Rollup merge of #145941 - Urgau:int_to_ptr_transmutes-unsized, r=lcnr

Disable `integer_to_ptr_transmutes` suggestion for unsized types

This PR disables the machine-applicable `integer_to_ptr_transmutes` lint suggestion for unsized types, as [`std::ptr::with_exposed_provenance`](https://doc.rust-lang.org/std/ptr/fn.with_exposed_provenance.html) requires sized types.

We should probably mention [`std::ptr::from_raw_parts`](https://doc.rust-lang.org/std/ptr/fn.from_raw_parts.html) when it becomes stable.

Related to https://github.com/rust-lang/rust/issues/145935

2 files changed, 19 insertions, 13 deletions

diff --git a/compiler/rustc_lint/src/lints.rs b/compiler/rustc_lint/src/lints.rs
index 426500dda4a..56d65ed08f9 100644
--- a/compiler/rustc_lint/src/lints.rs
+++ b/compiler/rustc_lint/src/lints.rs
@@ -1554,7 +1554,7 @@ impl<'a> LintDiagnostic<'a, ()> for DropGlue<'_> {
 #[help(lint_help_exposed_provenance)]
 pub(crate) struct IntegerToPtrTransmutes<'tcx> {
     #[subdiagnostic]
-    pub suggestion: IntegerToPtrTransmutesSuggestion<'tcx>,
+    pub suggestion: Option<IntegerToPtrTransmutesSuggestion<'tcx>>,
 }
 
 #[derive(Subdiagnostic)]
diff --git a/compiler/rustc_lint/src/transmute.rs b/compiler/rustc_lint/src/transmute.rs
index 239c8649041..98510eea73b 100644
--- a/compiler/rustc_lint/src/transmute.rs
+++ b/compiler/rustc_lint/src/transmute.rs
@@ -169,19 +169,25 @@ fn check_int_to_ptr_transmute<'tcx>(
         expr.hir_id,
         expr.span,
         IntegerToPtrTransmutes {
-            suggestion: if dst.is_ref() {
-                IntegerToPtrTransmutesSuggestion::ToRef {
-                    dst: *inner_ty,
-                    suffix,
-                    ref_mutbl: mutbl.prefix_str(),
-                    start_call: expr.span.shrink_to_lo().until(arg.span),
-                }
+            suggestion: if layout_inner_ty.is_sized() {
+                Some(if dst.is_ref() {
+                    IntegerToPtrTransmutesSuggestion::ToRef {
+                        dst: *inner_ty,
+                        suffix,
+                        ref_mutbl: mutbl.prefix_str(),
+                        start_call: expr.span.shrink_to_lo().until(arg.span),
+                    }
+                } else {
+                    IntegerToPtrTransmutesSuggestion::ToPtr {
+                        dst: *inner_ty,
+                        suffix,
+                        start_call: expr.span.shrink_to_lo().until(arg.span),
+                    }
+                })
             } else {
-                IntegerToPtrTransmutesSuggestion::ToPtr {
-                    dst: *inner_ty,
-                    suffix,
-                    start_call: expr.span.shrink_to_lo().until(arg.span),
-                }
+                // We can't suggest using `with_exposed_provenance` for unsized type
+                // so don't suggest anything.
+                None
             },
         },
     );