more dead-code annotations

Summary: 1.78.0 throws up this dead code. haven't investigated why but these occurrences only get flagged by the buck2-unsorted-mac test (e.g. https://www.internalfb.com/sandcastle/workflow/657525545598944430)

Reviewed By: ndmitchell, dtolnay

Differential Revision: D57212061

fbshipit-source-id: 87f5654150e935e424d4479c6bf35516d1490b03

starlark/src/values/types/string/repr.rs

@@ -25,6 +25,7 @@ use crate::values::types::string::simd::Vector;
 
 /// Check if any byte in the buffer is non-ASCII or need escape.
 #[inline(always)]
+#[allow(dead_code)]
 unsafe fn chunk_non_ascii_or_need_escape<V: Vector>(chunk: V) -> bool {
     #[allow(clippy::many_single_char_names)]
     unsafe fn or4<V: Vector>(a: V, b: V, c: V, d: V) -> V {
@@ -124,6 +125,7 @@ pub(crate) fn string_repr(str: &str, buffer: &mut String) {
     }
 
     #[inline(always)]
+    #[allow(dead_code)] // FIXME: Investigate if this is really needed, fails on Mac.
     unsafe fn loop_ascii_simd<V: Vector>(val: &str, buffer: &mut String) {
         // `buffer` must have enough capacity to contain `val` if it does not need escaping
         // followed by trailing double quote.

starlark/src/values/types/string/simd.rs

@@ -16,6 +16,7 @@
  */
 
 /// Fixed length byte vector API.
+#[allow(dead_code)] // FIXME: Investigate if this is really needed, fails on Mac
 pub(crate) trait Vector: Copy {
     /// Fill the vector with given byte value.
     unsafe fn splat(byte: u8) -> Self;
@@ -42,6 +43,7 @@ where
     /// This function is called when SIMD is not available.
     fn no_simd(self) -> R;
     /// This function is called when SIMD is available.
+    #[allow(dead_code)] // FIXME: Investigate if this is really needed, fails on Mac
     fn simd<V: Vector>(self) -> R;
 
     /// Call either `simd` or `no_simd` function.