checker: check unsafe array assign (fix #9651) (#15515)

cmd/tools/vgret.v

@@ -321,7 +321,7 @@ fn take_screenshots(opt Options, app AppConfig) ![]string {
 					os.setenv('$k', rv, true)
 				}
 
-				mut flags := app.capture.flags.join(' ')
+				flags := app.capture.flags.join(' ')
 				result := opt.verbose_execute('${os.quoted_path(v_exe)} $flags -d gg_record run ${os.quoted_path(app.abs_path)}')
 				if result.exit_code != 0 {
 					return error('Failed taking screenshot of `$app.abs_path`:\n$result.output')
@@ -336,7 +336,7 @@ fn take_screenshots(opt Options, app AppConfig) ![]string {
 
 				existing_screenshots := get_app_screenshots(out_path, app)!
 
-				mut flags := app.capture.flags
+				flags := app.capture.flags
 
 				mut p_app := os.new_process(app.abs_path)
 				p_app.set_args(flags)

cmd/tools/vpm.v

@@ -86,7 +86,7 @@ fn main() {
 			if module_names.len == 0 && os.exists('./v.mod') {
 				println('Detected v.mod file inside the project directory. Using it...')
 				manifest := vmod.from_file('./v.mod') or { panic(err) }
-				module_names = manifest.dependencies
+				module_names = manifest.dependencies.clone()
 			}
 			mut source := Source.vpm
 			if '--once' in options {

cmd/tools/vrepl.v

@@ -154,7 +154,7 @@ fn (r &Repl) current_source_code(should_add_temp_lines bool, not_add_print bool)
 		if !not_add_print {
 			lines = r.vstartup_lines.filter(!it.starts_with('print'))
 		} else {
-			lines = r.vstartup_lines
+			lines = r.vstartup_lines.clone()
 		}
 		all_lines << lines
 	}

vlib/datatypes/linked_list.v

@@ -83,7 +83,7 @@ pub fn (mut list LinkedList<T>) pop() ?T {
 		return error('Linked list is empty')
 	}
 	mut node := list.head
-	mut to_return := node.data
+	mut to_return := unsafe { node.data }
 	if unsafe { node.next == 0 } {
 		// first node case
 		// set to null
@@ -92,7 +92,7 @@ pub fn (mut list LinkedList<T>) pop() ?T {
 		for unsafe { node.next.next != 0 } {
 			node = node.next
 		}
-		to_return = node.next.data
+		to_return = unsafe { node.next.data }
 		// set to null
 		node.next = unsafe { nil }
 	}

vlib/math/big/special_array_ops.v

@@ -55,8 +55,8 @@ fn newton_divide_array_by_array(operand_a []u32, operand_b []u32, mut quotient [
 		q.inc()
 		r -= b
 	}
-	quotient = q.digits
+	quotient = q.digits.clone()
-	remainder = r.digits
+	remainder = r.digits.clone()
 
 	shrink_tail_zeros(mut remainder)
 }
@@ -241,7 +241,7 @@ fn toom3_multiply_digit_array(operand_a []u32, operand_b []u32, mut storage []u3
 
 	result := (((pinf.lshift(s) + t2).lshift(s) + t1).lshift(s) + tm1).lshift(s) + p0
 
-	storage = result.digits
+	storage = result.digits.clone()
 }
 
 [inline]

vlib/mysql/orm.v

@@ -66,7 +66,7 @@ pub fn (db Connection) @select(config orm.SelectConfig, data orm.QueryData, wher
 	stmt.bind_res(fields, dataptr, lens, num_fields)
 
 	mut row := 0
-	mut types := config.types
+	mut types := config.types.clone()
 	mut field_types := []FieldType{}
 	if config.is_count {
 		types = [orm.type_idx['u64']]

vlib/net/html/data_structures.v

@@ -54,13 +54,13 @@ fn (mut btree BTree) add_children(tag Tag) int {
 	btree.all_tags << tag
 	if btree.all_tags.len > 1 {
 		for btree.childrens.len <= btree.node_pointer {
-			mut temp_array := btree.childrens
+			mut temp_array := btree.childrens.clone()
 			temp_array << []int{}
 			btree.childrens = temp_array
 		}
 		btree.childrens[btree.node_pointer] << btree.all_tags.len - 1
 		for btree.parents.len < btree.all_tags.len {
-			mut temp_array := btree.parents
+			mut temp_array := btree.parents.clone()
 			temp_array << 0
 			btree.parents = temp_array
 		}

