32,11 +32,13 @@ fn (mut p Parser) assign_stmt() ast.Stmt {
 					name: ident.name
 					expr: exprs[i]
 					is_mut: ident.is_mut || p.inside_for
+					pos: ident.pos
 				})
 			} else {
 				p.scope.register(ident.name, ast.Var{
 					name: ident.name
 					is_mut: ident.is_mut || p.inside_for
+					pos: ident.pos
 				})
 			}
 		}

vlib/v/parser/fn.v

@@ -37,10 +37,14 @@ pub fn (mut p Parser) call_expr(is_c, is_js bool, mod string) ast.CallExpr {
 		p.scope.register('err', ast.Var{
 			name: 'err'
 			typ: table.string_type
+			pos: p.tok.position()
+			is_used: true
 		})
 		p.scope.register('errcode', ast.Var{
 			name: 'errcode'
 			typ: table.int_type
+			pos: p.tok.position()
+			is_used: true
 		})
 		is_or_block_used = true
 		or_stmts = p.parse_block_no_scope()
@@ -164,6 +168,8 @@ fn (mut p Parser) fn_decl() ast.FnDecl {
 			name: arg.name
 			typ: arg.typ
 			is_mut: arg.is_mut
+			pos: p.tok.position()
+			is_used: true
 		})
 		// Do not allow `mut` with simple types
 		// TODO move to checker?
@@ -264,6 +270,8 @@ fn (mut p Parser) anon_fn() ast.AnonFn {
 		p.scope.register(arg.name, ast.Var{
 			name: arg.name
 			typ: arg.typ
+			pos: p.tok.position()
+			is_used: true
 		})
 	}
 	mut return_type := table.void_type

vlib/v/parser/for.v

@@ -67,12 +67,16 @@ fn (mut p Parser) for_stmt() ast.Stmt {
 		}
 	} else if p.peek_tok.kind in [.key_in, .comma] {
 		// `for i in vals`, `for i in start .. end`
+		mut val_var_pos := p.tok.position()
 		mut key_var_name := ''
 		mut val_var_name := p.check_name()
 		if p.tok.kind == .comma {
 			p.check(.comma)
+			key_var_pos := val_var_pos
+			val_var_pos = p.tok.position()
 			key_var_name = val_var_name
 			val_var_name = p.check_name()
+			
 			if p.scope.known_var(key_var_name) {
 				p.error('redefinition of key iteration variable `$key_var_name`')
 			}
@@ -82,6 +86,7 @@ fn (mut p Parser) for_stmt() ast.Stmt {
 			p.scope.register(key_var_name, ast.Var{
 				name: key_var_name
 				typ: table.int_type
+				pos: key_var_pos
 			})
 		} else if p.scope.known_var(val_var_name) {
 			p.error('redefinition of value iteration variable `$val_var_name`')
@@ -104,11 +109,13 @@ fn (mut p Parser) for_stmt() ast.Stmt {
 			p.scope.register(val_var_name, ast.Var{
 				name: val_var_name
 				typ: table.int_type
+				pos: val_var_pos
 			})
 		} else {
 			// this type will be set in checker
 			p.scope.register(val_var_name, ast.Var{
 				name: val_var_name
+				pos: val_var_pos
 			})
 		}
 		p.inside_for = false

vlib/v/parser/if.v

@@ -43,12 +43,14 @@ fn (mut p Parser) if_expr() ast.IfExpr {
 		if p.peek_tok.kind == .decl_assign {
 			is_or = true
 			p.open_scope()
+			var_pos := p.tok.position()
 			var_name := p.check_name()
 			p.check(.decl_assign)
 			expr := p.expr(0)
 			p.scope.register(var_name, ast.Var{
 				name: var_name
 				expr: expr
+				pos: var_pos
 			})
 			cond = ast.IfGuardExpr{
 				var_name: var_name
@@ -89,6 +91,7 @@ fn (mut p Parser) match_expr() ast.MatchExpr {
 	if is_mut {
 		p.next()
 	}
+	cond_pos := p.tok.position()
 	cond := p.expr(0)
 	p.inside_match = false
 	p.check(.lcbr)
@@ -119,6 +122,8 @@ fn (mut p Parser) match_expr() ast.MatchExpr {
 			p.scope.register('it', ast.Var{
 				name: 'it'
 				typ: typ.to_ptr()
+				pos: cond_pos
+				is_used: true
 			})
 			// TODO
 			if p.tok.kind == .comma {

