joshuamegnauth54 · Nov 12, 2026
diff --git a/crates/stdlib/src/unicodedata.rs b/crates/stdlib/src/unicodedata.rs
@@ -31,6 +31,9 @@ impl<'a> TryFromBorrowedObject<'a> for NormalizeFormArg {
 
 #[pymodule]
 mod unicodedata {
+    use alloc::ffi::CString;
+    use rustpython_unicode::{UNICODE_VERSION, UNICODE_VERSION_LEGACY};
+
     use super::{NormalizeFormArg, unicode_core};
     use crate::vm::{
         Py, PyObject, PyObjectRef, PyPayload, PyResult, VirtualMachine,
@@ -312,23 +315,25 @@ mod unicodedata {
         inner: unicode_core::Ucd,
         /// Owns the bytes `unidata_version` points at.
         #[expect(dead_code, reason = "keeps the version string alive")]
-        version_owner: alloc::ffi::CString,
+        version_owner: CString,
         #[pymember]
         unidata_version: crate::vm::builtins::descriptor::CStrMember,
     }
 
     impl Ucd {
         pub(super) fn new(modern: bool) -> Self {
+            let inner = unicode_core::Ucd::new(modern);
             let text = if modern {
-                unicode_core::unicode_version()
+                UNICODE_VERSION
             } else {
-                "3.2.0".to_owned()
+                UNICODE_VERSION_LEGACY
             };
-            let version_owner = alloc::ffi::CString::new(text).unwrap_or_default();
+            let version_owner = CString::new(text)
+                .expect("Embedded Unicode version string should never have internal NULs");
             let unidata_version =
                 crate::vm::builtins::descriptor::CStrMember::new(version_owner.as_ptr());
             Self {
-                inner: unicode_core::Ucd::new(modern),
+                inner,
                 version_owner,
                 unidata_version,
             }
@@ -503,6 +508,6 @@ mod unicodedata {
 
     #[pyattr]
     fn unidata_version(_vm: &VirtualMachine) -> String {
-        unicode_core::unicode_version()
+        UNICODE_VERSION.into()
     }
 }
diff --git a/crates/unicode/build.rs b/crates/unicode/build.rs
@@ -457,17 +457,6 @@ fn generate_algo_names(names: Vec<(u32, Box<str>)>) {
     );
 }
 
-/// Block names and ranges from the same Unicode release as the other latest tables.
-fn generate_blocks() {
-    let mut writer = open_writer("blocks.rs");
-    write_slice_pre(&mut writer, "BLOCKS", "(u32, u32, &str)");
-    for line in UnicodeLineReader::from_file_name("Blocks.txt", true) {
-        let name = line.field(NonZeroUsize::new(1).unwrap(), None);
-        writeln!(writer, "({}, {}, {name:?}),", line.start, line.end).unwrap();
-    }
-    write_slice_post(&mut writer);
-}
-
 /// Formal name aliases (`NameAliases.txt`) and named sequences
 /// (`NamedSequences.txt`).  `unicodedata.lookup` consults both; `\N{}`
 /// accepts only a single character, so named sequences stay out of
@@ -1024,6 +1013,42 @@ fn generate_numeric_type_3_2(rx: mpsc::Receiver<NumericTypeDiffs>) {
     );
 }
 
