Auto merge of #124650 - oli-obk:pattern_types_syntax, r=<try>

Create const block DefIds in typeck instead of ast lowering

r? `@ghost`

this is a prerequisite for cleaning up pattern types and the range pattern HIR nodes in general. Right now they contain expressions, but they are supposed to only contain constants. In order to generate the anonymous constants lazily during typeck, we need to support generating new items with bodies during typeck in general. Transforming const blocks was the simplest change I could find to allow us to do that (everything else is much more invasive if we haven't already done it for const blocks).

compiler/rustc_ast/src/ast.rs

@@ -1393,7 +1393,7 @@ pub enum ExprKind {
     /// An array (e.g, `[a, b, c, d]`).
     Array(ThinVec<P<Expr>>),
     /// Allow anonymous constants from an inline `const` block
-    ConstBlock(AnonConst),
+    ConstBlock(P<Expr>),
     /// A function call
     ///
     /// The first field resolves to the function itself,

compiler/rustc_ast/src/mut_visit.rs

@@ -1411,7 +1411,7 @@ pub fn noop_visit_expr<T: MutVisitor>(
     match kind {
         ExprKind::Array(exprs) => visit_thin_exprs(exprs, vis),
         ExprKind::ConstBlock(anon_const) => {
-            vis.visit_anon_const(anon_const);
+            vis.visit_expr(anon_const);
         }
         ExprKind::Repeat(expr, count) => {
             vis.visit_expr(expr);

compiler/rustc_ast/src/visit.rs

@@ -951,7 +951,7 @@ pub fn walk_expr<'a, V: Visitor<'a>>(visitor: &mut V, expression: &'a Expr) -> V
         ExprKind::Array(subexpressions) => {
             walk_list!(visitor, visit_expr, subexpressions);
         }
-        ExprKind::ConstBlock(anon_const) => try_visit!(visitor.visit_anon_const(anon_const)),
+        ExprKind::ConstBlock(anon_const) => try_visit!(visitor.visit_expr(anon_const)),
         ExprKind::Repeat(element, count) => {
             try_visit!(visitor.visit_expr(element));
             try_visit!(visitor.visit_anon_const(count));

compiler/rustc_ast_lowering/src/expr.rs

@@ -74,14 +74,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
 
             let kind = match &e.kind {
                 ExprKind::Array(exprs) => hir::ExprKind::Array(self.lower_exprs(exprs)),
-                ExprKind::ConstBlock(c) => {
-                    let c = self.with_new_scopes(c.value.span, |this| hir::ConstBlock {
-                        def_id: this.local_def_id(c.id),
-                        hir_id: this.lower_node_id(c.id),
-                        body: this.lower_const_body(c.value.span, Some(&c.value)),
-                    });
-                    hir::ExprKind::ConstBlock(c)
-                }
+                ExprKind::ConstBlock(c) => hir::ExprKind::ConstBlock(self.lower_expr(c)),
                 ExprKind::Repeat(expr, count) => {
                     let expr = self.lower_expr(expr);
                     let count = self.lower_array_length(count);

compiler/rustc_ast_lowering/src/index.rs

@@ -236,14 +236,6 @@ impl<'a, 'hir> Visitor<'hir> for NodeCollector<'a, 'hir> {
         });
     }
 
-    fn visit_inline_const(&mut self, constant: &'hir ConstBlock) {
-        self.insert(DUMMY_SP, constant.hir_id, Node::ConstBlock(constant));
-
-        self.with_parent(constant.hir_id, |this| {
-            intravisit::walk_inline_const(this, constant);
-        });
-    }
-
     fn visit_expr(&mut self, expr: &'hir Expr<'hir>) {
         self.insert(expr.span, expr.hir_id, Node::Expr(expr));
 

