Merge commit '4f142aa1058f14f153f8bfd2d82f04ddb9982388' into clippyup

4 files changed, 122 insertions, 4 deletions

diff --git a/clippy_lints/src/casts/as_ptr_cast_mut.rs b/clippy_lints/src/casts/as_ptr_cast_mut.rs
new file mode 100644
index 00000000000..9409f4844f5
--- /dev/null
+++ b/clippy_lints/src/casts/as_ptr_cast_mut.rs
@@ -0,0 +1,38 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::source::snippet_opt;
+use rustc_errors::Applicability;
+use rustc_hir::{Expr, ExprKind};
+use rustc_lint::LateContext;
+use rustc_middle::{
+    mir::Mutability,
+    ty::{self, Ty, TypeAndMut},
+};
+
+use super::AS_PTR_CAST_MUT;
+
+pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_expr: &Expr<'_>, cast_to: Ty<'_>) {
+    if let ty::RawPtr(ptrty @ TypeAndMut { mutbl: Mutability::Mut, .. }) = cast_to.kind()
+        && let ty::RawPtr(TypeAndMut { mutbl: Mutability::Not, .. }) =
+            cx.typeck_results().node_type(cast_expr.hir_id).kind()
+        && let ExprKind::MethodCall(method_name, receiver, [], _) = cast_expr.peel_blocks().kind
+        && method_name.ident.name == rustc_span::sym::as_ptr
+        && let Some(as_ptr_did) = cx.typeck_results().type_dependent_def_id(cast_expr.peel_blocks().hir_id)
+        && let as_ptr_sig = cx.tcx.fn_sig(as_ptr_did)
+        && let Some(first_param_ty) = as_ptr_sig.skip_binder().inputs().iter().next()
+        && let ty::Ref(_, _, Mutability::Not) = first_param_ty.kind()
+        && let Some(recv) = snippet_opt(cx, receiver.span)
+    {
+        // `as_mut_ptr` might not exist
+        let applicability = Applicability::MaybeIncorrect;
+
+        span_lint_and_sugg(
+            cx,
+            AS_PTR_CAST_MUT,
+            expr.span,
+            &format!("casting the result of `as_ptr` to *{ptrty}"),
+            "replace with",
+            format!("{recv}.as_mut_ptr()"),
+            applicability
+        );
+    }
+}
diff --git a/clippy_lints/src/casts/cast_nan_to_int.rs b/clippy_lints/src/casts/cast_nan_to_int.rs
new file mode 100644
index 00000000000..322dc41b3a1
--- /dev/null
+++ b/clippy_lints/src/casts/cast_nan_to_int.rs
@@ -0,0 +1,28 @@
+use super::CAST_NAN_TO_INT;
+
+use clippy_utils::consts::{constant, Constant};
+use clippy_utils::diagnostics::span_lint_and_note;
+use rustc_hir::Expr;
+use rustc_lint::LateContext;
+use rustc_middle::ty::Ty;
+
+pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>, cast_expr: &Expr<'_>, from_ty: Ty<'_>, to_ty: Ty<'_>) {
+    if from_ty.is_floating_point() && to_ty.is_integral() && is_known_nan(cx, cast_expr) {
+        span_lint_and_note(
+            cx,
+            CAST_NAN_TO_INT,
+            expr.span,
+            &format!("casting a known NaN to {to_ty}"),
+            None,
+            "this always evaluates to 0",
+        );
+    }
+}
+
+fn is_known_nan(cx: &LateContext<'_>, e: &Expr<'_>) -> bool {
+    match constant(cx, cx.typeck_results(), e) {
+        Some((Constant::F64(n), _)) => n.is_nan(),
+        Some((Constant::F32(n), _)) => n.is_nan(),
+        _ => false,
+    }
+}
diff --git a/clippy_lints/src/casts/mod.rs b/clippy_lints/src/casts/mod.rs
index cc5d346b954..b72c4c772f1 100644
--- a/clippy_lints/src/casts/mod.rs
+++ b/clippy_lints/src/casts/mod.rs
@@ -1,8 +1,10 @@
+mod as_ptr_cast_mut;
 mod as_underscore;
 mod borrow_as_ptr;
 mod cast_abs_to_unsigned;
 mod cast_enum_constructor;
 mod cast_lossless;
+mod cast_nan_to_int;
 mod cast_possible_truncation;
 mod cast_possible_wrap;
 mod cast_precision_loss;
@@ -569,6 +571,7 @@ declare_clippy_lint! {
     pedantic,
     "borrowing just to cast to a raw pointer"
 }
+
 declare_clippy_lint! {
     /// ### What it does
     /// Checks for a raw slice being cast to a slice pointer
@@ -596,6 +599,54 @@ declare_clippy_lint! {
     "casting a slice created from a pointer and length to a slice pointer"
 }
 
