tell people how to set miri flags

cargo-miri/src/phases.rs

@@ -23,6 +23,12 @@ Subcommands:
     clean                    Clean the Miri cache & target directory
 
 The cargo options are exactly the same as for `cargo run` and `cargo test`, respectively.
+Furthermore, the following extra flags and environment variables are recognized for `run` and `test`:
+
+    --many-seeds[=from..to]  Run the program/tests many times with different seeds in the given range.
+                             The range defaults to `0..64`.
+
+    MIRIFLAGS                Extra flags to pass to the Miri driver. Use this to pass `-Zmiri-...` flags.
 
 Examples:
     cargo miri run

src/diagnostics.rs

@@ -227,8 +227,8 @@ pub fn report_error<'tcx>(
         let helps = match info {
             UnsupportedInIsolation(_) =>
                 vec![
-                    (None, format!("pass the flag `-Zmiri-disable-isolation` to disable isolation;")),
-                    (None, format!("or pass `-Zmiri-isolation-error=warn` to configure Miri to return an error code from isolated operations (if supported for that operation) and continue with a warning")),
+                    (None, format!("set `MIRIFLAGS=-Zmiri-disable-isolation` to disable isolation;")),
+                    (None, format!("or set `MIRIFLAGS=-Zmiri-isolation-error=warn` to make Miri return an error code from isolated operations (if supported for that operation) and continue with a warning")),
                 ],
             UnsupportedForeignItem(_) => {
                 vec![
@@ -463,19 +463,22 @@ pub fn report_leaks<'tcx>(
 ) {
     let mut any_pruned = false;
     for (id, kind, mut alloc) in leaks {
+        let mut title = format!(
+            "memory leaked: {id:?} ({}, size: {:?}, align: {:?})",
+            kind,
+            alloc.size().bytes(),
+            alloc.align.bytes()
+        );
         let Some(backtrace) = alloc.extra.backtrace.take() else {
+            ecx.tcx.dcx().err(title);
             continue;
         };
+        title.push_str(", allocated here:");
         let (backtrace, pruned) = prune_stacktrace(backtrace, &ecx.machine);
         any_pruned |= pruned;
         report_msg(
             DiagLevel::Error,
-            format!(
-                "memory leaked: {id:?} ({}, size: {:?}, align: {:?}), allocated here:",
-                kind,
-                alloc.size().bytes(),
-                alloc.align.bytes()
-            ),
+            title,
             vec![],
             vec![],
             vec![],
@@ -642,13 +645,9 @@ impl<'tcx> MiriMachine<'tcx> {
                     (
                         None,
                         format!(
-                            "This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`,"
+                            "This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`, which means that Miri might miss pointer bugs in this program."
                         ),
                     ),
-                    (
-                        None,
-                        format!("which means that Miri might miss pointer bugs in this program."),
-                    ),
                     (
                         None,
                         format!(
@@ -664,13 +663,13 @@ impl<'tcx> MiriMachine<'tcx> {
                     (
                         None,
                         format!(
-                            "You can then pass the `-Zmiri-strict-provenance` flag to Miri, to ensure you are not relying on `with_exposed_provenance` semantics."
+                            "You can then set `MIRIFLAGS=-Zmiri-strict-provenance` to ensure you are not relying on `with_exposed_provenance` semantics."
                         ),
                     ),
                     (
                         None,
                         format!(
-                            "Alternatively, the `-Zmiri-permissive-provenance` flag disables this warning."
+                            "Alternatively, `MIRIFLAGS=-Zmiri-permissive-provenance` disables this warning."
                         ),
                     ),
                 ],

