Auto merge of #121268 - Urgau:improve_ambi_wide_ptr_cmps, r=Nadrieril

Add detection of [Partial]Ord methods in the `ambiguous_wide_pointer_comparisons` lint

Partially addresses #121264 by adding diagnostics items for PartialOrd and Ord methods, detecting such diagnostics items as "binary operation" and suggesting the correct replacement.

I also took the opportunity to change the suggestion to use new methods `.cast()` on `*mut T` an d `*const T`.

Author: bors

compiler/rustc_lint/src/lints.rs

@@ -1668,14 +1668,16 @@ pub enum AmbiguousWidePointerComparisonsAddrSuggestion<'a> {
     Cast {
         deref_left: &'a str,
         deref_right: &'a str,
-        #[suggestion_part(code = "{deref_left}")]
+        paren_left: &'a str,
+        paren_right: &'a str,
+        #[suggestion_part(code = "({deref_left}")]
         left_before: Option<Span>,
-        #[suggestion_part(code = " as *const ()")]
-        left: Span,
-        #[suggestion_part(code = "{deref_right}")]
+        #[suggestion_part(code = "{paren_left}.cast::<()>()")]
+        left_after: Span,
+        #[suggestion_part(code = "({deref_right}")]
         right_before: Option<Span>,
-        #[suggestion_part(code = " as *const ()")]
-        right: Span,
+        #[suggestion_part(code = "{paren_right}.cast::<()>()")]
+        right_after: Span,
     },
 }
 

compiler/rustc_lint/src/types.rs

@@ -657,10 +657,16 @@ fn lint_nan<'tcx>(
     cx.emit_span_lint(INVALID_NAN_COMPARISONS, e.span, lint);
 }
 
+#[derive(Debug, PartialEq)]
+enum ComparisonOp {
+    BinOp(hir::BinOpKind),
+    Other,
+}
+
 fn lint_wide_pointer<'tcx>(
     cx: &LateContext<'tcx>,
     e: &'tcx hir::Expr<'tcx>,
-    binop: hir::BinOpKind,
+    cmpop: ComparisonOp,
     l: &'tcx hir::Expr<'tcx>,
     r: &'tcx hir::Expr<'tcx>,
 ) {
@@ -679,7 +685,7 @@ fn lint_wide_pointer<'tcx>(
         }
     };
 
-    // PartialEq::{eq,ne} takes references, remove any explicit references
+    // the left and right operands can have references, remove any explicit references
     let l = l.peel_borrows();
     let r = r.peel_borrows();
 
@@ -707,8 +713,8 @@ fn lint_wide_pointer<'tcx>(
         );
     };
 
-    let ne = if binop == hir::BinOpKind::Ne { "!" } else { "" };
-    let is_eq_ne = matches!(binop, hir::BinOpKind::Eq | hir::BinOpKind::Ne);
+    let ne = if cmpop == ComparisonOp::BinOp(hir::BinOpKind::Ne) { "!" } else { "" };
+    let is_eq_ne = matches!(cmpop, ComparisonOp::BinOp(hir::BinOpKind::Eq | hir::BinOpKind::Ne));
     let is_dyn_comparison = l_inner_ty_is_dyn && r_inner_ty_is_dyn;
 
     let left = e.span.shrink_to_lo().until(l_span.shrink_to_lo());
@@ -745,12 +751,12 @@ fn lint_wide_pointer<'tcx>(
                 AmbiguousWidePointerComparisonsAddrSuggestion::Cast {
                     deref_left,
                     deref_right,
-                    // those two Options are required for correctness as having
-                    // an empty span and an empty suggestion is not permitted
-                    left_before: (l_ty_refs != 0).then_some(left),
-                    right_before: (r_ty_refs != 0).then(|| r_span.shrink_to_lo()),
-                    left: l_span.shrink_to_hi(),
-                    right,
+                    paren_left: if l_ty_refs != 0 { ")" } else { "" },
+                    paren_right: if r_ty_refs != 0 { ")" } else { "" },
+                    left_before: (l_ty_refs != 0).then_some(l_span.shrink_to_lo()),
+                    left_after: l_span.shrink_to_hi(),
+                    right_before: (r_ty_refs != 0).then_some(r_span.shrink_to_lo()),
+                    right_after: r_span.shrink_to_hi(),
                 }
             },
         },
@@ -773,7 +779,7 @@ impl<'tcx> LateLintPass<'tcx> for TypeLimits {
                         cx.emit_span_lint(UNUSED_COMPARISONS, e.span, UnusedComparisons);
                     } else {
                         lint_nan(cx, e, binop, l, r);
-                        lint_wide_pointer(cx, e, binop.node, l, r);
+                        lint_wide_pointer(cx, e, ComparisonOp::BinOp(binop.node), l, r);
                     }
                 }
             }
@@ -782,16 +788,16 @@ impl<'tcx> LateLintPass<'tcx> for TypeLimits {
                 if let ExprKind::Path(ref qpath) = path.kind
                     && let Some(def_id) = cx.qpath_res(qpath, path.hir_id).opt_def_id()
                     && let Some(diag_item) = cx.tcx.get_diagnostic_name(def_id)
-                    && let Some(binop) = partialeq_binop(diag_item) =>
+                    && let Some(cmpop) = diag_item_cmpop(diag_item) =>
             {
-                lint_wide_pointer(cx, e, binop, l, r);
+                lint_wide_pointer(cx, e, cmpop, l, r);
             }
             hir::ExprKind::MethodCall(_, l, [r], _)
                 if let Some(def_id) = cx.typeck_results().type_dependent_def_id(e.hir_id)
                     && let Some(diag_item) = cx.tcx.get_diagnostic_name(def_id)
-                    && let Some(binop) = partialeq_binop(diag_item) =>
+                    && let Some(cmpop) = diag_item_cmpop(diag_item) =>
             {
-                lint_wide_pointer(cx, e, binop, l, r);
+                lint_wide_pointer(cx, e, cmpop, l, r);
             }
             _ => {}
         };
@@ -876,14 +882,20 @@ impl<'tcx> LateLintPass<'tcx> for TypeLimits {
             )
         }
 
