Auto merge of rust-lang#3418 - RalfJung:cargo-miri, r=RalfJung

bors · bors · commit 78d556e28d4e · 2024-03-26T10:53:20.000Z
cargo-miri, miri-script, tests/ui: misc simplifications and comments Parts of rust-lang/miri#3411 that can be landed now.
diff --git a/src/tools/miri/cargo-miri/src/phases.rs b/src/tools/miri/cargo-miri/src/phases.rs
@@ -192,12 +192,14 @@ pub fn phase_cargo_miri(mut args: impl Iterator<Item = String>) {
             "WARNING: Ignoring `RUSTC` environment variable; set `MIRI` if you want to control the binary used as the driver."
         );
     }
-    // Build scripts (and also cargo: https://github.com/rust-lang/cargo/issues/10885) will invoke
-    // `rustc` even when `RUSTC_WRAPPER` is set. To make sure everything is coherent, we want that
-    // to be the Miri driver, but acting as rustc, on the target level. (Target, rather than host,
-    // is needed for cross-interpretation situations.) This is not a perfect emulation of real rustc
-    // (it might be unable to produce binaries since the sysroot is check-only), but it's as close
-    // as we can get, and it's good enough for autocfg.
+    // Ideally we would set RUSTC to some non-existent path, so we can be sure our wrapping is
+    // always applied. However, buggy build scripts (https://github.com/eyre-rs/eyre/issues/84) and
+    // also cargo (https://github.com/rust-lang/cargo/issues/10885) will invoke `rustc` even when
+    // `RUSTC_WRAPPER` is set, bypassing the wrapper. To make sure everything is coherent, we want
+    // that to be the Miri driver, but acting as rustc, on the target level. (Target, rather than
+    // host, is needed for cross-interpretation situations.) This is not a perfect emulation of real
+    // rustc (it might be unable to produce binaries since the sysroot is check-only), but it's as
+    // close as we can get, and it's good enough for autocfg.
     //
     // In `main`, we need the value of `RUSTC` to distinguish RUSTC_WRAPPER invocations from rustdoc
     // or TARGET_RUNNER invocations, so we canonicalize it here to make it exceedingly unlikely that
@@ -251,6 +253,16 @@ pub fn phase_rustc(mut args: impl Iterator<Item = String>, phase: RustcPhase) {
     /// Cargo does not give us this information directly, so we need to check
     /// various command-line flags.
     fn is_runnable_crate() -> bool {
+        // Determine whether this is cargo invoking rustc to get some infos. Ideally we'd check "is
+        // there a filename passed to rustc", but that's very hard as we would have to know whether
+        // e.g. `--print foo` is a booolean flag `--print` followed by filename `foo` or equivalent
+        // to `--print=foo`. So instead we use this more fragile approach of detecting the presence
+        // of a "query" flag rather than the absence of a filename.
+        let info_query = get_arg_flag_value("--print").is_some() || has_arg_flag("-vV");
+        if info_query {
+            // Nothing to run.
+            return false;
+        }
         let is_bin = get_arg_flag_value("--crate-type").as_deref().unwrap_or("bin") == "bin";
         let is_test = has_arg_flag("--test");
         is_bin || is_test
@@ -297,8 +309,6 @@ pub fn phase_rustc(mut args: impl Iterator<Item = String>, phase: RustcPhase) {
     let verbose = std::env::var("MIRI_VERBOSE")
         .map_or(0, |verbose| verbose.parse().expect("verbosity flag must be an integer"));
     let target_crate = is_target_crate();
-    // Determine whether this is cargo invoking rustc to get some infos.
-    let info_query = get_arg_flag_value("--print").is_some() || has_arg_flag("-vV");
 
     let store_json = |info: CrateRunInfo| {
         if get_arg_flag_value("--emit").unwrap_or_default().split(',').any(|e| e == "dep-info") {
@@ -325,7 +335,7 @@ pub fn phase_rustc(mut args: impl Iterator<Item = String>, phase: RustcPhase) {
         }
     };
 
