Prevent unnecessary lints from triggering

Author: rail-rain

clippy_lints/src/loops.rs

@@ -768,12 +768,14 @@ fn check_for_loop<'tcx>(
     body: &'tcx Expr<'_>,
     expr: &'tcx Expr<'_>,
 ) {
-    check_for_loop_range(cx, pat, arg, body, expr);
+    let is_manual_memcpy_triggered = detect_manual_memcpy(cx, pat, arg, body, expr);
+    if !is_manual_memcpy_triggered {
+        check_for_loop_range(cx, pat, arg, body, expr);
+        check_for_loop_explicit_counter(cx, pat, arg, body, expr);
+    }
     check_for_loop_arg(cx, pat, arg, expr);
-    check_for_loop_explicit_counter(cx, pat, arg, body, expr);
     check_for_loop_over_map_kv(cx, pat, arg, body, expr);
     check_for_mut_range_bound(cx, arg, body);
-    detect_manual_memcpy(cx, pat, arg, body, expr);
     detect_same_item_push(cx, pat, arg, body, expr);
 }
 
@@ -1152,7 +1154,7 @@ fn detect_manual_memcpy<'tcx>(
     arg: &'tcx Expr<'_>,
     body: &'tcx Expr<'_>,
     expr: &'tcx Expr<'_>,
-) {
+) -> bool {
     if let Some(higher::Range {
         start: Some(start),
         end: Some(end),
@@ -1222,9 +1224,11 @@ fn detect_manual_memcpy<'tcx>(
                     big_sugg,
                     Applicability::Unspecified,
                 );
+                return true;
             }
         }
     }
+    false
 }
 
 // Scans the body of the for loop and determines whether lint should be given

tests/ui/manual_memcpy.rs

@@ -115,7 +115,6 @@ pub fn manual_copy(src: &[i32], dst: &mut [i32], dst2: &mut [i32]) {
     }
 }
 
-#[allow(clippy::needless_range_loop, clippy::explicit_counter_loop)]
 pub fn manual_copy_with_counters(src: &[i32], dst: &mut [i32], dst2: &mut [i32]) {
     let mut count = 0;
     for i in 3..src.len() {

tests/ui/manual_memcpy.stderr

@@ -79,49 +79,49 @@ LL |     for i in 0..0 {
    |              ^^^^ help: try replacing the loop by: `dst[..0].clone_from_slice(&src[..0])`
 
 error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:121:14
+  --> $DIR/manual_memcpy.rs:120:14
    |
 LL |     for i in 3..src.len() {
    |              ^^^^^^^^^^^^ help: try replacing the loop by: `dst[3..src.len()].clone_from_slice(&src[..(src.len() - 3)])`
 
 error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:127:14
+  --> $DIR/manual_memcpy.rs:126:14
    |
 LL |     for i in 3..src.len() {
    |              ^^^^^^^^^^^^ help: try replacing the loop by: `dst[..(src.len() - 3)].clone_from_slice(&src[3..])`
 
 error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:133:14
+  --> $DIR/manual_memcpy.rs:132:14
    |
 LL |     for i in 0..src.len() {
    |              ^^^^^^^^^^^^ help: try replacing the loop by: `dst[3..(src.len() + 3)].clone_from_slice(&src[..])`
 
 error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:139:14
+  --> $DIR/manual_memcpy.rs:138:14
    |
 LL |     for i in 0..src.len() {
    |              ^^^^^^^^^^^^ help: try replacing the loop by: `dst[..src.len()].clone_from_slice(&src[3..(src.len() + 3)])`
 
 error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:145:14
+  --> $DIR/manual_memcpy.rs:144:14
    |
 LL |     for i in 3..(3 + src.len()) {
    |              ^^^^^^^^^^^^^^^^^^ help: try replacing the loop by: `dst[3..((3 + src.len()))].clone_from_slice(&src[..((3 + src.len()) - 3)])`
 
 error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:151:14
+  --> $DIR/manual_memcpy.rs:150:14
    |
 LL |     for i in 5..src.len() {
    |              ^^^^^^^^^^^^ help: try replacing the loop by: `dst[5..src.len()].clone_from_slice(&src[(3 - 2)..((src.len() - 2) + 3 - 5)])`
 
 error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:157:14
+  --> $DIR/manual_memcpy.rs:156:14
    |
 LL |     for i in 3..10 {
    |              ^^^^^ help: try replacing the loop by: `dst[3..10].clone_from_slice(&src[5..(10 + 5 - 3)])`
 
 error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:164:14
+  --> $DIR/manual_memcpy.rs:163:14
    |
 LL |     for i in 0..src.len() {
    |              ^^^^^^^^^^^^
@@ -133,13 +133,13 @@ LL |     dst2[30..(src.len() + 30)].clone_from_slice(&src[..]) {
    |
 
 error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:174:14
+  --> $DIR/manual_memcpy.rs:173:14
    |
 LL |     for i in 0..1 << 1 {
    |              ^^^^^^^^^ help: try replacing the loop by: `dst[(0 << 1)..((1 << 1) + (0 << 1))].clone_from_slice(&src[2..((1 << 1) + 2)])`
 
 error: it looks like you're manually copying between slices
-  --> $DIR/manual_memcpy.rs:182:14
+  --> $DIR/manual_memcpy.rs:181:14
    |
 LL |     for i in 0..src.len() {
    |              ^^^^^^^^^^^^ help: try replacing the loop by: `dst[..src.len()].clone_from_slice(&src[..])`