Auto merge of rust-lang#138803 - matthiaskrgr:rollup-qtvr8ov, r=matthiaskrgr

Rollup of 8 pull requests

Successful merges:

 - rust-lang#136769 (Provide optional `Read`/`Write` methods for stdio)
 - rust-lang#138410 (Couple mir building cleanups)
 - rust-lang#138490 (Forward `stream_position` in `Arc<File>` as well)
 - rust-lang#138535 (Cleanup `LangString::parse`)
 - rust-lang#138536 (stable_mir: Add `MutMirVisitor`)
 - rust-lang#138673 (Fix build failure on Trusty)
 - rust-lang#138750 (Make `crate_hash` not iterate over `hir_crate` owners anymore)
 - rust-lang#138763 (jsondocck: Replace `jsonpath_lib` with `jsonpath-rust`)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/stable_mir/src/mir.rs

@@ -5,4 +5,4 @@ pub mod pretty;
 pub mod visit;
 
 pub use body::*;
-pub use visit::MirVisitor;
+pub use visit::{MirVisitor, MutMirVisitor};

compiler/stable_mir/src/mir/body.rs

@@ -77,6 +77,22 @@ impl Body {
         &self.locals[self.arg_count + 1..]
     }
 
+    /// Returns a mutable reference to the local that holds this function's return value.
+    pub(crate) fn ret_local_mut(&mut self) -> &mut LocalDecl {
+        &mut self.locals[RETURN_LOCAL]
+    }
+
+    /// Returns a mutable slice of locals corresponding to this function's arguments.
+    pub(crate) fn arg_locals_mut(&mut self) -> &mut [LocalDecl] {
+        &mut self.locals[1..][..self.arg_count]
+    }
+
+    /// Returns a mutable slice of inner locals for this function.
+    /// Inner locals are those that are neither the return local nor the argument locals.
+    pub(crate) fn inner_locals_mut(&mut self) -> &mut [LocalDecl] {
+        &mut self.locals[self.arg_count + 1..]
+    }
+
     /// Convenience function to get all the locals in this function.
     ///
     /// Locals are typically accessed via the more specific methods `ret_local`,