vlib/v/parser/parser.v

@@ -195,16 +195,22 @@ pub fn (mut p Parser) open_scope() {
 }
 
 pub fn (mut p Parser) close_scope() {
-	if !p.pref.is_repl && !p.pref.is_fmt {
+	if !p.pref.is_repl && !p.scanner.is_fmt {
-		for v in p.scope.unused_vars() {
+		for _, obj in p.scope.objects {
-			if p.pref.is_prod {
+			match obj {
-				p.error_with_pos('Unused variable: $v.name', v.pos)
+				ast.Var {
-			} else {
+					if !it.is_used && !it.name.starts_with('__') {
-				p.warn_with_pos('Unused variable: $v.name', v.pos)
+						if p.pref.is_prod {
+							p.error_with_pos('Unused variable: $it.name', it.pos)
+						} else {
+							p.warn_with_pos('Unused variable: $it.name', it.pos)
+						}
+					}
+				}
+				else {}
 			}
 		}
 	}
-	p.scope.clear_unused_vars()
 	p.scope.end_pos = p.tok.pos
 	p.scope.parent.children << p.scope
 	p.scope = p.scope.parent
@@ -393,9 +399,6 @@ pub fn (mut p Parser) stmt() ast.Stmt {
 			}
 		}
 		.key_mut, .key_static, .key_var {
-			if p.peek_tok.kind == .name && p.peek_tok.lit != '_' && !p.peek_tok.lit.starts_with('__') {
-				p.scope.register_unused_var(p.peek_tok.lit, p.peek_tok.position())
-			}
 			return p.assign_stmt()
 		}
 		.key_for {
@@ -457,14 +460,7 @@ pub fn (mut p Parser) stmt() ast.Stmt {
 		else {
 			// `x := ...`
 			if p.tok.kind == .name && p.peek_tok.kind in [.decl_assign, .comma] {
-				register_unused := p.peek_tok.kind == .decl_assign
+				return p.assign_stmt()
-				lit := p.tok.lit
-				pos := p.tok.position()
-				ret := p.assign_stmt()
-				if register_unused && lit != '_' && !lit.starts_with('__') {
-					p.scope.register_unused_var(lit, pos)
-				}
-				return ret
 			} else if p.tok.kind == .name && p.peek_tok.kind == .colon {
 				// `label:`
 				name := p.check_name()
@@ -472,8 +468,6 @@ pub fn (mut p Parser) stmt() ast.Stmt {
 				return ast.GotoLabel{
 					name: name
 				}
-			} else if p.tok.kind == .name {
-				p.scope.remove_unused_var(p.tok.lit)
 			}
 			epos := p.tok.position()
 			expr := p.expr(0)
@@ -609,7 +603,16 @@ pub fn (mut p Parser) name_expr() ast.Expr {
 	if p.tok.lit in ['r', 'c', 'js'] && p.peek_tok.kind == .string && p.prev_tok.kind != .str_dollar {
 		return p.string_expr()
 	}
-	known_var := p.scope.known_var(p.tok.lit)
+	mut known_var := false
+	if obj := p.scope.find(p.tok.lit) {
+		match mut obj {
+			ast.Var {
+				known_var = true
+				it.is_used = true
+			}
+			else {}
+		}
+	}
 	if p.peek_tok.kind == .dot && !known_var && (is_c || is_js || p.known_import(p.tok.lit) ||
 		p.mod.all_after('.') == p.tok.lit) {
 		if is_c {
@@ -753,6 +756,8 @@ fn (mut p Parser) index_expr(left ast.Expr) ast.IndexExpr {
 fn (mut p Parser) filter() {
 	p.scope.register('it', ast.Var{
 		name: 'it'
+		pos: p.tok.position()
+		is_used: true
 	})
 }
 
