Auto merge of #59987 - saleemjaffer:refactor_adjust_castkinds, r=oli-obk

Refactor Adjust and CastKind

fixes #59588

src/librustc/middle/expr_use_visitor.rs

@@ -705,11 +705,7 @@ impl<'a, 'gcx, 'tcx> ExprUseVisitor<'a, 'gcx, 'tcx> {
             debug!("walk_adjustment expr={:?} adj={:?}", expr, adjustment);
             match adjustment.kind {
                 adjustment::Adjust::NeverToAny |
-                adjustment::Adjust::ReifyFnPointer |
-                adjustment::Adjust::UnsafeFnPointer |
-                adjustment::Adjust::ClosureFnPointer(_) |
-                adjustment::Adjust::MutToConstPointer |
-                adjustment::Adjust::Unsize => {
+                adjustment::Adjust::Pointer(_)  => {
                     // Creating a closure/fn-pointer or unsizing consumes
                     // the input and stores it into the resulting rvalue.
                     self.delegate_consume(expr.hir_id, expr.span, &cmt);

src/librustc/middle/mem_categorization.rs

@@ -619,12 +619,8 @@ impl<'a, 'gcx, 'tcx> MemCategorizationContext<'a, 'gcx, 'tcx> {
             }
 
             adjustment::Adjust::NeverToAny |
-            adjustment::Adjust::ReifyFnPointer |
-            adjustment::Adjust::UnsafeFnPointer |
-            adjustment::Adjust::ClosureFnPointer(_) |
-            adjustment::Adjust::MutToConstPointer |
-            adjustment::Adjust::Borrow(_) |
-            adjustment::Adjust::Unsize => {
+            adjustment::Adjust::Pointer(_) |
+            adjustment::Adjust::Borrow(_) => {
                 // Result is an rvalue.
                 Ok(self.cat_rvalue_node(expr.hir_id, expr.span, target))
             }

src/librustc/mir/mod.rs

@@ -36,6 +36,7 @@ use crate::ty::{
     UserTypeAnnotationIndex,
 };
 use crate::ty::print::{FmtPrinter, Printer};
+use crate::ty::adjustment::{PointerCast};
 
 pub use crate::mir::interpret::AssertMessage;
 
@@ -2342,29 +2343,11 @@ pub enum Rvalue<'tcx> {
     Aggregate(Box<AggregateKind<'tcx>>, Vec<Operand<'tcx>>),
 }
 
+
 #[derive(Clone, Copy, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)]
 pub enum CastKind {
     Misc,
-
-    /// Converts unique, zero-sized type for a fn to fn()
-    ReifyFnPointer,
-
-    /// Converts non capturing closure to fn() or unsafe fn().
-    /// It cannot convert a closure that requires unsafe.
-    ClosureFnPointer(hir::Unsafety),
-
-    /// Converts safe fn() to unsafe fn()
-    UnsafeFnPointer,
-
-    /// Coerces *mut T to *const T, preserving T.
-    MutToConstPointer,
-
-    /// "Unsize" -- convert a thin-or-fat pointer to a fat pointer.
-    /// codegen must figure out the details once full monomorphization
-    /// is known. For example, this could be used to cast from a
-    /// `&[i32;N]` to a `&[i32]`, or a `Box<T>` to a `Box<dyn Trait>`
-    /// (presuming `T: Trait`).
-    Unsize,
+    Pointer(PointerCast),
 }
 
 #[derive(Clone, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)]

src/librustc/ty/adjustment.rs

@@ -5,6 +5,34 @@ use crate::ty::subst::SubstsRef;
 use rustc_macros::HashStable;
 
