better `TyKind::Debug`

9 files changed, 176 insertions, 78 deletions

diff --git a/compiler/rustc_middle/src/ty/context.rs b/compiler/rustc_middle/src/ty/context.rs
index 2bde55bc4fd..0cde46ae4c2 100644
--- a/compiler/rustc_middle/src/ty/context.rs
+++ b/compiler/rustc_middle/src/ty/context.rs
@@ -115,6 +115,16 @@ impl<'tcx> Interner for TyCtxt<'tcx> {
     type FreeRegion = ty::FreeRegion;
     type RegionVid = ty::RegionVid;
     type PlaceholderRegion = ty::PlaceholderRegion;
+
+    fn ty_and_mut_to_parts(
+        TypeAndMut { ty, mutbl }: TypeAndMut<'tcx>,
+    ) -> (Self::Ty, Self::Mutability) {
+        (ty, mutbl)
+    }
+
+    fn mutability_is_mut(mutbl: Self::Mutability) -> bool {
+        mutbl.is_mut()
+    }
 }
 
 type InternedSet<'tcx, T> = ShardedHashMap<InternedInSet<'tcx, T>, ()>;
diff --git a/compiler/rustc_middle/src/ty/mod.rs b/compiler/rustc_middle/src/ty/mod.rs
index a8d0dca37ff..025432fcaa8 100644
--- a/compiler/rustc_middle/src/ty/mod.rs
+++ b/compiler/rustc_middle/src/ty/mod.rs
@@ -1496,7 +1496,7 @@ impl<'tcx> OpaqueHiddenType<'tcx> {
 /// identified by both a universe, as well as a name residing within that universe. Distinct bound
 /// regions/types/consts within the same universe simply have an unknown relationship to one
 /// another.
-#[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, PartialOrd, Ord)]
+#[derive(Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
 #[derive(HashStable, TyEncodable, TyDecodable)]
 pub struct Placeholder<T> {
     pub universe: UniverseIndex,
diff --git a/compiler/rustc_middle/src/ty/print/pretty.rs b/compiler/rustc_middle/src/ty/print/pretty.rs
index a064174e261..1c216960d11 100644
--- a/compiler/rustc_middle/src/ty/print/pretty.rs
+++ b/compiler/rustc_middle/src/ty/print/pretty.rs
@@ -685,29 +685,30 @@ pub trait PrettyPrinter<'tcx>:
             }
             ty::FnPtr(ref bare_fn) => p!(print(bare_fn)),
             ty::Infer(infer_ty) => {
-                let verbose = self.should_print_verbose();
+                if self.should_print_verbose() {
+                    p!(write("{:?}", ty.kind()));
+                    return Ok(self);
+                }
+
                 if let ty::TyVar(ty_vid) = infer_ty {
                     if let Some(name) = self.ty_infer_name(ty_vid) {
                         p!(write("{}", name))
                     } else {
-                        if verbose {
-                            p!(write("{:?}", infer_ty))
-                        } else {
-                            p!(write("{}", infer_ty))
-                        }
+                        p!(write("{}", infer_ty))
                     }
                 } else {
-                    if verbose { p!(write("{:?}", infer_ty)) } else { p!(write("{}", infer_ty)) }
+                    p!(write("{}", infer_ty))
                 }
             }
             ty::Error(_) => p!("[type error]"),
             ty::Param(ref param_ty) => p!(print(param_ty)),
             ty::Bound(debruijn, bound_ty) => match bound_ty.kind {
-                ty::BoundTyKind::Anon => debug_bound_var(&mut self, debruijn, bound_ty.var)?,
+                ty::BoundTyKind::Anon => {
+                    rustc_type_ir::debug_bound_var(&mut self, debruijn, bound_ty.var)?
+                }
                 ty::BoundTyKind::Param(_, s) => match self.should_print_verbose() {
-                    true if debruijn == ty::INNERMOST => p!(write("^{}", s)),
-                    true => p!(write("^{}_{}", debruijn.index(), s)),
-                    false => p!(write("{}", s)),
+                    true => p!(write("{:?}", ty.kind())),
+                    false => p!(write("{s}")),
                 },
             },
             ty::Adt(def, substs) => {
@@ -740,10 +741,11 @@ pub trait PrettyPrinter<'tcx>:
                 }
             }
             ty::Placeholder(placeholder) => match placeholder.bound.kind {
-                ty::BoundTyKind::Anon => {
-                    debug_placeholder_var(&mut self, placeholder.universe, placeholder.bound.var)?;
-                }
-                ty::BoundTyKind::Param(_, name) => p!(write("{}", name)),
+                ty::BoundTyKind::Anon => p!(write("{placeholder:?}")),
+                ty::BoundTyKind::Param(_, name) => match self.should_print_verbose() {
+                    true => p!(write("{:?}", ty.kind())),
+                    false => p!(write("{name}")),
+                },
             },
             ty::Alias(ty::Opaque, ty::AliasTy { def_id, substs, .. }) => {
                 // We use verbose printing in 'NO_QUERIES' mode, to
@@ -1372,11 +1374,9 @@ pub trait PrettyPrinter<'tcx>:
             }
 
