Rollup merge of #115972 - RalfJung:const-consistency, r=oli-obk

rename mir::Constant -> mir::ConstOperand, mir::ConstKind -> mir::Const

Also, be more consistent with the `to/eval_bits` methods... we had some that take a type and some that take a size, and then sometimes the one that takes a type is called `bits_for_ty`.

Turns out that `ty::Const`/`mir::ConstKind` carry their type with them, so we don't need to even pass the type to those `eval_bits` functions at all.

However this is not properly consistent yet: in `ty` we have most of the methods on `ty::Const`, but in `mir` we have them on `mir::ConstKind`. And indeed those two types are the ones that correspond to each other. So `mir::ConstantKind` should actually be renamed to `mir::Const`. But what to do with `mir::Constant`? It carries around a span, that's really more like a constant operand that appears as a MIR operand... it's more suited for `syntax.rs` than `consts.rs`, but the bigger question is, which name should it get if we want to align the `mir` and `ty` types? `ConstOperand`? `ConstOp`? `Literal`? It's not a literal but it has a field called `literal` so it would at least be consistently wrong-ish...

``@oli-obk`` any ideas?

1 files changed, 6 insertions, 11 deletions

diff --git a/compiler/rustc_middle/src/ty/consts.rs b/compiler/rustc_middle/src/ty/consts.rs
index ba871d6478b..2518f0cf2e9 100644
--- a/compiler/rustc_middle/src/ty/consts.rs
+++ b/compiler/rustc_middle/src/ty/consts.rs
@@ -339,24 +339,19 @@ impl<'tcx> Const<'tcx> {
     /// Attempts to evaluate the given constant to bits. Can fail to evaluate in the presence of
     /// generics (or erroneous code) or if the value can't be represented as bits (e.g. because it
     /// contains const generic parameters or pointers).
-    pub fn try_eval_bits(
-        self,
-        tcx: TyCtxt<'tcx>,
-        param_env: ParamEnv<'tcx>,
-        ty: Ty<'tcx>,
-    ) -> Option<u128> {
+    pub fn try_eval_bits(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> Option<u128> {
         let int = self.try_eval_scalar_int(tcx, param_env)?;
-        assert_eq!(self.ty(), ty);
-        let size = tcx.layout_of(param_env.with_reveal_all_normalized(tcx).and(ty)).ok()?.size;
+        let size =
+            tcx.layout_of(param_env.with_reveal_all_normalized(tcx).and(self.ty())).ok()?.size;
         // if `ty` does not depend on generic parameters, use an empty param_env
         int.to_bits(size).ok()
     }
 
     #[inline]
     /// Panics if the value cannot be evaluated or doesn't contain a valid integer of the given type.
-    pub fn eval_bits(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>, ty: Ty<'tcx>) -> u128 {
-        self.try_eval_bits(tcx, param_env, ty)
-            .unwrap_or_else(|| bug!("expected bits of {:#?}, got {:#?}", ty, self))
+    pub fn eval_bits(self, tcx: TyCtxt<'tcx>, param_env: ParamEnv<'tcx>) -> u128 {
+        self.try_eval_bits(tcx, param_env)
+            .unwrap_or_else(|| bug!("expected bits of {:#?}, got {:#?}", self.ty(), self))
     }
 
     #[inline]