make miri script smarter: auto-determine MIRI_SYSROOT, handle MIRI_TEST_TARGET

Author: RalfJung

README.md

@@ -141,14 +141,16 @@ 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].
 
-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
+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 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:
 
 ```
 ./miri test

miri

@@ -7,33 +7,76 @@ SYSROOT=$(rustc --print sysroot)
 # We enable line-only debuginfo for backtraces.
 export RUSTFLAGS="-C link-args=-Wl,-rpath,$SYSROOT/lib/rustlib/$TARGET/lib -C debug-assertions -C debuginfo=1"
 
-COMMAND="$1"
-shift
+## Helper functions
 
-case "$COMMAND" in
-install)
-    exec cargo install --path "$(dirname "$0")" --force --locked --offline
-    ;;
-build|test|run)
-    # Basic build
-    cargo build --release
-
-    # We we want to just build, we are done.
-    if [ "$COMMAND" = "build" ]; then exit 0; fi
+# 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 "$MIRI_SYSROOT" ]; then
-        # sysroot already set
+        # Sysroot already set, use that.
         true
     elif echo "$SYSROOT" | egrep -q 'build/[^/]+/stage'; then
-	# a local rustc build, assume we have a proper libstd in $SYSROOT
-	true
+        # A local rustc build.
+        if [ -n "$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 $SYSROOT.
+	    true
+        fi
     else
-	# we have to build a sysroot
-	cargo run --release --bin cargo-miri -- miri setup
-	export MIRI_SYSROOT=$HOME/.cache/miri/HOST
+	# 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 +3,27 @@ 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
+    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