add Miri build script (#745)

add Miri build script

Author: RalfJung

.travis.yml

@@ -16,7 +16,6 @@ env:
   global:
   - RUST_TEST_NOCAPTURE=1
   - RUST_BACKTRACE=1
-  - RUSTFLAGS="-C debug-assertions"
 
 before_script:
 # Linux: install extra stuff for cross-compilation

Cargo.toml

@@ -40,12 +40,15 @@ rustc_version = { version = "0.2.3", optional = true }
 env_logger = "0.6"
 log = "0.4"
 shell-escape = "0.1.4"
+hex = "0.3.2"
+rand = "0.6"
 # A noop dependency that changes in the Rust repository, it's a bit of a hack.
 # See the `src/tools/rustc-workspace-hack/README.md` file in `rust-lang/rust`
 # for more information.
 rustc-workspace-hack = "1.0.0"
-hex = "0.3.2"
-rand = "0.6"
+# Depend on num-traits with default features to avoid having to rebuild
+# between "cargo build" and "cargo intall".
+num-traits = "*"
 
 [build-dependencies]
 vergen = "3"

README.md

@@ -141,42 +141,30 @@ version of `rustc` that, instead of compiling your code, runs it.  It accepts
 all the same flags as `rustc` (though the ones only affecting code generation
 and linking obviously will have no effect) [and more][miri-flags].
 
-To run the Miri driver, you need to have the `MIRI_SYSROOT` environment variable
-set to an appropriate sysroot.  You can generate such a sysroot with the
-following incantation:
-
-```
-cargo run --bin cargo-miri -- miri setup
-```
-
-This basically runs the `cargo-miri` binary (which backs the `cargo miri`
-subcommand) with `cargo`, and asks it to `setup`.  It should in the end print
-the directory where the libstd was built.  In the following, we will assume it
-is `~/.cache/miri/HOST`; you may have to adjust that if you are not using Linux.
-
-Now you can run the driver directly using
+Running the Miri driver requires some fiddling with environment variables, so
+the `miri` script helps you do that.  For example, you can run the driver on a
+particular file by doing
 
 ```sh
-MIRI_SYSROOT=~/.cache/miri/HOST cargo run tests/run-pass/format.rs # or whatever test you like
+./miri run tests/run-pass/format.rs
+./miri run tests/run-pass/hello.rs --target i686-unknown-linux-gnu
 ```
 
-and you can run the test suite using
+and you can run the test suite using:
 
 ```
-cargo test
+./miri test
 ```
 
-We recommend adding the `--release` flag to make tests run faster.
-
-`cargo test --release FILTER` only runs those tests that contain `FILTER` in
-their filename (including the base directory, e.g. `cargo test --release fail`
-will run all compile-fail 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).
 
 You can get a trace of which MIR statements are being executed by setting the
 `MIRI_LOG` environment variable.  For example:
 
 ```sh
-MIRI_LOG=info cargo run tests/run-pass/vecs.rs
+MIRI_LOG=info ./miri run tests/run-pass/vecs.rs
 ```
 
 Setting `MIRI_LOG` like this will configure logging for Miri itself as well as
@@ -185,7 +173,7 @@ can also do more targeted configuration, e.g. the following helps debug the
 stacked borrows implementation:
 
 ```sh
-MIRI_LOG=rustc_mir::interpret=info,miri::stacked_borrows cargo run tests/run-pass/vecs.rs
+MIRI_LOG=rustc_mir::interpret=info,miri::stacked_borrows ./miri run tests/run-pass/vecs.rs
 ```
 
 In addition, you can set `MIRI_BACKTRACE=1` to get a backtrace of where an
@@ -199,7 +187,7 @@ is probably easier to test it with the cargo wrapper.  You can install your
 development version of Miri using
 
 ```
-cargo install --path . --force
+./miri install
 ```
 