-        fn partialeq_binop(diag_item: Symbol) -> Option<hir::BinOpKind> {
-            if diag_item == sym::cmp_partialeq_eq {
-                Some(hir::BinOpKind::Eq)
-            } else if diag_item == sym::cmp_partialeq_ne {
-                Some(hir::BinOpKind::Ne)
-            } else {
-                None
-            }
+        fn diag_item_cmpop(diag_item: Symbol) -> Option<ComparisonOp> {
+            Some(match diag_item {
+                sym::cmp_ord_max => ComparisonOp::Other,
+                sym::cmp_ord_min => ComparisonOp::Other,
+                sym::ord_cmp_method => ComparisonOp::Other,
+                sym::cmp_partialeq_eq => ComparisonOp::BinOp(hir::BinOpKind::Eq),
+                sym::cmp_partialeq_ne => ComparisonOp::BinOp(hir::BinOpKind::Ne),
+                sym::cmp_partialord_cmp => ComparisonOp::Other,
+                sym::cmp_partialord_ge => ComparisonOp::BinOp(hir::BinOpKind::Ge),
+                sym::cmp_partialord_gt => ComparisonOp::BinOp(hir::BinOpKind::Gt),
+                sym::cmp_partialord_le => ComparisonOp::BinOp(hir::BinOpKind::Le),
+                sym::cmp_partialord_lt => ComparisonOp::BinOp(hir::BinOpKind::Lt),
+                _ => return None,
+            })
         }
     }
 }

compiler/rustc_span/src/symbol.rs

@@ -531,8 +531,15 @@ symbols! {
         cmp,
         cmp_max,
         cmp_min,
+        cmp_ord_max,
+        cmp_ord_min,
         cmp_partialeq_eq,
         cmp_partialeq_ne,
+        cmp_partialord_cmp,
+        cmp_partialord_ge,
+        cmp_partialord_gt,
+        cmp_partialord_le,
+        cmp_partialord_lt,
         cmpxchg16b_target_feature,
         cmse_nonsecure_entry,
         coerce_unsized,

library/core/src/cmp.rs

@@ -848,6 +848,7 @@ pub trait Ord: Eq + PartialOrd<Self> {
     #[stable(feature = "ord_max_min", since = "1.21.0")]
     #[inline]
     #[must_use]
+    #[cfg_attr(not(bootstrap), rustc_diagnostic_item = "cmp_ord_max")]
     fn max(self, other: Self) -> Self
     where
         Self: Sized,
@@ -868,6 +869,7 @@ pub trait Ord: Eq + PartialOrd<Self> {
     #[stable(feature = "ord_max_min", since = "1.21.0")]
     #[inline]
     #[must_use]
+    #[cfg_attr(not(bootstrap), rustc_diagnostic_item = "cmp_ord_min")]
     fn min(self, other: Self) -> Self
     where
         Self: Sized,
@@ -1154,6 +1156,7 @@ pub trait PartialOrd<Rhs: ?Sized = Self>: PartialEq<Rhs> {
     /// ```
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[cfg_attr(not(bootstrap), rustc_diagnostic_item = "cmp_partialord_cmp")]
     fn partial_cmp(&self, other: &Rhs) -> Option<Ordering>;
 
