Auto merge of #105880 - Nilstrieb:make-newtypes-less-not-rust, r=oli-obk

Improve syntax of `newtype_index`

This makes it more like proper Rust and also makes the implementation a lot simpler.

Mostly just turns weird flags in the body into proper attributes.

It should probably also be converted to an attribute macro instead of function-like, but that can be done in a future PR.

8 files changed, 47 insertions, 63 deletions

diff --git a/compiler/rustc_middle/src/middle/region.rs b/compiler/rustc_middle/src/middle/region.rs
index c886175c6ea..94ca38c0e75 100644
--- a/compiler/rustc_middle/src/middle/region.rs
+++ b/compiler/rustc_middle/src/middle/region.rs
@@ -147,9 +147,8 @@ rustc_index::newtype_index! {
     ///
     /// * The subscope with `first_statement_index == 1` is scope of `c`,
     ///   and thus does not include EXPR_2, but covers the `...`.
-    pub struct FirstStatementIndex {
-        derive [HashStable]
-    }
+    #[derive(HashStable)]
+    pub struct FirstStatementIndex {}
 }
 
 // compilation error if size of `ScopeData` is not the same as a `u32`
diff --git a/compiler/rustc_middle/src/mir/coverage.rs b/compiler/rustc_middle/src/mir/coverage.rs
index 0b55757eb03..e7bb3ab0bc3 100644
--- a/compiler/rustc_middle/src/mir/coverage.rs
+++ b/compiler/rustc_middle/src/mir/coverage.rs
@@ -10,10 +10,10 @@ rustc_index::newtype_index! {
     /// CounterValueReference.as_u32() (which ascend from 1) or an ExpressionOperandId.as_u32()
     /// (which _*descend*_ from u32::MAX). Id value `0` (zero) represents a virtual counter with a
     /// constant value of `0`.
+    #[derive(HashStable)]
+    #[max = 0xFFFF_FFFF]
+    #[debug_format = "ExpressionOperandId({})"]
     pub struct ExpressionOperandId {
-        derive [HashStable]
-        DEBUG_FORMAT = "ExpressionOperandId({})",
-        MAX = 0xFFFF_FFFF,
     }
 }
 
@@ -32,11 +32,10 @@ impl ExpressionOperandId {
 }
 
 rustc_index::newtype_index! {
-    pub struct CounterValueReference {
-        derive [HashStable]
-        DEBUG_FORMAT = "CounterValueReference({})",
-        MAX = 0xFFFF_FFFF,
-    }
+    #[derive(HashStable)]
+    #[max = 0xFFFF_FFFF]
+    #[debug_format = "CounterValueReference({})"]
+    pub struct CounterValueReference {}
 }
 
 impl CounterValueReference {
@@ -56,33 +55,30 @@ rustc_index::newtype_index! {
     /// InjectedExpressionId.as_u32() converts to ExpressionOperandId.as_u32()
     ///
     /// Values descend from u32::MAX.
-    pub struct InjectedExpressionId {
-        derive [HashStable]
-        DEBUG_FORMAT = "InjectedExpressionId({})",
-        MAX = 0xFFFF_FFFF,
-    }
+    #[derive(HashStable)]
+    #[max = 0xFFFF_FFFF]
+    #[debug_format = "InjectedExpressionId({})"]
+    pub struct InjectedExpressionId {}
 }
 
 rustc_index::newtype_index! {
     /// InjectedExpressionIndex.as_u32() translates to u32::MAX - ExpressionOperandId.as_u32()
     ///
     /// Values ascend from 0.
-    pub struct InjectedExpressionIndex {
-        derive [HashStable]
-        DEBUG_FORMAT = "InjectedExpressionIndex({})",
-        MAX = 0xFFFF_FFFF,
-    }
+    #[derive(HashStable)]
+    #[max = 0xFFFF_FFFF]
+    #[debug_format = "InjectedExpressionIndex({})"]
+    pub struct InjectedExpressionIndex {}
 }
 