-    let runnable_crate = !info_query && is_runnable_crate();
+    let runnable_crate = is_runnable_crate();
 
     if runnable_crate && target_crate {
         assert!(
@@ -399,7 +409,7 @@ pub fn phase_rustc(mut args: impl Iterator<Item = String>, phase: RustcPhase) {
     let mut emit_link_hack = false;
     // Arguments are treated very differently depending on whether this crate is
     // for interpretation by Miri, or for use by a build script / proc macro.
-    if !info_query && target_crate {
+    if target_crate {
         // Forward arguments, but remove "link" from "--emit" to make this a check-only build.
         let emit_flag = "--emit";
         while let Some(arg) = args.next() {
@@ -433,17 +443,14 @@ pub fn phase_rustc(mut args: impl Iterator<Item = String>, phase: RustcPhase) {
             cmd.arg("-C").arg("panic=abort");
         }
     } else {
-        // For host crates (but not when we are just printing some info),
-        // we might still have to set the sysroot.
-        if !info_query {
-            // When we're running `cargo-miri` from `x.py` we need to pass the sysroot explicitly
-            // due to bootstrap complications.
-            if let Some(sysroot) = std::env::var_os("MIRI_HOST_SYSROOT") {
-                cmd.arg("--sysroot").arg(sysroot);
-            }
+        // This is a host crate.
+        // When we're running `cargo-miri` from `x.py` we need to pass the sysroot explicitly
+        // due to bootstrap complications.
+        if let Some(sysroot) = std::env::var_os("MIRI_HOST_SYSROOT") {
+            cmd.arg("--sysroot").arg(sysroot);
         }
 
-        // For host crates or when we are printing, just forward everything.
+        // Forward everything.
         cmd.args(args);
     }
 
@@ -455,9 +462,7 @@ pub fn phase_rustc(mut args: impl Iterator<Item = String>, phase: RustcPhase) {
 
     // Run it.
     if verbose > 0 {
-        eprintln!(
-            "[cargo-miri rustc] target_crate={target_crate} runnable_crate={runnable_crate} info_query={info_query}"
-        );
+        eprintln!("[cargo-miri rustc] target_crate={target_crate} runnable_crate={runnable_crate}");
     }
 
     // Create a stub .rlib file if "link" was requested by cargo.
@@ -546,15 +551,13 @@ pub fn phase_runner(mut binary_args: impl Iterator<Item = String>, phase: Runner
     // but when we run here, cargo does not interpret the JSON any more. `--json`
     // then also needs to be dropped.
     let mut args = info.args.into_iter();
-    let error_format_flag = "--error-format";
-    let json_flag = "--json";
     while let Some(arg) = args.next() {
         if arg == "--extern" {
             forward_patched_extern_arg(&mut args, &mut cmd);
-        } else if let Some(suffix) = arg.strip_prefix(error_format_flag) {
+        } else if let Some(suffix) = arg.strip_prefix("--error-format") {
             assert!(suffix.starts_with('='));
             // Drop this argument.
-        } else if let Some(suffix) = arg.strip_prefix(json_flag) {
+        } else if let Some(suffix) = arg.strip_prefix("--json") {
             assert!(suffix.starts_with('='));
             // Drop this argument.
         } else {
@@ -592,13 +595,11 @@ pub fn phase_rustdoc(mut args: impl Iterator<Item = String>) {
     // just default to a straight-forward invocation for now:
     let mut cmd = Command::new("rustdoc");
 
