Rollup merge of #124007 - RalfJung:miri, r=RalfJung

Miri subtree update

r? ``@ghost``

Author: matthiaskrgr

Cargo.lock

@@ -3364,9 +3364,9 @@ dependencies = [
 
 [[package]]
 name = "rustc-build-sysroot"
-version = "0.4.5"
+version = "0.4.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a26170e1d79ea32f7ccec3188dd13cfc1f18c82764a9cbc1071667c0f865a4ea"
+checksum = "a9bf37423495cd3a6a9ef8c75fc4566de0d26de0ab75f36f67a426e58df5768c"
 dependencies = [
  "anyhow",
  "rustc_version",

src/tools/miri/README.md

@@ -451,36 +451,32 @@ Some native rustc `-Z` flags are also very relevant for Miri:
 * `-Zmir-emit-retag` controls whether `Retag` statements are emitted. Miri
   enables this per default because it is needed for [Stacked Borrows] and [Tree Borrows].
 
-Moreover, Miri recognizes some environment variables:
+Moreover, Miri recognizes some environment variables (unless noted otherwise, these are supported
+by all intended entry points, i.e. `cargo miri` and `./miri {test,run}`):
 
 * `MIRI_AUTO_OPS` indicates whether the automatic execution of rustfmt, clippy and toolchain setup
   should be skipped. If it is set to `no`, they are skipped. This is used to allow automated IDE
   actions to avoid the auto ops.
 * `MIRI_LOG`, `MIRI_BACKTRACE` control logging and backtrace printing during
   Miri executions, also [see "Testing the Miri driver" in `CONTRIBUTING.md`][testing-miri].
-* `MIRIFLAGS` (recognized by `cargo miri` and the test suite) defines extra
-  flags to be passed to Miri.
-* `MIRI_LIB_SRC` defines the directory where Miri expects the sources of the
-  standard library that it will build and use for interpretation. This directory
-  must point to the `library` subdirectory of a `rust-lang/rust` repository
-  checkout.
-* `MIRI_SYSROOT` (recognized by `cargo miri` and the Miri driver) indicates the sysroot to use. When
-  using `cargo miri`, this skips the automatic setup -- only set this if you do not want to use the
-  automatically created sysroot. For directly invoking the Miri driver, this variable (or a
-  `--sysroot` flag) is mandatory. When invoking `cargo miri setup`, this indicates where the sysroot
-  will be put.
-* `MIRI_TEST_TARGET` (recognized by the test suite and the `./miri` script) indicates which target
+* `MIRIFLAGS` defines extra flags to be passed to Miri.
+* `MIRI_LIB_SRC` defines the directory where Miri expects the sources of the standard library that
+  it will build and use for interpretation. This directory must point to the `library` subdirectory
+  of a `rust-lang/rust` repository checkout.
+* `MIRI_SYSROOT` indicates the sysroot to use. When using `cargo miri`, this skips the automatic
+  setup -- only set this if you do not want to use the automatically created sysroot. When invoking
+  `cargo miri setup`, this indicates where the sysroot will be put.
+* `MIRI_TEST_TARGET` (recognized by `./miri {test,run}`) indicates which target
   architecture to test against.  `miri` and `cargo miri` accept the `--target` flag for the same
   purpose.
-* `MIRI_TEST_THREADS` (recognized by the test suite): set the number of threads to use for running tests.
-  By default the number of cores is used.
-* `MIRI_NO_STD` (recognized by `cargo miri`) makes sure that the target's sysroot is built without
-  libstd. This allows testing and running no_std programs.
-  (Miri has a heuristic to detect no-std targets based on the target name; this environment variable
-  is only needed when that heuristic fails.)
-* `RUSTC_BLESS` (recognized by the test suite and `cargo-miri-test/run-test.py`): overwrite all
+* `MIRI_TEST_THREADS` (recognized by `./miri test`): set the number of threads to use for running tests.
+  By default, the number of cores is used.
+* `MIRI_NO_STD` makes sure that the target's sysroot is built without libstd. This allows testing
+  and running no_std programs. (Miri has a heuristic to detect no-std targets based on the target
+  name; this environment variable is only needed when that heuristic fails.)
+* `RUSTC_BLESS` (recognized by `./miri test` and `cargo-miri-test/run-test.py`): overwrite all
   `stderr` and `stdout` files instead of checking whether the output matches.
-* `MIRI_SKIP_UI_CHECKS` (recognized by the test suite): don't check whether the
+* `MIRI_SKIP_UI_CHECKS` (recognized by `./miri test`): don't check whether the
   `stderr` or `stdout` files match the actual output.
 