 
+#[derive(Clone, Copy, Debug, PartialEq, Eq, RustcEncodable, RustcDecodable, HashStable)]
+pub enum PointerCast {
+    /// Go from a fn-item type to a fn-pointer type.
+    ReifyFnPointer,
+
+    /// Go from a safe fn pointer to an unsafe fn pointer.
+    UnsafeFnPointer,
+
+    /// Go from a non-capturing closure to an fn pointer or an unsafe fn pointer.
+    /// It cannot convert a closure that requires unsafe.
+    ClosureFnPointer(hir::Unsafety),
+
+    /// Go from a mut raw pointer to a const raw pointer.
+    MutToConstPointer,
+
+    /// Unsize a pointer/reference value, e.g., `&[T; n]` to
+    /// `&[T]`. Note that the source could be a thin or fat pointer.
+    /// This will do things like convert thin pointers to fat
+    /// pointers, or convert structs containing thin pointers to
+    /// structs containing fat pointers, or convert between fat
+    /// pointers. We don't store the details of how the transform is
+    /// done (in fact, we don't know that, because it might depend on
+    /// the precise type parameters). We just store the target
+    /// type. Codegen backends and miri figure out what has to be done
+    /// based on the precise source/target type at hand.
+    Unsize,
+}
+
 /// Represents coercing a value to a different type of value.
 ///
 /// We transform values by following a number of `Adjust` steps in order.
@@ -56,36 +84,13 @@ pub enum Adjust<'tcx> {
     /// Go from ! to any type.
     NeverToAny,
 
-    /// Go from a fn-item type to a fn-pointer type.
-    ReifyFnPointer,
-
-    /// Go from a safe fn pointer to an unsafe fn pointer.
-    UnsafeFnPointer,
-
-    /// Go from a non-capturing closure to an fn pointer or an unsafe fn pointer.
-    /// It cannot convert a closure that requires unsafe.
-    ClosureFnPointer(hir::Unsafety),
-
-    /// Go from a mut raw pointer to a const raw pointer.
-    MutToConstPointer,
-
     /// Dereference once, producing a place.
     Deref(Option<OverloadedDeref<'tcx>>),
 
     /// Take the address and produce either a `&` or `*` pointer.
     Borrow(AutoBorrow<'tcx>),
 
-    /// Unsize a pointer/reference value, e.g., `&[T; n]` to
-    /// `&[T]`. Note that the source could be a thin or fat pointer.
-    /// This will do things like convert thin pointers to fat
-    /// pointers, or convert structs containing thin pointers to
-    /// structs containing fat pointers, or convert between fat
-    /// pointers. We don't store the details of how the transform is
-    /// done (in fact, we don't know that, because it might depend on
-    /// the precise type parameters). We just store the target
-    /// type. Codegen backends and miri figure out what has to be done
-    /// based on the precise source/target type at hand.
-    Unsize,
+    Pointer(PointerCast),
 }
 
