use rust-version for the MSRV

.github/workflows/rust.yml

@@ -80,12 +80,15 @@ jobs:
       - name: Checkout sources
         uses: actions/checkout@v2
 
-      - name: Install Rust toolchain
-        run: rustup default 1.56.0
+      - name: Install tombl
+        run: cargo install tombl
 
-      - name: Default features
-        run: cargo build
-        working-directory: ./tests/smoke-test
+      - name: Smoke test
+        run: |
+          eval $(tombl -e msrv=package.rust-version Cargo.toml)
+          rustup update $msrv
+          cd ./tests/smoke-test
+          cargo +$msrv build
 
   embedded:
     name: Build (embedded)

Cargo.toml

@@ -5,6 +5,7 @@ name = "bitflags"
 #   2. number in readme (for breaking changes)
 version = "2.0.0"
 edition = "2021"
+rust-version = "1.56.0"
 authors = ["The Rust Project Developers"]
 license = "MIT OR Apache-2.0"
 keywords = ["bit", "bitmask", "bitflags", "flags"]

README.md

@@ -56,4 +56,5 @@ fn main() {
 
 ## Rust Version Support
 
-The minimum supported Rust version is 1.56.0. This may be bumped in minor releases as necessary.
+The minimum supported Rust version is documented in the `Cargo.toml` file.
+This may be bumped in minor releases as necessary.