             ty::ConstKind::Bound(debruijn, bound_var) => {
-                debug_bound_var(&mut self, debruijn, bound_var)?
+                rustc_type_ir::debug_bound_var(&mut self, debruijn, bound_var)?
             }
-            ty::ConstKind::Placeholder(placeholder) => {
-                debug_placeholder_var(&mut self, placeholder.universe, placeholder.bound)?;
-            },
+            ty::ConstKind::Placeholder(placeholder) => p!(write("{placeholder:?}")),
             // FIXME(generic_const_exprs):
             // write out some legible representation of an abstract const?
             ty::ConstKind::Expr(_) => p!("[const expr]"),
@@ -3065,27 +3065,3 @@ pub struct OpaqueFnEntry<'tcx> {
     fn_trait_ref: Option<ty::PolyTraitRef<'tcx>>,
     return_ty: Option<ty::Binder<'tcx, Term<'tcx>>>,
 }
-
-pub fn debug_bound_var<T: std::fmt::Write>(
-    fmt: &mut T,
-    debruijn: ty::DebruijnIndex,
-    var: ty::BoundVar,
-) -> Result<(), std::fmt::Error> {
-    if debruijn == ty::INNERMOST {
-        write!(fmt, "^{}", var.index())
-    } else {
-        write!(fmt, "^{}_{}", debruijn.index(), var.index())
-    }
-}
-
-pub fn debug_placeholder_var<T: std::fmt::Write>(
-    fmt: &mut T,
-    universe: ty::UniverseIndex,
-    bound: ty::BoundVar,
-) -> Result<(), std::fmt::Error> {
-    if universe == ty::UniverseIndex::ROOT {
-        write!(fmt, "!{}", bound.index())
-    } else {
-        write!(fmt, "!{}_{}", universe.index(), bound.index())
-    }
-}
diff --git a/compiler/rustc_middle/src/ty/structural_impls.rs b/compiler/rustc_middle/src/ty/structural_impls.rs
index 16cb6c91046..a965450d27d 100644
--- a/compiler/rustc_middle/src/ty/structural_impls.rs
+++ b/compiler/rustc_middle/src/ty/structural_impls.rs
@@ -88,7 +88,35 @@ impl fmt::Debug for ty::FreeRegion {
 
 impl<'tcx> fmt::Debug for ty::FnSig<'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "({:?}; c_variadic: {})->{:?}", self.inputs(), self.c_variadic, self.output())
+        let ty::FnSig { inputs_and_output: _, c_variadic, unsafety, abi } = self;
+
+        write!(f, "{}", unsafety.prefix_str())?;
+        match abi {
+            rustc_target::spec::abi::Abi::Rust => (),
+            abi => write!(f, "extern \"{abi:?}\" ")?,
+        };
+
+        write!(f, "fn(")?;
+        let inputs = self.inputs();
+        match inputs.len() {
+            0 if *c_variadic => write!(f, "...)")?,
+            0 => write!(f, ")")?,
+            _ => {
+                for ty in &self.inputs()[0..(self.inputs().len() - 1)] {
+                    write!(f, "{ty:?}, ")?;
+                }
+                write!(f, "{:?}", self.inputs().last().unwrap())?;
+                if *c_variadic {
+                    write!(f, "...")?;
+                }
+                write!(f, ")")?;
+            }
+        }
+
+        match self.output().kind() {
+            ty::Tuple(list) if list.is_empty() => Ok(()),
+            _ => write!(f, " -> {:?}", self.output()),
+        }
     }
 }
 