 /// An overloaded autoderef step, representing a `Deref(Mut)::deref(_mut)`

src/librustc/ty/structural_impls.rs

@@ -326,6 +326,7 @@ CloneTypeFoldableAndLiftImpls! {
     crate::ty::IntVarValue,
     crate::ty::ParamConst,
     crate::ty::ParamTy,
+    crate::ty::adjustment::PointerCast,
     crate::ty::RegionVid,
     crate::ty::UniverseIndex,
     crate::ty::Variance,
@@ -626,16 +627,8 @@ impl<'a, 'tcx> Lift<'tcx> for ty::adjustment::Adjust<'a> {
         match *self {
             ty::adjustment::Adjust::NeverToAny =>
                 Some(ty::adjustment::Adjust::NeverToAny),
-            ty::adjustment::Adjust::ReifyFnPointer =>
-                Some(ty::adjustment::Adjust::ReifyFnPointer),
-            ty::adjustment::Adjust::UnsafeFnPointer =>
-                Some(ty::adjustment::Adjust::UnsafeFnPointer),
-            ty::adjustment::Adjust::ClosureFnPointer(unsafety) =>
-                Some(ty::adjustment::Adjust::ClosureFnPointer(unsafety)),
-            ty::adjustment::Adjust::MutToConstPointer =>
-                Some(ty::adjustment::Adjust::MutToConstPointer),
-            ty::adjustment::Adjust::Unsize =>
-                Some(ty::adjustment::Adjust::Unsize),
+            ty::adjustment::Adjust::Pointer(ptr) =>
+                Some(ty::adjustment::Adjust::Pointer(ptr)),
             ty::adjustment::Adjust::Deref(ref overloaded) => {
                 tcx.lift(overloaded).map(ty::adjustment::Adjust::Deref)
             }
@@ -1185,11 +1178,7 @@ BraceStructTypeFoldableImpl! {
 EnumTypeFoldableImpl! {
     impl<'tcx> TypeFoldable<'tcx> for ty::adjustment::Adjust<'tcx> {
         (ty::adjustment::Adjust::NeverToAny),
-        (ty::adjustment::Adjust::ReifyFnPointer),
-        (ty::adjustment::Adjust::UnsafeFnPointer),
-        (ty::adjustment::Adjust::ClosureFnPointer)(a),
-        (ty::adjustment::Adjust::MutToConstPointer),
-        (ty::adjustment::Adjust::Unsize),
+        (ty::adjustment::Adjust::Pointer)(a),
         (ty::adjustment::Adjust::Deref)(a),
         (ty::adjustment::Adjust::Borrow)(a),
     }

src/librustc_codegen_ssa/mir/rvalue.rs

@@ -1,4 +1,4 @@
-use rustc::ty::{self, Ty};
+use rustc::ty::{self, Ty, adjustment::{PointerCast}};
 use rustc::ty::cast::{CastTy, IntTy};
 use rustc::ty::layout::{self, LayoutOf, HasTyCtxt};
 use rustc::mir;
@@ -37,7 +37,7 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                bx
            }
 
-            mir::Rvalue::Cast(mir::CastKind::Unsize, ref source, _) => {
+            mir::Rvalue::Cast(mir::CastKind::Pointer(PointerCast::Unsize), ref source, _) => {
                 // The destination necessarily contains a fat pointer, so if
                 // it's a scalar pair, it's a fat pointer or newtype thereof.
                 if bx.cx().is_backend_scalar_pair(dest.layout) {
@@ -178,7 +178,7 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                 let cast = bx.cx().layout_of(self.monomorphize(&mir_cast_ty));
 
                 let val = match *kind {
-                    mir::CastKind::ReifyFnPointer => {
+                    mir::CastKind::Pointer(PointerCast::ReifyFnPointer) => {
                         match operand.layout.ty.sty {
                             ty::FnDef(def_id, substs) => {
                                 if bx.cx().tcx().has_attr(def_id, "rustc_args_required_const") {
@@ -193,7 +193,7 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                             }
                         }
                     }
-                    mir::CastKind::ClosureFnPointer(_) => {
+                    mir::CastKind::Pointer(PointerCast::ClosureFnPointer(_)) => {
                         match operand.layout.ty.sty {
                             ty::Closure(def_id, substs) => {
                                 let instance = monomorphize::resolve_closure(
@@ -205,11 +205,11 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                             }
                         }
                     }
-                    mir::CastKind::UnsafeFnPointer => {
+                    mir::CastKind::Pointer(PointerCast::UnsafeFnPointer) => {
                         // this is a no-op at the LLVM level
                         operand.val
                     }
-                    mir::CastKind::Unsize => {
+                    mir::CastKind::Pointer(PointerCast::Unsize) => {
                         assert!(bx.cx().is_backend_scalar_pair(cast));
                         match operand.val {
                             OperandValue::Pair(lldata, llextra) => {
@@ -236,7 +236,7 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                             }
                         }
                     }
-                    mir::CastKind::MutToConstPointer
+                    mir::CastKind::Pointer(PointerCast::MutToConstPointer)
                     | mir::CastKind::Misc if bx.cx().is_backend_scalar_pair(operand.layout) => {
                         if let OperandValue::Pair(data_ptr, meta) = operand.val {
                             if bx.cx().is_backend_scalar_pair(cast) {
@@ -254,7 +254,7 @@ impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
                             bug!("Unexpected non-Pair operand")
                         }
                     }
-                    mir::CastKind::MutToConstPointer
+                    mir::CastKind::Pointer(PointerCast::MutToConstPointer)
                     | mir::CastKind::Misc => {
                         assert!(bx.cx().is_backend_immediate(cast));
                         let ll_t_out = bx.cx().immediate_backend_type(cast);