src/eval.rs

@@ -468,22 +468,15 @@ pub fn eval_entry<'tcx>(
         // Check for thread leaks.
         if !ecx.have_all_terminated() {
             tcx.dcx().err("the main thread terminated without waiting for all remaining threads");
-            tcx.dcx().note("pass `-Zmiri-ignore-leaks` to disable this check");
+            tcx.dcx().note("set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check");
             return None;
         }
         // Check for memory leaks.
         info!("Additional static roots: {:?}", ecx.machine.static_roots);
         let leaks = ecx.find_leaked_allocations(&ecx.machine.static_roots);
         if !leaks.is_empty() {
             report_leaks(&ecx, leaks);
-            let leak_message = "the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check";
-            if ecx.machine.collect_leak_backtraces {
-                // If we are collecting leak backtraces, each leak is a distinct error diagnostic.
-                tcx.dcx().note(leak_message);
-            } else {
-                // If we do not have backtraces, we just report an error without any span.
-                tcx.dcx().err(leak_message);
-            };
+            tcx.dcx().note("set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check");
             // Ignore the provided return code - let the reported error
             // determine the return code.
             return None;

tests/fail-dep/concurrency/libc_pthread_create_main_terminate.stderr

@@ -1,6 +1,6 @@
 error: the main thread terminated without waiting for all remaining threads
 
-note: pass `-Zmiri-ignore-leaks` to disable this check
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 

tests/fail-dep/libc/aligned_alloc_size_zero_leak.stderr

@@ -9,7 +9,7 @@ LL |         aligned_alloc(2, 0);
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-note: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 

tests/fail-dep/libc/fs/isolated_stdin.stderr

@@ -4,8 +4,8 @@ error: unsupported operation: `read` from stdin not available when isolation is
 LL |         libc::read(0, bytes.as_mut_ptr() as *mut libc::c_void, 512);
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `read` from stdin not available when isolation is enabled
    |
-   = help: pass the flag `-Zmiri-disable-isolation` to disable isolation;
-   = help: or pass `-Zmiri-isolation-error=warn` to configure Miri to return an error code from isolated operations (if supported for that operation) and continue with a warning
+   = help: set `MIRIFLAGS=-Zmiri-disable-isolation` to disable isolation;
+   = help: or set `MIRIFLAGS=-Zmiri-isolation-error=warn` to make Miri return an error code from isolated operations (if supported for that operation) and continue with a warning
    = note: BACKTRACE:
    = note: inside `main` at $DIR/isolated_stdin.rs:LL:CC
 

tests/fail-dep/libc/malloc_zero_memory_leak.stderr

@@ -9,7 +9,7 @@ LL |         let _ptr = libc::malloc(0);
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-note: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 

tests/fail-dep/libc/posix_memalign_size_zero_leak.stderr

@@ -9,7 +9,7 @@ LL |     let _ = unsafe { libc::posix_memalign(&mut ptr, align, size) };
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-note: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 

tests/fail/intrinsics/ptr_metadata_uninit_slice_len.stderr

@@ -4,12 +4,11 @@ warning: integer-to-pointer cast
 LL |         (*p.as_mut_ptr().cast::<[*const i32; 2]>())[0] = 4 as *const i32;
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ integer-to-pointer cast
    |
-   = help: This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`,
-   = help: which means that Miri might miss pointer bugs in this program.
+   = help: This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`, which means that Miri might miss pointer bugs in this program.
    = help: See https://doc.rust-lang.org/nightly/std/ptr/fn.with_exposed_provenance.html for more details on that operation.
    = help: To ensure that Miri does not miss bugs in your program, use Strict Provenance APIs (https://doc.rust-lang.org/nightly/std/ptr/index.html#strict-provenance, https://crates.io/crates/sptr) instead.
-   = help: You can then pass the `-Zmiri-strict-provenance` flag to Miri, to ensure you are not relying on `with_exposed_provenance` semantics.
-   = help: Alternatively, the `-Zmiri-permissive-provenance` flag disables this warning.
+   = help: You can then set `MIRIFLAGS=-Zmiri-strict-provenance` to ensure you are not relying on `with_exposed_provenance` semantics.
+   = help: Alternatively, `MIRIFLAGS=-Zmiri-permissive-provenance` disables this warning.
    = note: BACKTRACE:
    = note: inside `main` at $DIR/ptr_metadata_uninit_slice_len.rs:LL:CC
 

