rust: fix remaning clippy issues and add clippy to CI

Author: benma

.ci/ci

@@ -23,6 +23,10 @@ make prepare-tidy
 make -j8 unit-test
 make -j8 run-unit-tests
 make -j8 run-rust-unit-tests
+
+# Rust linter
+make -j8 run-rust-clippy
+
 # Check that coverage report building is working.
 make coverage
 

src/rust/bitbox02-rust-c/src/util.rs

@@ -189,7 +189,7 @@ impl CStrMut {
     /// then are available.
     pub fn write<F>(&mut self, req: usize, f: F)
     where
-        F: FnOnce(&mut [u8]) -> (),
+        F: FnOnce(&mut [u8]),
     {
         // Must be room for requested amount of bytes and null terminator.
         if self.cap - self.len < req + 1 {

src/rust/bitbox02-rust-c/src/workflow.rs

@@ -155,7 +155,7 @@ pub unsafe extern "C" fn rust_workflow_confirm_blocking(
 ) -> bool {
     let title = crate::util::rust_util_cstr(params.title);
     let body = crate::util::rust_util_cstr(params.body);
-    if params.font != core::ptr::null() {
+    if !params.font.is_null() {
         panic!("Only default font supported");
     }
     let params = confirm::Params {

src/rust/bitbox02-rust/src/workflow/unlock.rs

@@ -66,7 +66,7 @@ pub async fn unlock_keystore(title: &str) -> bool {
         Ok(()) => true,
         Err(keystore::Error::IncorrectPassword { remaining_attempts }) => {
             let msg = match remaining_attempts {
-                1 => format!("Wrong password\n1 try remains"),
+                1 => "Wrong password\n1 try remains".into(),
                 n => format!("Wrong password\n{} tries remain", n),
             };
             status(&msg, false).await;