Rollup merge of #108044 - RalfJung:from-addr-invalid, r=oli-obk

interpret: rename Pointer::from_addr → from_addr_invalid

This function corresponds to `ptr::invalid` in the standard library; the previous name was not clear enough IMO.

compiler/rustc_const_eval/src/interpret/machine.rs

@@ -517,7 +517,7 @@ pub macro compile_time_machine(<$mir: lifetime, $tcx: lifetime>) {
         // Allow these casts, but make the pointer not dereferenceable.
         // (I.e., they behave like transmutation.)
         // This is correct because no pointers can ever be exposed in compile-time evaluation.
-        Ok(Pointer::from_addr(addr))
+        Ok(Pointer::from_addr_invalid(addr))
     }
 
     #[inline(always)]

compiler/rustc_const_eval/src/interpret/place.rs

@@ -178,7 +178,7 @@ impl<'tcx, Prov: Provenance> MPlaceTy<'tcx, Prov> {
     pub fn fake_alloc_zst(layout: TyAndLayout<'tcx>) -> Self {
         assert!(layout.is_zst());
         let align = layout.align.abi;
-        let ptr = Pointer::from_addr(align.bytes()); // no provenance, absolute address
+        let ptr = Pointer::from_addr_invalid(align.bytes()); // no provenance, absolute address
         MPlaceTy { mplace: MemPlace { ptr, meta: MemPlaceMeta::None }, layout, align }
     }
 

compiler/rustc_middle/src/mir/interpret/error.rs

@@ -323,7 +323,7 @@ impl fmt::Display for UndefinedBehaviorInfo {
                 write!(
                     f,
                     "{msg}{pointer} is a dangling pointer (it has no provenance)",
-                    pointer = Pointer::<Option<AllocId>>::from_addr(*i),
+                    pointer = Pointer::<Option<AllocId>>::from_addr_invalid(*i),
                 )
             }
             AlignmentCheckFailed { required, has } => write!(

compiler/rustc_middle/src/mir/interpret/pointer.rs

@@ -251,14 +251,16 @@ impl<Prov> Pointer<Option<Prov>> {
 }
 
 impl<Prov> Pointer<Option<Prov>> {
+    /// Creates a pointer to the given address, with invalid provenance (i.e., cannot be used for
+    /// any memory access).
     #[inline(always)]
-    pub fn from_addr(addr: u64) -> Self {
+    pub fn from_addr_invalid(addr: u64) -> Self {
         Pointer { provenance: None, offset: Size::from_bytes(addr) }
     }
 
     #[inline(always)]
     pub fn null() -> Self {
-        Pointer::from_addr(0)
+        Pointer::from_addr_invalid(0)
     }
 }
 

compiler/rustc_middle/src/mir/interpret/value.rs

@@ -322,7 +322,7 @@ impl<'tcx, Prov: Provenance> Scalar<Prov> {
             Right(ptr) => Ok(ptr.into()),
             Left(bits) => {
                 let addr = u64::try_from(bits).unwrap();
-                Ok(Pointer::from_addr(addr))
+                Ok(Pointer::from_addr_invalid(addr))
             }
         }
     }