src/librustc_mir/borrow_check/nll/explain_borrow/mod.rs

@@ -10,6 +10,7 @@ use rustc::mir::{
     Projection, ProjectionElem, Rvalue, Statement, StatementKind, TerminatorKind,
 };
 use rustc::ty::{self, TyCtxt};
+use rustc::ty::adjustment::{PointerCast};
 use rustc_data_structures::fx::FxHashSet;
 use rustc_errors::DiagnosticBuilder;
 use syntax_pos::Span;
@@ -580,7 +581,9 @@ impl<'cx, 'gcx, 'tcx> MirBorrowckCtxt<'cx, 'gcx, 'tcx> {
                         },
                         // If we see a unsized cast, then if it is our data we should check
                         // whether it is being cast to a trait object.
-                        Rvalue::Cast(CastKind::Unsize, operand, ty) => match operand {
+                        Rvalue::Cast(
+                            CastKind::Pointer(PointerCast::Unsize), operand, ty
+                        ) => match operand {
                             Operand::Copy(Place::Base(PlaceBase::Local(from)))
                             | Operand::Move(Place::Base(PlaceBase::Local(from)))
                                 if *from == target =>

src/librustc_mir/borrow_check/nll/type_check/mod.rs

@@ -36,6 +36,7 @@ use rustc::traits::query::type_op;
 use rustc::traits::query::type_op::custom::CustomTypeOp;
 use rustc::traits::query::{Fallible, NoSolution};
 use rustc::traits::{ObligationCause, PredicateObligations};
+use rustc::ty::adjustment::{PointerCast};
 use rustc::ty::fold::TypeFoldable;
 use rustc::ty::subst::{Subst, SubstsRef, UnpackedKind, UserSubsts};
 use rustc::ty::{
@@ -1972,7 +1973,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
 
             Rvalue::Cast(cast_kind, op, ty) => {
                 match cast_kind {
-                    CastKind::ReifyFnPointer => {
+                    CastKind::Pointer(PointerCast::ReifyFnPointer) => {
                         let fn_sig = op.ty(mir, tcx).fn_sig(tcx);
 
                         // The type that we see in the fcx is like
@@ -2001,7 +2002,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
                         }
                     }
 
-                    CastKind::ClosureFnPointer(unsafety) => {
+                    CastKind::Pointer(PointerCast::ClosureFnPointer(unsafety)) => {
                         let sig = match op.ty(mir, tcx).sty {
                             ty::Closure(def_id, substs) => {
                                 substs.closure_sig_ty(def_id, tcx).fn_sig(tcx)
@@ -2027,7 +2028,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
                         }
                     }
 
-                    CastKind::UnsafeFnPointer => {
+                    CastKind::Pointer(PointerCast::UnsafeFnPointer) => {
                         let fn_sig = op.ty(mir, tcx).fn_sig(tcx);
 
                         // The type that we see in the fcx is like
@@ -2056,7 +2057,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
                         }
                     }
 
-                    CastKind::Unsize => {
+                    CastKind::Pointer(PointerCast::Unsize) => {
                         let &ty = ty;
                         let trait_ref = ty::TraitRef {
                             def_id: tcx.lang_items().coerce_unsized_trait().unwrap(),
@@ -2070,7 +2071,7 @@ impl<'a, 'gcx, 'tcx> TypeChecker<'a, 'gcx, 'tcx> {
                         );
                     }
 