 rustc_index::newtype_index! {
     /// MappedExpressionIndex values ascend from zero, and are recalculated indexes based on their
     /// array position in the LLVM coverage map "Expressions" array, which is assembled during the
     /// "mapgen" process. They cannot be computed algorithmically, from the other `newtype_index`s.
-    pub struct MappedExpressionIndex {
-        derive [HashStable]
-        DEBUG_FORMAT = "MappedExpressionIndex({})",
-        MAX = 0xFFFF_FFFF,
-    }
+    #[derive(HashStable)]
+    #[max = 0xFFFF_FFFF]
+    #[debug_format = "MappedExpressionIndex({})"]
+    pub struct MappedExpressionIndex {}
 }
 
 impl From<CounterValueReference> for ExpressionOperandId {
diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs
index bdaa586c698..ffdf61d4244 100644
--- a/compiler/rustc_middle/src/mir/mod.rs
+++ b/compiler/rustc_middle/src/mir/mod.rs
@@ -654,10 +654,10 @@ impl SourceInfo {
 // Variables and temps
 
 rustc_index::newtype_index! {
+    #[derive(HashStable)]
+    #[debug_format = "_{}"]
     pub struct Local {
-        derive [HashStable]
-        DEBUG_FORMAT = "_{}",
-        const RETURN_PLACE = 0,
+        const RETURN_PLACE = 0;
     }
 }
 
@@ -1146,10 +1146,10 @@ rustc_index::newtype_index! {
     ///     https://rustc-dev-guide.rust-lang.org/appendix/background.html#what-is-a-dataflow-analysis
     /// [`CriticalCallEdges`]: ../../rustc_const_eval/transform/add_call_guards/enum.AddCallGuards.html#variant.CriticalCallEdges
     /// [guide-mir]: https://rustc-dev-guide.rust-lang.org/mir/
+    #[derive(HashStable)]
+    #[debug_format = "bb{}"]
     pub struct BasicBlock {
-        derive [HashStable]
-        DEBUG_FORMAT = "bb{}",
-        const START_BLOCK = 0,
+        const START_BLOCK = 0;
     }
 }
 
@@ -1530,10 +1530,9 @@ rustc_index::newtype_index! {
     /// [wrapper]: https://rustc-dev-guide.rust-lang.org/appendix/glossary.html#newtype
     /// [CFG]: https://rustc-dev-guide.rust-lang.org/appendix/background.html#cfg
     /// [mir-datatypes]: https://rustc-dev-guide.rust-lang.org/mir/index.html#mir-data-types
-    pub struct Field {
-        derive [HashStable]
-        DEBUG_FORMAT = "field[{}]"
-    }
+    #[derive(HashStable)]
+    #[debug_format = "field[{}]"]
+    pub struct Field {}
 }
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
@@ -1757,10 +1756,10 @@ impl Debug for Place<'_> {
 // Scopes
 
 rustc_index::newtype_index! {
+    #[derive(HashStable)]
+    #[debug_format = "scope[{}]"]
     pub struct SourceScope {
-        derive [HashStable]
-        DEBUG_FORMAT = "scope[{}]",
-        const OUTERMOST_SOURCE_SCOPE = 0,
+        const OUTERMOST_SOURCE_SCOPE = 0;
     }
 }
 
