Deny warnings in ci

.github/workflows/check.yml

@@ -4,6 +4,8 @@ jobs:
   check:
     name: cargo-check
     runs-on: ubuntu-20.04
+    env:
+      RUSTFLAGS: "-D warnings"
     steps:
       - uses: actions/checkout@v2
       - run: sudo apt-get update

.github/workflows/clippy.yml

@@ -3,6 +3,8 @@ name: Clippy check
 jobs:
   clippy_check:
     runs-on: ubuntu-20.04
+    env:
+      RUSTFLAGS: "-D warnings"
     steps:
       - uses: actions/checkout@v2
       - uses: actions-rs/toolchain@v1

.github/workflows/rustfmt.yml

@@ -4,6 +4,8 @@ jobs:
   fmt:
     name: Rustfmt
     runs-on: ubuntu-20.04
+    env:
+      RUSTFLAGS: "-D warnings"
     steps:
       - uses: actions/checkout@v2
       - uses: actions-rs/toolchain@v1

.github/workflows/tests_host.yml

@@ -4,6 +4,8 @@ jobs:
   check:
     name: Check and Lint
     runs-on: ubuntu-20.04
+    env:
+      RUSTFLAGS: "-D warnings"
     steps:
       - uses: actions/checkout@v2
       - uses: actions-rs/toolchain@v1

rp2040-hal/src/lib.rs

@@ -4,7 +4,6 @@
 //! NOTE This HAL is still under active development. This API will remain volatile until 1.0.0
 
 #![deny(missing_docs)]
-#![deny(warnings)]
 #![no_std]
 
 extern crate cortex_m;