From 9d3bef15e43c7ae3a43205a4c386f16ac09d4524 Mon Sep 17 00:00:00 2001
From: Turiiya <34311583+ttytm@users.noreply.github.com>
Date: Thu, 25 Apr 2024 01:14:42 +0200
Subject: [PATCH] checker: turn array assign warning into error (#21341)

---
 vlib/v/checker/assign.v                       | 22 +++++--------------
 vlib/v/checker/tests/array_assign_err.out     |  2 +-
 .../checker/tests/array_or_map_assign_err.out |  7 ------
 3 files changed, 6 insertions(+), 25 deletions(-)

diff --git a/vlib/v/checker/assign.v b/vlib/v/checker/assign.v
index 52f1eda91..9c766c6cc 100644
--- a/vlib/v/checker/assign.v
+++ b/vlib/v/checker/assign.v
@@ -498,26 +498,14 @@ 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)
 
-		old_assign_error_condition := 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
-		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 ${node.op.str()} array1` (or use `unsafe`)',
-				node.pos)
-		}
-		// Do not allow `a = val.array_field`, only `a = val.array_field.clone()`
-		// TODO: turn this warning into an error after 2022/09/24
-		// TODO: and remove the less strict check from above.
 		if left_sym.kind == .array && !c.inside_unsafe && right_sym.kind == .array
 			&& left is ast.Ident && !left.is_blank_ident() && right in [ast.Ident, ast.SelectorExpr]
 			&& ((node.op == .decl_assign && left.is_mut) || node.op == .assign) {
-			// no point to show the notice, if the old error was already shown:
-			if !old_assign_error_condition {
-				mut_str := if node.op == .decl_assign { 'mut ' } else { '' }
-				c.warn('use `${mut_str}array2 ${node.op.str()} array1.clone()` instead of `${mut_str}array2 ${node.op.str()} array1` (or use `unsafe`)',
-					node.pos)
-			}
+			// Do not allow direct array assignments outside unsafe.
+			// E.g.: `a2 = a1` wants `a2 = a1.clone()`, `a = val.arr_field` wants `a = val.arr_field.clone()`
+			mut_str := if node.op == .decl_assign { 'mut ' } else { '' }
+			c.error('use `${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 {
 			right_info := right_sym.info as ast.Array
diff --git a/vlib/v/checker/tests/array_assign_err.out b/vlib/v/checker/tests/array_assign_err.out
index f68603df2..a6f69cf58 100644
--- a/vlib/v/checker/tests/array_assign_err.out
+++ b/vlib/v/checker/tests/array_assign_err.out
@@ -1,4 +1,4 @@
-vlib/v/checker/tests/array_assign_err.vv:8:8: warning: use `mut array2 := array1.clone()` instead of `mut array2 := array1` (or use `unsafe`)
+vlib/v/checker/tests/array_assign_err.vv:8:8: error: 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
diff --git a/vlib/v/checker/tests/array_or_map_assign_err.out b/vlib/v/checker/tests/array_or_map_assign_err.out
index c1788de34..853e2fc78 100644
--- a/vlib/v/checker/tests/array_or_map_assign_err.out
+++ b/vlib/v/checker/tests/array_or_map_assign_err.out
@@ -1,10 +1,3 @@
-vlib/v/checker/tests/array_or_map_assign_err.vv:3:5: error: use `array2 := array1.clone()` instead of `array2 := array1` (or use `unsafe`)
-    1 | fn main() {
-    2 |     a1 := [1, 2, 3]
-    3 |     a2 := a1
-      |        ~~
-    4 |     mut a3 := []int{}
-    5 |     a3 = a1
 vlib/v/checker/tests/array_or_map_assign_err.vv:5:5: error: use `array2 = array1.clone()` instead of `array2 = array1` (or use `unsafe`)
     3 |     a2 := a1
     4 |     mut a3 := []int{}
-- 
2.39.5