fix: fixed build errors when only v2 is enabled

Author: zonyitoo

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "shadowsocks-crypto"
-version = "0.5.6"
+version = "0.5.7"
 authors = ["luozijun <luozijun.assistant@gmail.com>", "ty <zonyitoo@gmail.com>"]
 edition = "2021"
 license = "MIT"
@@ -27,7 +27,7 @@ v1-aead-extra = [
     "subtle",
     "ctr",
 ]
-v2 = ["aes", "aes-gcm", "blake3", "chacha20poly1305", "bytes"]
+v2 = ["aes", "aes-gcm", "blake3", "chacha20poly1305", "bytes", "cfg-if"]
 v2-extra = ["v2", "chacha20poly1305/reduced-round"]
 
 ring = ["ring-compat"]

src/kind.rs

@@ -503,6 +503,7 @@ impl CipherKind {
             RC4 => Rc4::nonce_size(),
             CHACHA20 => Chacha20::nonce_size(),
 
+            #[allow(unreachable_patterns)]
             _ => panic!("only support Stream ciphers"),
         }
     }
@@ -513,7 +514,9 @@ impl CipherKind {
         use self::CipherKind::*;
 
         match *self {
+            #[cfg(feature = "v1-aead")]
             AES_128_GCM => Aes128Gcm::tag_size(),
+            #[cfg(feature = "v1-aead")]
             AES_256_GCM => Aes256Gcm::tag_size(),
 
             #[cfg(feature = "v1-aead-extra")]
@@ -526,6 +529,7 @@ impl CipherKind {
             #[cfg(feature = "v1-aead-extra")]
             AES_256_CCM => Aes256Ccm::tag_size(),
 
+            #[cfg(feature = "v1-aead")]
             CHACHA20_POLY1305 => ChaCha20Poly1305::tag_size(),
 
             #[cfg(feature = "v1-aead-extra")]