# Contribution Guide
-If you want to hack on miri yourself, great! Here are some resources you might
+If you want to hack on Miri yourself, great! Here are some resources you might
find useful.
## Getting started
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
For example, you can (cross-)run the driver on a particular file by doing
```sh
-./miri run tests/run-pass/format.rs
-./miri run tests/run-pass/hello.rs --target i686-unknown-linux-gnu
+./miri run tests/pass/format.rs
+./miri run tests/pass/hello.rs --target i686-unknown-linux-gnu
```
and you can (cross-)run the entire test suite using:
MIRI_TEST_TARGET=i686-unknown-linux-gnu ./miri test
```
+If your target doesn't support libstd, you can run miri with
+
+```
+MIRI_NO_STD=1 MIRI_TEST_TARGET=thumbv7em-none-eabihf ./miri test tests/fail/alloc/no_global_allocator.rs
+MIRI_NO_STD=1 ./miri run tests/pass/no_std.rs --target thumbv7em-none-eabihf
+```
+
+to avoid attempting (and failing) to build libstd. Note that almost no tests will pass
+this way, but you can run individual tests.
+
`./miri test FILTER` only runs those tests that contain `FILTER` in their
filename (including the base directory, e.g. `./miri test fail` will run all
compile-fail tests).
`MIRI_LOG` environment variable. For example:
```sh
-MIRI_LOG=info ./miri run tests/run-pass/vecs.rs
+MIRI_LOG=info ./miri run tests/pass/vec.rs
```
Setting `MIRI_LOG` like this will configure logging for Miri itself as well as
stacked borrows implementation:
```sh
-MIRI_LOG=rustc_mir::interpret=info,miri::stacked_borrows ./miri run tests/run-pass/vecs.rs
+MIRI_LOG=rustc_mir::interpret=info,miri::stacked_borrows ./miri run tests/pass/vec.rs
```
In addition, you can set `MIRI_BACKTRACE=1` to get a backtrace of where an
evaluation error was originally raised.
+#### UI testing
+
+We use ui-testing in Miri, meaning we generate `.stderr` and `.stdout` files for the output
+produced by Miri. You can use `./miri bless` to automatically (re)generate these files when
+you add new tests or change how Miri presents certain output.
+
+Note that when you also use `MIRIFLAGS` to change optimizations and similar, the ui output
+will change in unexpected ways. In order to still be able
+to run the other checks while ignoring the ui output, use `MIRI_SKIP_UI_CHECKS=1 ./miri test`.
+
+For more info on how to configure ui tests see [the documentation on the ui test crate][ui_test]
+
+[ui_test]: ui_test/README.md
+
### Testing `cargo miri`
Working with the driver directly gives you full control, but you also lose all
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
`MIRI_TEST_TARGET` environment variable to execute the test for another target.
+### Using a modified standard library
+
+Miri re-builds the standard library into a custom sysroot, so it is fairly easy
+to test Miri against a modified standard library -- you do not even have to
+build Miri yourself, the Miri shipped by `rustup` will work. All you have to do
+is set the `MIRI_LIB_SRC` environment variable to the `library` folder of a
+`rust-lang/rust` repository checkout. Note that changing files in that directory
+does not automatically trigger a re-build of the standard library; you have to
+clear the Miri build cache manually (on Linux, `rm -rf ~/.cache/miri`;
+and on Windows, `rmdir /S "%LOCALAPPDATA%\rust-lang\miri\cache"`).
+
+### Benchmarking
+
+Miri comes with a few benchmarks; you can run `./miri bench` to run them with the locally built
+Miri. Note: this will run `./miri install` as a side-effect. Also requires `hyperfine` to be
+installed (`cargo install hyperfine`).
+
+## Configuring `rust-analyzer`
+
+To configure `rust-analyzer` and VS Code for working on Miri, save the following
+to `.vscode/settings.json` in your local Miri clone:
+
+```json
+{
+ "rust-analyzer.rustc.source": "discover",
+ "rust-analyzer.linkedProjects": [
+ "./Cargo.toml",
+ "./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",
+ ],
+ "rust-analyzer.rustfmt.extraArgs": [
+ "+nightly"
+ ],
+}
+```
+
+> #### Note
+>
+> If you are [building Miri with a locally built rustc][], set
+> `rust-analyzer.rustcSource` to the relative path from your Miri clone to the
+> root `Cargo.toml` of the locally built rustc. For example, the path might look
+> like `../rust/Cargo.toml`.
+
+See the rustc-dev-guide's docs on ["Configuring `rust-analyzer` for `rustc`"][rdg-r-a]
+for more information about configuring VS Code and `rust-analyzer`.
+
+[rdg-r-a]: https://rustc-dev-guide.rust-lang.org/building/suggested.html#configuring-rust-analyzer-for-rustc
+
## Advanced topic: other build environments
We described above the simplest way to get a working build environment for Miri,
### Building Miri with a locally built rustc
+[building Miri with a locally built rustc]: #building-miri-with-a-locally-built-rustc
+
A big part of the Miri driver lives in rustc, so working on Miri will sometimes
require using a locally built rustc. The bug you want to fix may actually be on
the rustc side, or you just need to get more detailed trace of the execution
than what is possible with release builds -- in both cases, you should develop
-miri against a rustc you compiled yourself, with debug assertions (and hence
+Miri against a rustc you compiled yourself, with debug assertions (and hence
tracing) enabled.
The setup for a local rustc works as follows:
# Clone the rust-lang/rust repo.
git clone https://github.com/rust-lang/rust rustc
cd rustc
-cp config.toml.example config.toml
-# Now edit `config.toml` and set `debug-assertions = true`.
+# Create a config.toml with defaults for working on Miri.
+./x.py setup compiler
+ # Now edit `config.toml` and under `[rust]` set `debug-assertions = true`.
-# Build a stage 1 rustc.
+# Build a stage 2 rustc, and build the rustc libraries with that rustc.
# This step can take 30 minutes or more.
-./x.py build --stage 1 compiler/rustc
+./x.py build --stage 2 compiler/rustc
# If you change something, you can get a faster rebuild by doing
-./x.py build --keep-stage 0 --stage 1 compiler/rustc
+./x.py build --keep-stage 0 --stage 2 compiler/rustc
# You may have to change the architecture in the next command
-rustup toolchain link stage1 build/x86_64-unknown-linux-gnu/stage1
+rustup toolchain link stage2 build/x86_64-unknown-linux-gnu/stage2
# Now cd to your Miri directory, then configure rustup
-rustup override set stage1
+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
+location is printed after the library build: "A libstd for Miri is now available in ...".
+
+Note: `./x.py --stage 2 compiler/rustc` currently errors with `thread 'main'
+panicked at 'fs::read(stamp) failed with No such file or directory (os error 2)`,
+you can simply ignore that error; Miri will build anyway.
+
+For more information about building and configuring a local compiler,
+see <https://rustc-dev-guide.rust-lang.org/building/how-to-build-and-run.html>.
+
With this, you should now have a working development setup! See
[above](#building-and-testing-miri) for how to proceed working on Miri.
projects / rust.git / blobdiff