v.builder, builtin: use ANSI encoding for the .rsp file under Windows; add builtin string_to_ansi_not_null_terminated + tests (#22409)

vlib/builtin/utf8.c.v

@@ -2,6 +2,7 @@ module builtin
 
 import strings
 
+const cp_acp = 0
 const cp_utf8 = 65001
 
 // to_wide returns a pointer to an UTF-16 version of the string receiver.
@@ -92,3 +93,27 @@ pub fn string_from_wide2(_wstr &u16, len int) string {
 		return res
 	}
 }
+
+// wide_to_ansi create an ANSI string, given a windows
+// style string, encoded in UTF-16.
+// It use CP_ACP, which is ANSI code page identifier, as dest encoding.
+// NOTE: It return a vstring(encoded in UTF-8) []u8 under Linux.
+pub fn wide_to_ansi(_wstr &u16) []u8 {
+	$if windows {
+		num_bytes := C.WideCharToMultiByte(cp_acp, 0, _wstr, -1, 0, 0, 0, 0)
+		if num_bytes != 0 {
+			mut str_to := []u8{len: num_bytes}
+			C.WideCharToMultiByte(cp_acp, 0, _wstr, -1, &char(str_to.data), str_to.len,
+				0, 0)
+			return str_to
+		} else {
+			return []u8{}
+		}
+	} $else {
+		s := unsafe { string_from_wide(_wstr) }
+		mut str_to := []u8{len: s.len + 1}
+		unsafe { vmemcpy(str_to.data, s.str, s.len) }
+		return str_to
+	}
+	return []u8{} // TODO: remove this, bug?
+}

vlib/builtin/utf8.v

@@ -184,3 +184,13 @@ pub fn utf8_str_visible_length(s string) int {
 	}
 	return l
 }
+
+// string_to_ansi_not_null_terminated returns an ANSI version of the string `_str`.
+// NOTE: This is most useful for converting a vstring to an ANSI string under Windows.
+// NOTE: The ANSI string return is not null-terminated, then you can use `os.write_file_array` write an ANSI file.
+pub fn string_to_ansi_not_null_terminated(_str string) []u8 {
+	wstr := _str.to_wide()
+	mut ansi := wide_to_ansi(wstr)
+	ansi.pop() // remove tailing zero
+	return ansi
+}

vlib/builtin/utf8_test.v

@@ -76,3 +76,12 @@ fn test_reverse_cyrillic_with_string_from_wide() {
 	z := unsafe { string_from_wide(ws) }
 	assert z == s
 }
+
+fn test_wide_to_ansi() {
+	ws := 'abc'.to_wide()
+	assert wide_to_ansi(ws) == [u8(97), 98, 99, 0]
+}
+
+fn test_string_to_ansi_not_null_terminated() {
+	assert string_to_ansi_not_null_terminated('abc') == [u8(97), 98, 99]
+}

vlib/v/builder/cc.v

@@ -666,8 +666,14 @@ pub fn (mut v Builder) cc() {
 			response_file_content = str_args.replace('\\', '\\\\')
 			rspexpr := '@${response_file}'
 			cmd = '${v.quote_compiler_name(ccompiler)} ${os.quoted_path(rspexpr)}'
-			os.write_file(response_file, response_file_content) or {
-				verror('Unable to write to C response file "${response_file}"')
+			$if windows {
+				os.write_file_array(response_file, string_to_ansi_not_null_terminated(response_file_content)) or {
+					verror('Unable to write to C response file "${response_file}"')
+				}
+			} $else {
+				os.write_file(response_file, response_file_content) or {
+					verror('Unable to write to C response file "${response_file}"')
+				}
 			}
 		}
 		if !v.ccoptions.debug_mode {

vlib/v/builder/msvc_windows.v

@@ -355,9 +355,9 @@ pub fn (mut v Builder) cc_msvc() {
 		a << env_ldflags
 	}
 	v.dump_c_options(a)
-	args := '\xEF\xBB\xBF' + a.join(' ')
+	args := a.join(' ')
 	// write args to a file so that we dont smash createprocess
-	os.write_file(out_name_cmd_line, args) or {
+	os.write_file_array(out_name_cmd_line, string_to_ansi_not_null_terminated(args)) or {
 		verror('Unable to write response file to "${out_name_cmd_line}"')
 	}
 	cmd := '"${r.full_cl_exe_path}" "@${out_name_cmd_line}"'