-    let extern_flag = "--extern";
-    let runtool_flag = "--runtool";
     while let Some(arg) = args.next() {
-        if arg == extern_flag {
+        if arg == "--extern" {
             // Patch --extern arguments to use *.rmeta files, since phase_cargo_rustc only creates stub *.rlib files.
             forward_patched_extern_arg(&mut args, &mut cmd);
-        } else if arg == runtool_flag {
+        } else if arg == "--runtool" {
             // An existing --runtool flag indicates cargo is running in cross-target mode, which we don't support.
             // Note that this is only passed when cargo is run with the unstable -Zdoctest-xcompile flag;
             // otherwise, we won't be called as rustdoc at all.
diff --git a/src/tools/miri/miri-script/src/commands.rs b/src/tools/miri/miri-script/src/commands.rs
@@ -479,10 +479,11 @@ impl Command {
         Ok(())
     }
 
-    fn run(dep: bool, flags: Vec<OsString>) -> Result<()> {
+    fn run(dep: bool, mut flags: Vec<OsString>) -> Result<()> {
         let mut e = MiriEnv::new()?;
         // Scan for "--target" to overwrite the "MIRI_TEST_TARGET" env var so
-        // that we set the MIRI_SYSROOT up the right way.
+        // that we set the MIRI_SYSROOT up the right way. We must make sure that
+        // MIRI_TEST_TARGET and `--target` are in sync.
         use itertools::Itertools;
         let target = flags
             .iter()
@@ -493,33 +494,35 @@ impl Command {
             // Found it!
             e.sh.set_var("MIRI_TEST_TARGET", target);
         } else if let Ok(target) = std::env::var("MIRI_TEST_TARGET") {
-            // Make sure miri actually uses this target.
-            let miriflags = e.sh.var("MIRIFLAGS").unwrap_or_default();
-            e.sh.set_var("MIRIFLAGS", format!("{miriflags} --target {target}"));
+            // Convert `MIRI_TEST_TARGET` into `--target`.
+            flags.push("--target".into());
+            flags.push(target.into());
         }
-        // Scan for "--edition" (we'll set one ourselves if that flag is not present).
+        // Scan for "--edition", set one ourselves if that flag is not present.
         let have_edition =
             flags.iter().take_while(|arg| *arg != "--").any(|arg| *arg == "--edition");
+        if !have_edition {
+            flags.push("--edition=2021".into()); // keep in sync with `tests/ui.rs`.`
+        }
 
         // Prepare a sysroot.
         e.build_miri_sysroot(/* quiet */ true)?;
 
-        // Then run the actual command.
+        // Then run the actual command. Also add MIRIFLAGS.
         let miri_manifest = path!(e.miri_dir / "Cargo.toml");
         let miri_flags = e.sh.var("MIRIFLAGS").unwrap_or_default();
         let miri_flags = flagsplit(&miri_flags);
         let toolchain = &e.toolchain;
         let extra_flags = &e.cargo_extra_flags;
-        let edition_flags = (!have_edition).then_some("--edition=2021"); // keep in sync with `tests/ui.rs`.`
         if dep {
             cmd!(
                 e.sh,
-                "cargo +{toolchain} --quiet test {extra_flags...} --manifest-path {miri_manifest} --test ui -- --miri-run-dep-mode {miri_flags...} {edition_flags...} {flags...}"
+                "cargo +{toolchain} --quiet test {extra_flags...} --manifest-path {miri_manifest} --test ui -- --miri-run-dep-mode {miri_flags...} {flags...}"
             ).quiet().run()?;
         } else {
             cmd!(
                 e.sh,
-                "cargo +{toolchain} --quiet run {extra_flags...} --manifest-path {miri_manifest} -- {miri_flags...} {edition_flags...} {flags...}"
+                "cargo +{toolchain} --quiet run {extra_flags...} --manifest-path {miri_manifest} -- {miri_flags...} {flags...}"
             ).quiet().run()?;
         }
         Ok(())
diff --git a/src/tools/miri/tests/ui.rs b/src/tools/miri/tests/ui.rs
@@ -54,34 +54,13 @@ fn build_so_for_c_ffi_tests() -> PathBuf {
     so_file_path
 }
 
