checker: error on a.slice(x,y) outside `builtin`

examples/flappylearning/modules/neuroevolution/neuronevolution.v

@@ -50,7 +50,7 @@ mut:
 fn (mut n Network) populate(network []int) {
 	assert network.len >= 2
 	input := network[0]
-	hiddens := network.slice(1, network.len - 1)
+	hiddens := network[1..network.len-1]
 	output := network[network.len - 1]
 	mut index := 0
 	mut previous_neurons := 0

vlib/builtin/array_test.v

@@ -255,9 +255,9 @@ fn test_left() {
 
 fn test_slice() {
 	a := [1, 2, 3, 4]
-	b := a.slice(2, 4)
+	b := a[2..4]
 	assert b.len == 2
-	assert a.slice(1, 2).len == 1
+	assert a[1..2].len == 1
 	assert a.len == 4
 }
 
@@ -355,7 +355,7 @@ fn test_clone() {
 	assert nums2.len == 5
 	assert nums.str() == '[1, 2, 3, 4, 100]'
 	assert nums2.str() == '[1, 2, 3, 4, 100]'
-	assert nums.slice(1, 3).str() == '[2, 3]'
+	assert nums[1..3].str() == '[2, 3]'
 }
 
 /*

vlib/crypto/aes/aes_cbc.v

@@ -94,21 +94,20 @@ pub fn (mut x AesCbc) decrypt_blocks(mut dst []byte, src []byte) {
 	mut start := end - x.block_size
 	mut prev := start - x.block_size
 	// Copy the last block of ciphertext in preparation as the new iv.
-	copy(x.tmp, src.slice(start, end))
+	copy(x.tmp, src[start..end])
 	// Loop over all but the first block.
 	for start > 0 {
-		mut src_chunk := src.slice(start, end)
-		x.b.decrypt(mut (*dst).slice(start, end), mut src_chunk)
-		cipher.xor_bytes(mut (*dst).slice(start, end), (*dst).slice(start, end), src.slice(prev,
-			start))
+		mut src_chunk := src[start..end]
+		x.b.decrypt(mut (*dst)[start..end], mut src_chunk)
+		cipher.xor_bytes(mut (*dst)[start..end], (*dst)[start..end], src[prev..start])
 		end = start
 		start = prev
 		prev -= x.block_size
 	}
 	// The first block is special because it uses the saved iv.
-	mut src_chunk := src.slice(start, end)
-	x.b.decrypt(mut (*dst).slice(start, end), mut src_chunk)
-	cipher.xor_bytes(mut (*dst).slice(start, end), (*dst).slice(start, end), x.iv)
+	mut src_chunk := src[start..end]
+	x.b.decrypt(mut (*dst)[start..end], mut src_chunk)
+	cipher.xor_bytes(mut (*dst)[start..end], (*dst)[start..end], x.iv)
 	// Set the new iv to the first block we copied earlier.
 	x.iv = x.tmp
 	x.tmp = x.iv

vlib/crypto/aes/block_generic.v

@@ -41,9 +41,9 @@ import encoding.binary
 fn encrypt_block_generic(xk []u32, mut dst []byte, src []byte) {
 	_ = src[15] // early bounds check
 	mut s0 := binary.big_endian_u32(src[..4])
-	mut s1 := binary.big_endian_u32(src.slice(4, 8))
-	mut s2 := binary.big_endian_u32(src.slice(8, 12))
-	mut s3 := binary.big_endian_u32(src.slice(12, 16))
+	mut s1 := binary.big_endian_u32(src[4..8])
+	mut s2 := binary.big_endian_u32(src[8..12])
+	mut s3 := binary.big_endian_u32(src[12..16])
 	// First round just XORs input with key.
 	s0 ^= xk[0]
 	s1 ^= xk[1]
@@ -83,18 +83,18 @@ fn encrypt_block_generic(xk []u32, mut dst []byte, src []byte) {
 	s3 ^= xk[k + 3]
 	_ := dst[15] // early bounds check
 	binary.big_endian_put_u32(mut (*dst)[0..4], s0)
-	binary.big_endian_put_u32(mut (*dst).slice(4, 8), s1)
-	binary.big_endian_put_u32(mut (*dst).slice(8, 12), s2)
-	binary.big_endian_put_u32(mut (*dst).slice(12, 16), s3)
+	binary.big_endian_put_u32(mut (*dst)[4..8], s1)
+	binary.big_endian_put_u32(mut (*dst)[8..12], s2)
+	binary.big_endian_put_u32(mut (*dst)[12..16], s3)
 }
 
 // Decrypt one block from src into dst, using the expanded key xk.
 fn decrypt_block_generic(xk []u32, mut dst []byte, src []byte) {
 	_ = src[15] // early bounds check
 	mut s0 := binary.big_endian_u32(src[0..4])
-	mut s1 := binary.big_endian_u32(src.slice(4, 8))
-	mut s2 := binary.big_endian_u32(src.slice(8, 12))
-	mut s3 := binary.big_endian_u32(src.slice(12, 16))
+	mut s1 := binary.big_endian_u32(src[4..8])
+	mut s2 := binary.big_endian_u32(src[8..12])
+	mut s3 := binary.big_endian_u32(src[12..16])
 	// First round just XORs input with key.
 	s0 ^= xk[0]
 	s1 ^= xk[1]
@@ -134,9 +134,9 @@ fn decrypt_block_generic(xk []u32, mut dst []byte, src []byte) {
 	s3 ^= xk[k + 3]
 	_ = dst[15] // early bounds check
 	binary.big_endian_put_u32(mut (*dst)[..4], s0)
-	binary.big_endian_put_u32(mut (*dst).slice(4, 8), s1)
-	binary.big_endian_put_u32(mut (*dst).slice(8, 12), s2)
-	binary.big_endian_put_u32(mut (*dst).slice(12, 16), s3)
+	binary.big_endian_put_u32(mut (*dst)[4..8], s1)
+	binary.big_endian_put_u32(mut (*dst)[8..12], s2)
+	binary.big_endian_put_u32(mut (*dst)[12..16], s3)
 }
 
 // Apply s_box0 to each byte in w.

vlib/v/checker/checker.v

@@ -1270,6 +1270,10 @@ pub fn (mut c Checker) call_method(mut call_expr ast.CallExpr) table.Type {
 		mut elem_typ := table.void_type
 		is_filter_map := method_name in ['filter', 'map']
 		is_sort := method_name == 'sort'
+		is_slice := method_name == 'slice'
+		if is_slice && !c.is_builtin_mod {
+			c.error('.slice() is a private method, use `x[start..end]` instead', call_expr.pos)
+		}
 		if is_filter_map || is_sort {
 			array_info := left_type_sym.info as table.Array
 			if is_filter_map {

vlib/v/checker/tests/method_array_slice.out

@@ -0,0 +1,7 @@
+vlib/v/checker/tests/method_array_slice.vv:5:12: error: .slice() is a private method, use `x[start..end]` instead
+    3 | fn main() {
+    4 |     a := os.args.clone()
+    5 |     println(a.slice(1))
+      |               ~~~~~~~~
+    6 |     println(a[1..])
+    7 | }

vlib/v/checker/tests/method_array_slice.vv

@@ -0,0 +1,7 @@
+import os
+
+fn main() {
+	a := os.args.clone()
+	println(a.slice(1))
+	println(a[1..])
+}