Rollup merge of #141536 - Urgau:ambi_wide_ptr-cmp-diag, r=fee1-dead

Improve `ambiguous_wide_pointer_comparisons` lint compare diagnostics

This PR improves the `ambiguous_wide_pointer_comparisons` lint compare diagnostics: `cmp`/`partial_cmp`, but also the operators `<`/`>`/`>=`/`<=`, by:
1. removing the reference to `std::ptr::addr_eq` which only works for equality
2. and adding an `#[expect]` suggestion for keeping the current behavior

Fixes rust-lang/rust#141510

3 files changed, 101 insertions, 63 deletions

diff --git a/compiler/rustc_lint/messages.ftl b/compiler/rustc_lint/messages.ftl
index 7fdf26bf3af..b470dea5e82 100644
--- a/compiler/rustc_lint/messages.ftl
+++ b/compiler/rustc_lint/messages.ftl
@@ -13,6 +13,8 @@ lint_ambiguous_negative_literals = `-` has lower precedence than method calls, w
 lint_ambiguous_wide_pointer_comparisons = ambiguous wide pointer comparison, the comparison includes metadata which may not be expected
     .addr_metadata_suggestion = use explicit `std::ptr::eq` method to compare metadata and addresses
     .addr_suggestion = use `std::ptr::addr_eq` or untyped pointers to only compare their addresses
+    .cast_suggestion = use untyped pointers to only compare their addresses
+    .expect_suggestion = or expect the lint to compare the pointers metadata and addresses
 
 lint_associated_const_elided_lifetime = {$elided ->
         [true] `&` without an explicit lifetime name cannot be used here
diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs
index af8fa8ffa1f..caad2694f19 100644
--- a/compiler/rustc_lint/src/lints.rs
+++ b/compiler/rustc_lint/src/lints.rs
@@ -1782,13 +1782,20 @@ pub(crate) enum InvalidNanComparisonsSuggestion {
 #[derive(LintDiagnostic)]
 pub(crate) enum AmbiguousWidePointerComparisons<'a> {
     #[diag(lint_ambiguous_wide_pointer_comparisons)]
-    Spanful {
+    SpanfulEq {
         #[subdiagnostic]
         addr_suggestion: AmbiguousWidePointerComparisonsAddrSuggestion<'a>,
         #[subdiagnostic]
         addr_metadata_suggestion: Option<AmbiguousWidePointerComparisonsAddrMetadataSuggestion<'a>>,
     },
     #[diag(lint_ambiguous_wide_pointer_comparisons)]
+    SpanfulCmp {
+        #[subdiagnostic]
+        cast_suggestion: AmbiguousWidePointerComparisonsCastSuggestion<'a>,
+        #[subdiagnostic]
+        expect_suggestion: AmbiguousWidePointerComparisonsExpectSuggestion<'a>,
+    },
+    #[diag(lint_ambiguous_wide_pointer_comparisons)]
     #[help(lint_addr_metadata_suggestion)]
     #[help(lint_addr_suggestion)]
     Spanless,
@@ -1816,48 +1823,67 @@ pub(crate) struct AmbiguousWidePointerComparisonsAddrMetadataSuggestion<'a> {
 }
 
