Auto merge of #3881 - RalfJung:miri-run, r=RalfJung

./miri run: directly run binary instead of using 'cargo run'

This avoids re-building miri without dev dependencies, so it makes `./miri run` a lot faster if `./miri test` was already executed before.

ci/ci.sh

@@ -26,7 +26,7 @@ time ./miri install
 # We enable all features to make sure the Stacked Borrows consistency check runs.
 echo "Building debug version of Miri"
 export CARGO_EXTRA_FLAGS="$CARGO_EXTRA_FLAGS --all-features"
-time ./miri build --all-targets # the build that all the `./miri test` below will use
+time ./miri build # the build that all the `./miri test` below will use
 
 endgroup
 

miri-script/Cargo.toml

@@ -23,3 +23,4 @@ xshell = "0.2.6"
 rustc_version = "0.4"
 dunce = "1.0.4"
 directories = "5"
+serde_json = "1"

miri-script/src/commands.rs

@@ -494,11 +494,15 @@ impl Command {
         flags: Vec<String>,
     ) -> Result<()> {
         let mut e = MiriEnv::new()?;
+
+        // Preparation: get a sysroot, and get the miri binary.
+        let miri_sysroot = e.build_miri_sysroot(/* quiet */ !verbose, target.as_deref())?;
+        let miri_bin =
+            e.build_get_binary(".").context("failed to get filename of miri executable")?;
+
         // More flags that we will pass before `flags`
         // (because `flags` may contain `--`).
         let mut early_flags = Vec::<OsString>::new();
-
-        // Add target, edition to flags.
         if let Some(target) = &target {
             early_flags.push("--target".into());
             early_flags.push(target.into());
@@ -508,9 +512,6 @@ impl Command {
         }
         early_flags.push("--edition".into());
         early_flags.push(edition.as_deref().unwrap_or("2021").into());
-
-        // Prepare a sysroot, add it to the flags. (Also builds cargo-miri, which we need.)
-        let miri_sysroot = e.build_miri_sysroot(/* quiet */ !verbose, target.as_deref())?;
         early_flags.push("--sysroot".into());
         early_flags.push(miri_sysroot.into());
 
@@ -529,7 +530,7 @@ impl Command {
                     .arg("--")
                     .args(&["--miri-run-dep-mode"])
             } else {
-                e.cargo_cmd(".", "run").args(quiet_flag).arg("--")
+                cmd!(e.sh, "{miri_bin}")
             };
             cmd.set_quiet(!verbose);
             // Add Miri flags

miri-script/src/util.rs

@@ -1,10 +1,11 @@
 use std::ffi::{OsStr, OsString};
+use std::io::BufRead;
 use std::ops::Range;
 use std::path::{Path, PathBuf};
 use std::sync::atomic::{AtomicBool, AtomicU32, Ordering};
 use std::thread;
 
-use anyhow::{anyhow, Context, Result};
+use anyhow::{anyhow, bail, Context, Result};
 use dunce::canonicalize;
 use path_macro::path;
 use xshell::{cmd, Cmd, Shell};
@@ -126,21 +127,40 @@ impl MiriEnv {
 
     pub fn build(&self, crate_dir: impl AsRef<OsStr>, args: &[String], quiet: bool) -> Result<()> {
         let quiet_flag = if quiet { Some("--quiet") } else { None };
-        // We build the tests as well, (a) to avoid having rebuilds when building the tests later
-        // and (b) to have more parallelism during the build of Miri and its tests.
-        // This means `./miri run` without `--dep` will build Miri twice (for the sysroot with
-        // dev-dependencies, and then for running without dev-dependencies), but the way more common
-        // `./miri test` will avoid building Miri twice.
-        let mut cmd = self
-            .cargo_cmd(crate_dir, "build")
-            .args(&["--bins", "--tests"])
-            .args(quiet_flag)
-            .args(args);
+        // We build all targets, since building *just* the bin target doesnot include
+        // `dev-dependencies` and that changes feature resolution. This also gets us more
+        // parallelism in `./miri test` as we build Miri and its tests together.
+        let mut cmd =
+            self.cargo_cmd(crate_dir, "build").args(&["--all-targets"]).args(quiet_flag).args(args);
         cmd.set_quiet(quiet);
         cmd.run()?;
         Ok(())
     }
 
+    /// Returns the path to the main crate binary. Assumes that `build` has been called before.
+    pub fn build_get_binary(&self, crate_dir: impl AsRef<OsStr>) -> Result<PathBuf> {
+        let cmd =
+            self.cargo_cmd(crate_dir, "build").args(&["--all-targets", "--message-format=json"]);
+        let output = cmd.output()?;
+        let mut bin = None;
+        for line in output.stdout.lines() {
+            let line = line?;
+            if line.starts_with("{") {
+                let json: serde_json::Value = serde_json::from_str(&line)?;
+                if json["reason"] == "compiler-artifact"
+                    && !json["profile"]["test"].as_bool().unwrap()
+                    && !json["executable"].is_null()
+                {
+                    if bin.is_some() {
+                        bail!("found two binaries in cargo output");
+                    }
+                    bin = Some(PathBuf::from(json["executable"].as_str().unwrap()))
+                }
+            }
+        }
+        bin.ok_or_else(|| anyhow!("found no binary in cargo output"))
+    }
+
     pub fn check(&self, crate_dir: impl AsRef<OsStr>, args: &[String]) -> Result<()> {
         self.cargo_cmd(crate_dir, "check").arg("--all-targets").args(args).run()?;
         Ok(())