Auto merge of #144269 - jieyouxu:rollup-137ysl2, r=jieyouxu

Rollup of 14 pull requests

Successful merges:

 - rust-lang/rust#142097 (gpu offload host code generation)
 - rust-lang/rust#143430 (Lower extra lifetimes before normal generic params.)
 - rust-lang/rust#143768 (Constify Try, From, TryFrom and relevant traits)
 - rust-lang/rust#143816 (Implement `check` for compiletest and RA using tool macro)
 - rust-lang/rust#143985 (rustc_public: de-StableMIR-ize)
 - rust-lang/rust#144027 (clippy: make tests work in stage 1)
 - rust-lang/rust#144080 (Mitigate `#[align]` name resolution ambiguity regression with a rename)
 - rust-lang/rust#144176 (Add approval blocking labels for new bors)
 - rust-lang/rust#144187 (fix handling of base address for TypeId allocations)
 - rust-lang/rust#144212 (Remove the ptr_unique lang item)
 - rust-lang/rust#144243 (Subtree update of `rust-analyzer`)
 - rust-lang/rust#144246 (Don't use another main test file as auxiliary)
 - rust-lang/rust#144251 (rustc-dev-guide subtree update)
 - rust-lang/rust#144254 (opt-dist: make `artifact-dir` an absolute path for `opt-dist local`)

r? `@ghost`
`@rustbot` modify labels: rollup

1 files changed, 5 insertions, 13 deletions

diff --git a/compiler/rustc_const_eval/src/const_eval/machine.rs b/compiler/rustc_const_eval/src/const_eval/machine.rs
index f24fb18f83b..a18ae79f318 100644
--- a/compiler/rustc_const_eval/src/const_eval/machine.rs
+++ b/compiler/rustc_const_eval/src/const_eval/machine.rs
@@ -279,23 +279,15 @@ impl<'tcx> CompileTimeInterpCx<'tcx> {
     fn guaranteed_cmp(&mut self, a: Scalar, b: Scalar) -> InterpResult<'tcx, u8> {
         interp_ok(match (a, b) {
             // Comparisons between integers are always known.
-            (Scalar::Int { .. }, Scalar::Int { .. }) => {
-                if a == b {
-                    1
-                } else {
-                    0
-                }
-            }
-            // Comparisons of abstract pointers with null pointers are known if the pointer
-            // is in bounds, because if they are in bounds, the pointer can't be null.
-            // Inequality with integers other than null can never be known for sure.
-            (Scalar::Int(int), ptr @ Scalar::Ptr(..))
-            | (ptr @ Scalar::Ptr(..), Scalar::Int(int))
+            (Scalar::Int(a), Scalar::Int(b)) => (a == b) as u8,
+            // Comparisons of null with an arbitrary scalar can be known if `scalar_may_be_null`
+            // indicates that the scalar can definitely *not* be null.
+            (Scalar::Int(int), ptr) | (ptr, Scalar::Int(int))
                 if int.is_null() && !self.scalar_may_be_null(ptr)? =>
             {
                 0
             }
-            // Equality with integers can never be known for sure.
+            // Other ways of comparing integers and pointers can never be known for sure.
             (Scalar::Int { .. }, Scalar::Ptr(..)) | (Scalar::Ptr(..), Scalar::Int { .. }) => 2,
             // FIXME: return a `1` for when both sides are the same pointer, *except* that
             // some things (like functions and vtables) do not have stable addresses