1 files changed, 47 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/cast_lossless_integer.rs b/src/tools/clippy/tests/ui/cast_lossless_integer.rs
new file mode 100644
index 000000000..34bb47181
--- /dev/null
+++ b/src/tools/clippy/tests/ui/cast_lossless_integer.rs
@@ -0,0 +1,47 @@
+// run-rustfix
+
+#![allow(clippy::no_effect, clippy::unnecessary_operation, dead_code)]
+#![warn(clippy::cast_lossless)]
+
+fn main() {
+    // Test clippy::cast_lossless with casts to integer types
+    let _ = 1i8 as i16;
+    let _ = 1i8 as i32;
+    let _ = 1i8 as i64;
+    let _ = 1u8 as i16;
+    let _ = 1u8 as i32;
+    let _ = 1u8 as i64;
+    let _ = 1u8 as u16;
+    let _ = 1u8 as u32;
+    let _ = 1u8 as u64;
+    let _ = 1i16 as i32;
+    let _ = 1i16 as i64;
+    let _ = 1u16 as i32;
+    let _ = 1u16 as i64;
+    let _ = 1u16 as u32;
+    let _ = 1u16 as u64;
+    let _ = 1i32 as i64;
+    let _ = 1u32 as i64;
+    let _ = 1u32 as u64;
+
+    // Test with an expression wrapped in parens
+    let _ = (1u8 + 1u8) as u16;
+}
+
+// The lint would suggest using `f64::from(input)` here but the `XX::from` function is not const,
+// so we skip the lint if the expression is in a const fn.
+// See #3656
+const fn abc(input: u16) -> u32 {
+    input as u32
+}
+
+// Same as the above issue. We can't suggest `::from` in const fns in impls
+mod cast_lossless_in_impl {
+    struct A;
+
+    impl A {
+        pub const fn convert(x: u32) -> u64 {
+            x as u64
+        }
+    }
+}