avoid lowercasing platforms

Author: RalfJung

src/eval.rs

@@ -169,7 +169,7 @@ pub fn create_ecx<'mir, 'tcx: 'mir>(
 pub fn eval_main<'tcx>(tcx: TyCtxt<'tcx>, main_id: DefId, config: MiriConfig) -> Option<i64> {
     // FIXME: We always ignore leaks on some platforms where we do not
     // correctly implement TLS destructors.
-    let target_os = tcx.sess.target.target.target_os.to_lowercase();
+    let target_os = tcx.sess.target.target.target_os.as_str();
     let ignore_leaks = config.ignore_leaks || target_os == "windows" || target_os == "macos";
 
     let (mut ecx, ret_place) = match create_ecx(tcx, main_id, config) {

src/helpers.rs

@@ -373,7 +373,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
     /// if this is not the case.
     fn assert_platform(&self, platform: &str, name: &str) {
         assert_eq!(
-            self.eval_context_ref().tcx.sess.target.target.target_os.to_lowercase(),
+            self.eval_context_ref().tcx.sess.target.target.target_os,
             platform,
             "`{}` is only available on the `{}` platform",
             name,

src/shims/foreign_items.rs

@@ -455,7 +455,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
                 this.write_scalar(Scalar::from_f64(res), dest)?;
             }
 
-            _ => match this.tcx.sess.target.target.target_os.to_lowercase().as_str() {
+            _ => match this.tcx.sess.target.target.target_os.as_str() {
                 "linux" | "macos" => return posix::EvalContextExt::emulate_foreign_item_by_name(this, link_name, args, dest, ret),
                 "windows" => return windows::EvalContextExt::emulate_foreign_item_by_name(this, link_name, args, dest, ret),
                 target => throw_unsup_format!("The {} target platform is not supported", target),

src/shims/foreign_items/posix.rs

@@ -322,7 +322,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
             }
 
             _ => {
-                match this.tcx.sess.target.target.target_os.to_lowercase().as_str() {
+                match this.tcx.sess.target.target.target_os.as_str() {
                     "linux" => return linux::EvalContextExt::emulate_foreign_item_by_name(this, link_name, args, dest, ret),
                     "macos" => return macos::EvalContextExt::emulate_foreign_item_by_name(this, link_name, args, dest, ret),
                     _ => unreachable!(),