Ignore manual_slice_size_calculation in code from macro expansions

clippy_lints/src/manual_slice_size_calculation.rs

@@ -1,4 +1,3 @@
-// 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, std_or_core};
@@ -45,6 +44,7 @@ impl<'tcx> LateLintPass<'tcx> for ManualSliceSizeCalculation {
         if !in_constant(cx, expr.hir_id)
             && let ExprKind::Binary(ref op, left, right) = expr.kind
             && BinOpKind::Mul == op.node
+            && !expr.span.from_expansion()
             && let Some(receiver) = simplify(cx, left, right)
         {
             let ctxt = expr.span.ctxt();
@@ -55,12 +55,12 @@ impl<'tcx> LateLintPass<'tcx> for ManualSliceSizeCalculation {
             span_lint_and_sugg(
                 cx,
                 MANUAL_SLICE_SIZE_CALCULATION,
-                    expr.span,
-                    "manual slice size calculation",
-                    "try",
-                    format!("{sugg}::mem::size_of_val({val_name})"),
-                    Applicability::MachineApplicable,
-                );
+                expr.span,
+                "manual slice size calculation",
+                "try",
+                format!("{sugg}::mem::size_of_val({val_name})"),
+                app,
+            );
         }
     }
 }
@@ -81,9 +81,9 @@ fn simplify_half<'tcx>(
     expr1: &'tcx Expr<'tcx>,
     expr2: &'tcx Expr<'tcx>,
 ) -> Option<&'tcx Expr<'tcx>> {
-    if
+    if !expr1.span.from_expansion()
         // expr1 is `[T1].len()`?
-        let ExprKind::MethodCall(method_path, receiver, _, _) = expr1.kind
+        && let ExprKind::MethodCall(method_path, receiver, _, _) = expr1.kind
         && method_path.ident.name == sym::len
         && let receiver_ty = cx.typeck_results().expr_ty(receiver)
         && let ty::Slice(ty1) = receiver_ty.peel_refs().kind()

tests/ui/manual_slice_size_calculation.fixed

@@ -1,8 +1,12 @@
 // run-rustfix
+// aux-build:proc_macros.rs
 #![allow(unused)]
 #![warn(clippy::manual_slice_size_calculation)]
 
+extern crate proc_macros;
+
 use core::mem::{align_of, size_of};
+use proc_macros::external;
 
 fn main() {
     let v_i32 = Vec::<i32>::new();
@@ -19,13 +23,18 @@ fn main() {
     let _ = std::mem::size_of_val(s_i32); // WARNING
     let _ = std::mem::size_of_val(s_i32); // WARNING
 
+    let _ = std::mem::size_of_val(external!(&[1u64][..]));
+
     // 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
 
+    let _ = external!($s_i32.len() * size_of::<i32>());
+    let _ = external!($s_i32.len()) * size_of::<i32>();
+
     // False negatives:
     let _ = 5 * size_of::<i32>() * s_i32.len(); // Ok (MISSED OPPORTUNITY)
     let _ = size_of::<i32>() * 5 * s_i32.len(); // Ok (MISSED OPPORTUNITY)

tests/ui/manual_slice_size_calculation.rs

@@ -1,8 +1,12 @@
 // run-rustfix
+// aux-build:proc_macros.rs
 #![allow(unused)]
 #![warn(clippy::manual_slice_size_calculation)]
 
+extern crate proc_macros;
+
 use core::mem::{align_of, size_of};
+use proc_macros::external;
 
 fn main() {
     let v_i32 = Vec::<i32>::new();
@@ -19,13 +23,18 @@ fn main() {
     let _ = s_i32.len() * size; // WARNING
     let _ = len * size; // WARNING
 
+    let _ = external!(&[1u64][..]).len() * size_of::<u64>();
+
     // 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
 
+    let _ = external!($s_i32.len() * size_of::<i32>());
+    let _ = external!($s_i32.len()) * size_of::<i32>();
+
     // False negatives:
     let _ = 5 * size_of::<i32>() * s_i32.len(); // Ok (MISSED OPPORTUNITY)
     let _ = size_of::<i32>() * 5 * s_i32.len(); // Ok (MISSED OPPORTUNITY)

tests/ui/manual_slice_size_calculation.stderr

@@ -1,40 +1,46 @@
 error: manual slice size calculation
-  --> $DIR/manual_slice_size_calculation.rs:12:13
+  --> $DIR/manual_slice_size_calculation.rs:16:13
    |
 LL |     let _ = s_i32.len() * size_of::<i32>(); // WARNING
    |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::mem::size_of_val(s_i32)`
    |
    = note: `-D clippy::manual-slice-size-calculation` implied by `-D warnings`
 
 error: manual slice size calculation
-  --> $DIR/manual_slice_size_calculation.rs:13:13
+  --> $DIR/manual_slice_size_calculation.rs:17:13
    |
 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:14:13
+  --> $DIR/manual_slice_size_calculation.rs:18:13
    |
 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:18:13
+  --> $DIR/manual_slice_size_calculation.rs:22:13
    |
 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:19:13
+  --> $DIR/manual_slice_size_calculation.rs:23:13
    |
 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:20:13
+  --> $DIR/manual_slice_size_calculation.rs:24:13
    |
 LL |     let _ = len * size; // WARNING
    |             ^^^^^^^^^^ help: try: `std::mem::size_of_val(s_i32)`
 
-error: aborting due to 6 previous errors
+error: manual slice size calculation
+  --> $DIR/manual_slice_size_calculation.rs:26:13
+   |
+LL |     let _ = external!(&[1u64][..]).len() * size_of::<u64>();
+   |             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ help: try: `std::mem::size_of_val(external!(&[1u64][..]))`
+
+error: aborting due to 7 previous errors