v/vlib/v/checker/assign.v

592 lines
20 KiB
V

// Copyright (c) 2019-2022 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license that can be found in the LICENSE file.
module checker
import v.ast
import v.pref
// TODO 600 line function
pub fn (mut c Checker) assign_stmt(mut node ast.AssignStmt) {
c.expected_type = ast.none_type // TODO a hack to make `x := if ... work`
defer {
c.expected_type = ast.void_type
}
is_decl := node.op == .decl_assign
right_first := node.right[0]
node.left_types = []
mut right_len := node.right.len
mut right_type0 := ast.void_type
for i, mut right in node.right {
if right in [ast.CallExpr, ast.IfExpr, ast.LockExpr, ast.MatchExpr] {
if right in [ast.IfExpr, ast.MatchExpr] && node.left.len == node.right.len && !is_decl
&& node.left[i] in [ast.Ident, ast.SelectorExpr] && !node.left[i].is_blank_ident() {
c.expected_type = c.expr(node.left[i])
}
right_type := c.expr(right)
c.fail_if_unreadable(right, right_type, 'right-hand side of assignment')
if i == 0 {
right_type0 = right_type
node.right_types = [
c.check_expr_opt_call(right, right_type0),
]
}
right_type_sym := c.table.sym(right_type)
if right_type_sym.kind == .multi_return {
if node.right.len > 1 {
c.error('cannot use multi-value $right_type_sym.name in single-value context',
right.pos())
}
node.right_types = right_type_sym.mr_info().types
right_len = node.right_types.len
} else if right_type == ast.void_type {
right_len = 0
}
}
if mut right is ast.InfixExpr {
if right.op == .arrow {
c.error('cannot use `<-` on the right-hand side of an assignment, as it does not return any values',
right.pos)
}
}
if mut right is ast.Ident {
if right.is_mut {
c.error('unexpected `mut` on right-hand side of assignment', right.mut_pos)
}
}
if mut right is ast.None {
c.error('you can not assign a `none` value to a variable', right.pos)
}
}
if node.left.len != right_len {
if right_first is ast.CallExpr {
if node.left_types.len > 0 && node.left_types[0] == ast.void_type {
// If it's a void type, it's an unknown variable, already had an error earlier.
return
}
c.error('assignment mismatch: $node.left.len variable(s) but `${right_first.name}()` returns $right_len value(s)',
node.pos)
} else {
c.error('assignment mismatch: $node.left.len variable(s) $right_len value(s)',
node.pos)
}
return
}
for i, mut left in node.left {
if mut left is ast.CallExpr {
// ban `foo() = 10`
c.error('cannot call function `${left.name}()` on the left side of an assignment',
left.pos)
} else if mut left is ast.PrefixExpr {
// ban `*foo() = 10`
if left.right is ast.CallExpr && left.op == .mul {
c.error('cannot dereference a function call on the left side of an assignment, use a temporary variable',
left.pos)
}
} else if mut left is ast.IndexExpr {
if left.index is ast.RangeExpr {
c.error('cannot reassign using range expression on the left side of an assignment',
left.pos)
}
}
is_blank_ident := left.is_blank_ident()
mut left_type := ast.void_type
if !is_decl && !is_blank_ident {
if left in [ast.Ident, ast.SelectorExpr] {
c.prevent_sum_type_unwrapping_once = true
}
left_type = c.expr(left)
c.expected_type = c.unwrap_generic(left_type)
}
if node.right_types.len < node.left.len { // first type or multi return types added above
old_inside_ref_lit := c.inside_ref_lit
if mut left is ast.Ident {
if mut left.info is ast.IdentVar {
c.inside_ref_lit = c.inside_ref_lit || left.info.share == .shared_t
}
}
c.inside_decl_rhs = is_decl
right_type := c.expr(node.right[i])
c.inside_decl_rhs = false
c.inside_ref_lit = old_inside_ref_lit
if node.right_types.len == i {
node.right_types << c.check_expr_opt_call(node.right[i], right_type)
}
}
mut right := if i < node.right.len { node.right[i] } else { node.right[0] }
mut right_type := node.right_types[i]
if mut right is ast.Ident {
right_sym := c.table.sym(right_type)
if right_sym.info is ast.Struct {
if right_sym.info.generic_types.len > 0 {
if obj := right.scope.find(right.name) {
right_type = obj.typ
}
}
}