 The following environment variables are *internal* and must not be used by

src/tools/miri/cargo-miri/Cargo.lock

@@ -194,9 +194,9 @@ dependencies = [
 
 [[package]]
 name = "rustc-build-sysroot"
-version = "0.4.5"
+version = "0.4.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a26170e1d79ea32f7ccec3188dd13cfc1f18c82764a9cbc1071667c0f865a4ea"
+checksum = "a9bf37423495cd3a6a9ef8c75fc4566de0d26de0ab75f36f67a426e58df5768c"
 dependencies = [
  "anyhow",
  "rustc_version",

src/tools/miri/cargo-miri/Cargo.toml

@@ -18,7 +18,7 @@ directories = "5"
 rustc_version = "0.4"
 serde_json = "1.0.40"
 cargo_metadata = "0.18.0"
-rustc-build-sysroot = "0.4.1"
+rustc-build-sysroot = "0.4.6"
 
 # Enable some feature flags that dev-dependencies need but dependencies
 # do not.  This makes `./miri install` after `./miri build` faster.

src/tools/miri/cargo-miri/src/phases.rs

@@ -172,8 +172,6 @@ pub fn phase_cargo_miri(mut args: impl Iterator<Item = String>) {
     // Forward all further arguments (not consumed by `ArgSplitFlagValue`) to cargo.
     cmd.args(args);
 
-    // Let it know where the Miri sysroot lives.
-    cmd.env("MIRI_SYSROOT", miri_sysroot);
     // Set `RUSTC_WRAPPER` to ourselves.  Cargo will prepend that binary to its usual invocation,
     // i.e., the first argument is `rustc` -- which is what we use in `main` to distinguish
     // the two codepaths. (That extra argument is why we prefer this over setting `RUSTC`.)
@@ -200,10 +198,7 @@ pub fn phase_cargo_miri(mut args: impl Iterator<Item = String>) {
     // 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.
+    // that to be the Miri driver, but acting as rustc, in host mode.
     //
     // 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
@@ -212,14 +207,19 @@ pub fn phase_cargo_miri(mut args: impl Iterator<Item = String>) {
     // bootstrap `rustc` thing in our way! Instead, we have MIRI_HOST_SYSROOT to use for host
     // builds.
     cmd.env("RUSTC", fs::canonicalize(find_miri()).unwrap());
-    cmd.env("MIRI_BE_RUSTC", "target"); // we better remember to *unset* this in the other phases!
+    // In case we get invoked as RUSTC without the wrapper, let's be a host rustc. This makes no
+    // sense for cross-interpretation situations, but without the wrapper, this will use the host
+    // sysroot, so asking it to behave like a target build makes even less sense.
+    cmd.env("MIRI_BE_RUSTC", "host"); // we better remember to *unset* this in the other phases!
 
     // Set rustdoc to us as well, so we can run doctests.
     if let Some(orig_rustdoc) = env::var_os("RUSTDOC") {
         cmd.env("MIRI_ORIG_RUSTDOC", orig_rustdoc);
     }
     cmd.env("RUSTDOC", &cargo_miri_path);
 
+    // Forward some crucial information to our own re-invocations.
+    cmd.env("MIRI_SYSROOT", miri_sysroot);
     cmd.env("MIRI_LOCAL_CRATES", local_crates(&metadata));
     if verbose > 0 {
         cmd.env("MIRI_VERBOSE", verbose.to_string()); // This makes the other phases verbose.
@@ -412,6 +412,12 @@ pub fn phase_rustc(mut args: impl Iterator<Item = String>, phase: RustcPhase) {
     // 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 target_crate {
+        if phase != RustcPhase::Setup {
+            // Set the sysroot -- except during setup, where we don't have an existing sysroot yet
+            // and where the bootstrap wrapper adds its own `--sysroot` flag so we can't set ours.
+            cmd.arg("--sysroot").arg(env::var_os("MIRI_SYSROOT").unwrap());
+        }
+
         // Forward arguments, but patched.
         let emit_flag = "--emit";
         // This hack helps bootstrap run standard library tests in Miri. The issue is as follows:
@@ -574,6 +580,12 @@ pub fn phase_runner(mut binary_args: impl Iterator<Item = String>, phase: Runner
         cmd.env(name, val);
     }
 