 and then you can use it as if it was installed by `rustup`.  Make sure you use
@@ -235,18 +223,7 @@ rustup override set custom
 ```
 
 With this, you should now have a working development setup!  See
-[above][testing-miri] for how to proceed working with the Miri driver.  Notice
-that rustc's sysroot is already built for Miri in this case, so you can set
-`MIRI_SYSROOT=$(rustc --print sysroot)`.
-
-Running `cargo miri` in this setup is a bit more complicated, because the Miri
-binary you just created needs help to find the libraries it links against.  On
-Linux, you can set the rpath to make this "just work":
-
-```sh
-export RUSTFLAGS="-C link-args=-Wl,-rpath,$(rustc --print sysroot)/lib/rustlib/x86_64-unknown-linux-gnu/lib"
-cargo install --path . --force
-```
+[above][testing-miri] for how to proceed working with the Miri driver.
 
 ### Miri `-Z` flags and environment variables
 [miri-flags]: #miri--z-flags-and-environment-variables

miri

@@ -0,0 +1,83 @@
+#!/bin/sh
+set -e
+# I'd love to use `jq` for parsing the JSON properly, but macOS is totally underequipped for this kind of work.
+TARGET=$(rustc --print target-spec-json -Z unstable-options | grep llvm-target | cut -d '"' -f 4)
+SYSROOT=$(rustc --print sysroot)
+# We set the rpath so that Miri finds the private rustc libraries it needs.
+# We enable debug-assertions to get tracing.
+# We enable line-only debuginfo for backtraces.
+export RUSTFLAGS="-C link-args=-Wl,-rpath,$SYSROOT/lib/rustlib/$TARGET/lib -C debug-assertions -C debuginfo=1"
+
+## Helper functions
+
+# Build a sysroot and set MIRI_SYSROOT to use it.  Arguments are passed to `cargo miri setup`.
+build_sysroot() {
+    # Build once, for the user to see.
+    cargo run --release --bin cargo-miri -- miri setup "$@"
+    # Call again, to just set env var.
+    eval $(cargo run --release -q --bin cargo-miri -- miri setup --env "$@")
+    export MIRI_SYSROOT
+}
+
+# Prepare and set MIRI_SYSROOT.  Respects `MIRI_TEST_TARGET` and takes into account
+# locally built vs. distributed rustc.
+find_sysroot() {
+    # Get ourselves a sysroot
+    if [ -n "$MIRI_SYSROOT" ]; then
+        # Sysroot already set, use that.
+        true
+    elif echo "$SYSROOT" | egrep -q 'build/[^/]+/stage'; then
+        # A local rustc build.
+        if [ -n "$MIRI_TEST_TARGET" ]; then
+            # Foreign targets still need a build.  Use the rustc sources.
+            export XARGO_RUST_SRC="$SYSROOT/../../../src"
+            build_sysroot --target "$MIRI_TEST_TARGET"
+        else
+            # Assume we have a proper host libstd in $SYSROOT.
+            true
+        fi
+    else
+        # A normal toolchain.  We have to build a sysroot either way.
+        if [ -n "$MIRI_TEST_TARGET" ]; then
+            build_sysroot --target "$MIRI_TEST_TARGET"
+        else
+            build_sysroot
+        fi
+    fi
+}
+
+## Main
+
+COMMAND="$1"
+shift
+
+case "$COMMAND" in
+install)
+    # "--locked" to respect the Cargo.lock file if it exists,
+    # "--offline" to avoid querying the registry (for yanked packages).
+    exec cargo "$COMMAND" --path "$(dirname "$0")" --force --locked --offline "$@"
+    ;;
+build)
+    # Build, and let caller control flags.
+    exec cargo "$COMMAND" --release "$@"
+    ;;
+test|run)
+    # In "run" mode, scan for "--target" to set the "MIRI_TEST_TARGET" env var so
+    # that we set the MIRI_SYSROOT up the right way.
+    if [ "$COMMAND" = "run" ] && [ -z "$MIRI_TEST_TARGET" ]; then
+        for ARG in "$@"; do
+            if [ "$LAST_ARG" = "--target" ]; then
+                # Found it!
+                export MIRI_TEST_TARGET="$ARG"
+                break
+            fi
+            LAST_ARG="$ARG"
+        done
+    fi
+    # First build and get a sysroot.
+    cargo build --release
+    find_sysroot
+    # Then run the actual command.
+    exec cargo "$COMMAND" --release "$@"
+    ;;
+esac

src/bin/cargo-miri.rs

@@ -243,6 +243,7 @@ path = "lib.rs"
     File::create(dir.join("lib.rs")).unwrap();
     // Run xargo.
     let target = get_arg_flag_value("--target");
+    let print_env = !ask_user && has_arg_flag("--env"); // whether we just print the necessary environment variable
     let mut command = Command::new("xargo");
     command.arg("build").arg("-q")
         .current_dir(&dir)
@@ -265,7 +266,9 @@ path = "lib.rs"
     };
     let sysroot = if is_host { dir.join("HOST") } else { PathBuf::from(dir) };
     std::env::set_var("MIRI_SYSROOT", &sysroot);
-    if !ask_user {
+    if print_env {
+        println!("MIRI_SYSROOT={}", sysroot.display());
+    } else if !ask_user {
         println!("A libstd for Miri is now available in `{}`", sysroot.display());
     }
 }

travis.sh

@@ -3,36 +3,29 @@ set -euo pipefail
 
 # Determine configuration
 if [ "$TRAVIS_OS_NAME" == osx ]; then
-  MIRI_SYSROOT_BASE=~/Library/Caches/miri.miri.miri/
   FOREIGN_TARGET=i686-apple-darwin
 else
-  MIRI_SYSROOT_BASE=~/.cache/miri/
   FOREIGN_TARGET=i686-unknown-linux-gnu
 fi
 
 # Prepare
 echo "Build and install miri"
-cargo build --release --all-features --all-targets
-cargo install --all-features --force --path .
-echo
-
-echo "Get ourselves a MIR-full libstd for the host and a foreign architecture"
-cargo miri setup
-cargo miri setup --target "$FOREIGN_TARGET"
+./miri build --all-features --all-targets
+./miri install
 echo
 
 # Test
 function run_tests {
-  cargo test --release --all-features
-  test-cargo-miri/run-test.py
+    ./miri test
+    # "miri test" has built the sysroot for us, now this should pass without
+    # any interactive questions.
+    test-cargo-miri/run-test.py
 }
 
 echo "Test host architecture"
-export MIRI_SYSROOT="$MIRI_SYSROOT_BASE"/HOST
 run_tests
 echo
 
 echo "Test foreign architecture ($FOREIGN_TARGET)"
-export MIRI_SYSROOT="$MIRI_SYSROOT_BASE" MIRI_TEST_TARGET="$FOREIGN_TARGET"
-run_tests
+MIRI_TEST_TARGET="$FOREIGN_TARGET" run_tests
 echo