} else if right is ast.ComptimeSelector {
right_type = c.comptime_fields_default_type
}
if is_decl {
// check generic struct init and return unwrap generic struct type
if mut right is ast.StructInit {
if right.typ.has_flag(.generic) {
c.expr(right)
right_type = right.typ
}
} else if mut right is ast.PrefixExpr {
if right.op == .amp && right.right is ast.StructInit {
right_type = c.expr(right)
}
}
if right.is_auto_deref_var() {
left_type = ast.mktyp(right_type.deref())
} else {
left_type = ast.mktyp(right_type)
}
if left_type == ast.int_type {
if mut right is ast.IntegerLiteral {
mut is_large := right.val.len > 13
if !is_large && right.val.len > 8 {
val := right.val.i64()
is_large = val > int_max || val < int_min
}
if is_large {
c.error('overflow in implicit type `int`, use explicit type casting instead',
right.pos)
}
}
}
} else {
// Make sure the variable is mutable
c.fail_if_immutable(left)
// left_type = c.expr(left)
}
if right_type.is_ptr() && left_type.is_ptr() {
if mut right is ast.Ident {
if mut right.obj is ast.Var {
mut obj := unsafe { &right.obj }
if c.fn_scope != voidptr(0) {
obj = c.fn_scope.find_var(right.obj.name) or { obj }
}
if obj.is_stack_obj && !c.inside_unsafe {
type_sym := c.table.sym(obj.typ.set_nr_muls(0))
if !type_sym.is_heap() && !c.pref.translated && !c.file.is_translated {
suggestion := if type_sym.kind == .struct_ {
'declaring `$type_sym.name` as `[heap]`'
} else {
'wrapping the `$type_sym.name` object in a `struct` declared as `[heap]`'
}
c.error('`$right.name` cannot be assigned outside `unsafe` blocks as it might refer to an object stored on stack. Consider ${suggestion}.',
right.pos)
}
}
}
}
}
// Do not allow `a := 0; b := 0; a = &b`
if !is_decl && left is ast.Ident && !is_blank_ident && !left_type.is_real_pointer()
&& right_type.is_real_pointer() && !right_type.has_flag(.shared_f) {
left_sym := c.table.sym(left_type)
if left_sym.kind != .function {
c.warn(
'cannot assign a reference to a value (this will be an error soon) left=${c.table.type_str(left_type)} $left_type.is_ptr() ' +
'right=${c.table.type_str(right_type)} $right_type.is_real_pointer() ptr=$right_type.is_ptr()',
node.pos)
}
}
node.left_types << left_type
match mut left {
ast.Ident {
if left.kind == .blank_ident {
left_type = right_type
node.left_types[i] = right_type
if node.op !in [.assign, .decl_assign] {
c.error('cannot modify blank `_` identifier', left.pos)
}
} else if left.info !is ast.IdentVar {
c.error('cannot assign to $left.kind `$left.name`', left.pos)
} else {
if is_decl {
c.check_valid_snake_case(left.name, 'variable name', left.pos)
if left.name in reserved_type_names {
c.error('invalid use of reserved type `$left.name` as a variable name',
left.pos)
}
}
mut ident_var_info := left.info as ast.IdentVar
if ident_var_info.share == .shared_t {
left_type = left_type.set_flag(.shared_f)
if is_decl {
if left_type.nr_muls() > 1 {
c.error('shared cannot be multi level reference', left.pos)
}
left_type = left_type.set_nr_muls(1)
}
} else if left_type.has_flag(.shared_f) {
left_type = left_type.clear_flag(.shared_f)
}
if ident_var_info.share == .atomic_t {
left_type = left_type.set_flag(.atomic_f)
}
node.left_types[i] = left_type
ident_var_info.typ = left_type
left.info = ident_var_info
if left_type != 0 {
match mut left.obj {
ast.Var {
left.obj.typ = left_type
if left.obj.is_auto_deref {
left.obj.is_used = true
}
if !left_type.is_ptr() {
if c.table.sym(left_type).is_heap() {
left.obj.is_auto_heap = true
}
}
if left_type in ast.unsigned_integer_type_idxs {
if mut right is ast.IntegerLiteral {
if right.val[0] == `-` {
c.error('Cannot assign negative value to unsigned integer type',
right.pos)
}
}
}
}
ast.GlobalField {
left.obj.typ = left_type
}
else {}
}
}
if is_decl {
full_name := '${left.mod}.$left.name'
if obj := c.file.global_scope.find(full_name) {
if obj is ast.ConstField {
c.warn('duplicate of a const name `$full_name`', left.pos)
}
}
}
}
}
ast.PrefixExpr {
// Do now allow `*x = y` outside `unsafe`
