Move PtrEq into Operators lin pass

Author: Jarcho

clippy_lints/src/lib.register_all.rs

@@ -253,6 +253,7 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![
     LintId::of(operators::MISREFACTORED_ASSIGN_OP),
     LintId::of(operators::MODULO_ONE),
     LintId::of(operators::OP_REF),
+    LintId::of(operators::PTR_EQ),
     LintId::of(option_env_unwrap::OPTION_ENV_UNWRAP),
     LintId::of(overflow_check_conditional::OVERFLOW_CHECK_CONDITIONAL),
     LintId::of(partialeq_ne_impl::PARTIALEQ_NE_IMPL),
@@ -261,7 +262,6 @@ store.register_group(true, "clippy::all", Some("clippy_all"), vec![
     LintId::of(ptr::INVALID_NULL_PTR_USAGE),
     LintId::of(ptr::MUT_FROM_REF),
     LintId::of(ptr::PTR_ARG),
-    LintId::of(ptr_eq::PTR_EQ),
     LintId::of(ptr_offset_with_cast::PTR_OFFSET_WITH_CAST),
     LintId::of(question_mark::QUESTION_MARK),
     LintId::of(ranges::MANUAL_RANGE_CONTAINS),

clippy_lints/src/lib.register_lints.rs

@@ -424,6 +424,7 @@ store.register_lints(&[
     operators::MODULO_ONE,
     operators::NEEDLESS_BITWISE_BOOL,
     operators::OP_REF,
+    operators::PTR_EQ,
     operators::VERBOSE_BIT_MASK,
     option_env_unwrap::OPTION_ENV_UNWRAP,
     option_if_let_else::OPTION_IF_LET_ELSE,
@@ -443,7 +444,6 @@ store.register_lints(&[
     ptr::INVALID_NULL_PTR_USAGE,
     ptr::MUT_FROM_REF,
     ptr::PTR_ARG,
-    ptr_eq::PTR_EQ,
     ptr_offset_with_cast::PTR_OFFSET_WITH_CAST,
     pub_use::PUB_USE,
     question_mark::QUESTION_MARK,

clippy_lints/src/lib.register_style.rs

@@ -96,9 +96,9 @@ store.register_group(true, "clippy::style", Some("clippy_style"), vec![
     LintId::of(non_expressive_names::JUST_UNDERSCORES_AND_DIGITS),
     LintId::of(operators::ASSIGN_OP_PATTERN),
     LintId::of(operators::OP_REF),
+    LintId::of(operators::PTR_EQ),
     LintId::of(ptr::CMP_NULL),
     LintId::of(ptr::PTR_ARG),
-    LintId::of(ptr_eq::PTR_EQ),
     LintId::of(question_mark::QUESTION_MARK),
     LintId::of(ranges::MANUAL_RANGE_CONTAINS),
     LintId::of(redundant_field_names::REDUNDANT_FIELD_NAMES),

clippy_lints/src/lib.rs

@@ -332,7 +332,6 @@ mod path_buf_push_overwrite;
 mod pattern_type_mismatch;
 mod precedence;
 mod ptr;
-mod ptr_eq;
 mod ptr_offset_with_cast;
 mod pub_use;
 mod question_mark;
@@ -537,7 +536,6 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
     store.register_late_pass(|| Box::new(enum_clike::UnportableVariant));
     store.register_late_pass(|| Box::new(float_literal::FloatLiteral));
     store.register_late_pass(|| Box::new(ptr::Ptr));
-    store.register_late_pass(|| Box::new(ptr_eq::PtrEq));
     store.register_late_pass(|| Box::new(needless_bool::NeedlessBool));
     store.register_late_pass(|| Box::new(needless_bool::BoolComparison));
     store.register_late_pass(|| Box::new(needless_for_each::NeedlessForEach));

clippy_lints/src/operators/mod.rs

@@ -21,6 +21,7 @@ mod modulo_arithmetic;
 mod modulo_one;
 mod needless_bitwise_bool;
 mod op_ref;
+mod ptr_eq;
 mod verbose_bit_mask;
 
 declare_clippy_lint! {
@@ -656,6 +657,35 @@ declare_clippy_lint! {
     "Boolean expressions that use bitwise rather than lazy operators"
 }
 