compiler/rustc_ast_pretty/src/pprust/state/expr.rs

@@ -380,8 +380,9 @@ impl<'a> State<'a> {
             ast::ExprKind::Array(exprs) => {
                 self.print_expr_vec(exprs);
             }
-            ast::ExprKind::ConstBlock(anon_const) => {
-                self.print_expr_anon_const(anon_const, attrs);
+            ast::ExprKind::ConstBlock(expr) => {
+                self.word_space("const");
+                self.print_expr(expr, FixupContext::default());
             }
             ast::ExprKind::Repeat(element, count) => {
                 self.print_expr_repeat(element, count);

compiler/rustc_const_eval/src/const_eval/fn_queries.rs

@@ -38,7 +38,6 @@ fn constness(tcx: TyCtxt<'_>, def_id: LocalDefId) -> hir::Constness {
     match node {
         hir::Node::Ctor(_)
         | hir::Node::AnonConst(_)
-        | hir::Node::ConstBlock(_)
         | hir::Node::ImplItem(hir::ImplItem { kind: hir::ImplItemKind::Const(..), .. }) => {
             hir::Constness::Const
         }

compiler/rustc_const_eval/src/const_eval/machine.rs

@@ -6,7 +6,6 @@ use std::ops::ControlFlow;
 use rustc_ast::Mutability;
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::fx::IndexEntry;
-use rustc_hir::def::DefKind;
 use rustc_hir::def_id::DefId;
 use rustc_hir::def_id::LocalDefId;
 use rustc_hir::LangItem;
@@ -392,18 +391,7 @@ impl<'mir, 'tcx> interpret::Machine<'mir, 'tcx> for CompileTimeInterpreter<'mir,
         instance: ty::InstanceDef<'tcx>,
     ) -> InterpResult<'tcx, &'tcx mir::Body<'tcx>> {
         match instance {
-            ty::InstanceDef::Item(def) => {
-                if ecx.tcx.is_ctfe_mir_available(def) {
-                    Ok(ecx.tcx.mir_for_ctfe(def))
-                } else if ecx.tcx.def_kind(def) == DefKind::AssocConst {
-                    ecx.tcx.dcx().bug("This is likely a const item that is missing from its impl");
-                } else {
-                    // `find_mir_or_eval_fn` checks that this is a const fn before even calling us,
-                    // so this should be unreachable.
-                    let path = ecx.tcx.def_path_str(def);
-                    bug!("trying to call extern function `{path}` at compile-time");
-                }
-            }
+            ty::InstanceDef::Item(def) => Ok(ecx.tcx.mir_for_ctfe(def)),
             _ => Ok(ecx.tcx.instance_mir(instance)),
         }
     }

compiler/rustc_hir/src/hir.rs

@@ -1592,14 +1592,6 @@ pub struct AnonConst {
     pub span: Span,
 }
 
-/// An inline constant expression `const { something }`.
-#[derive(Copy, Clone, Debug, HashStable_Generic)]
-pub struct ConstBlock {
-    pub hir_id: HirId,
-    pub def_id: LocalDefId,
-    pub body: BodyId,
-}
-
 /// An expression.
 #[derive(Debug, Clone, Copy, HashStable_Generic)]
 pub struct Expr<'hir> {
@@ -1886,7 +1878,7 @@ pub fn is_range_literal(expr: &Expr<'_>) -> bool {
 #[derive(Debug, Clone, Copy, HashStable_Generic)]
 pub enum ExprKind<'hir> {
     /// Allow anonymous constants from an inline `const` block
-    ConstBlock(ConstBlock),
+    ConstBlock(&'hir Expr<'hir>),
     /// An array (e.g., `[a, b, c, d]`).
     Array(&'hir [Expr<'hir>]),
     /// A function call.
@@ -3609,7 +3601,6 @@ pub enum Node<'hir> {
     Variant(&'hir Variant<'hir>),
     Field(&'hir FieldDef<'hir>),
     AnonConst(&'hir AnonConst),
-    ConstBlock(&'hir ConstBlock),
     Expr(&'hir Expr<'hir>),
     ExprField(&'hir ExprField<'hir>),
     Stmt(&'hir Stmt<'hir>),
@@ -3670,7 +3661,6 @@ impl<'hir> Node<'hir> {
             Node::PreciseCapturingNonLifetimeArg(a) => Some(a.ident),
             Node::Param(..)
             | Node::AnonConst(..)
-            | Node::ConstBlock(..)
             | Node::Expr(..)
             | Node::Stmt(..)
             | Node::Block(..)
@@ -3768,7 +3758,6 @@ impl<'hir> Node<'hir> {
             }
 