if left.op == .mul {
if !c.inside_unsafe && !c.pref.translated && !c.file.is_translated {
c.error('modifying variables via dereferencing can only be done in `unsafe` blocks',
node.pos)
} else if mut left.right is ast.Ident {
// mark `p` in `*p = val` as used:
if mut left.right.obj is ast.Var {
left.right.obj.is_used = true
}
}
}
if is_decl {
c.error('non-name on the left side of `:=`', left.pos)
}
}
ast.SelectorExpr {
if mut left.expr is ast.IndexExpr {
if left.expr.is_map {
left.expr.is_setter = true
}
}
}
else {
if mut left is ast.IndexExpr {
// eprintln('>>> left.is_setter: ${left.is_setter:10} | left.is_map: ${left.is_map:10} | left.is_array: ${left.is_array:10}')
if left.is_map && left.is_setter {
left.recursive_mapset_is_setter(true)
}
}
if is_decl {
c.error('non-name `$left` on left side of `:=`', left.pos())
}
}
}
left_type_unwrapped := c.unwrap_generic(left_type)
right_type_unwrapped := c.unwrap_generic(right_type)
if right_type_unwrapped == 0 {
// right type was a generic `T`
continue
}
if c.pref.translated || c.file.is_translated {
// TODO fix this in C2V instead, for example cast enums to int before using `|` on them.
// TODO replace all c.pref.translated checks with `$if !translated` for performance
continue
}
if left_type_unwrapped == 0 {
continue
}
left_sym := c.table.sym(left_type_unwrapped)
right_sym := c.table.sym(right_type_unwrapped)
if left_sym.kind == .array && !c.inside_unsafe && node.op in [.assign, .decl_assign]
&& right_sym.kind == .array && left is ast.Ident && !left.is_blank_ident()
&& right is ast.Ident {
// Do not allow `a = b`, only `a = b.clone()`
c.error('use `array2 $node.op.str() array1.clone()` instead of `array2 $node.op.str() array1` (or use `unsafe`)',
node.pos)
}
if left_sym.kind == .array && right_sym.kind == .array {
// `mut arr := [u8(1),2,3]`
// `arr = [byte(4),5,6]`
left_info := left_sym.info as ast.Array
left_elem_type := c.table.unaliased_type(left_info.elem_type)
right_info := right_sym.info as ast.Array
right_elem_type := c.table.unaliased_type(right_info.elem_type)
if left_type_unwrapped.nr_muls() == right_type_unwrapped.nr_muls()
&& left_info.nr_dims == right_info.nr_dims && left_elem_type == right_elem_type {
continue
}
}
if left_sym.kind == .array_fixed && !c.inside_unsafe && node.op in [.assign, .decl_assign]
&& right_sym.kind == .array_fixed && left is ast.Ident && !left.is_blank_ident()
&& right is ast.Ident {
if right_sym.info is ast.ArrayFixed {
if right_sym.info.elem_type.is_ptr() {
c.error('assignment from one fixed array to another with a pointer element type is prohibited outside of `unsafe`',
node.pos)
}
}
}
if left_sym.kind == .map && node.op in [.assign, .decl_assign] && right_sym.kind == .map
&& !left.is_blank_ident() && right.is_lvalue()
&& (!right_type.is_ptr() || (right is ast.Ident && right.is_auto_deref_var())) {
// Do not allow `a = b`
c.error('cannot copy map: call `move` or `clone` method (or use a reference)',
right.pos())
}
left_is_ptr := left_type.is_ptr() || left_sym.is_pointer()
if left_is_ptr && !left.is_auto_deref_var() {
if !c.inside_unsafe && node.op !in [.assign, .decl_assign] {
// ptr op=
c.warn('pointer arithmetic is only allowed in `unsafe` blocks', node.pos)
}
right_is_ptr := right_type.is_ptr() || right_sym.is_pointer()
if !right_is_ptr && node.op == .assign && right_type_unwrapped.is_number() {
c.error('cannot assign to `$left`: ' +
c.expected_msg(right_type_unwrapped, left_type_unwrapped), right.pos())
}
if !right_sym.is_number() && !left_type.has_flag(.shared_f)
&& (right is ast.StructInit || !right_is_ptr) {
left_name := c.table.type_to_str(left_type_unwrapped)
mut rtype := right_type_unwrapped
if rtype.is_ptr() {
rtype = rtype.deref()
}
right_name := c.table.type_to_str(rtype)
c.error('mismatched types `$left_name` and `$right_name`', node.pos)
}
}
// Single side check
match node.op {
.assign {} // No need to do single side check for =. But here put it first for speed.
