Consider the cargo workspace when checking if a frame is local

[saethlin]

DefId::is_local returns a result which is technically correct, but doesn't match the user's intuition when running integration tests or doctests. This incorporates the workspace crates mentioned in cargo metadata into the check for whether a frame is local to match user intuition.

For example, here is the backtrace you get from MIRIFLAGS=-Zmiri-tag-raw-pointers cargo miri test in bytes 1.1.0:

   --> /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/core/src/slice/raw.rs:131:14
    |
131 |     unsafe { &mut *ptr::slice_from_raw_parts_mut(data, len) }
    |              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ trying to reborrow for Unique at alloc67158, but parent tag <untagged> does not have an appropriate item in the borrow stack
    |
    = help: this indicates a potential bug in the program: it performed an invalid operation, but the rules it violated are still experimental
    = help: see https://github.com/rust-lang/unsafe-code-guidelines/blob/master/wip/stacked-borrows.md for further information
            
    = note: inside `std::slice::from_raw_parts_mut::<u8>` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/core/src/slice/raw.rs:131:14
    = note: inside `bytes::bytes::rebuild_boxed_slice` at /tmp/bytes-1.1.0/src/bytes.rs:938:19
    = note: inside closure at /tmp/bytes-1.1.0/src/bytes.rs:904:18
    = note: inside `<std::sync::atomic::AtomicPtr<()> as bytes::loom::sync::atomic::AtomicMut<()>>::with_mut::<[closure@bytes::bytes::promotable_even_drop::{closure#0}], ()>` at /tmp/bytes-1.1.0/src/loom.rs:17:17
    = note: inside `bytes::bytes::promotable_even_drop` at /tmp/bytes-1.1.0/src/bytes.rs:895:5
    = note: inside `<bytes::Bytes as std::ops::Drop>::drop` at /tmp/bytes-1.1.0/src/bytes.rs:515:18
    = note: inside `std::ptr::drop_in_place::<bytes::Bytes> - shim(Some(bytes::Bytes))` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:188:1
note: inside `copy_to_bytes_less` at tests/test_buf.rs:112:1
   --> tests/test_buf.rs:112:1
    |
112 | }
    | ^
note: inside closure at tests/test_buf.rs:106:1
   --> tests/test_buf.rs:106:1
    |
105 |   #[test]
    |   ------- in this procedural macro expansion
106 | / fn copy_to_bytes_less() {
107 | |     let mut buf = &b"hello world"[..];
108 | |
109 | |     let bytes = buf.copy_to_bytes(5);
110 | |     assert_eq!(bytes, &b"hello"[..]);
111 | |     assert_eq!(buf, &b" world"[..])
112 | | }
    | |_^
    = note: this error originates in the attribute macro `test` (in Nightly builds, run with -Z macro-backtrace for more info)

We get these because the integration tests are occurring in a crate called test, not the actual bytes crate. With this PR, we get this:

    = note: inside `std::slice::from_raw_parts_mut::<u8>` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/core/src/slice/raw.rs:131:14
note: inside `bytes::bytes::rebuild_boxed_slice` at /tmp/bytes-1.1.0/src/bytes.rs:938:19
   --> /tmp/bytes-1.1.0/src/bytes.rs:938:19
    |
938 |     Box::from_raw(slice::from_raw_parts_mut(buf, cap))
    |                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: inside closure at /tmp/bytes-1.1.0/src/bytes.rs:904:18
   --> /tmp/bytes-1.1.0/src/bytes.rs:904:18
    |
904 |             drop(rebuild_boxed_slice(buf, ptr, len));
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: inside `<std::sync::atomic::AtomicPtr<()> as bytes::loom::sync::atomic::AtomicMut<()>>::with_mut::<[closure@bytes::bytes::promotable_even_drop::{closure#0}], ()>` at /tmp/bytes-1.1.0/src/loom.rs:17:17
   --> /tmp/bytes-1.1.0/src/loom.rs:17:17
    |
17  |                 f(self.get_mut())
    |                 ^^^^^^^^^^^^^^^^^
note: inside `bytes::bytes::promotable_even_drop` at /tmp/bytes-1.1.0/src/bytes.rs:895:5
   --> /tmp/bytes-1.1.0/src/bytes.rs:895:5
    |
895 | /     data.with_mut(|shared| {
896 | |         let shared = *shared;
897 | |         let kind = shared as usize & KIND_MASK;
898 | |
...   |
905 | |         }
906 | |     });
    | |______^
note: inside `<bytes::Bytes as std::ops::Drop>::drop` at /tmp/bytes-1.1.0/src/bytes.rs:515:18
   --> /tmp/bytes-1.1.0/src/bytes.rs:515:18
    |
515 |         unsafe { (self.vtable.drop)(&mut self.data, self.ptr, self.len) }
    |                  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    = note: inside `std::ptr::drop_in_place::<bytes::Bytes> - shim(Some(bytes::Bytes))` at /home/ben/.rustup/toolchains/miri/lib/rustlib/src/rust/library/core/src/ptr/mod.rs:188:1
note: inside `copy_to_bytes_less` at tests/test_buf.rs:112:1
   --> tests/test_buf.rs:112:1
    |
112 | }
    | ^
note: inside closure at tests/test_buf.rs:106:1
   --> tests/test_buf.rs:106:1
    |
105 |   #[test]
    |   ------- in this procedural macro expansion
106 | / fn copy_to_bytes_less() {
107 | |     let mut buf = &b"hello world"[..];
108 | |
109 | |     let bytes = buf.copy_to_bytes(5);
110 | |     assert_eq!(bytes, &b"hello"[..]);
111 | |     assert_eq!(buf, &b" world"[..])
112 | | }
    | |_^
    = note: this error originates in the attribute macro `test` (in Nightly builds, run with -Z macro-backtrace for more info)

Note that this kind of inflation is rather rare to see. Most backtraces change not at all or only a tiny bit.

I originally implemented this to support another improvement to Miri diagnostics, but I think this is hairy enough to deserve its own PR, if somewhat poorly-motivated.

[bors]

☔ The latest upstream changes (presumably #2029) made this pull request unmergeable. Please resolve the merge conflicts.

[RalfJung]

Thanks!

@bors r+

[bors]

📌 Commit 65125df has been approved by RalfJung

[bors]

⌛ Testing commit 65125df with merge 5d72cd9...

[bors]

☀️ Test successful - checks-actions
Approved by: RalfJung
Pushing 5d72cd9 to master...