Auto merge of rust-lang#87648 - JulianKnodt:const_eq_constrain, r=oli-obk

allow eq constraints on associated constants

Updates rust-lang#70256

(cc `@varkor,` `@Centril)`

Author: bors

Cargo.lock

@@ -335,7 +335,7 @@ dependencies = [
  "cargo-test-macro",
  "cargo-test-support",
  "cargo-util",
- "clap 3.0.6",
+ "clap",
  "crates-io",
  "crossbeam-utils",
  "curl",
@@ -615,28 +615,13 @@ dependencies = [
  "ansi_term 0.12.1",
  "atty",
  "bitflags",
- "strsim 0.8.0",
- "textwrap 0.11.0",
+ "strsim",
+ "textwrap",
  "unicode-width",
  "vec_map",
  "yaml-rust 0.3.5",
 ]
 
-[[package]]
-name = "clap"
-version = "3.0.6"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1957aa4a5fb388f0a0a73ce7556c5b42025b874e5cdc2c670775e346e97adec0"
-dependencies = [
- "atty",
- "bitflags",
- "indexmap",
- "os_str_bytes",
- "strsim 0.10.0",
- "termcolor",
- "textwrap 0.14.2",
-]
-
 [[package]]
 name = "clippy"
 version = "0.1.60"
@@ -669,7 +654,7 @@ version = "0.0.1"
 dependencies = [
  "bytecount",
  "cargo_metadata 0.14.0",
- "clap 2.34.0",
+ "clap",
  "indoc",
  "itertools 0.10.1",
  "opener",
@@ -1751,7 +1736,7 @@ name = "installer"
 version = "0.0.0"
 dependencies = [
  "anyhow",
- "clap 2.34.0",
+ "clap",
  "flate2",
  "lazy_static",
  "num_cpus",
@@ -2190,7 +2175,7 @@ dependencies = [
  "ammonia",
  "anyhow",
  "chrono",
- "clap 2.34.0",
+ "clap",
  "elasticlunr-rs",
  "env_logger 0.7.1",
  "handlebars",
@@ -2521,15 +2506,6 @@ dependencies = [
  "winapi",
 ]
 
-[[package]]
-name = "os_str_bytes"
-version = "6.0.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8e22443d1643a904602595ba1cd8f7d896afe56d26712531c5ff73a15b2fbf64"
-dependencies = [
- "memchr",
-]
-
 [[package]]
 name = "output_vt100"
 version = "0.1.2"
@@ -2934,7 +2910,7 @@ source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b0b4b5faaf07040474e8af74a9e19ff167d5d204df5db5c5c765edecfb900358"
 dependencies = [
  "bitflags",
- "clap 2.34.0",
+ "clap",
  "derive_more",
  "env_logger 0.7.1",
  "humantime 2.0.1",
@@ -3282,7 +3258,7 @@ dependencies = [
 name = "rustbook"
 version = "0.1.0"
 dependencies = [
- "clap 2.34.0",
+ "clap",
  "env_logger 0.7.1",
  "mdbook",
 ]
@@ -4898,19 +4874,13 @@ version = "0.8.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8ea5119cdb4c55b55d432abb513a0429384878c15dde60cc77b1c99de1a95a6a"
 
-[[package]]
-name = "strsim"
-version = "0.10.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "73473c0e59e6d5812c5dfe2a064a6444949f089e20eec9a2e5506596494e4623"
-
 [[package]]
 name = "structopt"
 version = "0.3.25"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "40b9788f4202aa75c240ecc9c15c65185e6a39ccdeb0fd5d008b98825464c87c"
 dependencies = [
- "clap 2.34.0",
+ "clap",
  "lazy_static",
  "structopt-derive",
 ]
@@ -5081,12 +5051,6 @@ dependencies = [
  "unicode-width",
 ]
 