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks for the result of a `&self`-taking `as_ptr` being cast to a mutable pointer
+    ///
+    /// ### Why is this bad?
+    /// Since `as_ptr` takes a `&self`, the pointer won't have write permissions unless interior
+    /// mutability is used, making it unlikely that having it as a mutable pointer is correct.
+    ///
+    /// ### Example
+    /// ```rust
+    /// let string = String::with_capacity(1);
+    /// let ptr = string.as_ptr() as *mut u8;
+    /// unsafe { ptr.write(4) }; // UNDEFINED BEHAVIOUR
+    /// ```
+    /// Use instead:
+    /// ```rust
+    /// let mut string = String::with_capacity(1);
+    /// let ptr = string.as_mut_ptr();
+    /// unsafe { ptr.write(4) };
+    /// ```
+    #[clippy::version = "1.66.0"]
+    pub AS_PTR_CAST_MUT,
+    nursery,
+    "casting the result of the `&self`-taking `as_ptr` to a mutabe pointer"
+}
+
+declare_clippy_lint! {
+    /// ### What it does
+    /// Checks for a known NaN float being cast to an integer
+    ///
+    /// ### Why is this bad?
+    /// NaNs are cast into zero, so one could simply use this and make the
+    /// code more readable. The lint could also hint at a programmer error.
+    ///
+    /// ### Example
+    /// ```rust,ignore
+    /// let _: (0.0_f32 / 0.0) as u64;
+    /// ```
+    /// Use instead:
+    /// ```rust,ignore
+    /// let _: = 0_u64;
+    /// ```
+    #[clippy::version = "1.64.0"]
+    pub CAST_NAN_TO_INT,
+    suspicious,
+    "casting a known floating-point NaN into an integer"
+}
+
 pub struct Casts {
     msrv: Option<RustcVersion>,
 }
@@ -627,7 +678,9 @@ impl_lint_pass!(Casts => [
     CAST_ABS_TO_UNSIGNED,
     AS_UNDERSCORE,
     BORROW_AS_PTR,
-    CAST_SLICE_FROM_RAW_PARTS
+    CAST_SLICE_FROM_RAW_PARTS,
+    AS_PTR_CAST_MUT,
+    CAST_NAN_TO_INT,
 ]);
 
 impl<'tcx> LateLintPass<'tcx> for Casts {
@@ -653,6 +706,7 @@ impl<'tcx> LateLintPass<'tcx> for Casts {
                 return;
             }
             cast_slice_from_raw_parts::check(cx, expr, cast_expr, cast_to, self.msrv);
+            as_ptr_cast_mut::check(cx, expr, cast_expr, cast_to);
             fn_to_numeric_cast_any::check(cx, expr, cast_expr, cast_from, cast_to);
             fn_to_numeric_cast::check(cx, expr, cast_expr, cast_from, cast_to);
             fn_to_numeric_cast_with_truncation::check(cx, expr, cast_expr, cast_from, cast_to);
@@ -664,6 +718,7 @@ impl<'tcx> LateLintPass<'tcx> for Casts {
                     cast_precision_loss::check(cx, expr, cast_from, cast_to);
                     cast_sign_loss::check(cx, expr, cast_expr, cast_from, cast_to);
                     cast_abs_to_unsigned::check(cx, expr, cast_expr, cast_from, cast_to, self.msrv);
+                    cast_nan_to_int::check(cx, expr, cast_expr, cast_from, cast_to);
                 }
                 cast_lossless::check(cx, expr, cast_expr, cast_from, cast_to, self.msrv);
                 cast_enum_constructor::check(cx, expr, cast_expr, cast_from);
diff --git a/clippy_lints/src/casts/unnecessary_cast.rs b/clippy_lints/src/casts/unnecessary_cast.rs
index 21ed7f4844c..c8596987e4d 100644
--- a/clippy_lints/src/casts/unnecessary_cast.rs
+++ b/clippy_lints/src/casts/unnecessary_cast.rs
@@ -59,9 +59,6 @@ pub(super) fn check<'tcx>(
                 lint_unnecessary_cast(cx, expr, literal_str, cast_from, cast_to);
                 return false;
             },
-            LitKind::Int(_, LitIntType::Unsuffixed) | LitKind::Float(_, LitFloatType::Unsuffixed) => {
-                return false;
-            },
             LitKind::Int(_, LitIntType::Signed(_) | LitIntType::Unsigned(_))
             | LitKind::Float(_, LitFloatType::Suffixed(_))
                 if cast_from.kind() == cast_to.kind() =>