@@ -2755,10 +2754,9 @@ impl<'tcx> TypeVisitable<'tcx> for UserTypeProjection {
 }
 
 rustc_index::newtype_index! {
-    pub struct Promoted {
-        derive [HashStable]
-        DEBUG_FORMAT = "promoted[{}]"
-    }
+    #[derive(HashStable)]
+    #[debug_format = "promoted[{}]"]
+    pub struct Promoted {}
 }
 
 impl<'tcx> Debug for Constant<'tcx> {
diff --git a/compiler/rustc_middle/src/mir/query.rs b/compiler/rustc_middle/src/mir/query.rs
index efd7357afc4..a8a4532223c 100644
--- a/compiler/rustc_middle/src/mir/query.rs
+++ b/compiler/rustc_middle/src/mir/query.rs
@@ -130,10 +130,9 @@ pub struct UnsafetyCheckResult {
 }
 
 rustc_index::newtype_index! {
-    pub struct GeneratorSavedLocal {
-        derive [HashStable]
-        DEBUG_FORMAT = "_{}",
-    }
+    #[derive(HashStable)]
+    #[debug_format = "_{}"]
+    pub struct GeneratorSavedLocal {}
 }
 
 /// The layout of generator state.
diff --git a/compiler/rustc_middle/src/thir.rs b/compiler/rustc_middle/src/thir.rs
index 8bef9dfe099..ac903010c8d 100644
--- a/compiler/rustc_middle/src/thir.rs
+++ b/compiler/rustc_middle/src/thir.rs
@@ -35,9 +35,8 @@ macro_rules! thir_with_elements {
         $(
             newtype_index! {
                 #[derive(HashStable)]
-                pub struct $id {
-                    DEBUG_FORMAT = $format
-                }
+                #[debug_format = $format]
+                pub struct $id {}
             }
         )*
 
diff --git a/compiler/rustc_middle/src/ty/structural_impls.rs b/compiler/rustc_middle/src/ty/structural_impls.rs
index 3c6800cf293..30073b541ec 100644
--- a/compiler/rustc_middle/src/ty/structural_impls.rs
+++ b/compiler/rustc_middle/src/ty/structural_impls.rs
@@ -99,12 +99,6 @@ impl<'tcx> fmt::Debug for ty::ConstVid<'tcx> {
     }
 }
 
-impl fmt::Debug for ty::RegionVid {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "'_#{}r", self.index())
-    }
-}
-
 impl<'tcx> fmt::Debug for ty::TraitRef<'tcx> {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         with_no_trimmed_paths!(fmt::Display::fmt(self, f))
diff --git a/compiler/rustc_middle/src/ty/sty.rs b/compiler/rustc_middle/src/ty/sty.rs
index 66aeebab88b..e13b68c83b5 100644
--- a/compiler/rustc_middle/src/ty/sty.rs
+++ b/compiler/rustc_middle/src/ty/sty.rs
@@ -1378,9 +1378,8 @@ pub struct ConstVid<'tcx> {
 rustc_index::newtype_index! {
     /// A **region** (lifetime) **v**ariable **ID**.
     #[derive(HashStable)]
-    pub struct RegionVid {
-        DEBUG_FORMAT = custom,
-    }
+    #[debug_format = "'_#{}r"]
+    pub struct RegionVid {}
 }
 
 impl Atom for RegionVid {
@@ -1391,7 +1390,7 @@ impl Atom for RegionVid {
 
 rustc_index::newtype_index! {
     #[derive(HashStable)]
-    pub struct BoundVar { .. }
+    pub struct BoundVar {}
 }
 
 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
diff --git a/compiler/rustc_middle/src/ty/typeck_results.rs b/compiler/rustc_middle/src/ty/typeck_results.rs
index 4fe85d4366f..136a4906c58 100644
--- a/compiler/rustc_middle/src/ty/typeck_results.rs
+++ b/compiler/rustc_middle/src/ty/typeck_results.rs
@@ -608,10 +608,10 @@ impl<'a, V> LocalTableInContextMut<'a, V> {
 }
 
 rustc_index::newtype_index! {
+    #[derive(HashStable)]
+    #[debug_format = "UserType({})"]
     pub struct UserTypeAnnotationIndex {
-        derive [HashStable]
-        DEBUG_FORMAT = "UserType({})",
-        const START_INDEX = 0,
+        const START_INDEX = 0;
     }
 }