RustPython · youknowone · Sep 1, 2026 · Aug 31, 2026 · Aug 31, 2026 · Sep 1, 2026
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/Cargo.toml b/Cargo.toml
@@ -215,7 +215,6 @@ dyn-clone = "1.0.10"
 exitcode = "1.1.2"
 flame = "0.2.2"
 flamer = "0.5"
-flate2 = { version = "1.1.9", default-features = false }
 # Bump only when the openssl crate bumps it
 foreign-types-shared = "0.1"
 gethostname = "1.0.2"
@@ -241,6 +240,7 @@ xz = "0.4.6-rc.0"
 xz-sys = "0.4.6-rc.0"
 libsqlite3-sys = "0.38"
 libz-rs-sys = "0.6"
+zlib-rs = { version = "=0.6.7", default-features = false, features = ["rust-allocator", "__internal-api"] }
 lock_api = "0.4"
 log = "0.4.30"
 lz4_flex = "0.13"

diff --git a/Lib/test/test_zlib.py b/Lib/test/test_zlib.py
@@ -489,7 +489,6 @@ def test_clear_unconsumed_tail(self):
         ddata += dco.decompress(dco.unconsumed_tail)
         self.assertEqual(dco.unconsumed_tail, b"")
 
-    @unittest.expectedFailure # TODO: RUSTPYTHON; Z_BLOCK support in flate2
     def test_flushes(self):
         # Test flush() with the various options, using all the
         # different levels in order to provide more variations.
@@ -809,7 +808,6 @@ def test_large_unconsumed_tail(self, size):
         finally:
             comp = uncomp = data = None
 
-    @unittest.expectedFailure # TODO: RUSTPYTHON; wbits=0 support in flate2
     def test_wbits(self):
         # wbits=0 only supported since zlib v1.2.3.5
         supports_wbits_0 = ZLIB_RUNTIME_VERSION_TUPLE >= (1, 2, 3, 5)

diff --git a/crates/common/Cargo.toml b/crates/common/Cargo.toml
@@ -14,9 +14,11 @@ binascii = ["dep:base64", "dep:crc32fast"]
 cjk-codecs = []
 inet = ["std"]
 json = ["dep:memchr", "std"]
+lzma = ["std", "dep:xz", "dep:xz-sys"]
 std = []
 threading = ["parking_lot", "std"]
 wasm_js = ["getrandom/wasm_js"]
+zlib = ["std", "dep:libz-rs-sys", "dep:zlib-rs"]
 
 [dependencies]
 rustpython-literal = { workspace = true }
@@ -30,17 +32,24 @@ crc32fast = { workspace = true, optional = true }
 getrandom = { workspace = true }
 itertools = { workspace = true }
 libc = { workspace = true }
+libz-rs-sys = { workspace = true, optional = true }
 malachite-bigint = { workspace = true }
 malachite-q = { workspace = true }
 malachite-base = { workspace = true }
 memchr = { workspace = true, optional = true }
 num-traits = { workspace = true }
 parking_lot = { workspace = true, optional = true }
 radium = { workspace = true }
-
+zlib-rs = { workspace = true, optional = true }
 lock_api = { workspace = true }
 siphasher = { workspace = true }
 num-complex = { workspace = true }
 
+[target.'cfg(not(any(target_os = "android", target_arch = "wasm32")))'.dependencies]
+# RustPython does not expose `_lzma` on these targets; keep the native engine's
+# dependency boundary with its common-module owner rather than in stdlib.
+xz = { workspace = true, optional = true }
+xz-sys = { workspace = true, optional = true }
+
 [lints]
 workspace = true