Make OsStr and CStr a bit more usable with queries

compiler/rustc_data_structures/src/stable_hasher.rs

@@ -565,6 +565,12 @@ where
     }
 }
 
+impl_stable_traits_for_trivial_type!(::std::ffi::OsStr);
+impl_stable_traits_for_trivial_type!(::std::ffi::OsString);
+
+impl_stable_traits_for_trivial_type!(::std::ffi::CStr);
+impl_stable_traits_for_trivial_type!(::std::ffi::CString);
+
 impl_stable_traits_for_trivial_type!(::std::path::Path);
 impl_stable_traits_for_trivial_type!(::std::path::PathBuf);
 

compiler/rustc_middle/src/query/erase.rs

@@ -1,3 +1,4 @@
+use std::ffi::{CStr, OsStr};
 use std::intrinsics::transmute_unchecked;
 use std::mem::MaybeUninit;
 
@@ -65,6 +66,18 @@ impl<T> EraseType for &'_ [T] {
     type Result = [u8; size_of::<&'static [()]>()];
 }
 
+impl EraseType for &'_ str {
+    type Result = [u8; size_of::<&'static str>()];
+}
+
+impl EraseType for &'_ OsStr {
+    type Result = [u8; size_of::<&'static OsStr>()];
+}
+
+impl EraseType for &'_ CStr {
+    type Result = [u8; size_of::<&'static CStr>()];
+}
+
 impl<T> EraseType for &'_ ty::List<T> {
     type Result = [u8; size_of::<&'static ty::List<()>>()];
 }
@@ -180,6 +193,18 @@ impl<T> EraseType for Option<&'_ [T]> {
     type Result = [u8; size_of::<Option<&'static [()]>>()];
 }
 
+impl EraseType for Option<&'_ str> {
+    type Result = [u8; size_of::<Option<&'static str>>()];
+}
+
+impl EraseType for Option<&'_ OsStr> {
+    type Result = [u8; size_of::<Option<&'static OsStr>>()];
+}
+
+impl EraseType for Option<&'_ CStr> {
+    type Result = [u8; size_of::<Option<&'static CStr>>()];
+}
+
 impl EraseType for Option<mir::DestructuredConstant<'_>> {
     type Result = [u8; size_of::<Option<mir::DestructuredConstant<'static>>>()];
 }