tests/fail/memleak.stderr

@@ -18,7 +18,7 @@ LL |     std::mem::forget(Box::new(42));
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-note: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 

tests/fail/memleak_no_backtrace.rs

@@ -1,5 +1,5 @@
 //@compile-flags: -Zmiri-disable-leak-backtraces
-//@error-in-other-file: the evaluated program leaked memory
+//@error-in-other-file: memory leaked
 //@normalize-stderr-test: ".*│.*" -> "$$stripped$$"
 
 fn main() {

tests/fail/memleak_no_backtrace.stderr

@@ -1,4 +1,6 @@
-error: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+error: memory leaked: ALLOC (Rust heap, size: 4, align: 4)
+
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 

tests/fail/memleak_rc.rs

@@ -1,6 +1,6 @@
 //@error-in-other-file: memory leaked
-//@stderr-per-bitwidth
 //@normalize-stderr-test: ".*│.*" -> "$$stripped$$"
+//@normalize-stderr-test: "Rust heap, size: [0-9]+, align: [0-9]+" -> "Rust heap, SIZE, ALIGN"
 
 use std::cell::RefCell;
 use std::rc::Rc;

tests/fail/memleak_rc.32bit.stderr → tests/fail/memleak_rc.stderr

@@ -1,4 +1,4 @@
-error: memory leaked: ALLOC (Rust heap, size: 16, align: 4), allocated here:
+error: memory leaked: ALLOC (Rust heap, SIZE, ALIGN), allocated here:
   --> RUSTLIB/alloc/src/alloc.rs:LL:CC
    |
 LL |         __rust_alloc(layout.size(), layout.align())
@@ -19,7 +19,7 @@ LL |     let x = Dummy(Rc::new(RefCell::new(None)));
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-note: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 

tests/fail/shims/fs/isolated_file.stderr

@@ -4,8 +4,8 @@ error: unsupported operation: `open` not available when isolation is enabled
 LL |         let fd = cvt_r(|| unsafe { open64(path.as_ptr(), flags, opts.mode as c_int) })?;
    |                                    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ `open` not available when isolation is enabled
    |
-   = help: pass the flag `-Zmiri-disable-isolation` to disable isolation;
-   = help: or pass `-Zmiri-isolation-error=warn` to configure Miri to return an error code from isolated operations (if supported for that operation) and continue with a warning
+   = help: set `MIRIFLAGS=-Zmiri-disable-isolation` to disable isolation;
+   = help: or set `MIRIFLAGS=-Zmiri-isolation-error=warn` to make Miri return an error code from isolated operations (if supported for that operation) and continue with a warning
    = note: BACKTRACE:
    = note: inside closure at RUSTLIB/std/src/sys/pal/PLATFORM/fs.rs:LL:CC
    = note: inside `std::sys::pal::PLATFORM::cvt_r::<i32, {closure@std::sys::pal::PLATFORM::fs::File::open_c::{closure#0}}>` at RUSTLIB/std/src/sys/pal/PLATFORM/mod.rs:LL:CC

tests/fail/tls_macro_leak.stderr

@@ -27,7 +27,7 @@ LL | |         });
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-note: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 

tests/fail/tls_static_leak.stderr

@@ -18,7 +18,7 @@ LL |         TLS.set(Some(Box::leak(Box::new(123))));
 
 note: some details are omitted, run with `MIRIFLAGS=-Zmiri-backtrace=full` for a verbose backtrace
 
