Auto merge of rust-lang#2375 - RalfJung:rustup, r=RalfJung

Rustup

Author: bors

CONTRIBUTING.md

@@ -28,11 +28,6 @@ install that exact version of rustc as a toolchain:
 This will set up a rustup toolchain called `miri` and set it as an override for
 the current directory.
 
-If you want to also have `clippy` installed, you need to run this:
-```
-./rustup-toolchain "" -c clippy
-```
-
 [`rustup-toolchain-install-master`]: https://github.com/kennytm/rustup-toolchain-install-master
 
 ## Building and testing Miri
@@ -131,6 +126,8 @@ development version of Miri using
 
 and then you can use it as if it was installed by `rustup`.  Make sure you use
 the same toolchain when calling `cargo miri` that you used when installing Miri!
+Usually this means you have to write `cargo +miri miri ...` to select the `miri`
+toolchain that was installed by `./rustup-toolchain`.
 
 There's a test for the cargo wrapper in the `test-cargo-miri` directory; run
 `./run-test.py` in there to execute it. Like `./miri test`, this respects the

rust-version

@@ -1 +1 @@
-0ed9c64c3e63acac9bd77abce62501696c390450
+6077b7cda466afa2b75a62b232ab46dbeb148bcb

src/helpers.rs

@@ -259,7 +259,7 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriEvalContextExt<'mir, 'tcx
         let mir = this.load_mir(f.def, None)?;
         let dest = match dest {
             Some(dest) => *dest,
-            None => MPlaceTy::dangling(this.layout_of(mir.return_ty())?).into(),
+            None => MPlaceTy::fake_alloc_zst(this.layout_of(mir.return_ty())?).into(),
         };
         this.push_stack_frame(f, mir, &dest, stack_pop)?;