ignore manual_slice_fill in other test files

rust-lang · Jan 30, 2025 · 801090f · 801090f
1 parent 609839e
commit 801090f
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Showing 9 changed files with 197 additions and 76 deletions.
diff --git a/clippy_lints/src/loops/manual_slice_fill.rs b/clippy_lints/src/loops/manual_slice_fill.rs
@@ -5,12 +5,13 @@ use clippy_utils::msrvs::{self, Msrv};
 use clippy_utils::source::{HasSession, snippet_with_applicability};
 use clippy_utils::ty::implements_trait;
 use clippy_utils::{higher, peel_blocks_with_stmt, span_contains_comment};
-use rustc_ast::RangeLimits;
 use rustc_ast::ast::LitKind;
+use rustc_ast::{RangeLimits, UnOp};
 use rustc_data_structures::packed::Pu128;
 use rustc_errors::Applicability;
 use rustc_hir::QPath::Resolved;
-use rustc_hir::{Expr, ExprKind};
+use rustc_hir::def::Res;
+use rustc_hir::{Expr, ExprKind, Pat};
 use rustc_lint::LateContext;
 use rustc_span::source_map::Spanned;
 use rustc_span::sym;
@@ -19,55 +20,91 @@ use super::MANUAL_SLICE_FILL;
 
 pub(super) fn check<'tcx>(
     cx: &LateContext<'tcx>,
+    pat: &'tcx Pat<'_>,
     arg: &'tcx Expr<'_>,
     body: &'tcx Expr<'_>,
     expr: &'tcx Expr<'_>,
     msrv: &Msrv,
 ) {
-    if msrv.meets(msrvs::SLICE_FILL)
-        && let Some(higher::Range {
-            start: Some(start),
-            end: Some(end),
-            limits: RangeLimits::HalfOpen,
-        }) = higher::Range::hir(arg)
+    if !msrv.meets(msrvs::SLICE_FILL) {
+        return;
+    }
+
+    // `for _ in 0..slice.len() { slice[_] = value; }`
+    if let Some(higher::Range {
+        start: Some(start),
+        end: Some(end),
+        limits: RangeLimits::HalfOpen,
+    }) = higher::Range::hir(arg)
         && let ExprKind::Lit(Spanned {
             node: LitKind::Int(Pu128(0), _),
             ..
         }) = start.kind
-        && let ExprKind::Block(_, _) = body.kind
+        && let ExprKind::Block(..) = body.kind
+        // Check if the body is an assignment to a slice element.
         && let ExprKind::Assign(assignee, assignval, _) = peel_blocks_with_stmt(body).kind
         && let ExprKind::Index(slice, _, _) = assignee.kind
-        && let ExprKind::MethodCall(path, recv, _, _) = end.kind
-        && let ExprKind::Path(Resolved(_, recvpath)) = recv.kind
-        && let ExprKind::Path(Resolved(_, slicepath)) = slice.kind
+        // Check if `len()` is used for the range end.
+        && let ExprKind::MethodCall(path, recv,..) = end.kind
+        && path.ident.name == sym::len
+        // Check if the slice which is being assigned to is the same as the one being iterated over.
+        && let ExprKind::Path(Resolved(_, recv_path)) = recv.kind
+        && let ExprKind::Path(Resolved(_, slice_path)) = slice.kind
+        && recv_path.res == slice_path.res
+        && !assignval.span.from_expansion()
         && switch_to_eager_eval(cx, assignval)
         && span_is_local(assignval.span)
-        && path.ident.name == sym::len
-        // Ensure that the slice used as the range in the loop matches the slice being manipulated inside the loop.
-        && recvpath.res == slicepath.res
-        && slice.span.eq_ctxt(path.ident.span)
         // The `fill` method cannot be used if the slice's element type does not implement the `Clone` trait.
         && let Some(clone_trait) = cx.tcx.lang_items().clone_trait()
         && implements_trait(cx, cx.typeck_results().expr_ty(slice), clone_trait, &[])
     {
-        let mut app = if span_contains_comment(cx.sess().source_map(), body.span) {
-            Applicability::MaybeIncorrect // Comments may be informational.
-        } else {
-            Applicability::MachineApplicable
-        };
-
-        span_lint_and_sugg(
-            cx,
-            MANUAL_SLICE_FILL,
-            expr.span,
-            "manually filling a slice",
-            "try",
-            format!(
-                "{}.fill({});",
-                snippet_with_applicability(cx, slice.span, "..", &mut app),
-                snippet_with_applicability(cx, assignval.span, "..", &mut app),
-            ),
-            app,
-        );
+        sugg(cx, body, expr, slice.span, assignval.span);
     }
+    // `for _ in &mut slice { *_ = value; }`
+    else if let ExprKind::AddrOf(_, _, recv) = arg.kind
+        // Check if the body is an assignment to a slice element.
+        && let ExprKind::Assign(assignee, assignval, _) = peel_blocks_with_stmt(body).kind
+        && let ExprKind::Unary(UnOp::Deref, slice_iter) = assignee.kind
+        && let ExprKind::Path(Resolved(_, recv_path)) = recv.kind
+        // Check if the slice which is being assigned to is the same as the one being iterated over.
+        && let ExprKind::Path(Resolved(_, slice_path)) = slice_iter.kind
+        && let Res::Local(local) = slice_path.res
+        && local == pat.hir_id
+        && !assignval.span.from_expansion()
+        && switch_to_eager_eval(cx, assignval)
+        && span_is_local(assignval.span)
+        // The `fill` method cannot be used if the slice's element type does not implement the `Clone` trait.
+        && let Some(clone_trait) = cx.tcx.lang_items().clone_trait()
+        && implements_trait(cx, cx.typeck_results().expr_ty(recv), clone_trait, &[])
+    {
+        sugg(cx, body, expr, recv_path.span, assignval.span);
+    }
+}
+
+fn sugg<'tcx>(
+    cx: &LateContext<'tcx>,
+    body: &'tcx Expr<'_>,
+    expr: &'tcx Expr<'_>,
+    slice_span: rustc_span::Span,
+    assignval_span: rustc_span::Span,
+) {
+    let mut app = if span_contains_comment(cx.sess().source_map(), body.span) {
+        Applicability::MaybeIncorrect // Comments may be informational.
+    } else {
+        Applicability::MachineApplicable
+    };
+
+    span_lint_and_sugg(
+        cx,
+        MANUAL_SLICE_FILL,
+        expr.span,
+        "manually filling a slice",
+        "try",
+        format!(
+            "{}.fill({});",
+            snippet_with_applicability(cx, slice_span, "..", &mut app),
+            snippet_with_applicability(cx, assignval_span, "..", &mut app),
+        ),
+        app,
+    );
 }
diff --git a/clippy_lints/src/loops/mod.rs b/clippy_lints/src/loops/mod.rs
@@ -850,7 +850,7 @@ impl Loops {
     ) {
         let is_manual_memcpy_triggered = manual_memcpy::check(cx, pat, arg, body, expr);
         if !is_manual_memcpy_triggered {
-            manual_slice_fill::check(cx, arg, body, expr, &self.msrv);
+            manual_slice_fill::check(cx, pat, arg, body, expr, &self.msrv);
             needless_range_loop::check(cx, pat, arg, body, expr);
             explicit_counter_loop::check(cx, pat, arg, body, expr, label);
         }