vlib/semver/parse.v

@@ -62,7 +62,7 @@ fn (raw_ver RawVersion) coerce() ?Version {
 }
 
 fn (raw_ver RawVersion) complete() RawVersion {
-	mut raw_ints := raw_ver.raw_ints
+	mut raw_ints := raw_ver.raw_ints.clone()
 	for raw_ints.len < 3 {
 		raw_ints << '0'
 	}

vlib/v/ast/table.v

@@ -399,7 +399,7 @@ pub fn (t &Table) get_embeds(sym &TypeSymbol, options GetEmbedsOptions) [][]Type
 	if unalias_sym.info is Struct {
 		for embed in unalias_sym.info.embeds {
 			embed_sym := t.sym(embed)
-			mut preceding := options.preceding
+			mut preceding := options.preceding.clone()
 			preceding << embed
 			embeds << t.get_embeds(embed_sym, preceding: preceding)
 		}
@@ -1932,7 +1932,7 @@ pub fn (mut t Table) unwrap_generic_type(typ Type, generic_names []string, concr
 					}
 				}
 			}
-			mut all_methods := ts.methods
+			mut all_methods := unsafe { ts.methods }
 			for imethod in imethods {
 				for mut method in all_methods {
 					if imethod.name == method.name {
@@ -2097,7 +2097,7 @@ pub fn (mut t Table) generic_insts_to_concrete() {
 							}
 							sym.register_method(method)
 						}
-						mut all_methods := parent.methods
+						mut all_methods := unsafe { parent.methods }
 						for imethod in imethods {
 							for mut method in all_methods {
 								if imethod.name == method.name {

vlib/v/checker/assign.v

@@ -338,13 +338,29 @@ pub fn (mut c Checker) assign_stmt(mut node ast.AssignStmt) {
 		}
 		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()
+		old_assign_error_condition := left_sym.kind == .array && !c.inside_unsafe
-			&& right is ast.Ident {
+			&& node.op in [.assign, .decl_assign] && right_sym.kind == .array && left is ast.Ident
+			&& !left.is_blank_ident() && right is ast.Ident
+		if old_assign_error_condition {
 			// Do not allow `a = b`, only `a = b.clone()`
 			c.error('use `array2 $node.op.str() array1.clone()` instead of `array2 $node.op.str() array1` (or use `unsafe`)',
 				node.pos)
 		}
+		// Do not allow `a = val.array_field`, only `a = val.array_field.clone()`
+		// TODO: turn this warning into an error after 2022/09/24
+		// TODO: and remove the less strict check from above.
+		if left_sym.kind == .array && !c.inside_unsafe && right_sym.kind == .array
+			&& left is ast.Ident && !left.is_blank_ident() && right in [ast.Ident, ast.SelectorExpr]
+			&& ((node.op == .decl_assign && (left as ast.Ident).is_mut)
+			|| node.op == .assign) {
+			// no point to show the notice, if the old error was already shown:
+			if !old_assign_error_condition {
+				mut_str := if node.op == .decl_assign { 'mut ' } else { '' }
+				c.note('use `${mut_str}array2 $node.op.str() array1.clone()` instead of `${mut_str}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]`

vlib/v/checker/check_types.v

@@ -756,8 +756,8 @@ pub fn (mut c Checker) infer_fn_generic_types(func ast.Fn, mut node ast.CallExpr
 					mut concrete_types := []ast.Type{}
 					match arg_sym.info {
 						ast.Struct, ast.Interface, ast.SumType {
-							generic_types = arg_sym.info.generic_types
+							generic_types = arg_sym.info.generic_types.clone()
-							concrete_types = arg_sym.info.concrete_types
+							concrete_types = arg_sym.info.concrete_types.clone()
 						}
 						else {}
 					}

vlib/v/checker/checker.v

@@ -542,7 +542,7 @@ pub fn (mut c Checker) expand_iface_embeds(idecl &ast.InterfaceDecl, level int,
 	mut ares := []ast.InterfaceEmbedding{}
 	for ie in iface_embeds {
 		if iface_decl := c.table.interfaces[ie.typ] {
-			mut list := iface_decl.embeds
+			mut list := iface_decl.embeds.clone()
 			if !iface_decl.are_embeds_expanded {
 				list = c.expand_iface_embeds(idecl, level + 1, iface_decl.embeds)
 				c.table.interfaces[ie.typ].embeds = list

