Store UNICODE_VERSION as a tuple

Remove the UnicodeVersion struct containing
major, minor and update fields and replace it with
a 3-tuple containing the version number.
As the value of each field is limited to 255
use u8 to store them.

src/libcore/char/mod.rs

@@ -37,8 +37,6 @@ pub use self::decode::{decode_utf16, DecodeUtf16, DecodeUtf16Error};
 
 // unstable re-exports
 #[unstable(feature = "unicode_version", issue = "49726")]
-pub use crate::unicode::version::UnicodeVersion;
-#[unstable(feature = "unicode_version", issue = "49726")]
 pub use crate::unicode::UNICODE_VERSION;
 
 use crate::fmt::{self, Write};

src/libcore/unicode/mod.rs

@@ -3,19 +3,14 @@
 
 pub(crate) mod printable;
 mod unicode_data;
-pub(crate) mod version;
-
-use version::UnicodeVersion;
 
 /// The version of [Unicode](http://www.unicode.org/) that the Unicode parts of
 /// `char` and `str` methods are based on.
+///
+/// The version numbering scheme is explained in
+/// [Unicode 11.0 or later, Section 3.1 Versions of the Unicode Standard](https://www.unicode.org/versions/Unicode11.0.0/ch03.pdf#page=4).
 #[unstable(feature = "unicode_version", issue = "49726")]
-pub const UNICODE_VERSION: UnicodeVersion = UnicodeVersion {
-    major: unicode_data::UNICODE_VERSION.0,
-    minor: unicode_data::UNICODE_VERSION.1,
-    micro: unicode_data::UNICODE_VERSION.2,
-    _priv: (),
-};
+pub const UNICODE_VERSION: (u8, u8, u8) = unicode_data::UNICODE_VERSION;
 
 // For use in liballoc, not re-exported in libstd.
 pub mod derived_property {

src/libcore/unicode/unicode_data.rs

@@ -94,7 +94,7 @@ fn skip_search<const SOR: usize, const OFFSETS: usize>(
     offset_idx % 2 == 1
 }
 
-pub const UNICODE_VERSION: (u32, u32, u32) = (13, 0, 0);
+pub const UNICODE_VERSION: (u8, u8, u8) = (13, 0, 0);
 
 #[rustfmt::skip]
 pub mod alphabetic {

src/test/ui/char_unicode.rs

@@ -7,6 +7,6 @@ pub fn main() {
     check(std::char::UNICODE_VERSION);
 }
 
-pub fn check(unicode_version: std::char::UnicodeVersion) {
-    assert!(unicode_version.major >= 10);
+pub fn check(unicode_version: (u8, u8, u8)) {
+    assert!(unicode_version.0 >= 10);
 }

src/tools/unicode-table-generator/src/main.rs

@@ -295,7 +295,7 @@ fn main() {
 
 fn version() -> String {
     let mut out = String::new();
-    out.push_str("pub const UNICODE_VERSION: (u32, u32, u32) = ");
+    out.push_str("pub const UNICODE_VERSION: (u8, u8, u8) = ");
 
     let readme =
         std::fs::read_to_string(std::path::Path::new(UNICODE_DIRECTORY).join("ReadMe.txt"))