+    if phase != RunnerPhase::Rustdoc {
+        // Set the sysroot. Not necessary in rustdoc, where we already set the sysroot in
+        // `phase_rustdoc`. rustdoc will forward that flag when invoking rustc (i.e., us), so the
+        // flag is present in `info.args`.
+        cmd.arg("--sysroot").arg(env::var_os("MIRI_SYSROOT").unwrap());
+    }
     // Forward rustc arguments.
     // We need to patch "--extern" filenames because we forced a check-only
     // build without cargo knowing about that: replace `.rlib` suffix by

src/tools/miri/miri-script/src/commands.rs

@@ -2,6 +2,7 @@ use std::env;
 use std::ffi::OsString;
 use std::io::Write;
 use std::ops::Not;
+use std::path::PathBuf;
 use std::process;
 use std::thread;
 use std::time;
@@ -20,10 +21,11 @@ const JOSH_FILTER: &str =
 const JOSH_PORT: &str = "42042";
 
 impl MiriEnv {
-    fn build_miri_sysroot(&mut self, quiet: bool) -> Result<()> {
-        if self.sh.var("MIRI_SYSROOT").is_ok() {
+    /// Returns the location of the sysroot.
+    fn build_miri_sysroot(&mut self, quiet: bool) -> Result<PathBuf> {
+        if let Some(miri_sysroot) = self.sh.var_os("MIRI_SYSROOT") {
             // Sysroot already set, use that.
-            return Ok(());
+            return Ok(miri_sysroot.into());
         }
         let manifest_path = path!(self.miri_dir / "cargo-miri" / "Cargo.toml");
         let Self { toolchain, cargo_extra_flags, .. } = &self;
@@ -57,8 +59,8 @@ impl MiriEnv {
             .with_context(|| "`cargo miri setup` failed")?;
             panic!("`cargo miri setup` didn't fail again the 2nd time?");
         };
-        self.sh.set_var("MIRI_SYSROOT", output);
-        Ok(())
+        self.sh.set_var("MIRI_SYSROOT", &output);
+        Ok(output.into())
     }
 }
 
@@ -505,8 +507,10 @@ impl Command {
             flags.push("--edition=2021".into()); // keep in sync with `tests/ui.rs`.`
         }
 
-        // Prepare a sysroot.
-        e.build_miri_sysroot(/* quiet */ true)?;
+        // Prepare a sysroot, and add it to the flags.
+        let miri_sysroot = e.build_miri_sysroot(/* quiet */ true)?;
+        flags.push("--sysroot".into());
+        flags.push(miri_sysroot.into());
 
         // Then run the actual command. Also add MIRIFLAGS.
         let miri_manifest = path!(e.miri_dir / "Cargo.toml");

src/tools/miri/src/bin/miri.rs

@@ -282,25 +282,6 @@ fn run_compiler(
     callbacks: &mut (dyn rustc_driver::Callbacks + Send),
     using_internal_features: std::sync::Arc<std::sync::atomic::AtomicBool>,
 ) -> ! {
-    if target_crate {
-        // Miri needs a custom sysroot for target crates.
-        // If no `--sysroot` is given, the `MIRI_SYSROOT` env var is consulted to find where
-        // that sysroot lives, and that is passed to rustc.
-        let sysroot_flag = "--sysroot";
-        if !args.iter().any(|e| e.starts_with(sysroot_flag)) {
-            // Using the built-in default here would be plain wrong, so we *require*
-            // the env var to make sure things make sense.
-            let miri_sysroot = env::var("MIRI_SYSROOT").unwrap_or_else(|_| {
-                show_error!(
-                    "Miri was invoked in 'target' mode without `MIRI_SYSROOT` or `--sysroot` being set"
-                    )
-            });
-
-            args.push(sysroot_flag.to_owned());
-            args.push(miri_sysroot);
-        }
-    }
-
     // Don't insert `MIRI_DEFAULT_ARGS`, in particular, `--cfg=miri`, if we are building
     // a "host" crate. That may cause procedural macros (and probably build scripts) to
     // depend on Miri-only symbols, such as `miri_resolve_frame`:

src/tools/miri/src/helpers.rs

@@ -83,6 +83,17 @@ const UNIX_IO_ERROR_TABLE: &[(&str, std::io::ErrorKind)] = {
         ("EAGAIN", WouldBlock),
     ]
 };
+// This mapping should match `decode_error_kind` in
+// <https://github.com/rust-lang/rust/blob/master/library/std/src/sys/pal/windows/mod.rs>.
+const WINDOWS_IO_ERROR_TABLE: &[(&str, std::io::ErrorKind)] = {
+    use std::io::ErrorKind::*;
+    // FIXME: this is still incomplete.
+    &[
+        ("ERROR_ACCESS_DENIED", PermissionDenied),
+        ("ERROR_FILE_NOT_FOUND", NotFound),
+        ("ERROR_INVALID_PARAMETER", InvalidInput),
+    ]
+};
 
