refact(api): lower MSRV to 1.65.0

.github/workflows/ci.yml

@@ -26,13 +26,19 @@ jobs:
   msrv:
     name: MSRV
     runs-on: ubuntu-latest
+    env:
+      CARGO_UNSTABLE_SPARSE_REGISTRY: true
     steps:
       - name: Checkout repository
         uses: actions/checkout@v3
-      - name: Install Rust 1.70.0
-        run: rustup toolchain install 1.70.0
-      - name: Set Rust 1.70.0 as default
-        run: rustup default 1.70.0
+      - name: Install Rust 1.65.0
+        # NOTE: We are actually installing the first nightly 1.66.0. It should
+        # be equivalent to stable 1.65.0. We need the nightly version to use the
+        # sparse registry feature. This massively improves the index download.
+        # Link: https://blog.rust-lang.org/2022/06/22/sparse-registry-testing.html
+        run: rustup toolchain install nightly-2022-09-18
+      - name: Set Rust 1.65.0 as default
+        run: rustup default nightly-2022-09-18
       - name: Check MSRV
         run: cargo check --all-features
 

Cargo.toml

@@ -6,8 +6,8 @@ and eventually fair lock for mutual exclusion, referred to as Malthusian lock.
 name = "malthlock"
 version = "0.1.0"
 edition = "2021"
-# NOTE: Rust 1.70 is required for `AtomicPtr::as_ptr`.
-rust-version = "1.70.0"
+# NOTE: Rust 1.65 is required for GATs and let-else statements.
+rust-version = "1.65.0"
 license = "MIT OR Apache-2.0"
 readme = "README.md"
 documentation = "https://docs.rs/malthlock"

Makefile.toml

@@ -22,8 +22,13 @@ args = ["rustdoc", "--all-features", "--open", "--", "--default-theme", "ayu"]
 
 # Check MSRV.
 [tasks.msrv]
-toolchain = "1.70.0"
+# NOTE: We are actually installing the first nightly 1.66.0. It should be
+# equivalent to stable 1.65.0. We need the nightly version to use the sparse
+# registry feature. This massively improves the index download.
+# Link: https://blog.rust-lang.org/2022/06/22/sparse-registry-testing.html
+toolchain = "nightly-2022-09-18"
 command = "cargo"
+env = { "CARGO_UNSTABLE_SPARSE_REGISTRY" = "true" }
 args = ["check", "--all-features"]
 
 # Check semver viloations.

README.md

@@ -3,10 +3,8 @@
 ## Minimum Supported Rust Version (MSRV)
 
 This crate is guaranteed to compile on a Minimum Supported Rust Version (MSRV)
-of 1.70.0 and above. This version will not be changed without a minor version
-bump. If you intend to use this crate but can only target a older Rust version,
-feel free to open a issue with your specific target, it is possible to lower
-this crate MSRV substantially, it just has not been explored yet.
+of 1.65.0 and above. This version will not be changed without a minor version
+bump.
 
 ## License