+/// Block names and ranges from the same Unicode release as the other latest tables.
+fn generate_blocks() {
+    let mut writer = open_writer("blocks.rs");
+    write_slice_pre(&mut writer, "BLOCKS", "(u32, u32, &str)");
+    for line in UnicodeLineReader::from_file_name("Blocks.txt", true) {
+        let name = line.field(NonZeroUsize::new(1).unwrap(), None);
+        writeln!(writer, "({}, {}, {name:?}),", line.start, line.end).unwrap();
+    }
+    write_slice_post(&mut writer);
+}
+
+/// The version string of the latest Unicode database bundled with the standard
+/// library (`unicodedata.unidata_version`).
+pub fn unicode_version() {
+    // Report the vendored database version, not the compiler's Unicode version.
+    let version = open_reader("NameAliases.txt", true)
+        .lines()
+        .next()
+        .expect("should be able to read from vendored NameAliases.txt")
+        .expect("vendored NameAliases.txt must start with its Unicode version");
+    let version = version
+        .strip_prefix("# NameAliases-")
+        .expect("NameAliases.txt doesn't start with version info")
+        .strip_suffix(".txt")
+        .unwrap()
+        .trim();
+
+    println!("cargo:rustc-env=UNICODE_VERSION={version}");
+}
+
+/// Parsers that are standalone and read small files.
+fn small_parsers() {
+    generate_blocks();
+    unicode_version();
+}
+
 /// Run each UCD parser in parallel.
 fn drive_parsers() {
     let parsers = [
@@ -1034,7 +1059,7 @@ fn drive_parsers() {
         binary_props_3_2,
         combining_class_3_2,
         generate_name_lookups,
-        generate_blocks,
+        small_parsers,
     ];
 
     let mut handles = Vec::with_capacity(parsers.len() + 2);

diff --git a/crates/unicode/src/data.rs b/crates/unicode/src/data.rs
@@ -19,6 +19,9 @@ use icu_properties::props::{
 };
 use rustpython_wtf8::CodePoint;
 
+pub const UNICODE_VERSION: &str = env!("UNICODE_VERSION");
+pub const UNICODE_VERSION_LEGACY: &str = "3.2.0";
+
 // Latest Unicode
 include!(concat!(env!("OUT_DIR"), "/generated/blocks.rs"));
 include!(concat!(env!("OUT_DIR"), "/generated/algo_names.rs"));
@@ -237,20 +240,6 @@ pub fn membership_3_2(ch: u32) -> bool {
         .is_ok()
 }
 
-/// The version string of the latest Unicode database bundled with the standard
-/// library (`unicodedata.unidata_version`).
-#[must_use]
-pub fn unicode_version() -> String {
-    // Report the vendored database version, not the compiler's Unicode version.
-    include_str!("../unicode/latest/NameAliases.txt")
-        .lines()
-        .next()
-        .and_then(|header| header.strip_prefix("# NameAliases-"))
-        .and_then(|header| header.strip_suffix(".txt"))
-        .expect("vendored NameAliases.txt must start with its Unicode version")
-        .into()
-}
-
 /// Look up a name in the latest UCD (`unicodedata.lookup`).
 ///
 /// Named sequences are included; `\N{...}` should use [`lookup_character`]
@@ -546,9 +535,9 @@ impl Ucd {
     #[must_use]
     pub fn unidata_version(&self) -> String {
         if self.modern {
-            unicode_version()
+            UNICODE_VERSION.into()
         } else {
-            "3.2.0".into()
+            UNICODE_VERSION_LEGACY.into()
         }
     }
 }
@@ -565,7 +554,7 @@ mod tests {
 
     #[test]
     fn version_matches_vendored_database() {
-        assert_eq!(super::unicode_version(), "17.0.0");
+        assert_eq!(super::UNICODE_VERSION, "17.0.0");
         assert_eq!(Ucd::new(true).unidata_version(), "17.0.0");
     }
 

diff --git a/crates/unicode/src/lib.rs b/crates/unicode/src/lib.rs
@@ -16,5 +16,8 @@ pub mod grapheme;
 pub mod identifier;
 pub mod normalize;
 
-pub use data::{LookupResult, Ucd, character_name, lookup_character, lookup_name, unicode_version};
+pub use data::{
+    LookupResult, UNICODE_VERSION, UNICODE_VERSION_LEGACY, Ucd, character_name, lookup_character,
+    lookup_name,
+};
 pub use normalize::{NormalizeForm, is_normalized, normalize};