@@ -216,20 +244,37 @@ impl<'tcx> fmt::Debug for ty::ConstKind<'tcx> {
         match self {
             Param(param) => write!(f, "{param:?}"),
             Infer(var) => write!(f, "{var:?}"),
-            Bound(debruijn, var) => ty::print::debug_bound_var(f, *debruijn, *var),
-            Placeholder(placeholder) => {
-                ty::print::debug_placeholder_var(f, placeholder.universe, placeholder.bound)
-            }
+            Bound(debruijn, var) => rustc_type_ir::debug_bound_var(f, *debruijn, *var),
+            Placeholder(placeholder) => write!(f, "{placeholder:?}"),
             Unevaluated(uv) => {
                 f.debug_tuple("Unevaluated").field(&uv.substs).field(&uv.def).finish()
             }
             Value(valtree) => write!(f, "{valtree:?}"),
-            Error(_) => write!(f, "[const error]"),
+            Error(_) => write!(f, "{{const error}}"),
             Expr(expr) => write!(f, "{expr:?}"),
         }
     }
 }
 
+impl fmt::Debug for ty::BoundTy {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self.kind {
+            ty::BoundTyKind::Anon => write!(f, "{:?}", self.var),
+            ty::BoundTyKind::Param(_, sym) => write!(f, "{sym:?}"),
+        }
+    }
+}
+
+impl<T: fmt::Debug> fmt::Debug for ty::Placeholder<T> {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        if self.universe == ty::UniverseIndex::ROOT {
+            write!(f, "!{:?}", self.bound)
+        } else {
+            write!(f, "!{}_{:?}", self.universe.index(), self.bound)
+        }
+    }
+}
+
 ///////////////////////////////////////////////////////////////////////////
 // Atomic structs
 //
@@ -294,6 +339,7 @@ TrivialTypeTraversalAndLiftImpls! {
     crate::ty::AliasRelationDirection,
     crate::ty::Placeholder<crate::ty::BoundRegion>,
     crate::ty::Placeholder<crate::ty::BoundTy>,
+    crate::ty::Placeholder<ty::BoundVar>,
     crate::ty::ClosureKind,
     crate::ty::FreeRegion,
     crate::ty::InferTy,
@@ -310,7 +356,6 @@ TrivialTypeTraversalAndLiftImpls! {
     interpret::Scalar,
     rustc_target::abi::Size,
     ty::BoundVar,
-    ty::Placeholder<ty::BoundVar>,
 }
 
 TrivialTypeTraversalAndLiftImpls! {
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index e6d51c4ec97..0b722d9368b 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -1511,10 +1511,11 @@ impl Atom for RegionVid {
 
 rustc_index::newtype_index! {
     #[derive(HashStable)]
+    #[debug_format = "{}"]
     pub struct BoundVar {}
 }
 
-#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, TyDecodable)]
 #[derive(HashStable)]
 pub struct BoundTy {
     pub var: BoundVar,
diff --git a/compiler/rustc_type_ir/src/lib.rs b/compiler/rustc_type_ir/src/lib.rs
index f6b44bdf27e..ae16fbb162e 100644
--- a/compiler/rustc_type_ir/src/lib.rs
+++ b/compiler/rustc_type_ir/src/lib.rs
@@ -52,7 +52,7 @@ pub trait Interner: Sized {
     type PolyFnSig: Clone + Debug + Hash + Ord;
     type ListBinderExistentialPredicate: Clone + Debug + Hash + Ord;
     type BinderListTy: Clone + Debug + Hash + Ord;
-    type ListTy: Clone + Debug + Hash + Ord;
+    type ListTy: Clone + Debug + Hash + Ord + IntoIterator<Item = Self::Ty>;
     type AliasTy: Clone + Debug + Hash + Ord;
     type ParamTy: Clone + Debug + Hash + Ord;
     type BoundTy: Clone + Debug + Hash + Ord;
@@ -67,6 +67,9 @@ pub trait Interner: Sized {
     type FreeRegion: Clone + Debug + Hash + Ord;
     type RegionVid: Clone + Debug + Hash + Ord;
     type PlaceholderRegion: Clone + Debug + Hash + Ord;
+
+    fn ty_and_mut_to_parts(ty_and_mut: Self::TypeAndMut) -> (Self::Ty, Self::Mutability);
+    fn mutability_is_mut(mutbl: Self::Mutability) -> bool;
 }
 
