checker: warn about byte deprecation, when used as a fn parameter (#19629)

vlib/builtin/cfns_wrapper.c.v

@@ -3,7 +3,7 @@ module builtin
 // vstrlen returns the V length of the C string `s` (0 terminator is not counted).
 // The C string is expected to be a &byte pointer.
 [inline; unsafe]
-pub fn vstrlen(s &byte) int {
+pub fn vstrlen(s &u8) int {
 	return unsafe { C.strlen(&char(s)) }
 }
 

vlib/builtin/string_interpolation.v

@@ -64,7 +64,7 @@ pub fn (x StrIntpType) str() string {
 pub union StrIntpMem {
 pub mut:
 	d_c   u32
-	d_u8  byte
+	d_u8  u8
 	d_i8  i8
 	d_u16 u16
 	d_i16 i16
@@ -114,7 +114,7 @@ fn abs64(x i64) u64 {
 //---------------------------------------
 
 // convert from data format to compact u64
-pub fn get_str_intp_u64_format(fmt_type StrIntpType, in_width int, in_precision int, in_tail_zeros bool, in_sign bool, in_pad_ch byte, in_base int, in_upper_case bool) u64 {
+pub fn get_str_intp_u64_format(fmt_type StrIntpType, in_width int, in_precision int, in_tail_zeros bool, in_sign bool, in_pad_ch u8, in_base int, in_upper_case bool) u64 {
 	width := if in_width != 0 { abs64(in_width) } else { u64(0) }
 	allign := if in_width > 0 { u64(1 << 5) } else { u64(0) } // two bit 0 .left 1 .rigth, for now we use only one
 	upper_case := if in_upper_case { u64(1 << 7) } else { u64(0) }
@@ -131,7 +131,7 @@ pub fn get_str_intp_u64_format(fmt_type StrIntpType, in_width int, in_precision
 }
 
 // convert from data format to compact u32
-pub fn get_str_intp_u32_format(fmt_type StrIntpType, in_width int, in_precision int, in_tail_zeros bool, in_sign bool, in_pad_ch byte, in_base int, in_upper_case bool) u32 {
+pub fn get_str_intp_u32_format(fmt_type StrIntpType, in_width int, in_precision int, in_tail_zeros bool, in_sign bool, in_pad_ch u8, in_base int, in_upper_case bool) u32 {
 	width := if in_width != 0 { abs64(in_width) } else { u32(0) }
 	allign := if in_width > 0 { u32(1 << 5) } else { u32(0) } // two bit 0 .left 1 .rigth, for now we use only one
 	upper_case := if in_upper_case { u32(1 << 7) } else { u32(0) }

vlib/crypto/internal/subtle/comparison.v

@@ -1,7 +1,7 @@
 module subtle
 
 // constant_time_byte_eq returns 1 when x == y.
-pub fn constant_time_byte_eq(x byte, y byte) int {
+pub fn constant_time_byte_eq(x u8, y u8) int {
 	return int((u32(x ^ y) - 1) >> 31)
 }
 

vlib/db/mysql/stmt.c.v

@@ -188,7 +188,7 @@ pub fn (mut stmt Stmt) bind_bool(b &bool) {
 }
 
 // bind_byte binds a single byte value to the statement `stmt`
-pub fn (mut stmt Stmt) bind_byte(b &byte) {
+pub fn (mut stmt Stmt) bind_byte(b &u8) {
 	stmt.bind(mysql.mysql_type_tiny, b, 0)
 }
 

vlib/json/json_primitives.v

@@ -194,8 +194,8 @@ fn encode_i64(val i64) &C.cJSON {
 
 // TODO: remove when `byte` is removed
 [markused]
-fn encode_byte(root byte) &C.cJSON {
-	return encode_u8(u8(root))
+fn encode_byte(root u8) &C.cJSON {
+	return encode_u8(root)
 }
 
 [markused]

vlib/strings/builder.c.v

@@ -70,7 +70,7 @@ pub fn (mut b Builder) write_u8(data u8) {
 }
 
 // write_byte appends a single `data` byte to the accumulated buffer
-pub fn (mut b Builder) write_byte(data byte) {
+pub fn (mut b Builder) write_byte(data u8) {
 	b << data
 }
 

vlib/strings/builder.js.v

@@ -18,7 +18,7 @@ pub fn new_builder(initial_size int) Builder {
 	return []u8{cap: initial_size}
 }
 
-pub fn (mut b Builder) write_byte(data byte) {
+pub fn (mut b Builder) write_byte(data u8) {
 	b << data
 }
 

vlib/v/checker/fn.v

@@ -271,6 +271,9 @@ fn (mut c Checker) fn_decl(mut node ast.FnDecl) {
 			if c.check_import_sym_conflict(param.name) {
 				c.error('duplicate of an import symbol `${param.name}`', param.pos)
 			}
+			if arg_typ_sym.kind == .alias && arg_typ_sym.name == 'byte' {
+				c.warn('byte is deprecated, use u8 instead', param.type_pos)
+			}
 		}
 		if !node.is_method {
 			// Check if function name is already registered as imported module symbol

vlib/v/checker/tests/top_level_fn_builtin_decl_err.out

@@ -1,3 +1,10 @@
+vlib/v/checker/tests/top_level_fn_builtin_decl_err.vv:3:12: warning: byte is deprecated, use u8 instead
+    1 | 
+    2 | [inline]
+    3 | fn char(ch byte) fn (string) !(byte, string) {
+      |            ~~~~
+    4 |     return fn [ch] (input string) !(byte, string) {
+    5 |         return if input[0] == ch {
 vlib/v/checker/tests/top_level_fn_builtin_decl_err.vv:3:1: error: top level declaration cannot shadow builtin type
     1 | 
     2 | [inline]