diff --git a/tests/ui/manual_memcpy/without_loop_counters.rs b/tests/ui/manual_memcpy/without_loop_counters.rs
@@ -1,5 +1,10 @@
 #![warn(clippy::manual_memcpy)]
-#![allow(clippy::assigning_clones, clippy::useless_vec, clippy::needless_range_loop)]
+#![allow(
+    clippy::assigning_clones,
+    clippy::useless_vec,
+    clippy::needless_range_loop,
+    clippy::manual_slice_fill
+)]
 
 //@no-rustfix
 const LOOP_OFFSET: usize = 5000;

diff --git a/tests/ui/manual_memcpy/without_loop_counters.stderr b/tests/ui/manual_memcpy/without_loop_counters.stderr
@@ -1,5 +1,5 @@
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:9:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:14:5
    |
 LL | /     for i in 0..src.len() {
 LL | |
@@ -12,7 +12,7 @@ LL | |     }
    = help: to override `-D warnings` add `#[allow(clippy::manual_memcpy)]`
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:16:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:21:5
    |
 LL | /     for i in 0..src.len() {
 LL | |
@@ -21,7 +21,7 @@ LL | |     }
    | |_____^ help: try replacing the loop by: `dst[10..(src.len() + 10)].copy_from_slice(&src[..]);`
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:22:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:27:5
    |
 LL | /     for i in 0..src.len() {
 LL | |
@@ -30,7 +30,7 @@ LL | |     }
    | |_____^ help: try replacing the loop by: `dst[..src.len()].copy_from_slice(&src[10..(src.len() + 10)]);`
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:28:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:33:5
    |
 LL | /     for i in 11..src.len() {
 LL | |
@@ -39,7 +39,7 @@ LL | |     }
    | |_____^ help: try replacing the loop by: `dst[11..src.len()].copy_from_slice(&src[(11 - 10)..(src.len() - 10)]);`
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:34:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:39:5
    |
 LL | /     for i in 0..dst.len() {
 LL | |
@@ -48,7 +48,7 @@ LL | |     }
    | |_____^ help: try replacing the loop by: `dst.copy_from_slice(&src[..dst.len()]);`
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:48:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:53:5
    |
 LL | /     for i in 10..256 {
 LL | |
@@ -64,7 +64,7 @@ LL +     dst2[(10 + 500)..(256 + 500)].copy_from_slice(&src[10..256]);
    |
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:61:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:66:5
    |
 LL | /     for i in 10..LOOP_OFFSET {
 LL | |
@@ -73,7 +73,7 @@ LL | |     }
    | |_____^ help: try replacing the loop by: `dst[(10 + LOOP_OFFSET)..(LOOP_OFFSET + LOOP_OFFSET)].copy_from_slice(&src[(10 - some_var)..(LOOP_OFFSET - some_var)]);`
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:75:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:80:5
    |
 LL | /     for i in 0..src_vec.len() {
 LL | |
@@ -82,7 +82,7 @@ LL | |     }
    | |_____^ help: try replacing the loop by: `dst_vec[..src_vec.len()].copy_from_slice(&src_vec[..]);`
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:105:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:110:5
    |
 LL | /     for i in from..from + src.len() {
 LL | |
@@ -91,7 +91,7 @@ LL | |     }
    | |_____^ help: try replacing the loop by: `dst[from..(from + src.len())].copy_from_slice(&src[..(from + src.len() - from)]);`
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:110:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:115:5
    |
 LL | /     for i in from..from + 3 {
 LL | |
@@ -100,7 +100,7 @@ LL | |     }
    | |_____^ help: try replacing the loop by: `dst[from..(from + 3)].copy_from_slice(&src[..(from + 3 - from)]);`
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:116:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:121:5