 #[derive(Subdiagnostic)]
-pub(crate) enum AmbiguousWidePointerComparisonsAddrSuggestion<'a> {
-    #[multipart_suggestion(
-        lint_addr_suggestion,
-        style = "verbose",
-        // FIXME(#53934): make machine-applicable again
-        applicability = "maybe-incorrect"
-    )]
-    AddrEq {
-        ne: &'a str,
-        deref_left: &'a str,
-        deref_right: &'a str,
-        l_modifiers: &'a str,
-        r_modifiers: &'a str,
-        #[suggestion_part(code = "{ne}std::ptr::addr_eq({deref_left}")]
-        left: Span,
-        #[suggestion_part(code = "{l_modifiers}, {deref_right}")]
-        middle: Span,
-        #[suggestion_part(code = "{r_modifiers})")]
-        right: Span,
-    },
-    #[multipart_suggestion(
-        lint_addr_suggestion,
-        style = "verbose",
-        // FIXME(#53934): make machine-applicable again
-        applicability = "maybe-incorrect"
+#[multipart_suggestion(
+    lint_addr_suggestion,
+    style = "verbose",
+    // FIXME(#53934): make machine-applicable again
+    applicability = "maybe-incorrect"
+)]
+pub(crate) struct AmbiguousWidePointerComparisonsAddrSuggestion<'a> {
+    pub(crate) ne: &'a str,
+    pub(crate) deref_left: &'a str,
+    pub(crate) deref_right: &'a str,
+    pub(crate) l_modifiers: &'a str,
+    pub(crate) r_modifiers: &'a str,
+    #[suggestion_part(code = "{ne}std::ptr::addr_eq({deref_left}")]
+    pub(crate) left: Span,
+    #[suggestion_part(code = "{l_modifiers}, {deref_right}")]
+    pub(crate) middle: Span,
+    #[suggestion_part(code = "{r_modifiers})")]
+    pub(crate) right: Span,
+}
+
+#[derive(Subdiagnostic)]
+#[multipart_suggestion(
+    lint_cast_suggestion,
+    style = "verbose",
+    // FIXME(#53934): make machine-applicable again
+    applicability = "maybe-incorrect"
+)]
+pub(crate) struct AmbiguousWidePointerComparisonsCastSuggestion<'a> {
+    pub(crate) deref_left: &'a str,
+    pub(crate) deref_right: &'a str,
+    pub(crate) paren_left: &'a str,
+    pub(crate) paren_right: &'a str,
+    pub(crate) l_modifiers: &'a str,
+    pub(crate) r_modifiers: &'a str,
+    #[suggestion_part(code = "({deref_left}")]
+    pub(crate) left_before: Option<Span>,
+    #[suggestion_part(code = "{l_modifiers}{paren_left}.cast::<()>()")]
+    pub(crate) left_after: Span,
+    #[suggestion_part(code = "({deref_right}")]
+    pub(crate) right_before: Option<Span>,
+    #[suggestion_part(code = "{r_modifiers}{paren_right}.cast::<()>()")]
+    pub(crate) right_after: Span,
+}
+
+#[derive(Subdiagnostic)]
+#[multipart_suggestion(
+    lint_expect_suggestion,
+    style = "verbose",
+    // FIXME(#53934): make machine-applicable again
+    applicability = "maybe-incorrect"
+)]
+pub(crate) struct AmbiguousWidePointerComparisonsExpectSuggestion<'a> {
+    pub(crate) paren_left: &'a str,
+    pub(crate) paren_right: &'a str,
+    // FIXME(#127436): Adjust once resolved
+    #[suggestion_part(
+        code = r#"{{ #[expect(ambiguous_wide_pointer_comparisons, reason = "...")] {paren_left}"#
     )]
-    Cast {
-        deref_left: &'a str,
-        deref_right: &'a str,
-        paren_left: &'a str,
-        paren_right: &'a str,
-        l_modifiers: &'a str,
-        r_modifiers: &'a str,
-        #[suggestion_part(code = "({deref_left}")]
-        left_before: Option<Span>,
-        #[suggestion_part(code = "{l_modifiers}{paren_left}.cast::<()>()")]
-        left_after: Span,
-        #[suggestion_part(code = "({deref_right}")]
-        right_before: Option<Span>,
-        #[suggestion_part(code = "{r_modifiers}{paren_right}.cast::<()>()")]
-        right_after: Span,
-    },
+    pub(crate) before: Span,
+    #[suggestion_part(code = "{paren_right} }}")]
+    pub(crate) after: Span,
 }
 