-[[package]]
-name = "textwrap"
-version = "0.14.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0066c8d12af8b5acd21e00547c3797fde4e8677254a7ee429176ccebbe93dd80"
-
 [[package]]
 name = "thiserror"
 version = "1.0.30"

compiler/rustc_ast/src/ast.rs

@@ -224,7 +224,7 @@ pub enum AngleBracketedArg {
     /// Argument for a generic parameter.
     Arg(GenericArg),
     /// Constraint for an associated item.
-    Constraint(AssocTyConstraint),
+    Constraint(AssocConstraint),
 }
 
 impl AngleBracketedArg {
@@ -1843,19 +1843,38 @@ impl UintTy {
 /// A constraint on an associated type (e.g., `A = Bar` in `Foo<A = Bar>` or
 /// `A: TraitA + TraitB` in `Foo<A: TraitA + TraitB>`).
 #[derive(Clone, Encodable, Decodable, Debug)]
-pub struct AssocTyConstraint {
+pub struct AssocConstraint {
     pub id: NodeId,
     pub ident: Ident,
     pub gen_args: Option<GenericArgs>,
-    pub kind: AssocTyConstraintKind,
+    pub kind: AssocConstraintKind,
     pub span: Span,
 }
 
-/// The kinds of an `AssocTyConstraint`.
+/// The kinds of an `AssocConstraint`.
 #[derive(Clone, Encodable, Decodable, Debug)]
-pub enum AssocTyConstraintKind {
-    /// E.g., `A = Bar` in `Foo<A = Bar>`.
-    Equality { ty: P<Ty> },
+pub enum Term {
+    Ty(P<Ty>),
+    Const(AnonConst),
+}
+
+impl From<P<Ty>> for Term {
+    fn from(v: P<Ty>) -> Self {
+        Term::Ty(v)
+    }
+}
+
+impl From<AnonConst> for Term {
+    fn from(v: AnonConst) -> Self {
+        Term::Const(v)
+    }
+}
+
+/// The kinds of an `AssocConstraint`.
+#[derive(Clone, Encodable, Decodable, Debug)]
+pub enum AssocConstraintKind {
+    /// E.g., `A = Bar`, `A = 3` in `Foo<A = Bar>` where A is an associated type.
+    Equality { term: Term },
     /// E.g. `A: TraitA + TraitB` in `Foo<A: TraitA + TraitB>`.
     Bound { bounds: GenericBounds },
 }

compiler/rustc_ast/src/mut_visit.rs

@@ -165,8 +165,8 @@ pub trait MutVisitor: Sized {
         noop_visit_lifetime(l, self);
     }
 
-    fn visit_ty_constraint(&mut self, t: &mut AssocTyConstraint) {
-        noop_visit_ty_constraint(t, self);
+    fn visit_constraint(&mut self, t: &mut AssocConstraint) {
+        noop_visit_constraint(t, self);
     }
 
     fn visit_foreign_mod(&mut self, nm: &mut ForeignMod) {
@@ -430,8 +430,8 @@ pub fn noop_flat_map_arm<T: MutVisitor>(mut arm: Arm, vis: &mut T) -> SmallVec<[
     smallvec![arm]
 }
 