 /// Gets an instance for a path.
 ///
@@ -749,20 +760,12 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
             }
             throw_unsup_format!("io error {:?} cannot be translated into a raw os error", err_kind)
         } else if target.families.iter().any(|f| f == "windows") {
-            // FIXME: we have to finish implementing the Windows equivalent of this.
-            use std::io::ErrorKind::*;
-            Ok(this.eval_windows(
-                "c",
-                match err_kind {
-                    NotFound => "ERROR_FILE_NOT_FOUND",
-                    PermissionDenied => "ERROR_ACCESS_DENIED",
-                    _ =>
-                        throw_unsup_format!(
-                            "io error {:?} cannot be translated into a raw os error",
-                            err_kind
-                        ),
-                },
-            ))
+            for &(name, kind) in WINDOWS_IO_ERROR_TABLE {
+                if err_kind == kind {
+                    return Ok(this.eval_windows("c", name));
+                }
+            }
+            throw_unsup_format!("io error {:?} cannot be translated into a raw os error", err_kind);
         } else {
             throw_unsup_format!(
                 "converting io::Error into errnum is unsupported for OS {}",
@@ -786,8 +789,14 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
                     return Ok(Some(kind));
                 }
             }
-            // Our table is as complete as the mapping in std, so we are okay with saying "that's a
-            // strange one" here.
+            return Ok(None);
+        } else if target.families.iter().any(|f| f == "windows") {
+            let errnum = errnum.to_u32()?;
+            for &(name, kind) in WINDOWS_IO_ERROR_TABLE {
+                if errnum == this.eval_windows("c", name).to_u32()? {
+                    return Ok(Some(kind));
+                }
+            }
             return Ok(None);
         } else {
             throw_unsup_format!(
@@ -1344,3 +1353,18 @@ pub(crate) fn simd_element_to_bool(elem: ImmTy<'_, Provenance>) -> InterpResult<
         _ => throw_ub_format!("each element of a SIMD mask must be all-0-bits or all-1-bits"),
     })
 }
+
+/// Check whether an operation that writes to a target buffer was successful.
+/// Accordingly select return value.
+/// Local helper function to be used in Windows shims.
+pub(crate) fn windows_check_buffer_size((success, len): (bool, u64)) -> u32 {
+    if success {
+        // If the function succeeds, the return value is the number of characters stored in the target buffer,
+        // not including the terminating null character.
+        u32::try_from(len.checked_sub(1).unwrap()).unwrap()
+    } else {
+        // If the target buffer was not large enough to hold the data, the return value is the buffer size, in characters,
+        // required to hold the string and its terminating null character.
+        u32::try_from(len).unwrap()
+    }
+}

src/tools/miri/src/lib.rs

@@ -13,6 +13,7 @@
 #![feature(let_chains)]
 #![feature(lint_reasons)]
 #![feature(trait_upcasting)]
+#![feature(absolute_path)]
 // Configure clippy and other lints
 #![allow(
     clippy::collapsible_else_if,

src/tools/miri/src/shims/env.rs

@@ -9,21 +9,7 @@ use rustc_middle::ty::Ty;
 use rustc_target::abi::Size;
 
 use crate::*;
-
-/// Check whether an operation that writes to a target buffer was successful.
-/// Accordingly select return value.
-/// Local helper function to be used in Windows shims.
-fn windows_check_buffer_size((success, len): (bool, u64)) -> u32 {
-    if success {
-        // If the function succeeds, the return value is the number of characters stored in the target buffer,
-        // not including the terminating null character.
-        u32::try_from(len.checked_sub(1).unwrap()).unwrap()
-    } else {
-        // If the target buffer was not large enough to hold the data, the return value is the buffer size, in characters,
-        // required to hold the string and its terminating null character.
-        u32::try_from(len).unwrap()
-    }
-}
+use helpers::windows_check_buffer_size;
 
 #[derive(Default)]
 pub struct EnvVars<'tcx> {
@@ -164,7 +150,8 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
         let name_ptr = this.read_pointer(name_op)?;
         let name = this.read_os_str_from_wide_str(name_ptr)?;
         Ok(match this.machine.env_vars.map.get(&name) {
-            Some(var_ptr) => {
+            Some(&var_ptr) => {
+                this.set_last_error(Scalar::from_u32(0))?; // make sure this is unambiguously not an error
                 // The offset is used to strip the "{name}=" part of the string.
                 #[rustfmt::skip]
                 let name_offset_bytes = u64::try_from(name.len()).unwrap()
@@ -375,10 +362,12 @@ pub trait EvalContextExt<'mir, 'tcx: 'mir>: crate::MiriInterpCxExt<'mir, 'tcx> {
 
         // If we cannot get the current directory, we return 0
         match env::current_dir() {
-            Ok(cwd) =>
+            Ok(cwd) => {
+                this.set_last_error(Scalar::from_u32(0))?; // make sure this is unambiguously not an error
                 return Ok(Scalar::from_u32(windows_check_buffer_size(
                     this.write_path_to_wide_str(&cwd, buf, size, /*truncate*/ false)?,
-                ))),
+                )));
+            }
             Err(e) => this.set_last_error_from_io_error(e.kind())?,
         }
         Ok(Scalar::from_u32(0))