gistfile1.txt

C:\local\badmute>type .cargo\config.toml
[unstable]
build-std = ["core", "alloc", "std"]

C:\local\badmute>type src\main.rs
#[repr(C)] #[derive(Debug)] struct P{x:f32,y:f32}
#[repr(C)] #[derive(Debug)] struct Z{x:f32,y:f32}

fn main() {
    let mut v = vec![P{x:4.0,y:2.0}];
    v.reserve(10);
    unsafe{dbg!(std::mem::transmute::<Vec<P>, Vec<Z>>(v))};
}

C:\local\badmute>set RUSTFLAGS=-Zrandomize-layout -Zlayout-seed=11

C:\local\badmute>cargo +nightly run --target=x86_64-pc-windows-msvc
   Compiling core v0.0.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core)
   Compiling rustc-std-workspace-core v1.99.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\rustc-std-workspace-core)
   Compiling compiler_builtins v0.1.101
   Compiling libc v0.2.148
   Compiling alloc v0.0.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\alloc)
   Compiling cfg-if v1.0.0
   Compiling rustc-demangle v0.1.23
   Compiling unwind v0.0.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\unwind)
   Compiling rustc-std-workspace-alloc v1.99.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\rustc-std-workspace-alloc)
   Compiling panic_unwind v0.0.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\panic_unwind)
   Compiling panic_abort v0.0.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\panic_abort)
   Compiling hashbrown v0.14.0
   Compiling std_detect v0.1.5 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\stdarch\crates\std_detect)
   Compiling std v0.0.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\std)
   Compiling proc_macro v0.0.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\proc_macro)
   Compiling badmute v0.1.0 (C:\local\badmute)
    Finished dev [unoptimized + debuginfo] target(s) in 25.82s
     Running `target\x86_64-pc-windows-msvc\debug\badmute.exe`
[src\main.rs:7] std::mem::transmute::<Vec<P>, Vec<Z>>(v) = [
    Z {
        x: 4.0,
        y: 2.0,
    },
]

C:\local\badmute>cargo +nightly miri run --target=x86_64-pc-windows-msvc
Preparing a sysroot for Miri (target: x86_64-pc-windows-msvc)... done
   Compiling core v0.0.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\core)
   Compiling rustc-std-workspace-core v1.99.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\rustc-std-workspace-core)
   Compiling compiler_builtins v0.1.101
   Compiling libc v0.2.148
   Compiling alloc v0.0.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\alloc)
   Compiling cfg-if v1.0.0
   Compiling rustc-demangle v0.1.23
   Compiling unwind v0.0.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\unwind)
   Compiling rustc-std-workspace-alloc v1.99.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\rustc-std-workspace-alloc)
   Compiling panic_abort v0.0.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\panic_abort)
   Compiling panic_unwind v0.0.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\panic_unwind)
   Compiling std_detect v0.1.5 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\stdarch\crates\std_detect)
   Compiling hashbrown v0.14.0
   Compiling std v0.0.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\std)
   Compiling proc_macro v0.0.0 (C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\lib\rustlib\src\rust\library\proc_macro)
   Compiling badmute v0.1.0 (C:\local\badmute)
    Finished dev [unoptimized + debuginfo] target(s) in 19.85s
     Running `C:\Users\MaulingMonkey\.rustup\toolchains\nightly-x86_64-pc-windows-msvc\bin\cargo-miri.exe runner target\miri\x86_64-pc-windows-msvc\debug\badmute.exe`
[src\main.rs:7] std::mem::transmute::<Vec<P>, Vec<Z>>(v) = [
    Z {
        x: 4.0,
        y: 2.0,
    },
]