 /// Imagine you have a function `F: FnOnce(&[T]) -> R`, plus an iterator `iter`
@@ -390,7 +393,19 @@ impl DebruijnIndex {
     }
 }
 
-#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+pub fn debug_bound_var<T: std::fmt::Write>(
+    fmt: &mut T,
+    debruijn: DebruijnIndex,
+    var: impl std::fmt::Debug,
+) -> Result<(), std::fmt::Error> {
+    if debruijn == INNERMOST {
+        write!(fmt, "^{:?}", var)
+    } else {
+        write!(fmt, "^{}_{:?}", debruijn.index(), var)
+    }
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 #[derive(Encodable, Decodable, HashStable_Generic)]
 pub enum IntTy {
     Isize,
@@ -448,7 +463,7 @@ impl IntTy {
     }
 }
 
-#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Copy, Debug)]
+#[derive(Clone, PartialEq, Eq, PartialOrd, Ord, Hash, Copy)]
 #[derive(Encodable, Decodable, HashStable_Generic)]
 pub enum UintTy {
     Usize,
@@ -506,7 +521,7 @@ impl UintTy {
     }
 }
 
-#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug)]
+#[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 #[derive(Encodable, Decodable, HashStable_Generic)]
 pub enum FloatTy {
     F32,
diff --git a/compiler/rustc_type_ir/src/structural_impls.rs b/compiler/rustc_type_ir/src/structural_impls.rs
index 45a2e9023c9..553d7f31b2d 100644
--- a/compiler/rustc_type_ir/src/structural_impls.rs
+++ b/compiler/rustc_type_ir/src/structural_impls.rs
@@ -4,11 +4,12 @@
 
 use crate::fold::{FallibleTypeFolder, TypeFoldable};
 use crate::visit::{TypeVisitable, TypeVisitor};
-use crate::Interner;
+use crate::{FloatTy, IntTy, Interner, UintTy};
 use rustc_data_structures::functor::IdFunctor;
 use rustc_data_structures::sync::Lrc;
 use rustc_index::{Idx, IndexVec};
 
+use core::fmt;
 use std::ops::ControlFlow;
 