             Node::AnonConst(constant) => Some((constant.def_id, constant.body)),
-            Node::ConstBlock(constant) => Some((constant.def_id, constant.body)),
 
             _ => None,
         }
@@ -3837,7 +3826,6 @@ impl<'hir> Node<'hir> {
         expect_variant,       &'hir Variant<'hir>,      Node::Variant(n),      n;
         expect_field,         &'hir FieldDef<'hir>,     Node::Field(n),        n;
         expect_anon_const,    &'hir AnonConst,          Node::AnonConst(n),    n;
-        expect_inline_const,  &'hir ConstBlock,         Node::ConstBlock(n),   n;
         expect_expr,          &'hir Expr<'hir>,         Node::Expr(n),         n;
         expect_expr_field,    &'hir ExprField<'hir>,    Node::ExprField(n),    n;
         expect_stmt,          &'hir Stmt<'hir>,         Node::Stmt(n),         n;

compiler/rustc_hir/src/intravisit.rs

@@ -344,9 +344,6 @@ pub trait Visitor<'v>: Sized {
     fn visit_anon_const(&mut self, c: &'v AnonConst) -> Self::Result {
         walk_anon_const(self, c)
     }
-    fn visit_inline_const(&mut self, c: &'v ConstBlock) -> Self::Result {
-        walk_inline_const(self, c)
-    }
     fn visit_expr(&mut self, ex: &'v Expr<'v>) -> Self::Result {
         walk_expr(self, ex)
     }
@@ -716,22 +713,14 @@ pub fn walk_anon_const<'v, V: Visitor<'v>>(visitor: &mut V, constant: &'v AnonCo
     visitor.visit_nested_body(constant.body)
 }
 
-pub fn walk_inline_const<'v, V: Visitor<'v>>(
-    visitor: &mut V,
-    constant: &'v ConstBlock,
-) -> V::Result {
-    try_visit!(visitor.visit_id(constant.hir_id));
-    visitor.visit_nested_body(constant.body)
-}
-
 pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr<'v>) -> V::Result {
     try_visit!(visitor.visit_id(expression.hir_id));
     match expression.kind {
         ExprKind::Array(subexpressions) => {
             walk_list!(visitor, visit_expr, subexpressions);
         }
         ExprKind::ConstBlock(ref const_block) => {
-            try_visit!(visitor.visit_inline_const(const_block))
+            try_visit!(visitor.visit_expr(const_block))
         }
         ExprKind::Repeat(ref element, ref count) => {
             try_visit!(visitor.visit_expr(element));

compiler/rustc_hir_analysis/src/check/region.rs

@@ -407,11 +407,14 @@ fn resolve_expr<'tcx>(visitor: &mut RegionResolutionVisitor<'tcx>, expr: &'tcx h
     match expr.kind {
         // Manually recurse over closures and inline consts, because they are the only
         // case of nested bodies that share the parent environment.
-        hir::ExprKind::Closure(&hir::Closure { body, .. })
-        | hir::ExprKind::ConstBlock(hir::ConstBlock { body, .. }) => {
+        hir::ExprKind::Closure(&hir::Closure { body, .. }) => {
             let body = visitor.tcx.hir().body(body);
             visitor.visit_body(body);
         }
+        hir::ExprKind::ConstBlock(expr) => visitor.enter_body(expr.hir_id, |this| {
+            this.cx.var_parent = None;
+            resolve_local(this, None, Some(expr));
+        }),
         hir::ExprKind::AssignOp(_, left_expr, right_expr) => {
             debug!(
                 "resolve_expr - enabling pessimistic_yield, was previously {}",
@@ -782,25 +785,8 @@ impl<'tcx> RegionResolutionVisitor<'tcx> {
         }
         self.enter_scope(Scope { id, data: ScopeData::Node });
     }
-}
-
-impl<'tcx> Visitor<'tcx> for RegionResolutionVisitor<'tcx> {
-    fn visit_block(&mut self, b: &'tcx Block<'tcx>) {
-        resolve_block(self, b);
-    }
-
-    fn visit_body(&mut self, body: &'tcx hir::Body<'tcx>) {
-        let body_id = body.id();
-        let owner_id = self.tcx.hir().body_owner_def_id(body_id);
-
-        debug!(
-            "visit_body(id={:?}, span={:?}, body.id={:?}, cx.parent={:?})",
-            owner_id,
-            self.tcx.sess.source_map().span_to_diagnostic_string(body.value.span),
-            body_id,
-            self.cx.parent
-        );
 