.plus_assign, .minus_assign {
if left_type == ast.string_type {
if node.op != .plus_assign {
c.error('operator `$node.op` not defined on left operand type `$left_sym.name`',
left.pos())
}
if right_type != ast.string_type {
c.error('invalid right operand: $left_sym.name $node.op $right_sym.name',
right.pos())
}
} else if !left_sym.is_number()
&& left_sym.kind !in [.byteptr, .charptr, .struct_, .alias] {
c.error('operator `$node.op` not defined on left operand type `$left_sym.name`',
left.pos())
} else if !right_sym.is_number()
&& left_sym.kind !in [.byteptr, .charptr, .struct_, .alias] {
c.error('invalid right operand: $left_sym.name $node.op $right_sym.name',
right.pos())
}
}
.mult_assign, .div_assign {
if !left_sym.is_number() && !c.table.final_sym(left_type_unwrapped).is_int()
&& left_sym.kind !in [.struct_, .alias] {
c.error('operator $node.op.str() not defined on left operand type `$left_sym.name`',
left.pos())
} else if !right_sym.is_number() && !c.table.final_sym(left_type_unwrapped).is_int()
&& left_sym.kind !in [.struct_, .alias] {
c.error('operator $node.op.str() not defined on right operand type `$right_sym.name`',
right.pos())
}
}
.and_assign, .or_assign, .xor_assign, .mod_assign, .left_shift_assign,
.right_shift_assign {
if !left_sym.is_int() && !c.table.final_sym(left_type_unwrapped).is_int() {
c.error('operator $node.op.str() not defined on left operand type `$left_sym.name`',
left.pos())
} else if !right_sym.is_int() && !c.table.final_sym(right_type_unwrapped).is_int() {
c.error('operator $node.op.str() not defined on right operand type `$right_sym.name`',
right.pos())
}
}
.unsigned_right_shift_assign {
if node.left.len != 1 || node.right.len != 1 {
c.error('unsupported operation: unable to lower expression for unsigned shift assignment.',
node.pos)
}
modified_left_type := if !left_type.is_int() {
c.error('invalid operation: shift on type `${c.table.sym(left_type).name}`',
node.pos)
ast.void_type_idx
} else if left_type.is_int_literal() {
// int literal => i64
ast.u32_type_idx
} else if left_type.is_unsigned() {
left_type
} else {
// signed types' idx adds with 5 will get correct relative unsigned type
// i8 => byte
// i16 => u16
// int => u32
// i64 => u64
// isize => usize
// i128 => u128 NOT IMPLEMENTED YET
left_type.idx() + ast.u32_type_idx - ast.int_type_idx
}
node = ast.AssignStmt{
op: .assign
pos: node.pos
comments: node.comments
end_comments: node.end_comments
left: node.left
right: [
ast.Expr(ast.InfixExpr{
left: ast.CastExpr{
expr: node.left[0]
typ: modified_left_type
typname: c.table.type_str(modified_left_type)
pos: node.pos
}
op: .right_shift
right: node.right[0]
left_type: modified_left_type
right_type: right_type
pos: node.pos
}),
]
left_types: node.left_types
right_types: node.right_types
is_static: node.is_static
is_simple: node.is_simple
has_cross_var: node.has_cross_var
}
}
else {}
}
if node.op in [.plus_assign, .minus_assign, .mod_assign, .mult_assign, .div_assign]
&& (left_sym.kind == .alias || (left_sym.kind == .struct_
&& right_sym.kind == .struct_)) {
left_name := c.table.type_to_str(left_type_unwrapped)
right_name := c.table.type_to_str(right_type_unwrapped)
