diff --git a/clippy_lints/src/loops/manual_memcpy.rs b/clippy_lints/src/loops/manual_memcpy.rs index 89f70519c..40d56240b 100644 --- a/clippy_lints/src/loops/manual_memcpy.rs +++ b/clippy_lints/src/loops/manual_memcpy.rs @@ -178,7 +178,9 @@ fn build_manual_memcpy_suggestion<'tcx>( let dst_base_str = snippet(cx, dst.base.span, "???"); let src_base_str = snippet(cx, src.base.span, "???"); - let dst = if dst_offset == sugg::EMPTY && dst_limit == sugg::EMPTY { + let dst = if (dst_offset == sugg::EMPTY && dst_limit == sugg::EMPTY) + || is_array_length_equal_to_range(cx, start, end, dst.base) + { dst_base_str } else { format!("{dst_base_str}[{}..{}]", dst_offset.maybe_par(), dst_limit.maybe_par()).into() @@ -190,11 +192,13 @@ fn build_manual_memcpy_suggestion<'tcx>( "clone_from_slice" }; - format!( - "{dst}.{method_str}(&{src_base_str}[{}..{}]);", - src_offset.maybe_par(), - src_limit.maybe_par() - ) + let src = if is_array_length_equal_to_range(cx, start, end, src.base) { + src_base_str + } else { + format!("{src_base_str}[{}..{}]", src_offset.maybe_par(), src_limit.maybe_par()).into() + }; + + format!("{dst}.{method_str}(&{src});") } /// a wrapper of `Sugg`. Besides what `Sugg` do, this removes unnecessary `0`; @@ -452,3 +456,34 @@ fn get_loop_counters<'a, 'tcx>( .into() }) } + +fn is_array_length_equal_to_range(cx: &LateContext<'_>, start: &Expr<'_>, end: &Expr<'_>, arr: &Expr<'_>) -> bool { + fn extract_lit_value(expr: &Expr<'_>) -> Option { + if let ExprKind::Lit(lit) = expr.kind + && let ast::LitKind::Int(value, _) = lit.node + { + Some(value) + } else { + None + } + } + + let arr_ty = cx.typeck_results().expr_ty(arr).peel_refs(); + + if let ty::Array(_, s) = arr_ty.kind() { + let size: u128 = if let Some(size) = s.try_eval_target_usize(cx.tcx, cx.param_env) { + size.into() + } else { + return false; + }; + + let range = match (extract_lit_value(start), extract_lit_value(end)) { + (Some(start_value), Some(end_value)) => end_value - start_value, + _ => return false, + }; + + size == range + } else { + false + } +} diff --git a/tests/ui/manual_memcpy/without_loop_counters.rs b/tests/ui/manual_memcpy/without_loop_counters.rs index a224001a3..8146091a2 100644 --- a/tests/ui/manual_memcpy/without_loop_counters.rs +++ b/tests/ui/manual_memcpy/without_loop_counters.rs @@ -138,6 +138,26 @@ pub fn manual_copy(src: &[i32], dst: &mut [i32], dst2: &mut [i32]) { for i in 0..dst.len() { dst[i] = src[i]; } + + // Range is equal to array length + let src = [0, 1, 2, 3, 4]; + let mut dst = [0; 4]; + for i in 0..4 { + //~^ ERROR: it looks like you're manually copying between slices + dst[i] = src[i]; + } + + let mut dst = [0; 6]; + for i in 0..5 { + //~^ ERROR: it looks like you're manually copying between slices + dst[i] = src[i]; + } + + let mut dst = [0; 5]; + for i in 0..5 { + //~^ ERROR: it looks like you're manually copying between slices + dst[i] = src[i]; + } } #[warn(clippy::needless_range_loop, clippy::manual_memcpy)] diff --git a/tests/ui/manual_memcpy/without_loop_counters.stderr b/tests/ui/manual_memcpy/without_loop_counters.stderr index b9dbda6ed..4b5cd274d 100644 --- a/tests/ui/manual_memcpy/without_loop_counters.stderr +++ b/tests/ui/manual_memcpy/without_loop_counters.stderr @@ -106,7 +106,7 @@ LL | / for i in 0..5 { LL | | LL | | dst[i - 0] = src[i]; LL | | } - | |_____^ help: try replacing the loop by: `dst[..5].copy_from_slice(&src[..5]);` + | |_____^ help: try replacing the loop by: `dst[..5].copy_from_slice(&src);` error: it looks like you're manually copying between slices --> $DIR/without_loop_counters.rs:121:5 @@ -120,11 +120,38 @@ LL | | } error: it looks like you're manually copying between slices --> $DIR/without_loop_counters.rs:145:5 | +LL | / for i in 0..4 { +LL | | +LL | | dst[i] = src[i]; +LL | | } + | |_____^ help: try replacing the loop by: `dst.copy_from_slice(&src[..4]);` + +error: it looks like you're manually copying between slices + --> $DIR/without_loop_counters.rs:151:5 + | +LL | / for i in 0..5 { +LL | | +LL | | dst[i] = src[i]; +LL | | } + | |_____^ help: try replacing the loop by: `dst[..5].copy_from_slice(&src);` + +error: it looks like you're manually copying between slices + --> $DIR/without_loop_counters.rs:157:5 + | +LL | / for i in 0..5 { +LL | | +LL | | dst[i] = src[i]; +LL | | } + | |_____^ help: try replacing the loop by: `dst.copy_from_slice(&src);` + +error: it looks like you're manually copying between slices + --> $DIR/without_loop_counters.rs:165:5 + | LL | / for i in 0..src.len() { LL | | LL | | dst[i] = src[i].clone(); LL | | } | |_____^ help: try replacing the loop by: `dst[..src.len()].clone_from_slice(&src[..]);` -error: aborting due to 13 previous errors +error: aborting due to 16 previous errors