-                    CastKind::MutToConstPointer => {
+                    CastKind::Pointer(PointerCast::MutToConstPointer) => {
                         let ty_from = match op.ty(mir, tcx).sty {
                             ty::RawPtr(ty::TypeAndMut {
                                 ty: ty_from,

src/librustc_mir/build/expr/as_place.rs

@@ -193,11 +193,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
             | ExprKind::Cast { .. }
             | ExprKind::Use { .. }
             | ExprKind::NeverToAny { .. }
-            | ExprKind::ReifyFnPointer { .. }
-            | ExprKind::ClosureFnPointer { .. }
-            | ExprKind::UnsafeFnPointer { .. }
-            | ExprKind::MutToConstPointer { .. }
-            | ExprKind::Unsize { .. }
+            | ExprKind::Pointer { .. }
             | ExprKind::Repeat { .. }
             | ExprKind::Borrow { .. }
             | ExprKind::If { .. }

src/librustc_mir/build/expr/as_rvalue.rs

@@ -154,25 +154,9 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
                 let source = unpack!(block = this.as_operand(block, scope, source));
                 block.and(Rvalue::Use(source))
             }
-            ExprKind::ReifyFnPointer { source } => {
+            ExprKind::Pointer { cast, source } => {
                 let source = unpack!(block = this.as_operand(block, scope, source));
-                block.and(Rvalue::Cast(CastKind::ReifyFnPointer, source, expr.ty))
-            }
-            ExprKind::UnsafeFnPointer { source } => {
-                let source = unpack!(block = this.as_operand(block, scope, source));
-                block.and(Rvalue::Cast(CastKind::UnsafeFnPointer, source, expr.ty))
-            }
-            ExprKind::ClosureFnPointer { source, unsafety } => {
-                let source = unpack!(block = this.as_operand(block, scope, source));
-                block.and(Rvalue::Cast(CastKind::ClosureFnPointer(unsafety), source, expr.ty))
-            }
-            ExprKind::MutToConstPointer { source } => {
-                let source = unpack!(block = this.as_operand(block, scope, source));
-                block.and(Rvalue::Cast(CastKind::MutToConstPointer, source, expr.ty))
-            }
-            ExprKind::Unsize { source } => {
-                let source = unpack!(block = this.as_operand(block, scope, source));
-                block.and(Rvalue::Cast(CastKind::Unsize, source, expr.ty))
+                block.and(Rvalue::Cast(CastKind::Pointer(cast), source, expr.ty))
             }
             ExprKind::Array { fields } => {
                 // (*) We would (maybe) be closer to codegen if we

src/librustc_mir/build/expr/category.rs

@@ -59,11 +59,7 @@ impl Category {
             | ExprKind::Box { .. }
             | ExprKind::Cast { .. }
             | ExprKind::Use { .. }
-            | ExprKind::ReifyFnPointer { .. }
-            | ExprKind::ClosureFnPointer { .. }
-            | ExprKind::UnsafeFnPointer { .. }
-            | ExprKind::MutToConstPointer { .. }
-            | ExprKind::Unsize { .. }
+            | ExprKind::Pointer { .. }
             | ExprKind::Repeat { .. }
             | ExprKind::Borrow { .. }
             | ExprKind::Assign { .. }

src/librustc_mir/build/expr/into.rs

@@ -380,11 +380,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
             | ExprKind::Box { .. }
             | ExprKind::Cast { .. }
             | ExprKind::Use { .. }
-            | ExprKind::ReifyFnPointer { .. }
-            | ExprKind::ClosureFnPointer { .. }
-            | ExprKind::UnsafeFnPointer { .. }
-            | ExprKind::MutToConstPointer { .. }
-            | ExprKind::Unsize { .. }
+            | ExprKind::Pointer { .. }
             | ExprKind::Repeat { .. }
             | ExprKind::Borrow { .. }
             | ExprKind::Array { .. }