-fn test_config(target: &str, path: &str, mode: Mode, with_dependencies: bool) -> Config {
+/// Does *not* set any args or env vars, since it is shared between the test runner and
+/// run_dep_mode.
+fn miri_config(target: &str, path: &str, mode: Mode, with_dependencies: bool) -> Config {
     // Miri is rustc-like, so we create a default builder for rustc and modify it
     let mut program = CommandBuilder::rustc();
     program.program = miri_path();
 
-    // Add some flags we always want.
-    program.args.push("-Dwarnings".into());
-    program.args.push("-Dunused".into());
-    program.args.push("-Ainternal_features".into());
-    if let Ok(extra_flags) = env::var("MIRIFLAGS") {
-        for flag in extra_flags.split_whitespace() {
-            program.args.push(flag.into());
-        }
-    }
-    program.args.push("-Zui-testing".into());
-    program.args.push("--target".into());
-    program.args.push(target.into());
-
-    // If we're on linux, and we're testing the extern-so functionality,
-    // then build the shared object file for testing external C function calls
-    // and push the relevant compiler flag.
-    if cfg!(target_os = "linux") && path.starts_with("tests/extern-so/") {
-        let so_file_path = build_so_for_c_ffi_tests();
-        let mut flag = std::ffi::OsString::from("-Zmiri-extern-so-file=");
-        flag.push(so_file_path.into_os_string());
-        program.args.push(flag);
-    }
-
     let mut config = Config {
         target: Some(target.to_owned()),
         stderr_filters: STDERR.clone(),
@@ -119,17 +98,38 @@ fn run_tests(
     with_dependencies: bool,
     tmpdir: &Path,
 ) -> Result<()> {
-    let mut config = test_config(target, path, mode, with_dependencies);
+    let mut config = miri_config(target, path, mode, with_dependencies);
 
     // Add a test env var to do environment communication tests.
     config.program.envs.push(("MIRI_ENV_VAR_TEST".into(), Some("0".into())));
-
     // Let the tests know where to store temp files (they might run for a different target, which can make this hard to find).
     config.program.envs.push(("MIRI_TEMP".into(), Some(tmpdir.to_owned().into())));
-
     // If a test ICEs, we want to see a backtrace.
     config.program.envs.push(("RUST_BACKTRACE".into(), Some("1".into())));
 
+    // Add some flags we always want.
+    config.program.args.push("-Dwarnings".into());
+    config.program.args.push("-Dunused".into());
+    config.program.args.push("-Ainternal_features".into());
+    if let Ok(extra_flags) = env::var("MIRIFLAGS") {
+        for flag in extra_flags.split_whitespace() {
+            config.program.args.push(flag.into());
+        }
+    }
+    config.program.args.push("-Zui-testing".into());
+    config.program.args.push("--target".into());
+    config.program.args.push(target.into());
+
+    // If we're on linux, and we're testing the extern-so functionality,
+    // then build the shared object file for testing external C function calls
+    // and push the relevant compiler flag.
+    if cfg!(target_os = "linux") && path.starts_with("tests/extern-so/") {
+        let so_file_path = build_so_for_c_ffi_tests();
+        let mut flag = std::ffi::OsString::from("-Zmiri-extern-so-file=");
+        flag.push(so_file_path.into_os_string());
+        config.program.args.push(flag);
+    }
+
     // Handle command-line arguments.
     let args = ui_test::Args::test()?;
     let default_bless = env::var_os("RUSTC_BLESS").is_some_and(|v| v != "0");
@@ -292,13 +292,12 @@ fn main() -> Result<()> {
 
 fn run_dep_mode(target: String, mut args: impl Iterator<Item = OsString>) -> Result<()> {
     let path = args.next().expect("./miri run-dep must be followed by a file name");
-    let mut config = test_config(
+    let config = miri_config(
         &target,
         "",
         Mode::Yolo { rustfix: RustfixMode::Disabled },
         /* with dependencies */ true,
     );
-    config.program.args.clear(); // We want to give the user full control over flags
     let dep_args = config.build_dependencies()?;
 
     let mut cmd = config.program.build(&config.out_dir);