vlib/v/checker/return.v

@@ -30,7 +30,7 @@ pub fn (mut c Checker) return_stmt(mut node ast.Return) {
 	exp_is_result := expected_type.has_flag(.result)
 	mut expected_types := [expected_type]
 	if expected_type_sym.info is ast.MultiReturn {
-		expected_types = expected_type_sym.info.types
+		expected_types = expected_type_sym.info.types.clone()
 		if c.table.cur_concrete_types.len > 0 {
 			expected_types = expected_types.map(c.unwrap_generic(it))
 		}

vlib/v/checker/tests/array_assign_err.out

@@ -0,0 +1,7 @@
+vlib/v/checker/tests/array_assign_err.vv:8:8: notice: use `mut array2 := array1.clone()` instead of `mut array2 := array1` (or use `unsafe`)
+    6 | fn main() {
+    7 |     a := Dumb{[1, 2, 3]}
+    8 |     mut b := a.v // I expect a compiler error
+      |           ~~
+    9 |     for _ in 0 .. 100 {
+   10 |         b << [4, 5, 6]

vlib/v/checker/tests/array_assign_err.vv

@@ -0,0 +1,13 @@
+struct Dumb {
+mut:
+	v []int
+}
+
+fn main() {
+	a := Dumb{[1, 2, 3]}
+	mut b := a.v // I expect a compiler error
+	for _ in 0 .. 100 {
+		b << [4, 5, 6]
+	}
+	println(a) // prints [4,5,6] in this case, but I've also seen crashes
+}

vlib/v/checker/tests/array_or_map_assign_err.out

@@ -10,10 +10,10 @@ vlib/v/checker/tests/array_or_map_assign_err.vv:5:5: error: use `array2 = array1
     4 |     mut a3 := []int{}
     5 |     a3 = a1
       |        ^
-    6 |
+    6 | 
     7 |     m1 := {'one': 1}
 vlib/v/checker/tests/array_or_map_assign_err.vv:8:8: error: cannot copy map: call `move` or `clone` method (or use a reference)
-    6 |
+    6 | 
     7 |     m1 := {'one': 1}
     8 |     m2 := m1
       |           ~~
@@ -24,10 +24,10 @@ vlib/v/checker/tests/array_or_map_assign_err.vv:10:7: error: cannot copy map: ca
     9 |     mut m3 := map[string]int{}
    10 |     m3 = m1
       |          ~~
-   11 |
+   11 | 
    12 |     _ = a2
 vlib/v/checker/tests/array_or_map_assign_err.vv:25:8: error: cannot copy map: call `move` or `clone` method (or use a reference)
-   23 |
+   23 | 
    24 | fn foo(mut m map[string]int) {
    25 |     m2 := m
       |           ^

vlib/v/fmt/fmt.v

@@ -1160,12 +1160,12 @@ pub fn (mut f Fmt) interface_decl(node ast.InterfaceDecl) {
 	immut_fields := if node.mut_pos < 0 { node.fields } else { node.fields[..node.mut_pos] }
 	mut_fields := if node.mut_pos < 0 { []ast.StructField{} } else { node.fields[node.mut_pos..] }
 
-	mut immut_methods := node.methods
+	mut immut_methods := node.methods.clone()
 	mut mut_methods := []ast.FnDecl{}
 	for i, method in node.methods {
 		if method.params[0].is_mut {
-			immut_methods = node.methods[..i]
+			immut_methods = node.methods[..i].clone()
-			mut_methods = node.methods[i..]
+			mut_methods = node.methods[i..].clone()
 			break
 		}
 	}

vlib/v/gen/c/cgen.v

@@ -1030,7 +1030,7 @@ fn (mut g Gen) register_result(t ast.Type) string {
 fn (mut g Gen) write_optionals() {
 	mut done := []string{}
 	rlock g.done_optionals {
-		done = g.done_optionals
+		done = g.done_optionals.clone()
 	}
 	for base, styp in g.optionals {
 		if base in done {
@@ -5814,7 +5814,7 @@ static inline __shared__$interface_name ${shared_fn_name}(__shared__$cctype* x)
 					}
 				}
 			}
-			mut methods := st_sym.methods
+			mut methods := st_sym.methods.clone()
 			method_names := methods.map(it.name)
 			match st_sym.info {
 				ast.Struct, ast.Interface, ast.SumType {

vlib/v/gen/golang/golang.v

@@ -1077,12 +1077,12 @@ pub fn (mut f Gen) interface_decl(node ast.InterfaceDecl) {
 	immut_fields := if node.mut_pos < 0 { node.fields } else { node.fields[..node.mut_pos] }
 	mut_fields := if node.mut_pos < 0 { []ast.StructField{} } else { node.fields[node.mut_pos..] }
 