@@ -783,10 +788,14 @@ fn (mut p Parser) dot_expr(left ast.Expr) ast.Expr {
 			p.scope.register('errcode', ast.Var{
 				name: 'errcode'
 				typ: table.int_type
+				pos: p.tok.position()
+				is_used: true
 			})
 			p.scope.register('err', ast.Var{
 				name: 'err'
 				typ: table.string_type
+				pos: p.tok.position()
+				is_used: true
 			})
 			is_or_block_used = true
 			or_stmts = p.parse_block_no_scope()
@@ -1028,9 +1037,6 @@ fn (mut p Parser) return_stmt() ast.Return {
 		}
 	}
 	for {
-		if p.tok.kind == .name {
-			p.scope.remove_unused_var(p.tok.lit)
-		}
 		expr := p.expr(0)
 		exprs << expr
 		if p.tok.kind == .comma {
@@ -1220,10 +1226,11 @@ fn (mut p Parser) type_decl() ast.TypeDecl {
 fn (mut p Parser) assoc() ast.Assoc {
 	var_name := p.check_name()
 	pos := p.tok.position()
-	v := p.scope.find_var(var_name) or {
+	mut v := p.scope.find_var(var_name) or {
 		p.error('unknown variable `$var_name`')
 		return ast.Assoc{}
 	}
+	v.is_used = true
 	// println('assoc var $name typ=$var.typ')
 	mut fields := []string{}
 	mut vals := []ast.Expr{}
@@ -1245,7 +1252,7 @@ fn (mut p Parser) assoc() ast.Assoc {
 		fields: fields
 		exprs: vals
 		pos: pos
-		typ: v.typ
+		// typ: v.typ
 	}
 }
 

vlib/v/parser/pratt.v

@@ -16,7 +16,6 @@ pub fn (mut p Parser) expr(precedence int) ast.Expr {
 	// Prefix
 	match p.tok.kind {
 		.name {
-			p.scope.remove_unused_var(p.tok.lit)
 			node = p.name_expr()
 			p.is_stmt_ident = is_stmt_ident
 		}
@@ -79,7 +78,6 @@ pub fn (mut p Parser) expr(precedence int) ast.Expr {
 					type_name: p.check_name()
 				}
 			} else {
-				p.scope.remove_unused_var(p.tok.lit)
 				sizeof_type := p.parse_type()
 				node = ast.SizeOf{
 					typ: sizeof_type
@@ -104,7 +102,6 @@ pub fn (mut p Parser) expr(precedence int) ast.Expr {
 			} else {
 				// it should be a struct
 				if p.peek_tok.kind == .pipe {
-					p.scope.remove_unused_var(p.tok.lit)
 					node = p.assoc()
 				} else if p.peek_tok.kind == .colon || p.tok.kind == .rcbr {
 					node = p.struct_init(true) // short_syntax: true

vlib/v/table/atypes.v

@@ -66,7 +66,7 @@ pub fn (t Type) is_ptr() bool {
 [inline]
 pub fn (t Type) set_nr_muls(nr_muls int) Type {
 	if nr_muls < 0 || nr_muls > 255 {
-		panic('typ_set_nr_muls: nr_muls must be between 0 & 255')
+		panic('set_nr_muls: nr_muls must be between 0 & 255')
 	}
 	return (((int(t) >> 24) & 0xff) << 24) | (nr_muls << 16) | (u16(t) & 0xffff)
 }
@@ -76,7 +76,7 @@ pub fn (t Type) set_nr_muls(nr_muls int) Type {
 pub fn (t Type) to_ptr() Type {
 	nr_muls := (int(t) >> 16) & 0xff
 	if nr_muls == 255 {
-		panic('type_to_pre: nr_muls is already at max of 255')
+		panic('to_ptr: nr_muls is already at max of 255')
 	}
 	return (((int(t) >> 24) & 0xff) << 24) | ((nr_muls + 1) << 16) | (u16(t) & 0xffff)
 }