checker: check for mut val in immutable obj (#8285)

cmd/tools/vtest-all.v

@@ -4,17 +4,38 @@ import os
 import term
 import time
 
-const vexe = os.getenv('VEXE')
+const (
-
+	vexe = os.getenv('VEXE')
-const vroot = os.dir(vexe)
+	vroot = os.dir(vexe)
-
+	args_string = os.args[1..].join(' ')
-const args_string = os.args[1..].join(' ')
+	vargs = args_string.all_before('test-all')
-
+)
-const vargs = args_string.all_before('test-all')
 
 fn main() {
-	commands := get_all_commands()
+	mut commands := get_all_commands()
-	commands.summary()
+	// summary
+	sw := time.new_stopwatch({})
+	for mut cmd in commands {
+		cmd.run()
+	}
+	spent := sw.elapsed().milliseconds()
+	oks := commands.filter(it.ecode == 0)
+	fails := commands.filter(it.ecode != 0)
+	println('')
+	println(term.header(term.colorize(term.yellow, term.colorize(term.bold, 'Summary of `v test-all`:')),
+		'-'))
+	println(term.colorize(term.yellow, 'Total runtime: $spent ms'))
+	for ocmd in oks {
+		msg := if ocmd.okmsg != '' { ocmd.okmsg } else { ocmd.line }
+		println(term.colorize(term.green, '>          OK: $msg '))
+	}
+	for fcmd in fails {
+		msg := if fcmd.errmsg != '' { fcmd.errmsg } else { fcmd.line }
+		println(term.colorize(term.red, '>      Failed: $msg '))
+	}
+	if fails.len > 0 {
+		exit(1)
+	}
 }
 
 struct Command {
@@ -80,28 +101,3 @@ fn (mut cmd Command) run() {
 	println(term.colorize(term.yellow, '> Running: "$cmd.line" took: $spent ms.'))
 	println('')
 }
-
-fn (commands []Command) summary() {
-	sw := time.new_stopwatch({})
-	for mut cmd in commands {
-		cmd.run()
-	}
-	spent := sw.elapsed().milliseconds()
-	oks := commands.filter(it.ecode == 0)
-	fails := commands.filter(it.ecode != 0)
-	println('')
-	println(term.header(term.colorize(term.yellow, term.colorize(term.bold, 'Summary of `v test-all`:')),
-		'-'))
-	println(term.colorize(term.yellow, 'Total runtime: $spent ms'))
-	for ocmd in oks {
-		msg := if ocmd.okmsg != '' { ocmd.okmsg } else { ocmd.line }
-		println(term.colorize(term.green, '>          OK: $msg '))
-	}
-	for fcmd in fails {
-		msg := if fcmd.errmsg != '' { fcmd.errmsg } else { fcmd.line }
-		println(term.colorize(term.red, '>      Failed: $msg '))
-	}
-	if fails.len > 0 {
-		exit(1)
-	}
-}

vlib/v/checker/checker.v

@@ -3079,6 +3079,26 @@ fn (mut c Checker) stmt(node ast.Stmt) {
 					}
 					if node.val_is_mut {
 						value_type = value_type.to_ptr()
+						match node.cond {
+							ast.Ident {
+								if node.cond.obj is ast.Var {
+									obj := node.cond.obj as ast.Var
+									if !obj.is_mut {
+										c.error('`$obj.name` is immutable, it cannot be changed',
+											node.cond.pos)
+									}
+								}
+							}
+							ast.ArrayInit {
+								c.error('array literal is immutable, it cannot be changed',
+									node.cond.pos)
+							}
+							ast.MapInit {
+								c.error('map literal is immutable, it cannot be changed',
+									node.cond.pos)
+							}
+							else {}
+						}
 					}
 					node.cond_type = typ
 					node.kind = sym.kind

vlib/v/checker/tests/for_in_mut_val_type.out

@@ -0,0 +1,42 @@
+vlib/v/checker/tests/for_in_mut_val_type.vv:3:15: error: `a1` is immutable, it cannot be changed
+    1 | fn main() {
+    2 |     a1 := [1, 2, 3]
+    3 |     for mut j in a1 {
+      |                  ~~
+    4 |         j *= 2
+    5 |     }
+vlib/v/checker/tests/for_in_mut_val_type.vv:7:15: error: `a2` is immutable, it cannot be changed
+    5 |     }
+    6 |     a2 := [1, 2, 3]!
+    7 |     for mut j in a2 {
+      |                  ~~
+    8 |         j *= 2
+    9 |     }
+vlib/v/checker/tests/for_in_mut_val_type.vv:11:18: error: `m` is immutable, it cannot be changed
+    9 |     }
+   10 |     m := {'aa': 1, 'bb': 2}
+   11 |     for _, mut j in m {
+      |                     ^
+   12 |         j *= 2
+   13 |     }
+vlib/v/checker/tests/for_in_mut_val_type.vv:14:15: error: array literal is immutable, it cannot be changed
+   12 |         j *= 2
+   13 |     }
+   14 |     for mut j in [1, 2, 3] {
+      |                  ~~~~~~~~~
+   15 |         j *= 2
+   16 |     }
+vlib/v/checker/tests/for_in_mut_val_type.vv:17:15: error: array literal is immutable, it cannot be changed
+   15 |         j *= 2
+   16 |     }
+   17 |     for mut j in [1, 2, 3]! {
+      |                  ~~~~~~~~~~
+   18 |         j *= 2
+   19 |     }
+vlib/v/checker/tests/for_in_mut_val_type.vv:20:19: error: map literal is immutable, it cannot be changed
+   18 |         j *= 2
+   19 |     }
+   20 |     for _, mut j in {'aa': 1, 'bb': 2} {
+      |                      ~~~~
+   21 |         j *= 2
+   22 |     }

vlib/v/checker/tests/for_in_mut_val_type.vv

@@ -0,0 +1,23 @@
+fn main() {
+	a1 := [1, 2, 3]
+	for mut j in a1 {
+		j *= 2
+	}
+	a2 := [1, 2, 3]!
+	for mut j in a2 {
+		j *= 2
+	}
+	m := {'aa': 1, 'bb': 2}
+	for _, mut j in m {
+		j *= 2
+	}
+	for mut j in [1, 2, 3] {
+		j *= 2
+	}
+	for mut j in [1, 2, 3]! {
+		j *= 2
+	}
+	for _, mut j in {'aa': 1, 'bb': 2} {
+		j *= 2
+	}
+}