-note: the evaluated program leaked memory, pass `-Zmiri-ignore-leaks` to disable this check
+note: set `MIRIFLAGS=-Zmiri-ignore-leaks` to disable this check
 
 error: aborting due to 1 previous error
 

tests/pass/box.stack.stderr

@@ -4,12 +4,11 @@ warning: integer-to-pointer cast
 LL |         let r2 = ((r as usize) + 0) as *mut i32;
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ integer-to-pointer cast
    |
-   = help: This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`,
-   = help: which means that Miri might miss pointer bugs in this program.
+   = help: This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`, which means that Miri might miss pointer bugs in this program.
    = help: See https://doc.rust-lang.org/nightly/std/ptr/fn.with_exposed_provenance.html for more details on that operation.
    = help: To ensure that Miri does not miss bugs in your program, use Strict Provenance APIs (https://doc.rust-lang.org/nightly/std/ptr/index.html#strict-provenance, https://crates.io/crates/sptr) instead.
-   = help: You can then pass the `-Zmiri-strict-provenance` flag to Miri, to ensure you are not relying on `with_exposed_provenance` semantics.
-   = help: Alternatively, the `-Zmiri-permissive-provenance` flag disables this warning.
+   = help: You can then set `MIRIFLAGS=-Zmiri-strict-provenance` to ensure you are not relying on `with_exposed_provenance` semantics.
+   = help: Alternatively, `MIRIFLAGS=-Zmiri-permissive-provenance` disables this warning.
    = note: BACKTRACE:
    = note: inside `into_raw` at $DIR/box.rs:LL:CC
 note: inside `main`

tests/pass/extern_types.stack.stderr

@@ -4,12 +4,11 @@ warning: integer-to-pointer cast
 LL |     let x: &Foo = unsafe { &*(16 as *const Foo) };
    |                              ^^^^^^^^^^^^^^^^^^ integer-to-pointer cast
    |
-   = help: This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`,
-   = help: which means that Miri might miss pointer bugs in this program.
+   = help: This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`, which means that Miri might miss pointer bugs in this program.
    = help: See https://doc.rust-lang.org/nightly/std/ptr/fn.with_exposed_provenance.html for more details on that operation.
    = help: To ensure that Miri does not miss bugs in your program, use Strict Provenance APIs (https://doc.rust-lang.org/nightly/std/ptr/index.html#strict-provenance, https://crates.io/crates/sptr) instead.
-   = help: You can then pass the `-Zmiri-strict-provenance` flag to Miri, to ensure you are not relying on `with_exposed_provenance` semantics.
-   = help: Alternatively, the `-Zmiri-permissive-provenance` flag disables this warning.
+   = help: You can then set `MIRIFLAGS=-Zmiri-strict-provenance` to ensure you are not relying on `with_exposed_provenance` semantics.
+   = help: Alternatively, `MIRIFLAGS=-Zmiri-permissive-provenance` disables this warning.
    = note: BACKTRACE:
    = note: inside `main` at $DIR/extern_types.rs:LL:CC
 

tests/pass/stacked-borrows/issue-miri-2389.stderr

@@ -4,12 +4,11 @@ warning: integer-to-pointer cast
 LL |         let wildcard = &root0 as *const Cell<i32> as usize as *const Cell<i32>;
    |                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ integer-to-pointer cast
    |
-   = help: This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`,
-   = help: which means that Miri might miss pointer bugs in this program.
+   = help: This program is using integer-to-pointer casts or (equivalently) `ptr::with_exposed_provenance`, which means that Miri might miss pointer bugs in this program.
    = help: See https://doc.rust-lang.org/nightly/std/ptr/fn.with_exposed_provenance.html for more details on that operation.
    = help: To ensure that Miri does not miss bugs in your program, use Strict Provenance APIs (https://doc.rust-lang.org/nightly/std/ptr/index.html#strict-provenance, https://crates.io/crates/sptr) instead.
-   = help: You can then pass the `-Zmiri-strict-provenance` flag to Miri, to ensure you are not relying on `with_exposed_provenance` semantics.
-   = help: Alternatively, the `-Zmiri-permissive-provenance` flag disables this warning.
+   = help: You can then set `MIRIFLAGS=-Zmiri-strict-provenance` to ensure you are not relying on `with_exposed_provenance` semantics.
+   = help: Alternatively, `MIRIFLAGS=-Zmiri-permissive-provenance` disables this warning.
    = note: BACKTRACE:
    = note: inside `main` at $DIR/issue-miri-2389.rs:LL:CC