Add a lint for sized integer types in a mutex

Author: fhartwig

README.md

@@ -6,7 +6,7 @@ A collection of lints to catch common mistakes and improve your Rust code.
 [Jump to usage instructions](#usage)
 
 ##Lints
-There are 60 lints included in this crate:
+There are 61 lints included in this crate:
 
 name                                                                                                   | default | meaning
 -------------------------------------------------------------------------------------------------------|---------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
@@ -38,6 +38,7 @@ name
 [modulo_one](https://github.com/Manishearth/rust-clippy/wiki#modulo_one)                               | warn    | taking a number modulo 1, which always returns 0
 [mut_mut](https://github.com/Manishearth/rust-clippy/wiki#mut_mut)                                     | allow   | usage of double-mut refs, e.g. `&mut &mut ...` (either copy'n'paste error, or shows a fundamental misunderstanding of references)
 [mutex_atomic](https://github.com/Manishearth/rust-clippy/wiki#mutex_atomic)                           | warn    | using a Mutex where an atomic value could be used instead
+[mutex_integer](https://github.com/Manishearth/rust-clippy/wiki#mutex_integer)                         | allow   | using a Mutex for an integer type
 [needless_bool](https://github.com/Manishearth/rust-clippy/wiki#needless_bool)                         | warn    | if-statements with plain booleans in the then- and else-clause, e.g. `if p { true } else { false }`
 [needless_lifetimes](https://github.com/Manishearth/rust-clippy/wiki#needless_lifetimes)               | warn    | using explicit lifetimes for references in function arguments when elision rules would allow omitting them
 [needless_range_loop](https://github.com/Manishearth/rust-clippy/wiki#needless_range_loop)             | warn    | for-looping over a range of indices where an iterator over items would do

src/lib.rs

@@ -96,6 +96,7 @@ pub fn plugin_registrar(reg: &mut Registry) {
         methods::RESULT_UNWRAP_USED,
         methods::WRONG_PUB_SELF_CONVENTION,
         mut_mut::MUT_MUT,
+        mutex_atomic::MUTEX_INTEGER,
         ptr_arg::PTR_ARG,
         shadow::SHADOW_REUSE,
         shadow::SHADOW_SAME,

src/mutex_atomic.rs

@@ -17,11 +17,18 @@ declare_lint! {
     "using a Mutex where an atomic value could be used instead"
 }
 
+declare_lint! {
+    pub MUTEX_INTEGER,
+    Allow,
+    "using a Mutex for an integer type"
+}
+
 impl LintPass for MutexAtomic {
     fn get_lints(&self) -> LintArray {
-        lint_array!(MUTEX_ATOMIC)
+        lint_array!(MUTEX_ATOMIC, MUTEX_INTEGER)
     }
 }
+
 pub struct MutexAtomic;
 
 impl LateLintPass for MutexAtomic {
@@ -33,7 +40,13 @@ impl LateLintPass for MutexAtomic {
                 if let Some(atomic_name) = get_atomic_name(mutex_param) {
                     let msg = format!("Consider using an {} instead of a \
                                        Mutex here.", atomic_name);
-                    span_lint(cx, MUTEX_ATOMIC, expr.span, &msg);
+                    match *mutex_param {
+                        ty::TyUint(t) if t != ast::TyUs =>
+                            span_lint(cx, MUTEX_INTEGER, expr.span, &msg),
+                        ty::TyInt(t) if t != ast::TyIs =>
+                            span_lint(cx, MUTEX_INTEGER, expr.span, &msg),
+                        _ => span_lint(cx, MUTEX_ATOMIC, expr.span, &msg)
+                    }
                 }
             }
         }
@@ -43,8 +56,8 @@ impl LateLintPass for MutexAtomic {
 fn get_atomic_name(ty: &ty::TypeVariants) -> Option<(&'static str)> {
     match *ty {
         ty::TyBool => Some("AtomicBool"),
-        ty::TyUint(ast::TyUs) => Some("AtomicUsize"),
-        ty::TyInt(ast::TyIs) => Some("AtomicIsize"),
+        ty::TyUint(_) => Some("AtomicUsize"),
+        ty::TyInt(_) => Some("AtomicIsize"),
         ty::TyRawPtr(_) => Some("AtomicPtr"),
         _ => None
     }

tests/compile-fail/mutex_atomic.rs

@@ -2,6 +2,7 @@
 
 #![plugin(clippy)]
 #![deny(clippy)]
+#![deny(mutex_integer)]
 
 fn main() {
     use std::sync::Mutex;
@@ -11,5 +12,7 @@ fn main() {
     let mut x = 4u32;
     Mutex::new(&x as *const u32); //~ERROR Consider using an AtomicPtr instead of a Mutex here.
     Mutex::new(&mut x as *mut u32); //~ERROR Consider using an AtomicPtr instead of a Mutex here.
+    Mutex::new(0u32); //~ERROR Consider using an AtomicUsize instead of a Mutex here.
+    Mutex::new(0i32); //~ERROR Consider using an AtomicIsize instead of a Mutex here.
     Mutex::new(0f32); // there are no float atomics, so this should not lint
 }