     /// This method tests less than (for `self` and `other`) and is used by the `<` operator.
@@ -1168,6 +1171,7 @@ pub trait PartialOrd<Rhs: ?Sized = Self>: PartialEq<Rhs> {
     #[inline]
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[cfg_attr(not(bootstrap), rustc_diagnostic_item = "cmp_partialord_lt")]
     fn lt(&self, other: &Rhs) -> bool {
         matches!(self.partial_cmp(other), Some(Less))
     }
@@ -1185,6 +1189,7 @@ pub trait PartialOrd<Rhs: ?Sized = Self>: PartialEq<Rhs> {
     #[inline]
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[cfg_attr(not(bootstrap), rustc_diagnostic_item = "cmp_partialord_le")]
     fn le(&self, other: &Rhs) -> bool {
         matches!(self.partial_cmp(other), Some(Less | Equal))
     }
@@ -1201,6 +1206,7 @@ pub trait PartialOrd<Rhs: ?Sized = Self>: PartialEq<Rhs> {
     #[inline]
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[cfg_attr(not(bootstrap), rustc_diagnostic_item = "cmp_partialord_gt")]
     fn gt(&self, other: &Rhs) -> bool {
         matches!(self.partial_cmp(other), Some(Greater))
     }
@@ -1218,6 +1224,7 @@ pub trait PartialOrd<Rhs: ?Sized = Self>: PartialEq<Rhs> {
     #[inline]
     #[must_use]
     #[stable(feature = "rust1", since = "1.0.0")]
+    #[cfg_attr(not(bootstrap), rustc_diagnostic_item = "cmp_partialord_ge")]
     fn ge(&self, other: &Rhs) -> bool {
         matches!(self.partial_cmp(other), Some(Greater | Equal))
     }

library/core/src/ptr/const_ptr.rs

@@ -1857,6 +1857,7 @@ impl<T: ?Sized> Ord for *const T {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> PartialOrd for *const T {
     #[inline]
+    #[allow(ambiguous_wide_pointer_comparisons)]
     fn partial_cmp(&self, other: &*const T) -> Option<Ordering> {
         Some(self.cmp(other))
     }

library/core/src/ptr/metadata.rs

@@ -258,6 +258,7 @@ impl<Dyn: ?Sized> PartialEq for DynMetadata<Dyn> {
 
 impl<Dyn: ?Sized> Ord for DynMetadata<Dyn> {
     #[inline]
+    #[allow(ambiguous_wide_pointer_comparisons)]
     fn cmp(&self, other: &Self) -> crate::cmp::Ordering {
         (self.vtable_ptr as *const VTable).cmp(&(other.vtable_ptr as *const VTable))
     }

library/core/src/ptr/mut_ptr.rs

@@ -2275,6 +2275,7 @@ impl<T: ?Sized> Ord for *mut T {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: ?Sized> PartialOrd for *mut T {
     #[inline(always)]
+    #[allow(ambiguous_wide_pointer_comparisons)]
     fn partial_cmp(&self, other: &*mut T) -> Option<Ordering> {
         Some(self.cmp(other))
     }

library/core/src/ptr/non_null.rs

@@ -1821,6 +1821,7 @@ impl<T: ?Sized> PartialEq for NonNull<T> {
 #[stable(feature = "nonnull", since = "1.25.0")]
 impl<T: ?Sized> Ord for NonNull<T> {
     #[inline]
+    #[allow(ambiguous_wide_pointer_comparisons)]
     fn cmp(&self, other: &Self) -> Ordering {
         self.as_ptr().cmp(&other.as_ptr())
     }
@@ -1829,6 +1830,7 @@ impl<T: ?Sized> Ord for NonNull<T> {
 #[stable(feature = "nonnull", since = "1.25.0")]
 impl<T: ?Sized> PartialOrd for NonNull<T> {
     #[inline]
+    #[allow(ambiguous_wide_pointer_comparisons)]
     fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
         self.as_ptr().partial_cmp(&other.as_ptr())
     }

tests/ui/lint/wide_pointer_comparisons.rs

@@ -37,6 +37,18 @@ fn main() {
     //~^ WARN ambiguous wide pointer comparison
     let _ = a.ne(&b);
     //~^ WARN ambiguous wide pointer comparison
+    let _ = a.cmp(&b);
+    //~^ WARN ambiguous wide pointer comparison
+    let _ = a.partial_cmp(&b);
+    //~^ WARN ambiguous wide pointer comparison
+    let _ = a.le(&b);
+    //~^ WARN ambiguous wide pointer comparison
+    let _ = a.lt(&b);
+    //~^ WARN ambiguous wide pointer comparison
+    let _ = a.ge(&b);
+    //~^ WARN ambiguous wide pointer comparison
+    let _ = a.gt(&b);
+    //~^ WARN ambiguous wide pointer comparison
 
     {
         // &*const ?Sized
@@ -68,6 +80,18 @@ fn main() {
         //~^ WARN ambiguous wide pointer comparison
         let _ = a.ne(b);
         //~^ WARN ambiguous wide pointer comparison
+        let _ = a.cmp(&b);
+        //~^ WARN ambiguous wide pointer comparison
+        let _ = a.partial_cmp(&b);
+        //~^ WARN ambiguous wide pointer comparison
+        let _ = a.le(&b);
+        //~^ WARN ambiguous wide pointer comparison
+        let _ = a.lt(&b);
+        //~^ WARN ambiguous wide pointer comparison
+        let _ = a.ge(&b);
+        //~^ WARN ambiguous wide pointer comparison
+        let _ = a.gt(&b);
+        //~^ WARN ambiguous wide pointer comparison
     }
 
     let s = "" as *const str;