1 files changed, 78 insertions, 3 deletions
diff --git a/src/tools/clippy/tests/ui/unnecessary_cast.rs b/src/tools/clippy/tests/ui/unnecessary_cast.rs
index 282b2f128..c7723ef51 100644
--- a/src/tools/clippy/tests/ui/unnecessary_cast.rs
+++ b/src/tools/clippy/tests/ui/unnecessary_cast.rs
@@ -1,13 +1,43 @@
 //@run-rustfix
+//@aux-build:extern_fake_libc.rs
 #![warn(clippy::unnecessary_cast)]
 #![allow(
-    unused_must_use,
     clippy::borrow_as_ptr,
     clippy::no_effect,
     clippy::nonstandard_macro_braces,
-    clippy::unnecessary_operation
+    clippy::unnecessary_operation,
+    nonstandard_style,
+    unused
 )]
 
+extern crate extern_fake_libc;
+
+type PtrConstU8 = *const u8;
+type PtrMutU8 = *mut u8;
+
+fn owo<T>(ptr: *const T) -> *const T {
+    ptr as *const T
+}
+
+fn uwu<T, U>(ptr: *const T) -> *const U {
+    ptr as *const U
+}
+
+mod fake_libc {
+    type pid_t = i32;
+    pub unsafe fn getpid() -> pid_t {
+        pid_t::from(0)
+    }
+    // Make sure a where clause does not break it
+    pub fn getpid_SAFE_TRUTH<T: Clone>(t: &T) -> pid_t
+    where
+        T: Clone,
+    {
+        t;
+        unsafe { getpid() }
+    }
+}
+
 #[rustfmt::skip]
 fn main() {
     // Test cast_unnecessary
@@ -22,6 +52,26 @@ fn main() {
     1_i32 as i32;
     1_f32 as f32;
 
+    let _: *mut u8 = [1u8, 2].as_ptr() as *const u8 as *mut u8;
+
+    [1u8, 2].as_ptr() as *const u8;
+    [1u8, 2].as_ptr() as *mut u8;
+    [1u8, 2].as_mut_ptr() as *mut u8;
+    [1u8, 2].as_mut_ptr() as *const u8;
+    [1u8, 2].as_ptr() as PtrConstU8;
+    [1u8, 2].as_ptr() as PtrMutU8;
+    [1u8, 2].as_mut_ptr() as PtrMutU8;
+    [1u8, 2].as_mut_ptr() as PtrConstU8;
+    let _: *const u8 = [1u8, 2].as_ptr() as _;
+    let _: *mut u8 = [1u8, 2].as_mut_ptr() as _;
+    let _: *const u8 = [1u8, 2].as_ptr() as *const _;
+    let _: *mut u8 = [1u8, 2].as_mut_ptr() as *mut _;
+
+    owo::<u32>([1u32].as_ptr()) as *const u32;
+    uwu::<u32, u8>([1u32].as_ptr()) as *const u8;
+    // this will not lint in the function body even though they have the same type, instead here
+    uwu::<u32, u32>([1u32].as_ptr()) as *const u32;
+
     // macro version
     macro_rules! foo {
         ($a:ident, $b:ident) => {
@@ -35,12 +85,37 @@ fn main() {
     foo!(b, f32);
     foo!(c, f64);
 
+    // do not lint cast from cfg-dependant type
+    let x = 0 as std::ffi::c_ulong;
+    let y = x as u64;
+    let x: std::ffi::c_ulong = 0;
+    let y = x as u64;
+
     // do not lint cast to cfg-dependant type
-    1 as std::os::raw::c_char;
+    let x = 1 as std::os::raw::c_char;
+    let y = x as u64;
 
     // do not lint cast to alias type
     1 as I32Alias;
     &1 as &I32Alias;
+    // or from
+    let x: I32Alias = 1;
+    let y = x as u64;
+    fake_libc::getpid_SAFE_TRUTH(&0u32) as i32;
+    extern_fake_libc::getpid_SAFE_TRUTH() as i32;
+    let pid = unsafe { fake_libc::getpid() };
+    pid as i32;
+
+    let i8_ptr: *const i8 = &1;
+    let u8_ptr: *const u8 = &1;
+
+    // cfg dependant pointees
+    i8_ptr as *const std::os::raw::c_char;
+    u8_ptr as *const std::os::raw::c_char;
+
+    // type aliased pointees
+    i8_ptr as *const std::ffi::c_char;
+    u8_ptr as *const std::ffi::c_char;
 
     // issue #9960
     macro_rules! bind_var {