-pub fn noop_visit_ty_constraint<T: MutVisitor>(
-    AssocTyConstraint { id, ident, gen_args, kind, span }: &mut AssocTyConstraint,
+pub fn noop_visit_constraint<T: MutVisitor>(
+    AssocConstraint { id, ident, gen_args, kind, span }: &mut AssocConstraint,
     vis: &mut T,
 ) {
     vis.visit_id(id);
@@ -440,12 +440,11 @@ pub fn noop_visit_ty_constraint<T: MutVisitor>(
         vis.visit_generic_args(gen_args);
     }
     match kind {
-        AssocTyConstraintKind::Equality { ref mut ty } => {
-            vis.visit_ty(ty);
-        }
-        AssocTyConstraintKind::Bound { ref mut bounds } => {
-            visit_bounds(bounds, vis);
-        }
+        AssocConstraintKind::Equality { ref mut term } => match term {
+            Term::Ty(ty) => vis.visit_ty(ty),
+            Term::Const(c) => vis.visit_anon_const(c),
+        },
+        AssocConstraintKind::Bound { ref mut bounds } => visit_bounds(bounds, vis),
     }
     vis.visit_span(span);
 }
@@ -555,7 +554,7 @@ pub fn noop_visit_angle_bracketed_parameter_data<T: MutVisitor>(
     let AngleBracketedArgs { args, span } = data;
     visit_vec(args, |arg| match arg {
         AngleBracketedArg::Arg(arg) => vis.visit_generic_arg(arg),
-        AngleBracketedArg::Constraint(constraint) => vis.visit_ty_constraint(constraint),
+        AngleBracketedArg::Constraint(constraint) => vis.visit_constraint(constraint),
     });
     vis.visit_span(span);
 }

compiler/rustc_ast/src/visit.rs

@@ -190,8 +190,8 @@ pub trait Visitor<'ast>: Sized {
     fn visit_generic_arg(&mut self, generic_arg: &'ast GenericArg) {
         walk_generic_arg(self, generic_arg)
     }
-    fn visit_assoc_ty_constraint(&mut self, constraint: &'ast AssocTyConstraint) {
-        walk_assoc_ty_constraint(self, constraint)
+    fn visit_assoc_constraint(&mut self, constraint: &'ast AssocConstraint) {
+        walk_assoc_constraint(self, constraint)
     }
     fn visit_attribute(&mut self, attr: &'ast Attribute) {
         walk_attribute(self, attr)
@@ -464,7 +464,7 @@ where
             for arg in &data.args {
                 match arg {
                     AngleBracketedArg::Arg(a) => visitor.visit_generic_arg(a),
-                    AngleBracketedArg::Constraint(c) => visitor.visit_assoc_ty_constraint(c),
+                    AngleBracketedArg::Constraint(c) => visitor.visit_assoc_constraint(c),
                 }
             }
         }
@@ -486,19 +486,17 @@ where
     }
 }
 
-pub fn walk_assoc_ty_constraint<'a, V: Visitor<'a>>(
-    visitor: &mut V,
-    constraint: &'a AssocTyConstraint,
-) {
+pub fn walk_assoc_constraint<'a, V: Visitor<'a>>(visitor: &mut V, constraint: &'a AssocConstraint) {
     visitor.visit_ident(constraint.ident);
     if let Some(ref gen_args) = constraint.gen_args {
         visitor.visit_generic_args(gen_args.span(), gen_args);
     }
     match constraint.kind {
-        AssocTyConstraintKind::Equality { ref ty } => {
-            visitor.visit_ty(ty);
-        }
-        AssocTyConstraintKind::Bound { ref bounds } => {
+        AssocConstraintKind::Equality { ref term } => match term {
+            Term::Ty(ty) => visitor.visit_ty(ty),
+            Term::Const(c) => visitor.visit_anon_const(c),
+        },
+        AssocConstraintKind::Bound { ref bounds } => {
             walk_list!(visitor, visit_param_bound, bounds);
         }
     }

compiler/rustc_ast_lowering/src/lib.rs

@@ -960,7 +960,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
     /// returns a `hir::TypeBinding` representing `Item`.
     fn lower_assoc_ty_constraint(
         &mut self,
-        constraint: &AssocTyConstraint,
+        constraint: &AssocConstraint,
         mut itctx: ImplTraitContext<'_, 'hir>,
     ) -> hir::TypeBinding<'hir> {
         debug!("lower_assoc_ty_constraint(constraint={:?}, itctx={:?})", constraint, itctx);
@@ -997,10 +997,14 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         };
 
