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Regression: usize to u32 conversion could not be compiled now #615

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#616
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Regression: usize to u32 conversion could not be compiled now#615
#616
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@tuguzT
tuguzT
opened on Jun 12, 2026

Before updating to nightly-2026-05-22, inline integer convertions like u32::try_from(usize_value).ok().unwrap() used to work, but after an update these are failing with such message:

  error: cannot offset a pointer to an arbitrary element
     --> <...\.rustup\toolchains\nightly-2026-05-22-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\convert\num.rs>:454:5
      |
  454 |     impl_try_from_unbounded!(usize => u32, u64, u128);
      |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      |
  note: used from within `<u32 as core::convert::TryFrom<usize>>::try_from`
     --> <...\.rustup\toolchains\nightly-2026-05-22-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\convert\num.rs>:454:5
      |
  454 |     impl_try_from_unbounded!(usize => u32, u64, u128);
      |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...

  error: cannot cast between pointer types
         from `*struct core::result::Result<u32, core::num::TryFromIntError> { discriminant: bool }`
           to `*u8`
     --> <...\.rustup\toolchains\nightly-2026-05-22-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\convert\num.rs>:454:5
      |
  454 |     impl_try_from_unbounded!(usize => u32, u64, u128);
      |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      |
  note: used from within `<u32 as core::convert::TryFrom<usize>>::try_from`
     --> <...\.rustup\toolchains\nightly-2026-05-22-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\convert\num.rs>:454:5
      |
  454 |     impl_try_from_unbounded!(usize => u32, u64, u128);
      |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...

  error: cannot cast between pointer types
         from `*u8`
           to `*u32`
     --> <...\.rustup\toolchains\nightly-2026-05-22-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\convert\num.rs>:454:5
      |
  454 |     impl_try_from_unbounded!(usize => u32, u64, u128);
      |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
      |
  note: used from within `<u32 as core::convert::TryFrom<usize>>::try_from`
     --> <...\.rustup\toolchains\nightly-2026-05-22-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\convert\num.rs>:454:5
      |
  454 |     impl_try_from_unbounded!(usize => u32, u64, u128);
      |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...

  error: cannot offset a pointer to an arbitrary element
     --> <...\.rustup\toolchains\nightly-2026-05-22-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\result.rs>:714:16
      |
  714 |             Ok(x) => Some(x),
      |                ^
      |
  note: used from within `<core::result::Result<u32, core::num::error::TryFromIntError>>::ok`
     --> <...\.rustup\toolchains\nightly-2026-05-22-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\result.rs>:714:16
      |
  714 |             Ok(x) => Some(x),
      |                ^
...

  error: cannot cast between pointer types
         from `*struct core::result::Result<u32, core::num::TryFromIntError> { discriminant: bool }`
           to `*u8`
     --> <...\.rustup\toolchains\nightly-2026-05-22-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\result.rs>:714:16
      |
  714 |             Ok(x) => Some(x),
      |                ^
      |
  note: used from within `<core::result::Result<u32, core::num::error::TryFromIntError>>::ok`
     --> <...\.rustup\toolchains\nightly-2026-05-22-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\result.rs>:714:16
      |
  714 |             Ok(x) => Some(x),
      |                ^
...

  error: cannot cast between pointer types
         from `*u8`
           to `*u32`
     --> <...\.rustup\toolchains\nightly-2026-05-22-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\result.rs>:714:16
      |
  714 |             Ok(x) => Some(x),
      |                ^
      |
  note: used from within `<core::result::Result<u32, core::num::error::TryFromIntError>>::ok`
     --> <...\.rustup\toolchains\nightly-2026-05-22-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core\src\result.rs>:714:16
      |
  714 |             Ok(x) => Some(x),
      |                ^
...

Activity

  1. tuguzT
    added
    bugSomething isn't working
    on Jun 12, 2026

  2. nazar-pc commented on Jun 12, 2026

    @nazar-pc
    nazar-pc
    on Jun 12, 2026
    Contributor

    I think I'm getting the same. Clippy is fine, but actual compilation is not:

    error: cannot offset a pointer to an arbitrary element
   --> </home/nazar-pc/.cache/rustup/toolchains/nightly-2026-05-22-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/convert/num.rs>:454:5
    |
454 |     impl_try_from_unbounded!(usize => u32, u64, u128);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
note: used from within `<u32 as core::convert::TryFrom<usize>>::try_from`
   --> </home/nazar-pc/.cache/rustup/toolchains/nightly-2026-05-22-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/convert/num.rs>:454:5
    |
454 |     impl_try_from_unbounded!(usize => u32, u64, u128);
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: called by `<core::iter::adapters::step_by::StepBy<core::ops::range::Range<u32>> as core::iter::adapters::step_by::StepByImpl<core::ops::range::Range<u32>>>::spec_next`
   --> </home/nazar-pc/.cache/rustup/toolchains/nightly-2026-05-22-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/adapters/step_by.rs>:574:1
    |
574 | spec_int_ranges!(u8 u16 u32 usize);
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
note: called by `<core::iter::adapters::step_by::StepBy<core::ops::range::Range<u32>> as core::iter::traits::iterator::Iterator>::next`
   --> </home/nazar-pc/.cache/rustup/toolchains/nightly-2026-05-22-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/iter/adapters/step_by.rs>:59:14
    |
 59 |         self.spec_next()
    |              ^^^^^^^^^^^
note: called by `ab_proof_of_space_gpu::shader::find_proofs::find_local_proof_targets::<1>`
   --> <crates/farmer/ab-proof-of-space-gpu/src/shader/find_proofs.rs>:113:9
    |
113 | /         for index in (subgroup_local_invocation_id..bucket_size).step_by(SUBGROUP_SIZE as usize) {
114 | |             let proof_targets = bucket[index as usize];
115 | |             if proof_targets.absolute_position < local_min_absolute_position[0] {
116 | |                 local_min_absolute_position[0] = proof_targets.absolute_position;
...   |
119 | |         }
    | |_________^

    #612 has the same issue as well.

  3. LegNeato
    added a commit that references this issue on Jun 14, 2026

    Fix codegen of Memory-repr enum payload accesses

    fb1d7d4

  4. LegNeato commented on Jun 14, 2026

    @LegNeato
    LegNeato
    on Jun 14, 2026
    Collaborator

    If ya'll could confirm #616 fixes it that would be great!

  5. LegNeato
    added 2 commits that reference this issue on Jun 14, 2026

    Fix codegen of Memory-repr enum payload accesses

    138d04a

    Fix codegen of Memory-repr enum payload accesses

    dfdd6e0
  6. Firestar99
    closed this as completedin #616on Jun 15, 2026
  7. Firestar99
    added a commit that references this issue on Jun 22, 2026

    Fix codegen of Memory-repr enum payload accesses

    67f1ff2
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