upstream master changes; and no libc on windows

Author: Ellen Arteca

.gitignore

@@ -10,3 +10,4 @@ perf.data
 perf.data.old
 flamegraph.svg
 tests/extern-so/libtestlib.so
+.auto-*

CONTRIBUTING.md

@@ -28,6 +28,11 @@ 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.
 
+You can also create a `.auto-everything` file (contents don't matter, can be empty), which
+will cause any `./miri` command to automatically call `rustup-toolchain`, `clippy` and `rustfmt`
+for you. If you don't want all of these to happen, you can add individual `.auto-toolchain`,
+`.auto-clippy` and `.auto-fmt` files respectively.
+
 [`rustup-toolchain-install-master`]: https://github.com/kennytm/rustup-toolchain-install-master
 
 ## Building and testing Miri
@@ -163,11 +168,15 @@ to `.vscode/settings.json` in your local Miri clone:
         "./cargo-miri/Cargo.toml"
     ],
     "rust-analyzer.checkOnSave.overrideCommand": [
+        "env",
+        "MIRI_AUTO_OPS=no",
         "./miri",
         "check",
         "--message-format=json"
     ],
     "rust-analyzer.buildScripts.overrideCommand": [
+        "env",
+        "MIRI_AUTO_OPS=no",
         "./miri",
         "check",
         "--message-format=json",
@@ -244,6 +253,14 @@ rustup toolchain link stage2 build/x86_64-unknown-linux-gnu/stage2
 rustup override set stage2
 ```
 
+Note: When you are working with a locally built rustc or any other toolchain that
+is not the same as the one in `rust-version`, you should not have `.auto-everything` or
+`.auto-toolchain` as that will keep resetting your toolchain.
+
+```
+rm -f .auto-everything .auto-toolchain
+```
+
 Important: You need to delete the Miri cache when you change the stdlib; otherwise the
 old, chached version will be used. On Linux, the cache is located at `~/.cache/miri`,
 and on Windows, it is located at `%LOCALAPPDATA%\rust-lang\miri\cache`; the exact

Cargo.lock

@@ -58,5 +58,6 @@ harness = false
 default = ["stack-cache"]
 stack-cache = []
 
-[profile.dev]
-opt-level = 2 # because it's too slow otherwise
+# Be aware that this file is inside a workspace when used via the
+# submodule in the rustc repo. That means there are many cargo features
+# we cannot use, such as profiles.

Cargo.toml

@@ -337,17 +337,6 @@ The remaining flags are for advanced use only, and more likely to change or be r
 Some of these are **unsound**, which means they can lead
 to Miri failing to detect cases of undefined behavior in a program.
 
-* `-Zmiri-allow-uninit-numbers` disables the check to ensure that number types (integer and float
-  types) always hold initialized data. (They must still be initialized when any actual operation,
-  such as arithmetic, is performed.) Using this flag is **unsound** and
-  [deprecated](https://github.com/rust-lang/miri/issues/2187). This has no effect when
-  `-Zmiri-disable-validation` is present.
-* `-Zmiri-allow-ptr-int-transmute` makes Miri more accepting of transmutation between pointers and
-  integers via `mem::transmute` or union/pointer type punning. This has two effects: it disables the
-  check against integers storing a pointer (i.e., data with provenance), thus allowing
-  pointer-to-integer transmutation, and it treats integer-to-pointer transmutation as equivalent to
-  a cast. Implies `-Zmiri-permissive-provenance`. Using this flag is **unsound** and
-  [deprecated](https://github.com/rust-lang/miri/issues/2188).
 * `-Zmiri-disable-abi-check` disables checking [function ABI]. Using this flag
   is **unsound**.
 * `-Zmiri-disable-alignment-check` disables checking pointer alignment, so you
@@ -412,6 +401,9 @@ Some native rustc `-Z` flags are also very relevant for Miri:
 
 Moreover, Miri recognizes some environment variables:
 
+* `MIRI_AUTO_OPS` indicates whether the automatic execution of rustfmt, clippy and rustup-toolchain
+  should be skipped. If it is set to any value, they are skipped. This is used for avoiding
+  infinite recursion in `./miri` and to allow automated IDE actions to avoid the auto ops.
 * `MIRI_LOG`, `MIRI_BACKTRACE` control logging and backtrace printing during
   Miri executions, also [see "Testing the Miri driver" in `CONTRIBUTING.md`][testing-miri].
 * `MIRIFLAGS` (recognized by `cargo miri` and the test suite) defines extra