 ///////////////////////////////////////////////////////////////////////////
@@ -163,3 +164,21 @@ impl<I: Interner, T: TypeVisitable<I>, Ix: Idx> TypeVisitable<I> for IndexVec<Ix
         self.iter().try_for_each(|t| t.visit_with(visitor))
     }
 }
+
+impl fmt::Debug for IntTy {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.name_str())
+    }
+}
+
+impl fmt::Debug for UintTy {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.name_str())
+    }
+}
+
+impl fmt::Debug for FloatTy {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.name_str())
+    }
+}
diff --git a/compiler/rustc_type_ir/src/sty.rs b/compiler/rustc_type_ir/src/sty.rs
index f7344bacc02..fa18f921ee4 100644
--- a/compiler/rustc_type_ir/src/sty.rs
+++ b/compiler/rustc_type_ir/src/sty.rs
@@ -294,7 +294,7 @@ impl<I: Interner> Clone for TyKind<I> {
             Str => Str,
             Array(t, c) => Array(t.clone(), c.clone()),
             Slice(t) => Slice(t.clone()),
-            RawPtr(t) => RawPtr(t.clone()),
+            RawPtr(p) => RawPtr(p.clone()),
             Ref(r, t, m) => Ref(r.clone(), t.clone(), m.clone()),
             FnDef(d, s) => FnDef(d.clone(), s.clone()),
             FnPtr(s) => FnPtr(s.clone()),
@@ -499,33 +499,65 @@ impl<I: Interner> hash::Hash for TyKind<I> {
 impl<I: Interner> fmt::Debug for TyKind<I> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         match self {
-            Bool => f.write_str("Bool"),
-            Char => f.write_str("Char"),
-            Int(i) => f.debug_tuple_field1_finish("Int", i),
-            Uint(u) => f.debug_tuple_field1_finish("Uint", u),
-            Float(float) => f.debug_tuple_field1_finish("Float", float),
+            Bool => write!(f, "bool"),
+            Char => write!(f, "char"),
+            Int(i) => write!(f, "{i:?}"),
+            Uint(u) => write!(f, "{u:?}"),
+            Float(float) => write!(f, "{float:?}"),
             Adt(d, s) => f.debug_tuple_field2_finish("Adt", d, s),
             Foreign(d) => f.debug_tuple_field1_finish("Foreign", d),
-            Str => f.write_str("Str"),
-            Array(t, c) => f.debug_tuple_field2_finish("Array", t, c),
-            Slice(t) => f.debug_tuple_field1_finish("Slice", t),
-            RawPtr(t) => f.debug_tuple_field1_finish("RawPtr", t),
-            Ref(r, t, m) => f.debug_tuple_field3_finish("Ref", r, t, m),
+            Str => write!(f, "str"),
+            Array(t, c) => write!(f, "[{t:?}; {c:?}]"),
+            Slice(t) => write!(f, "[{t:?}]"),
+            RawPtr(p) => {
+                let (ty, mutbl) = I::ty_and_mut_to_parts(p.clone());
+                match I::mutability_is_mut(mutbl) {
+                    true => write!(f, "*mut "),
+                    false => write!(f, "*const "),
+                }?;
+                write!(f, "{ty:?}")
+            }
+            Ref(r, t, m) => match I::mutability_is_mut(m.clone()) {
+                true => write!(f, "&{r:?} mut {t:?}"),
+                false => write!(f, "&{r:?} {t:?}"),
+            },
             FnDef(d, s) => f.debug_tuple_field2_finish("FnDef", d, s),
-            FnPtr(s) => f.debug_tuple_field1_finish("FnPtr", s),
-            Dynamic(p, r, repr) => f.debug_tuple_field3_finish("Dynamic", p, r, repr),
+            FnPtr(s) => write!(f, "{s:?}"),
+            Dynamic(p, r, repr) => match repr {
+                DynKind::Dyn => write!(f, "dyn {p:?} + {r:?}"),
+                DynKind::DynStar => write!(f, "dyn* {p:?} + {r:?}"),
+            },
             Closure(d, s) => f.debug_tuple_field2_finish("Closure", d, s),
             Generator(d, s, m) => f.debug_tuple_field3_finish("Generator", d, s, m),
             GeneratorWitness(g) => f.debug_tuple_field1_finish("GeneratorWitness", g),
             GeneratorWitnessMIR(d, s) => f.debug_tuple_field2_finish("GeneratorWitnessMIR", d, s),
-            Never => f.write_str("Never"),
-            Tuple(t) => f.debug_tuple_field1_finish("Tuple", t),
+            Never => write!(f, "!"),
+            Tuple(t) => {
+                let mut iter = t.clone().into_iter();
+
+                write!(f, "(")?;
+
+                match iter.next() {
+                    None => return write!(f, ")"),
+                    Some(ty) => write!(f, "{ty:?}")?,
+                };
+
+                match iter.next() {
+                    None => return write!(f, ",)"),
+                    Some(ty) => write!(f, "{ty:?})")?,
+                }
+
+                for ty in iter {
+                    write!(f, ", {ty:?}")?;
+                }
+                write!(f, ")")
+            }
             Alias(i, a) => f.debug_tuple_field2_finish("Alias", i, a),
-            Param(p) => f.debug_tuple_field1_finish("Param", p),
-            Bound(d, b) => f.debug_tuple_field2_finish("Bound", d, b),
-            Placeholder(p) => f.debug_tuple_field1_finish("Placeholder", p),
-            Infer(t) => f.debug_tuple_field1_finish("Infer", t),
-            TyKind::Error(e) => f.debug_tuple_field1_finish("Error", e),
+            Param(p) => write!(f, "{p:?}"),
+            Bound(d, b) => crate::debug_bound_var(f, *d, b),
+            Placeholder(p) => write!(f, "{p:?}"),
+            Infer(t) => write!(f, "{t:?}"),
+            TyKind::Error(_) => write!(f, "{{type error}}"),
         }
     }
 }
diff --git a/tests/ui/thir-print/thir-flat.stdout b/tests/ui/thir-print/thir-flat.stdout
index 9d467f73d09..b0aa44b56aa 100644
--- a/tests/ui/thir-print/thir-flat.stdout
+++ b/tests/ui/thir-print/thir-flat.stdout
@@ -1,7 +1,7 @@
 DefId(0:3 ~ thir_flat[7b97]::main):
 Thir {
     body_type: Fn(
-        ([]; c_variadic: false)->(),
+        fn(),
     ),
     arms: [],
     blocks: [