+    fn enter_body(&mut self, hir_id: hir::HirId, f: impl FnOnce(&mut Self)) {
         // Save all state that is specific to the outer function
         // body. These will be restored once down below, once we've
         // visited the body.
@@ -812,50 +798,73 @@ impl<'tcx> Visitor<'tcx> for RegionResolutionVisitor<'tcx> {
         // control flow assumptions. This doesn't apply to nested
         // bodies within the `+=` statements. See #69307.
         let outer_pessimistic_yield = mem::replace(&mut self.pessimistic_yield, false);
-        self.terminating_scopes.insert(body.value.hir_id.local_id);
-
-        self.enter_scope(Scope { id: body.value.hir_id.local_id, data: ScopeData::CallSite });
-        self.enter_scope(Scope { id: body.value.hir_id.local_id, data: ScopeData::Arguments });
+        self.terminating_scopes.insert(hir_id.local_id);
 
-        // The arguments and `self` are parented to the fn.
-        self.cx.var_parent = self.cx.parent.take();
-        for param in body.params {
-            self.visit_pat(param.pat);
-        }
+        self.enter_scope(Scope { id: hir_id.local_id, data: ScopeData::CallSite });
+        self.enter_scope(Scope { id: hir_id.local_id, data: ScopeData::Arguments });
 
-        // The body of the every fn is a root scope.
-        self.cx.parent = self.cx.var_parent;
-        if self.tcx.hir().body_owner_kind(owner_id).is_fn_or_closure() {
-            self.visit_expr(body.value)
-        } else {
-            // Only functions have an outer terminating (drop) scope, while
-            // temporaries in constant initializers may be 'static, but only
-            // according to rvalue lifetime semantics, using the same
-            // syntactical rules used for let initializers.
-            //
-            // e.g., in `let x = &f();`, the temporary holding the result from
-            // the `f()` call lives for the entirety of the surrounding block.
-            //
-            // Similarly, `const X: ... = &f();` would have the result of `f()`
-            // live for `'static`, implying (if Drop restrictions on constants
-            // ever get lifted) that the value *could* have a destructor, but
-            // it'd get leaked instead of the destructor running during the
-            // evaluation of `X` (if at all allowed by CTFE).
-            //
-            // However, `const Y: ... = g(&f());`, like `let y = g(&f());`,
-            // would *not* let the `f()` temporary escape into an outer scope
-            // (i.e., `'static`), which means that after `g` returns, it drops,
-            // and all the associated destruction scope rules apply.
-            self.cx.var_parent = None;
-            resolve_local(self, None, Some(body.value));
-        }
+        f(self);
 
