LLVM ERROR: "Vector elements must have same size" with -Zmir-opt-level=3

[matthiaskrgr]

Code

You may need a debug-assertions build of llvm to reproduce this.
Interestingly this only triggers with mir-opt-level 3 but not with 2.

#[derive(Clone)]
pub struct Foo(Bar, u32);

#[derive(Clone, Copy)]
pub struct Bar(u8, u8, u8);

fn main() {
    let foo: Vec<Foo> = Vec::new();
    let _ = foo.clone();
}

Meta

rustc --version --verbose:

rustc @ 371100b1fb811e604f7451eff3b06960587fe1af with full rustc + llvm debug assertions

Error output

rustc -Copt-level=3 103380.rs

rustc: /home/matthias/vcs/github/rust_debug_assertions/src/llvm-project/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:2907: llvm::Value *llvm::InnerLoopVectorizer::createBitOrPointerCast(llvm::Value *, llvm::VectorType *, const llvm::DataLayout &): Assertion `(DL.getTypeSizeInBits(SrcElemTy) == DL.getTypeSizeInBits(DstElemTy)) && "Vector elements must have same size"' failed.

Backtrace

rustc: /home/matthias/vcs/github/rust_debug_assertions/src/llvm-project/llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:2907: llvm::Value *llvm::InnerLoopVectorizer::createBitOrPointerCast(llvm::Value *, llvm::VectorType *, const llvm::DataLayout &): Assertion `(DL.getTypeSizeInBits(SrcElemTy) == DL.getTypeSizeInBits(DstElemTy)) && "Vector elements must have same size"' failed.

[nikic]

This is likely the same issue as llvm/llvm-project#58722.

[matthiaskrgr]

Probably :) , I looked for the assertion message in the rustc issue tracker but couldn't find anything related 😅