Document MSRV 1.32.0 and test it on CI

Author: eldruin

.travis.yml

@@ -17,7 +17,7 @@ matrix:
     - env: TARGET=x86_64-unknown-linux-gnu
       rust: nightly
       if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
-    
+
     - env: TARGET=armv7-unknown-linux-gnueabihf
       rust: stable
       if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
@@ -33,6 +33,22 @@ matrix:
       rust: stable
       if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
 
+    # MSRV
+    - env: TARGET=armv7-unknown-linux-gnueabihf
+      rust: 1.32.0
+      if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
+      addons:
+        apt:
+          packages:
+            - libc6-armhf-cross
+            - libc6-dev-armhf-cross
+            - gcc-arm-linux-gnueabihf
+
+    # MSRV
+    - env: TARGET=x86_64-unknown-linux-gnu
+      rust: 1.32.0
+      if: (branch = staging OR branch = trying) OR (type = pull_request AND branch = master)
+
 
 before_install:
   - set -e

README.md

@@ -15,13 +15,18 @@ See [gpio-cdev documentation](https://github.com/rust-embedded/gpio-cdev#sysfs-g
 
 This crate includes feature flag `gpio_cdev` that exposes `CdevPin` as wrapper around `LineHandle` from [gpio-cdev](https://crates.io/crates/gpio-cdev).
 To enable it update your Cargo.toml. Please note that in order to prevent `LineHandle` fd from closing you should
-assign to a variable, see [cdev issue](https://github.com/rust-embedded/gpio-cdev/issues/29) for more details.  
+assign to a variable, see [cdev issue](https://github.com/rust-embedded/gpio-cdev/issues/29) for more details.
 ```
 linux-embedded-hal = { version = "0.3", features = ["gpio_cdev"] }
-``` 
+```
 
 `SysfsPin` can be still used with feature flag `gpio_sysfs`.
 
+# Minimum Supported Rust Version (MSRV)
+
+This crate is guaranteed to compile on stable Rust 1.32.0 and up. It *might*
+compile with older versions but that may change in any new patch release.
+
 ## License
 
 Licensed under either of