-	mut immut_methods := node.methods
+	mut immut_methods := node.methods.clone()
 	mut mut_methods := []ast.FnDecl{}
 	for i, method in node.methods {
 		if method.params[0].is_mut {
-			immut_methods = node.methods[..i]
+			immut_methods = node.methods[..i].clone()
-			mut_methods = node.methods[i..]
+			mut_methods = node.methods[i..].clone()
 			break
 		}
 	}

vlib/v/gen/js/fn.v

@@ -675,7 +675,7 @@ fn (mut g JsGen) gen_method_decl(it ast.FnDecl, typ FnGenType) {
 			g.push_pub_var(name)
 		}
 	}
-	mut args := it.params
+	args := it.params
 
 	g.fn_args(args, it.is_variadic)
 	g.writeln(') {')
@@ -808,7 +808,7 @@ fn (mut g JsGen) gen_anon_fn(mut fun ast.AnonFn) {
 
 	g.write('return function (')
 
-	mut args := it.params
+	args := it.params
 
 	g.fn_args(args, it.is_variadic)
 	g.writeln(') {')

vlib/v/parser/assign.v

@@ -6,7 +6,7 @@ module parser
 import v.ast
 
 fn (mut p Parser) assign_stmt() ast.Stmt {
-	mut defer_vars := p.defer_vars
+	mut defer_vars := p.defer_vars.clone()
 	p.defer_vars = []ast.Ident{}
 
 	exprs, comments := p.expr_list()

vlib/v/parser/fn.v

@@ -728,7 +728,7 @@ fn (mut p Parser) anon_fn() ast.AnonFn {
 		tmp := p.label_names
 		p.label_names = []
 		stmts = p.parse_block_no_scope(false)
-		label_names = p.label_names
+		label_names = p.label_names.clone()
 		p.label_names = tmp
 	}
 	p.cur_fn_name = keep_fn_name

vlib/v/parser/parser.v

@@ -327,9 +327,9 @@ pub fn (mut p Parser) parse() &ast.File {
 	}
 	p.scope.end_pos = p.tok.pos
 
-	mut errors := p.errors
+	mut errors := p.errors.clone()
-	mut warnings := p.warnings
+	mut warnings := p.warnings.clone()
-	mut notices := p.notices
+	mut notices := p.notices.clone()
 
 	if p.pref.check_only {
 		errors << p.scanner.errors
@@ -2001,7 +2001,7 @@ fn (mut p Parser) parse_multi_expr(is_top_level bool) ast.Stmt {
 	tok := p.tok
 	mut pos := tok.pos()
 
-	mut defer_vars := p.defer_vars
+	mut defer_vars := p.defer_vars.clone()
 	p.defer_vars = []ast.Ident{}
 
 	left, left_comments := p.expr_list()
@@ -3374,7 +3374,7 @@ fn (mut p Parser) const_decl() ast.ConstDecl {
 	p.top_level_statement_start()
 	mut attrs := []ast.Attr{}
 	if p.attrs.len > 0 {
-		attrs = p.attrs
+		attrs = p.attrs.clone()
 		p.attrs = []
 	}
 	mut is_markused := false
@@ -3491,7 +3491,7 @@ fn (mut p Parser) return_stmt() ast.Return {
 fn (mut p Parser) global_decl() ast.GlobalDecl {
 	mut attrs := []ast.Attr{}
 	if p.attrs.len > 0 {
-		attrs = p.attrs
+		attrs = p.attrs.clone()
 		p.attrs = []
 	}
 

vlib/v/tests/shared_elem_test.v

@@ -64,7 +64,7 @@ struct Efg {
 
 fn test_shared_auto_init_array() {
 	e := Efg{}
-	shared a := e.a
+	shared a := unsafe { e.a }
 	lock a {
 		a << 23.0625
 		a << -133.25
@@ -81,11 +81,11 @@ fn test_shared_array_in_struct() {
 		a: [1.25, 2.75, 7, 13.0625]
 		i: 12
 	}
-	shared t := x.a
+	shared t := unsafe { x.a }
 	lock t {
 		t[2] = -1.125
 	}
-	shared tt := x.a
+	shared tt := unsafe { x.a }
 	v := rlock tt {
 		tt[3]
 	}