    |
 LL | /     for i in 0..5 {
 LL | |
@@ -109,7 +109,7 @@ LL | |     }
    | |_____^ help: try replacing the loop by: `dst[..5].copy_from_slice(&src);`
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:122:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:127:5
    |
 LL | /     for i in 0..0 {
 LL | |
@@ -118,7 +118,7 @@ LL | |     }
    | |_____^ help: try replacing the loop by: `dst[..0].copy_from_slice(&src[..0]);`
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:146:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:151:5
    |
 LL | /     for i in 0..4 {
 LL | |
@@ -127,7 +127,7 @@ LL | |     }
    | |_____^ help: try replacing the loop by: `dst.copy_from_slice(&src[..4]);`
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:152:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:157:5
    |
 LL | /     for i in 0..5 {
 LL | |
@@ -136,7 +136,7 @@ LL | |     }
    | |_____^ help: try replacing the loop by: `dst[..5].copy_from_slice(&src);`
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:158:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:163:5
    |
 LL | /     for i in 0..5 {
 LL | |
@@ -145,7 +145,7 @@ LL | |     }
    | |_____^ help: try replacing the loop by: `dst.copy_from_slice(&src);`
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:205:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:210:5
    |
 LL | /     for i in 0..5 {
 LL | |
@@ -154,7 +154,7 @@ LL | |     }
    | |_____^ help: try replacing the loop by: `dst.copy_from_slice(&src[0]);`
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:211:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:216:5
    |
 LL | /     for i in 0..5 {
 LL | |
@@ -163,7 +163,7 @@ LL | |     }
    | |_____^ help: try replacing the loop by: `dst.copy_from_slice(&src[0][1]);`
 
 error: it looks like you're manually copying between slices
-  --> tests/ui/manual_memcpy/without_loop_counters.rs:219:5
+  --> tests/ui/manual_memcpy/without_loop_counters.rs:224:5
    |
 LL | /     for i in 0..src.len() {
 LL | |

diff --git a/tests/ui/manual_slice_fill.fixed b/tests/ui/manual_slice_fill.fixed
@@ -7,6 +7,14 @@ macro_rules! assign_element {
     };
 }
 
+macro_rules! assign_element_2 {
+    ($i:expr) => {
+        $i = 0;
+    };
+}
+
+struct NoClone;
+
 fn num() -> usize {
     5
 }
@@ -19,6 +27,8 @@ fn should_lint() {
     let x = 5;
     some_slice.fill(x);
 
+    some_slice.fill(0);
+
     // This should trigger `manual_slice_fill`, but the applicability is `MaybeIncorrect` since comments
     // within the loop might be purely informational.
     some_slice.fill(0);
@@ -58,10 +68,34 @@ fn should_not_lint() {
         some_slice[i] = 0;
     }
 
-    struct NoClone;
     let mut vec: Vec<Option<NoClone>> = Vec::with_capacity(5);
     // Should not lint because `NoClone` does not have `Clone` trait.
     for i in 0..vec.len() {
         vec[i] = None;
     }
+
+    // Should not lint, as using a function to assign values to elements might be
+    // intentional. For example, the contents of `num()` could be temporary and subject to change
+    // later.
+    for i in &mut some_slice {
+        *i = num();
+    }
+
+    // Should not lint because this loop isn't equivalent to `fill`.
+    for i in &mut some_slice {
+        *i = 0;
+        println!("foo");
+    }
+
+    // Should not lint because it may be intentional to use a macro to perform an operation equivalent
+    // to `fill`.
+    for i in &mut some_slice {
+        assign_element_2!(*i);
+    }
+
+    let mut vec: Vec<Option<NoClone>> = Vec::with_capacity(5);
+    // Should not lint because `NoClone` does not have `Clone` trait.
+    for i in &mut vec {
+        *i = None;
+    }
 }