 #[derive(LintDiagnostic)]
diff --git a/compiler/rustc_lint/src/types.rs b/compiler/rustc_lint/src/types.rs
index f1c06dfe6ce..af134622d38 100644
--- a/compiler/rustc_lint/src/types.rs
+++ b/compiler/rustc_lint/src/types.rs
@@ -24,7 +24,8 @@ mod improper_ctypes;
 
 use crate::lints::{
     AmbiguousWidePointerComparisons, AmbiguousWidePointerComparisonsAddrMetadataSuggestion,
-    AmbiguousWidePointerComparisonsAddrSuggestion, AtomicOrderingFence, AtomicOrderingLoad,
+    AmbiguousWidePointerComparisonsAddrSuggestion, AmbiguousWidePointerComparisonsCastSuggestion,
+    AmbiguousWidePointerComparisonsExpectSuggestion, AtomicOrderingFence, AtomicOrderingLoad,
     AtomicOrderingStore, ImproperCTypes, InvalidAtomicOrderingDiag, InvalidNanComparisons,
     InvalidNanComparisonsSuggestion, UnpredictableFunctionPointerComparisons,
     UnpredictableFunctionPointerComparisonsSuggestion, UnusedComparisons, UsesPowerAlignment,
@@ -362,6 +363,7 @@ fn lint_wide_pointer<'tcx>(
     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 via_method_call = matches!(&e.kind, ExprKind::MethodCall(..) | ExprKind::Call(..));
 
     let left = e.span.shrink_to_lo().until(l_span.shrink_to_lo());
     let middle = l_span.shrink_to_hi().until(r_span.shrink_to_lo());
@@ -376,21 +378,21 @@ fn lint_wide_pointer<'tcx>(
     cx.emit_span_lint(
         AMBIGUOUS_WIDE_POINTER_COMPARISONS,
         e.span,
-        AmbiguousWidePointerComparisons::Spanful {
-            addr_metadata_suggestion: (is_eq_ne && !is_dyn_comparison).then(|| {
-                AmbiguousWidePointerComparisonsAddrMetadataSuggestion {
-                    ne,
-                    deref_left,
-                    deref_right,
-                    l_modifiers,
-                    r_modifiers,
-                    left,
-                    middle,
-                    right,
-                }
-            }),
-            addr_suggestion: if is_eq_ne {
-                AmbiguousWidePointerComparisonsAddrSuggestion::AddrEq {
+        if is_eq_ne {
+            AmbiguousWidePointerComparisons::SpanfulEq {
+                addr_metadata_suggestion: (!is_dyn_comparison).then(|| {
+                    AmbiguousWidePointerComparisonsAddrMetadataSuggestion {
+                        ne,
+                        deref_left,
+                        deref_right,
+                        l_modifiers,
+                        r_modifiers,
+                        left,
+                        middle,
+                        right,
+                    }
+                }),
+                addr_suggestion: AmbiguousWidePointerComparisonsAddrSuggestion {
                     ne,
                     deref_left,
                     deref_right,
@@ -399,9 +401,11 @@ fn lint_wide_pointer<'tcx>(
                     left,
                     middle,
                     right,
-                }
-            } else {
-                AmbiguousWidePointerComparisonsAddrSuggestion::Cast {
+                },
+            }
+        } else {
+            AmbiguousWidePointerComparisons::SpanfulCmp {
+                cast_suggestion: AmbiguousWidePointerComparisonsCastSuggestion {
                     deref_left,
                     deref_right,
                     l_modifiers,
@@ -412,8 +416,14 @@ fn lint_wide_pointer<'tcx>(
                     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(),
-                }
-            },
+                },
+                expect_suggestion: AmbiguousWidePointerComparisonsExpectSuggestion {
+                    paren_left: if via_method_call { "" } else { "(" },
+                    paren_right: if via_method_call { "" } else { ")" },
+                    before: e.span.shrink_to_lo(),
+                    after: e.span.shrink_to_hi(),
+                },
+            }
         },
     );
 }