+declare_clippy_lint! {
+    /// ### What it does
+    /// Use `std::ptr::eq` when applicable
+    ///
+    /// ### Why is this bad?
+    /// `ptr::eq` can be used to compare `&T` references
+    /// (which coerce to `*const T` implicitly) by their address rather than
+    /// comparing the values they point to.
+    ///
+    /// ### Example
+    /// ```rust
+    /// let a = &[1, 2, 3];
+    /// let b = &[1, 2, 3];
+    ///
+    /// assert!(a as *const _ as usize == b as *const _ as usize);
+    /// ```
+    /// Use instead:
+    /// ```rust
+    /// let a = &[1, 2, 3];
+    /// let b = &[1, 2, 3];
+    ///
+    /// assert!(std::ptr::eq(a, b));
+    /// ```
+    #[clippy::version = "1.49.0"]
+    pub PTR_EQ,
+    style,
+    "use `std::ptr::eq` when comparing raw pointers"
+}
+
 pub struct Operators {
     arithmetic_context: arithmetic::Context,
     verbose_bit_mask_threshold: u64,
@@ -684,6 +714,7 @@ impl_lint_pass!(Operators => [
     MODULO_ONE,
     MODULO_ARITHMETIC,
     NEEDLESS_BITWISE_BOOL,
+    PTR_EQ,
 ]);
 impl Operators {
     pub fn new(verbose_bit_mask_threshold: u64) -> Self {
@@ -707,6 +738,7 @@ impl<'tcx> LateLintPass<'tcx> for Operators {
                     erasing_op::check(cx, e, op.node, lhs, rhs);
                     identity_op::check(cx, e, op.node, lhs, rhs);
                     needless_bitwise_bool::check(cx, e, op.node, lhs, rhs);
+                    ptr_eq::check(cx, e, op.node, lhs, rhs);
                 }
                 self.arithmetic_context.check_binary(cx, e, op.node, lhs, rhs);
                 bit_mask::check(cx, e, op.node, lhs, rhs);

clippy_lints/src/operators/ptr_eq.rs

@@ -0,0 +1,65 @@
+use clippy_utils::diagnostics::span_lint_and_sugg;
+use clippy_utils::source::snippet_opt;
+use if_chain::if_chain;
+use rustc_errors::Applicability;
+use rustc_hir::{BinOpKind, Expr, ExprKind};
+use rustc_lint::LateContext;
+
+use super::PTR_EQ;
+
+static LINT_MSG: &str = "use `std::ptr::eq` when comparing raw pointers";
+
+pub(super) fn check<'tcx>(
+    cx: &LateContext<'tcx>,
+    expr: &'tcx Expr<'_>,
+    op: BinOpKind,
+    left: &'tcx Expr<'_>,
+    right: &'tcx Expr<'_>,
+) {
+    if BinOpKind::Eq == op {
+        let (left, right) = match (expr_as_cast_to_usize(cx, left), expr_as_cast_to_usize(cx, right)) {
+            (Some(lhs), Some(rhs)) => (lhs, rhs),
+            _ => (left, right),
+        };
+
+        if_chain! {
+            if let Some(left_var) = expr_as_cast_to_raw_pointer(cx, left);
+            if let Some(right_var) = expr_as_cast_to_raw_pointer(cx, right);
+            if let Some(left_snip) = snippet_opt(cx, left_var.span);
+            if let Some(right_snip) = snippet_opt(cx, right_var.span);
+            then {
+                span_lint_and_sugg(
+                    cx,
+                    PTR_EQ,
+                    expr.span,
+                    LINT_MSG,
+                    "try",
+                    format!("std::ptr::eq({}, {})", left_snip, right_snip),
+                    Applicability::MachineApplicable,
+                    );
+            }
+        }
+    }
+}
+
+// If the given expression is a cast to a usize, return the lhs of the cast
+// E.g., `foo as *const _ as usize` returns `foo as *const _`.
+fn expr_as_cast_to_usize<'tcx>(cx: &LateContext<'tcx>, cast_expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
+    if cx.typeck_results().expr_ty(cast_expr) == cx.tcx.types.usize {
+        if let ExprKind::Cast(expr, _) = cast_expr.kind {
+            return Some(expr);
+        }
+    }
+    None
+}
+
+// If the given expression is a cast to a `*const` pointer, return the lhs of the cast
+// E.g., `foo as *const _` returns `foo`.
+fn expr_as_cast_to_raw_pointer<'tcx>(cx: &LateContext<'tcx>, cast_expr: &'tcx Expr<'_>) -> Option<&'tcx Expr<'tcx>> {
+    if cx.typeck_results().expr_ty(cast_expr).is_unsafe_ptr() {
+        if let ExprKind::Cast(expr, _) = cast_expr.kind {
+            return Some(expr);
+        }
+    }
+    None
+}