fix: revert MSRV & toolchain to Rust 1.90 (#859)

* Revert MSRV to 1.90

* Run cargo-msrv on 1.91 in CI

Author: huitseeker

.github/actions/workspace-release/action.yml

@@ -32,6 +32,8 @@ runs:
 
     - name: Install Rust toolchain
       uses: dtolnay/rust-toolchain@stable
+      with:
+        toolchain: "1.90"
 
     - name: Cache cargo registry and git index
       uses: actions/cache@v4
@@ -55,8 +57,14 @@ runs:
       shell: bash
       run: cargo binstall --no-confirm --force cargo-msrv
 
+    - name: Install Rust 1.91 for cargo-msrv
+      shell: bash
+      run: rustup toolchain install 1.91
+
     - name: Check MSRV
       shell: bash
+      env:
+        RUSTUP_TOOLCHAIN: "1.91"
       run: |
         export PATH="$HOME/.cargo/bin:$PATH"
         ./scripts/check-msrv.sh

Cargo.toml

@@ -10,7 +10,7 @@ edition      = "2024"
 keywords     = ["crypto", "hash", "merkle", "miden"]
 license      = "MIT OR Apache-2.0"
 repository   = "https://github.com/0xMiden/crypto"
-rust-version = "1.93"
+rust-version = "1.90"
 version      = "0.23.0"
 
 [workspace.dependencies]

miden-crypto/src/utils/mod.rs

@@ -3,7 +3,7 @@
 use alloc::{boxed::Box, string::String, vec::Vec};
 use core::{
     fmt::{self, Write},
-    mem::MaybeUninit,
+    mem::{ManuallyDrop, MaybeUninit},
 };
 
 // Re-export serialization traits from miden-serde-utils
@@ -237,7 +237,10 @@ pub fn uninit_vector<T>(length: usize) -> Vec<MaybeUninit<T>> {
 /// # Safety
 /// All elements must be initialized before calling this function.
 pub unsafe fn assume_init_vec<T>(v: Vec<MaybeUninit<T>>) -> Vec<T> {
-    let (ptr, len, cap) = v.into_raw_parts();
+    let mut v = ManuallyDrop::new(v);
+    let ptr = v.as_mut_ptr();
+    let len = v.len();
+    let cap = v.capacity();
     // SAFETY: caller guarantees all elements are initialized.
     unsafe { Vec::from_raw_parts(ptr.cast::<T>(), len, cap) }
 }

rust-toolchain.toml

@@ -1,5 +1,5 @@
 [toolchain]
-channel    = "1.93"
+channel    = "1.90"
 components = ["clippy", "rust-src", "rustfmt"]
 profile    = "minimal"
 targets    = ["wasm32-unknown-unknown", "wasm32-wasip2"]