checker: do not allow direct initialization of builtin types (s := string{})

vlib/encoding/base64/base64.v

@@ -24,7 +24,7 @@ pub fn decode(data string) []byte {
 	unsafe {
 		buffer := malloc(size)
 		n := decode_in_buffer(data, buffer)
-		return array{element_size: 1, data: buffer, len: n, cap: size}
+		return buffer.vbytes(n)
 	}
 }
 
@@ -70,7 +70,8 @@ fn alloc_and_encode(src byteptr, len int) string {
 // the a base64 url encoded `string` passed in `data`.
 pub fn url_decode(data string) []byte {
 	mut result := data.replace_each(['-', '+', '_', '/'])
-	match result.len % 4 { // Pad with trailing '='s
+	match result.len % 4 {
+		// Pad with trailing '='s
 		2 { result += '==' } // 2 pad chars
 		3 { result += '=' } // 1 pad char
 		else {} // no padding
@@ -81,7 +82,8 @@ pub fn url_decode(data string) []byte {
 // url_decode_str is the string variant of url_decode
 pub fn url_decode_str(data string) string {
 	mut result := data.replace_each(['-', '+', '_', '/'])
-	match result.len % 4 { // Pad with trailing '='s
+	match result.len % 4 {
+		// Pad with trailing '='s
 		2 { result += '==' } // 2 pad chars
 		3 { result += '=' } // 1 pad char
 		else {} // no padding
@@ -132,19 +134,19 @@ pub fn decode_in_buffer(data &string, buffer byteptr) int {
 		mut char_c := 0
 		mut char_d := 0
 		if i < input_length {
-			char_a = index[unsafe { d[i] }]
+			char_a = base64.index[unsafe { d[i] }]
 			i++
 		}
 		if i < input_length {
-			char_b = index[unsafe { d[i] }]
+			char_b = base64.index[unsafe { d[i] }]
 			i++
 		}
 		if i < input_length {
-			char_c = index[unsafe { d[i] }]
+			char_c = base64.index[unsafe { d[i] }]
 			i++
 		}
 		if i < input_length {
-			char_d = index[unsafe { d[i] }]
+			char_d = base64.index[unsafe { d[i] }]
 			i++
 		}
 
@@ -180,7 +182,7 @@ fn encode_from_buffer(dest byteptr, src byteptr, src_len int) int {
 
 	mut d := src
 	mut b := dest
-	mut etable := byteptr(enc_table.str)
+	mut etable := byteptr(base64.enc_table.str)
 	for i < input_length {
 		mut octet_a := 0
 		mut octet_b := 0
@@ -210,7 +212,7 @@ fn encode_from_buffer(dest byteptr, src byteptr, src_len int) int {
 		j += 4
 	}
 
-	padding_length := ending_table[input_length % 3]
+	padding_length := base64.ending_table[input_length % 3]
 	for i = 0; i < padding_length; i++ {
 		unsafe {
 			b[output_length - 1 - i] = `=`

vlib/os/os_c.v

@@ -483,7 +483,7 @@ pub fn read_file_array<T>(path string) []T {
 	a := T{}
 	tsize := int(sizeof(a))
 	// prepare for reading, get current file size
-	mut fp := vfopen(path, 'rb') or { return array{} }
+	mut fp := vfopen(path, 'rb') or { return []T{} }
 	C.fseek(fp, 0, C.SEEK_END)
 	fsize := C.ftell(fp)
 	C.rewind(fp)
@@ -492,13 +492,15 @@ pub fn read_file_array<T>(path string) []T {
 	buf := unsafe { malloc(fsize) }
 	C.fread(buf, fsize, 1, fp)
 	C.fclose(fp)
-	return array{
+	return unsafe {
+		array{
 			element_size: tsize
 			data: buf
 			len: len
 			cap: len
 		}
 	}
+}
 
 pub fn on_segfault(f voidptr) {
 	$if windows {

vlib/v/ast/ast.v

@@ -1248,7 +1248,6 @@ pub fn (expr Expr) is_blank_ident() bool {
 pub fn (expr Expr) position() token.Position {
 	// all uncommented have to be implemented
 	match expr {
-		// KEKW2
 		AnonFn {
 			return expr.decl.pos
 		}

vlib/v/checker/checker.v

@@ -463,6 +463,16 @@ pub fn (mut c Checker) struct_init(mut struct_init ast.StructInit) table.Type {
 	utyp := c.unwrap_generic(struct_init.typ)
 	c.ensure_type_exists(utyp, struct_init.pos) or {}
 	type_sym := c.table.get_type_symbol(utyp)
+	// Make sure the first letter is capital, do not allow e.g. `x := string{}`,
+	// but `x := T{}` is ok.
+	if !c.is_builtin_mod && !c.inside_unsafe && type_sym.language == .v
+		&& c.cur_generic_types.len == 0 {
+		pos := type_sym.name.last_index('.') or { -1 }
+		first_letter := type_sym.name[pos + 1]
+		if !first_letter.is_capital() {
+			c.error('cannot initialize builtin type `$type_sym.name`', struct_init.pos)
+		}
+	}
 	if type_sym.kind == .sum_type && struct_init.fields.len == 1 {
 		sexpr := struct_init.fields[0].expr.str()
 		c.error('cast to sum type using `${type_sym.name}($sexpr)` not `$type_sym.name{$sexpr}`',

vlib/v/checker/tests/check_generic_int_init.out

@@ -1,4 +1,4 @@
-vlib/v/checker/tests/check_generic_int_init.vv:2:9: error: type `int` is private
+vlib/v/checker/tests/check_generic_int_init.vv:2:9: error: cannot initialize builtin type `int`
     1 | fn test<T>() T {
     2 |     return T{}
       |            ~~~

vlib/v/tests/comptime_if_expr_test.v

@@ -31,7 +31,7 @@ fn test_ct_expressions() {
 
 fn generic_t_is<O>() O {
 	$if O is string {
-		return 'It\'s a string!'
+		return "It's a string!"
 	} $else {
 		return O{}
 	}
@@ -41,13 +41,13 @@ fn generic_t_is<O>() O {
 struct GenericTIsTest {}
 
 fn test_generic_t_is() {
-	assert generic_t_is<string>() == 'It\'s a string!'
+	assert generic_t_is<string>() == "It's a string!"
 	assert generic_t_is<GenericTIsTest>() == GenericTIsTest{}
 }
 
 fn generic_t_is2<T>() ?T {
 	$if T is string {
-		return 'It\'s a string!'
+		return "It's a string!"
 	} $else {
 		return T{}
 	}
@@ -62,7 +62,7 @@ fn test_generic_t_is2() {
 		assert false
 		GenericTIsTest{}
 	}
-	assert res == 'It\'s a string!'
+	assert res == "It's a string!"
 	assert res2 == GenericTIsTest{}
 }
 
@@ -123,4 +123,3 @@ fn test_generic_t_is_with_else_if() {
 	x := generic_t_is_with_else_if<User>()
 	assert x == ['name', 'age']
 }
-