implement core::error::Error

this trait has been stabilised in Rust 1.81.0.

the existing custom `Error` types cannot be removed / replaced as that'd
be a breaking change. for the same reason it's not possible for them to
require `core::error::Error` being implemented.

however, we can add an `impl core::error::Error for dyn Error` for every
custom error type to provide an automatic coverage. HALs can still add
an implementation for their specific error type if they wish to add more
details (e.g. implement `source`).
as `core::error::Error` requires `core::fmt::Display` to be implemented
a simple blanket implementation has been added which prints the `Debug`
output.

existing `std` feature-gated implementations of `std::error::Error` have
also been moved to `core::error::Error` and the feature gate removed.

this raises the MSRV to 1.81.0 for most crates, but based on the MSRV
policy this should not be an issue.

Author: rursprung

.github/workflows/test.yml

@@ -38,23 +38,9 @@ jobs:
           --target thumbv7m-none-eabi
           --features async,defmt-03
 
-  msrv-1-60:
+  msrv-1-81:
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4
-      - uses: dtolnay/[email protected]
-      - run: >
-          cargo test
-          -p embedded-hal:1.0.0
-          -p embedded-hal-bus
-          -p embedded-hal-nb
-          -p embedded-io
-          -p embedded-io-adapters
-          -p embedded-can
-
-  msrv-1-75:
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: dtolnay/[email protected]
+      - uses: dtolnay/[email protected]
       - run: cargo test --workspace --all-features

README.md

@@ -64,7 +64,7 @@ on crates.io.
 
 ## Minimum Supported Rust Version (MSRV)
 
-This crate is guaranteed to compile on stable Rust 1.60 and up. It *might*
+This crate is guaranteed to compile on stable Rust 1.81 and up. It *might*
 compile with older versions but that may change in any new patch release.
 
 See [here](docs/msrv.md) for details on how the MSRV may be upgraded.

embedded-can/CHANGELOG.md

@@ -7,7 +7,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased]
 
-...
+- Added blanket `core::error::Error` and `core::fmt::Display` implementations for the custom `Error` traits
+- Increased MSRV to 1.81 due to `core::error::Error`
 
 ## [v0.4.1] - 2022-09-28
 

embedded-can/Cargo.toml

@@ -2,7 +2,7 @@
 name = "embedded-can"
 version = "0.4.1"
 edition = "2021"
-rust-version = "1.56"
+rust-version = "1.81"
 
 description = "HAL traits for Controller Area Network (CAN) devices."
 categories = ["embedded", "hardware-support", "no-std"]

embedded-can/README.md

@@ -19,7 +19,7 @@ This project is developed and maintained by the [HAL team](https://github.com/ru
 
 ## Minimum Supported Rust Version (MSRV)
 
-This crate is guaranteed to compile on stable Rust 1.60 and up. It *might*
+This crate is guaranteed to compile on stable Rust 1.81 and up. It *might*
 compile with older versions but that may change in any new patch release.
 
 See [here](../docs/msrv.md) for details on how the MSRV may be upgraded.

embedded-can/src/lib.rs

@@ -61,6 +61,14 @@ pub trait Error: core::fmt::Debug {
     fn kind(&self) -> ErrorKind;
 }
 
+impl core::fmt::Display for dyn Error {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        write!(f, "{:?}", self)
+    }
+}
+
+impl core::error::Error for dyn Error {}
+
 impl Error for core::convert::Infallible {
     fn kind(&self) -> ErrorKind {
         match *self {}

embedded-hal-bus/CHANGELOG.md

@@ -9,6 +9,8 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 - Added the `alloc` feature.
 - Added a new `RcDevice` for I2C and SPI, a reference-counting equivalent to `RefCellDevice`.
+- Migrated `std` feature-gated `std::error::Error` implementations to `core::error::Error`
+- Increased MSRV to 1.81 due to `core::error::Error`
 
 ## [v0.2.0] - 2024-04-23
 

embedded-hal-bus/Cargo.toml

@@ -15,7 +15,7 @@ repository = "https://github.com/rust-embedded/embedded-hal"
 version = "0.2.0"
 
 [features]
-# Enable shared bus implementations using `std::sync::Mutex`, and implement `std::error::Error` for `DeviceError`
+# Enable shared bus implementations using `std::sync::Mutex`
 std = ["alloc"]
 # Use `portable-atomic` to enable `atomic-device` on devices without native atomic CAS
 #

embedded-hal-bus/README.md

@@ -39,12 +39,11 @@ provides mechanisms to obtain multiple `I2c` instances out of a single `I2c` ins
   that does not natively support atomic CAS. If you enable this, you must also add `portable-atomic` to your crate with
   a feature flag such as `unsafe-assume-single-core` or `critical-section` to choose how atomic CAS is implemented.
   See <https://docs.rs/portable-atomic/1.7.0/portable_atomic/#optional-features> for more info.
-- **`std`**: enable shared bus implementations using `std::sync::Mutex`, and implement
-  `std::error::Error` for `DeviceError`.
+- **`std`**: enable shared bus implementations using `std::sync::Mutex`.
 
 ## Minimum Supported Rust Version (MSRV)
 
-This crate is guaranteed to compile on stable Rust 1.60 and up. It *might*
+This crate is guaranteed to compile on stable Rust 1.81 and up. It *might*
 compile with older versions but that may change in any new patch release.
 
 See [here](../docs/msrv.md) for details on how the MSRV may be upgraded.

embedded-hal-bus/src/spi/mod.rs

@@ -47,8 +47,7 @@ impl<BUS: Display, CS: Display> Display for DeviceError<BUS, CS> {
     }
 }
 
-#[cfg(feature = "std")]
-impl<BUS: Debug + Display, CS: Debug + Display> std::error::Error for DeviceError<BUS, CS> {}
+impl<BUS: Debug + Display, CS: Debug + Display> core::error::Error for DeviceError<BUS, CS> {}
 
 impl<BUS, CS> Error for DeviceError<BUS, CS>
 where