         // Restore context we had at the start.
         self.expr_and_pat_count = outer_ec;
         self.cx = outer_cx;
         self.terminating_scopes = outer_ts;
         self.pessimistic_yield = outer_pessimistic_yield;
     }
+}
+
+impl<'tcx> Visitor<'tcx> for RegionResolutionVisitor<'tcx> {
+    fn visit_block(&mut self, b: &'tcx Block<'tcx>) {
+        resolve_block(self, b);
+    }
+
+    fn visit_body(&mut self, body: &'tcx hir::Body<'tcx>) {
+        let body_id = body.id();
+        let owner_id = self.tcx.hir().body_owner_def_id(body_id);
+
+        debug!(
+            "visit_body(id={:?}, span={:?}, body.id={:?}, cx.parent={:?})",
+            owner_id,
+            self.tcx.sess.source_map().span_to_diagnostic_string(body.value.span),
+            body_id,
+            self.cx.parent
+        );
+
+        self.enter_body(body.value.hir_id, |this| {
+            if this.tcx.hir().body_owner_kind(owner_id).is_fn_or_closure() {
+                // The arguments and `self` are parented to the fn.
+                this.cx.var_parent = this.cx.parent.take();
+                for param in body.params {
+                    this.visit_pat(param.pat);
+                }
+
+                // The body of the every fn is a root scope.
+                this.cx.parent = this.cx.var_parent;
+                this.visit_expr(body.value)
+            } else {
+                // Only functions have an outer terminating (drop) scope, while
+                // temporaries in constant initializers may be 'static, but only
+                // according to rvalue lifetime semantics, using the same
+                // syntactical rules used for let initializers.
+                //
+                // e.g., in `let x = &f();`, the temporary holding the result from
+                // the `f()` call lives for the entirety of the surrounding block.
+                //
+                // Similarly, `const X: ... = &f();` would have the result of `f()`
+                // live for `'static`, implying (if Drop restrictions on constants
+                // ever get lifted) that the value *could* have a destructor, but
+                // it'd get leaked instead of the destructor running during the
+                // evaluation of `X` (if at all allowed by CTFE).
+                //
+                // However, `const Y: ... = g(&f());`, like `let y = g(&f());`,
+                // would *not* let the `f()` temporary escape into an outer scope
+                // (i.e., `'static`), which means that after `g` returns, it drops,
+                // and all the associated destruction scope rules apply.
+                this.cx.var_parent = None;
+                resolve_local(this, None, Some(body.value));
+            }
+        })
+    }
 
     fn visit_arm(&mut self, a: &'tcx Arm<'tcx>) {
         resolve_arm(self, a);

compiler/rustc_hir_analysis/src/collect/generics_of.rs

@@ -177,10 +177,10 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
                 }
             }
         }
-        Node::ConstBlock(_)
-        | Node::Expr(&hir::Expr { kind: hir::ExprKind::Closure { .. }, .. }) => {
-            Some(tcx.typeck_root_def_id(def_id.to_def_id()))
-        }
+        Node::Expr(&hir::Expr {
+            kind: hir::ExprKind::Closure { .. } | hir::ExprKind::ConstBlock { .. },
+            ..
+        }) => Some(tcx.typeck_root_def_id(def_id.to_def_id())),
         Node::Item(item) => match item.kind {
             ItemKind::OpaqueTy(&hir::OpaqueTy {
                 origin:
@@ -414,7 +414,7 @@ pub(super) fn generics_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::Generics {
     }
 
     // provide junk type parameter defs for const blocks.
-    if let Node::ConstBlock(_) = node {
+    if let Node::Expr(Expr { kind: ExprKind::ConstBlock(..), .. }) = node {
         own_params.push(ty::GenericParamDef {
             index: next_index(),
             name: Symbol::intern("<const_ty>"),

compiler/rustc_hir_analysis/src/collect/type_of.rs

@@ -484,8 +484,7 @@ pub(super) fn type_of(tcx: TyCtxt<'_>, def_id: LocalDefId) -> ty::EarlyBinder<Ty
         }
 
         Node::AnonConst(_) => anon_const_type_of(tcx, def_id),
-
-        Node::ConstBlock(_) => {
+        Node::Expr(&Expr { kind: ExprKind::ConstBlock(..), .. }) => {
             let args = ty::GenericArgs::identity_for_item(tcx, def_id.to_def_id());
             args.as_inline_const().ty()
         }