Add run-rustfix marker and test file

clippy_lints/src/manual_slice_size_calculation.rs

@@ -1,3 +1,4 @@
+// run-rustfix
 use clippy_utils::diagnostics::span_lint_and_sugg;
 use clippy_utils::source::snippet_with_context;
 use clippy_utils::{expr_or_init, in_constant};

tests/ui/manual_slice_size_calculation.fixed

@@ -0,0 +1,37 @@
+// run-rustfix
+#![allow(unused)]
+#![warn(clippy::manual_slice_size_calculation)]
+
+use core::mem::{align_of, size_of};
+
+fn main() {
+    let v_i32 = Vec::<i32>::new();
+    let s_i32 = v_i32.as_slice();
+
+    // True positives:
+    let _ = std::mem::size_of_val(s_i32); // WARNING
+    let _ = std::mem::size_of_val(s_i32); // WARNING
+    let _ = std::mem::size_of_val(s_i32) * 5; // WARNING
+
+    let len = s_i32.len();
+    let size = size_of::<i32>();
+    let _ = std::mem::size_of_val(s_i32); // WARNING
+    let _ = std::mem::size_of_val(s_i32); // WARNING
+    let _ = std::mem::size_of_val(s_i32); // WARNING
+
+    // True negatives:
+    let _ = size_of::<i32>() + s_i32.len(); // Ok, not a multiplication
+    let _ = size_of::<i32>() * s_i32.partition_point(|_| true); // Ok, not len()
+    let _ = size_of::<i32>() * v_i32.len(); // Ok, not a slice
+    let _ = align_of::<i32>() * s_i32.len(); // Ok, not size_of()
+    let _ = size_of::<u32>() * s_i32.len(); // Ok, different types
+
+    // False negatives:
+    let _ = 5 * size_of::<i32>() * s_i32.len(); // Ok (MISSED OPPORTUNITY)
+    let _ = size_of::<i32>() * 5 * s_i32.len(); // Ok (MISSED OPPORTUNITY)
+}
+
+const fn _const(s_i32: &[i32]) {
+    // True negative:
+    let _ = s_i32.len() * size_of::<i32>(); // Ok, can't use size_of_val in const
+}

tests/ui/manual_slice_size_calculation.rs

@@ -1,3 +1,4 @@
+// run-rustfix
 #![allow(unused)]
 #![warn(clippy::manual_slice_size_calculation)]
 

tests/ui/manual_slice_size_calculation.stderr

@@ -1,5 +1,5 @@
 error: manual slice size calculation
-  --> $DIR/manual_slice_size_calculation.rs:11:13
+  --> $DIR/manual_slice_size_calculation.rs:12:13
    |
 LL |     let _ = s_i32.len() * size_of::<i32>(); // WARNING
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::mem::size_of_val(s_i32)`
@@ -7,31 +7,31 @@ LL |     let _ = s_i32.len() * size_of::<i32>(); // WARNING
    = note: `-D clippy::manual-slice-size-calculation` implied by `-D warnings`
 
 error: manual slice size calculation
-  --> $DIR/manual_slice_size_calculation.rs:12:13
+  --> $DIR/manual_slice_size_calculation.rs:13:13
    |
 LL |     let _ = size_of::<i32>() * s_i32.len(); // WARNING
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::mem::size_of_val(s_i32)`
 
 error: manual slice size calculation
-  --> $DIR/manual_slice_size_calculation.rs:13:13
+  --> $DIR/manual_slice_size_calculation.rs:14:13
    |
 LL |     let _ = size_of::<i32>() * s_i32.len() * 5; // WARNING
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::mem::size_of_val(s_i32)`
 
 error: manual slice size calculation
-  --> $DIR/manual_slice_size_calculation.rs:17:13
+  --> $DIR/manual_slice_size_calculation.rs:18:13
    |
 LL |     let _ = len * size_of::<i32>(); // WARNING
    |             ^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::mem::size_of_val(s_i32)`
 
 error: manual slice size calculation
-  --> $DIR/manual_slice_size_calculation.rs:18:13
+  --> $DIR/manual_slice_size_calculation.rs:19:13
    |
 LL |     let _ = s_i32.len() * size; // WARNING
    |             ^^^^^^^^^^^^^^^^^^ help: try: `std::mem::size_of_val(s_i32)`
 
 error: manual slice size calculation
-  --> $DIR/manual_slice_size_calculation.rs:19:13
+  --> $DIR/manual_slice_size_calculation.rs:20:13
    |
 LL |     let _ = len * size; // WARNING
    |             ^^^^^^^^^^ help: try: `std::mem::size_of_val(s_i32)`