parent_sym := c.table.final_sym(left_type_unwrapped)
if left_sym.kind == .alias && right_sym.kind != .alias {
c.error('mismatched types `$left_name` and `$right_name`', node.pos)
}
extracted_op := match node.op {
.plus_assign { '+' }
.minus_assign { '-' }
.div_assign { '/' }
.mod_assign { '%' }
.mult_assign { '*' }
else { 'unknown op' }
}
if left_sym.kind == .struct_ && (left_sym.info as ast.Struct).generic_types.len > 0 {
continue
}
if method := left_sym.find_method(extracted_op) {
if method.return_type != left_type_unwrapped {
c.error('operator `$extracted_op` must return `$left_name` to be used as an assignment operator',
node.pos)
}
} else {
if parent_sym.is_primitive() {
c.error('cannot use operator methods on type alias for `$parent_sym.name`',
node.pos)
}
if left_name == right_name {
c.error('undefined operation `$left_name` $extracted_op `$right_name`',
node.pos)
} else {
c.error('mismatched types `$left_name` and `$right_name`', node.pos)
}
}
}
if !is_blank_ident && !left.is_auto_deref_var() && !right.is_auto_deref_var()
&& right_sym.kind != .placeholder && left_sym.kind != .interface_
&& !right_type.has_flag(.generic) && !left_type.has_flag(.generic) {
// Dual sides check (compatibility check)
c.check_expected(right_type_unwrapped, left_type_unwrapped) or {
// allow for ptr += 2
if left_type_unwrapped.is_ptr() && right_type_unwrapped.is_int()
&& node.op in [.plus_assign, .minus_assign] {
if !c.inside_unsafe {
c.warn('pointer arithmetic is only allowed in `unsafe` blocks',
node.pos)
}
} else {
c.error('cannot assign to `$left`: $err.msg()', right.pos())
}
}
}
if left_sym.kind == .interface_ {
if c.type_implements(right_type, left_type, right.pos()) {
if !right_type.is_ptr() && !right_type.is_pointer() && right_sym.kind != .interface_
&& !c.inside_unsafe {
c.mark_as_referenced(mut &node.right[i], true)
}
}
}
}
// this needs to run after the assign stmt left exprs have been run through checker
// so that ident.obj is set
// Check `x := &y` and `mut x := <-ch`
if right_first is ast.PrefixExpr {
right_node := right_first
left_first := node.left[0]
if left_first is ast.Ident {
assigned_var := left_first
mut is_shared := false
if left_first.info is ast.IdentVar {
is_shared = left_first.info.share == .shared_t
}
old_inside_ref_lit := c.inside_ref_lit
c.inside_ref_lit = c.inside_ref_lit || right_node.op == .amp || is_shared
c.expr(right_node.right)
c.inside_ref_lit = old_inside_ref_lit
if right_node.op == .amp {
if right_node.right is ast.Ident {
if right_node.right.obj is ast.Var {
v := right_node.right.obj
right_type0 = v.typ
}
if !c.inside_unsafe && assigned_var.is_mut() && !right_node.right.is_mut() {
c.error('`$right_node.right.name` is immutable, cannot have a mutable reference to it',
right_node.pos)
}
}
}
if right_node.op == .arrow {
if assigned_var.is_mut {
right_sym := c.table.sym(right_type0)
if right_sym.kind == .chan {
chan_info := right_sym.chan_info()
if chan_info.elem_type.is_ptr() && !chan_info.is_mut {
c.error('cannot have a mutable reference to object from `$right_sym.name`',
right_node.pos)
}
}
}
}
}
}
if node.left_types.len != node.left.len {
c.error('assign statement left type number mismatch', node.pos)
}
}