chore: Rustを1.91.0に上げ、1.89から1.91までの新機能を利用する (#1193)

cf.
- https://blog.rust-lang.org/2025/08/07/Rust-1.89.0/
- https://blog.rust-lang.org/2025/09/18/Rust-1.90.0/
- https://blog.rust-lang.org/2025/10/30/Rust-1.91.0/

Author: qryxip

Cargo.toml

@@ -123,7 +123,7 @@ rev = "de226a26e8e18edbdb1d6f986afe37bbbf35fbf4"
 version = "0.0.0"
 edition = "2024"
 publish = false
-rust-version = "1.88.0"
+rust-version = "1.91.0"
 license = "MIT"
 
 # min-sized-rustを元にrelease buildのサイズが小さくなるようにした

crates/downloader/src/main.rs

@@ -4,6 +4,7 @@ use std::{
     env,
     future::{self, Future},
     io::{self, Cursor, IsTerminal as _, Read, Write as _},
+    iter,
     num::NonZero,
     path::{Path, PathBuf},
     str::FromStr,
@@ -580,7 +581,7 @@ async fn main() -> anyhow::Result<()> {
     .transpose()?;
 
     ensure_confirmation(
-        &itertools::chain(
+        &iter::chain(
             models
                 .as_ref()
                 .map(|ModelsWithTerms { terms, .. }| &**terms)
@@ -833,7 +834,7 @@ fn find_onnxruntime(
                 .and_then(|text| text.try_into().ok())
                 .with_context(|| format!("リリースノート中の`{TARGET}`をパースできませんでした"))
         })
-        .collect::<Result<Vec<[_; 4]>, _>>()?
+        .collect::<Result<Vec<[_; _]>, _>>()?
         .into_iter()
         .filter(|&[spec_os, spec_cpu_arch, spec_devices, _]| {
             spec_os

crates/voicevox_core/src/engine/talk/interpret_query.rs

@@ -173,7 +173,7 @@ impl AudioQuery {
                 let phoneme_id = phoneme_data_list[i].phoneme_id();
 
                 for _ in 0..phoneme_length {
-                    let mut phonemes_vec = [0.; OjtPhoneme::num_phoneme()];
+                    let mut phonemes_vec = [0.; OjtPhoneme::num_phoneme()]; // TODO: Rust 1.89であればサイズが型推論可能になる
                     phonemes_vec[phoneme_id as usize] = 1.;
                     phoneme.push(phonemes_vec)
                 }

crates/voicevox_core/src/synthesizer.rs

@@ -151,6 +151,7 @@ impl AsyncExt for BlockingThreadPool {
 
 const DEFAULT_SAMPLING_RATE: u32 = 24000;
 /// 音が途切れてしまうのを避けるworkaround処理のためのパディング幅（フレーム数）
+// TODO: Rust 1.90であれば`{float}::round`がそのまま使える
 const PADDING_FRAME_LENGTH: usize = 38; // (0.4秒 * 24000Hz / 256.0).round()
 /// 音声生成の際、音声特徴量の前後に確保すべきマージン幅（フレーム数）
 /// モデルの受容野から計算される

crates/voicevox_core_c_api/Cargo.toml

@@ -29,7 +29,6 @@ const_format.workspace = true
 duplicate.workspace = true
 easy-ext.workspace = true
 educe.workspace = true
-itertools.workspace = true
 libc.workspace = true
 ndarray.workspace = true
 parking_lot = { workspace = true, features = ["arc_lock"] }
@@ -50,6 +49,7 @@ duct.workspace = true
 easy-ext.workspace = true
 inventory.workspace = true
 indexmap = { workspace = true, features = ["serde"] }
+itertools.workspace = true
 libloading.workspace = true
 libtest-mimic.workspace = true
 ndarray.workspace = true

crates/voicevox_core_c_api/src/helpers.rs

@@ -59,7 +59,7 @@ pub(crate) fn into_result_code_with_error(result: CApiResult<()>) -> VoicevoxRes
 }
 
 pub(crate) fn display_error(err: &impl std::error::Error) {
-    itertools::chain(
+    iter::chain(
         [err.to_string()],
         iter::successors(err.source(), |&e| e.source()).map(|e| format!("Caused by: {e}")),
     )

crates/voicevox_core_c_api/tests/e2e/testcases/user_dict_load.rs

@@ -34,7 +34,7 @@ impl assert_cdylib::TestCase for TestCase {
         // SAFETY: `voicevox_user_dict_new`には特にはsafety requirementsは無いはず。
         let dict = unsafe { lib.voicevox_user_dict_new() };
 
-        let mut word_uuid = [0u8; 16];
+        let mut word_uuid = [0u8; _];
 
         let word = {
             // SAFETY: `voicevox_user_dict_word_make` itself has no safety requirements.

crates/voicevox_core_c_api/tests/e2e/testcases/user_dict_manipulate.rs

@@ -52,7 +52,7 @@ impl assert_cdylib::TestCase for TestCase {
 
         // FIXME: This closure itself should be `unsafe`.
         let add_word = |dict: *const VoicevoxUserDict, word: &VoicevoxUserDictWord| -> Uuid {
-            let mut word_uuid = [0u8; 16];
+            let mut word_uuid = [0u8; _];
             assert_ok(unsafe {
                 // SAFETY:
                 // - `dict.surface` and `dict.pronunciation` are valid.

rust-toolchain

@@ -1 +1 @@
-1.88.0
+1.91.0