Port perf_convert_ascii

The "#[bench]" attribute is not allowed in stable Rust, so keep it behind
a new feature flag. Run on nightly Rust with

    $ cargo bench --features=bechmark
    test tests::encoding::bench::bench_convert_ascii ... bench:     125,988 ns/iter (+/- 1,128) = 1040 MB/s

Cargo.toml

@@ -78,6 +78,7 @@ path = "fish-rust/src/lib.rs"
 # These tests are run by fish_tests().
 default = ["fish-ffi-tests"]
 fish-ffi-tests = ["inventory"]
+benchmark = []
 
 # The following features are auto-detected by the build-script and should not be enabled manually.
 asan = []

fish-rust/src/lib.rs

@@ -1,3 +1,4 @@
+#![cfg_attr(feature = "benchmark", feature(test))]
 #![allow(non_camel_case_types)]
 #![allow(dead_code)]
 #![allow(non_upper_case_globals)]

fish-rust/src/tests/encoding.rs

@@ -17,3 +17,17 @@ fn test_convert_nulls() {
     let out_wstr = str2wcstring(&out_str);
     assert_eq!(input, &out_wstr);
 }
+
+#[cfg(feature = "benchmark")]
+mod bench {
+    extern crate test;
+    use crate::tests::encoding::str2wcstring;
+    use test::Bencher;
+
+    #[bench]
+    fn bench_convert_ascii(b: &mut Bencher) {
+        let s: [u8; 128 * 1024] = std::array::from_fn(|i| b'0' + u8::try_from(i % 10).unwrap());
+        b.bytes = u64::try_from(s.len()).unwrap();
+        b.iter(|| str2wcstring(&s));
+    }
+}

fish-rust/src/tests/mod.rs

@@ -6,6 +6,7 @@ mod complete;
 mod debounce;
 #[cfg(test)]
 mod editable_line;
+#[cfg(test)]
 mod encoding;
 mod env;
 mod env_universal_common;

src/fish_tests.cpp

@@ -408,24 +408,6 @@ static void test_convert_private_use() {
     }
 }
 
-// todo!("port this");
-static void perf_convert_ascii() {
-    std::string s(128 * 1024, '\0');
-    for (size_t i = 0; i < s.size(); i++) {
-        s[i] = (i % 10) + '0';
-    }
-    (void)str2wcstring(s);
-
-    double start = timef();
-    const int iters = 1024;
-    for (int i = 0; i < iters; i++) {
-        (void)str2wcstring(s);
-    }
-    double end = timef();
-    auto usec = static_cast<unsigned long long>(((end - start) * 1E6) / iters);
-    say(L"ASCII string conversion perf: %lu bytes in %llu usec", s.size(), usec);
-}
-
 // todo!("already ported, delete this");
 static void test_iothread() {
     say(L"Testing iothreads");
@@ -1203,7 +1185,6 @@ static const test_t s_tests[]{
     {TEST_GROUP("convert"), test_convert},
     {TEST_GROUP("convert"), test_convert_private_use},
     {TEST_GROUP("convert_ascii"), test_convert_ascii},
-    {TEST_GROUP("perf_convert_ascii"), perf_convert_ascii, true},
     {TEST_GROUP("iothread"), test_iothread},
     {TEST_GROUP("pthread"), test_pthread},
     {TEST_GROUP("lru"), test_lru},