Address even more clippy lints (theseus-os#805)

Satisfies and enables the following:
* `blocks_in_if_conditions`
* `comparison-chain`
* `declare_interior_mutable_const`
* `fn_to_numeric_cast`
* `comparison_chain`

Author: amab8901

applications/deps/src/lib.rs

@@ -406,13 +406,17 @@ fn find_crate(crate_name: &str) -> Result<(StrRef, StrongCrateRef), String> {
 fn find_section(section_name: &str) -> Result<StrongSectionRef, String> {
     let namespace = get_my_current_namespace();
     let matching_symbols = namespace.find_symbols_starting_with(section_name);
-    if matching_symbols.len() == 1 {
-        return matching_symbols[0].1.upgrade()
-            .ok_or_else(|| format!("Found matching symbol name but couldn't get reference to section"));
-    } else if matching_symbols.len() > 1 {
-        return Err(matching_symbols.into_iter().map(|(k, _v)| k).collect::<Vec<String>>().join("\n"));
-    } else {
-        // continue on
+    match matching_symbols.len() {
+        1 => return matching_symbols[0].1
+            .upgrade()
+            .ok_or_else(|| format!("Found matching symbol name but couldn't get reference to section")),
+        2.. => return Err(matching_symbols
+            .into_iter()
+            .map(|(k, _v)| k)
+            .collect::<Vec<String>>()
+            .join("\n")
+        ),
+        _ => { /* no matches, continue on */ },
     }
 
     // If it wasn't a global section in the symbol map, then we need to find its containing crate

kernel/deferred_interrupt_tasks/src/lib.rs

@@ -68,7 +68,7 @@ pub enum InterruptRegistrationError {
     /// the interrupt handler at the given `existing_handler_address`.
     IrqInUse {
         irq: u8,
-        existing_handler_address: u64
+        existing_handler_address: usize
     },
     /// The given error occurred when spawning the deferred interrupt task.
     SpawnError(&'static str),

kernel/frame_allocator/src/lib.rs

@@ -18,6 +18,7 @@
 //! We don't need to do so until we actually run out of address space or until 
 //! a requested address is in a chunk that needs to be merged.
 
+#![allow(clippy::blocks_in_if_conditions)]
 #![no_std]
 
 extern crate alloc;

kernel/interrupts/src/lib.rs

@@ -197,14 +197,14 @@ fn _enable_pic() {
 /// # Return
 /// * `Ok(())` if successfully registered, or
 /// * `Err(existing_handler_address)` if the given `interrupt_num` was already in use.
-pub fn register_interrupt(interrupt_num: u8, func: HandlerFunc) -> Result<(), u64> {
+pub fn register_interrupt(interrupt_num: u8, func: HandlerFunc) -> Result<(), usize> {
     let mut idt = IDT.lock();
 
     // If the existing handler stored in the IDT is either missing (has an address of `0`)
     // or is the default handler, that signifies the interrupt number is available.
     let idt_entry = &mut idt[interrupt_num as usize];
-    let existing_handler_addr = idt_entry.handler_addr().as_u64();
-    if existing_handler_addr == 0 || existing_handler_addr == unimplemented_interrupt_handler as u64 {
+    let existing_handler_addr = idt_entry.handler_addr().as_u64() as usize;
+    if existing_handler_addr == 0 || existing_handler_addr == unimplemented_interrupt_handler as usize {
         idt_entry.set_handler_fn(func);
         Ok(())
     } else {
@@ -225,7 +225,7 @@ pub fn register_msi_interrupt(func: HandlerFunc) -> Result<u8, &'static str> {
     // try to find an unused interrupt number in the IDT
     let interrupt_num = idt.slice(32..=255)
         .iter()
-        .rposition(|&entry| entry.handler_addr().as_u64() == unimplemented_interrupt_handler as u64)
+        .rposition(|&entry| entry.handler_addr().as_u64() as usize == unimplemented_interrupt_handler as usize)
         .map(|entry| entry + 32)
         .ok_or("register_msi_interrupt: no available interrupt handlers (BUG: IDT is full?)")?;
 
@@ -253,7 +253,7 @@ pub fn deregister_interrupt(interrupt_num: u8, func: HandlerFunc) -> Result<(),
 
     // check if the handler stored is the same as the one provided
     // this is to make sure no other application can deregister your interrupt
-    if idt[interrupt_num as usize].handler_addr().as_u64() == func as u64 {
+    if idt[interrupt_num as usize].handler_addr().as_u64() as usize == func as usize {
         idt[interrupt_num as usize].set_handler_fn(unimplemented_interrupt_handler);
         Ok(())
     }

kernel/mod_mgmt/src/lib.rs

@@ -1,3 +1,4 @@
+#![allow(clippy::blocks_in_if_conditions)]
 #![no_std]
 #![feature(let_chains)]
 

kernel/pit_clock/src/lib.rs

@@ -48,7 +48,7 @@ pub fn enable_interrupts(freq_hertz: u32) -> Result<(), &'static str> {
     // Register the interrupt handler
     match interrupts::register_interrupt(PIT_CHANNEL_0_IRQ, pit_timer_handler) {
         Ok(_) => { /* success, do nothing */}
-        Err(handler) if handler == pit_timer_handler as u64 => { /* already registered, do nothing */ }
+        Err(handler) if handler == pit_timer_handler as usize => { /* already registered, do nothing */ }
         Err(_other) => return Err(" PIT clock IRQ was already in use; sharing IRQs is currently unsupported"),
     }
 

kernel/serial_port/src/lib.rs

@@ -204,7 +204,7 @@ impl SerialPort {
                 };                
             }
             Err(InterruptRegistrationError::IrqInUse { irq, existing_handler_address }) => {
-                if existing_handler_address != interrupt_handler as u64 {
+                if existing_handler_address != interrupt_handler as usize {
                     error!("Failed to register interrupt handler at IRQ {:#X} for serial port {:#X}. \
                         Existing interrupt handler was a different handler, at address {:#X}.",
                         irq, base_port, existing_handler_address,

lints.txt

@@ -169,7 +169,7 @@ zst-offset
 assertions-on-constants
 assign-op-pattern
 disallowed-names
-# blocks-in-if-conditions
+blocks-in-if-conditions
 bool-assert-comparison
 borrow-interior-mutable-const
 builtin-type-shadow
@@ -180,9 +180,9 @@ cmp-null
 collapsible-else-if
 collapsible-if
 collapsible-match
-# comparison-chain
+comparison-chain
 comparison-to-empty
-# declare-interior-mutable-const
+declare-interior-mutable-const
 disallowed-methods
 disallowed-types
 double-must-use
@@ -192,7 +192,7 @@ enum-variant-names
 err-expect
 excessive-precision
 field-reassign-with-default
-# fn-to-numeric-cast
+fn-to-numeric-cast
 fn-to-numeric-cast-with-truncation
 for-kv-map
 # from-over-into