         let kind = match constraint.kind {
-            AssocTyConstraintKind::Equality { ref ty } => {
-                hir::TypeBindingKind::Equality { ty: self.lower_ty(ty, itctx) }
+            AssocConstraintKind::Equality { ref term } => {
+                let term = match term {
+                    Term::Ty(ref ty) => self.lower_ty(ty, itctx).into(),
+                    Term::Const(ref c) => self.lower_anon_const(c).into(),
+                };
+                hir::TypeBindingKind::Equality { term }
             }
-            AssocTyConstraintKind::Bound { ref bounds } => {
+            AssocConstraintKind::Bound { ref bounds } => {
                 let mut capturable_lifetimes;
                 let mut parent_def_id = self.current_hir_id_owner;
                 // Piggy-back on the `impl Trait` context to figure out the correct behavior.
@@ -1078,7 +1082,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
                             itctx,
                         );
 
-                        hir::TypeBindingKind::Equality { ty }
+                        hir::TypeBindingKind::Equality { term: ty.into() }
                     })
                 } else {
                     // Desugar `AssocTy: Bounds` into a type binding where the

compiler/rustc_ast_lowering/src/path.rs

@@ -420,7 +420,7 @@ impl<'a, 'hir> LoweringContext<'a, 'hir> {
         ty: &'hir hir::Ty<'hir>,
     ) -> hir::TypeBinding<'hir> {
         let ident = Ident::with_dummy_span(hir::FN_OUTPUT_NAME);
-        let kind = hir::TypeBindingKind::Equality { ty };
+        let kind = hir::TypeBindingKind::Equality { term: ty.into() };
         let args = arena_vec![self;];
         let bindings = arena_vec![self;];
         let gen_args = self.arena.alloc(hir::GenericArgs {

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -138,10 +138,10 @@ impl<'a> AstValidator<'a> {
         self.outer_impl_trait = old;
     }
 
-    fn visit_assoc_ty_constraint_from_generic_args(&mut self, constraint: &'a AssocTyConstraint) {
+    fn visit_assoc_constraint_from_generic_args(&mut self, constraint: &'a AssocConstraint) {
         match constraint.kind {
-            AssocTyConstraintKind::Equality { .. } => {}
-            AssocTyConstraintKind::Bound { .. } => {
+            AssocConstraintKind::Equality { .. } => {}
+            AssocConstraintKind::Bound { .. } => {
                 if self.is_assoc_ty_bound_banned {
                     self.err_handler().span_err(
                         constraint.span,
@@ -150,7 +150,7 @@ impl<'a> AstValidator<'a> {
                 }
             }
         }
-        self.visit_assoc_ty_constraint(constraint);
+        self.visit_assoc_constraint(constraint);
     }
 
     // Mirrors `visit::walk_ty`, but tracks relevant state.
@@ -1277,7 +1277,7 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
                         // are allowed to contain nested `impl Trait`.
                         AngleBracketedArg::Constraint(constraint) => {
                             self.with_impl_trait(None, |this| {
-                                this.visit_assoc_ty_constraint_from_generic_args(constraint);
+                                this.visit_assoc_constraint_from_generic_args(constraint);
                             });
                         }
                     }
@@ -1586,12 +1586,12 @@ fn deny_equality_constraints(
                                     let len = assoc_path.segments.len() - 1;
                                     let gen_args = args.as_ref().map(|p| (**p).clone());
                                     // Build `<Bar = RhsTy>`.
-                                    let arg = AngleBracketedArg::Constraint(AssocTyConstraint {
+                                    let arg = AngleBracketedArg::Constraint(AssocConstraint {
                                         id: rustc_ast::node_id::DUMMY_NODE_ID,
                                         ident: *ident,
                                         gen_args,
-                                        kind: AssocTyConstraintKind::Equality {
-                                            ty: predicate.rhs_ty.clone(),
+                                        kind: AssocConstraintKind::Equality {
+                                            term: predicate.rhs_ty.clone().into(),
                                         },
                                         span: ident.span,
                                     });