Auto merge of #142614 - workingjubilee:rollup-g5qf7y3, r=workingjubilee

Rollup of 10 pull requests

Successful merges:

 - #138538 (Make performance description of String::{insert,insert_str,remove} more precise)
 - #141946 (std: refactor explanation of `NonNull`)
 - #142216 (Miscellaneous RefCell cleanups)
 - #142371 (avoid `&mut P<T>` in `visit_expr` etc methods)
 - #142377 (Try unremapping compiler sources)
 - #142517 (Windows: Use anonymous pipes in Command)
 - #142542 (Manually invalidate caches in SimplifyCfg.)
 - #142563 (Refine run-make test ignores due to unpredictable `i686-pc-windows-gnu` unwind mechanism)
 - #142570 (Reject union default field values)
 - #142584 (Handle same-crate macro for borrowck semicolon suggestion)

r? `@ghost`
`@rustbot` modify labels: rollup

Author: bors

compiler/rustc_ast/src/ast.rs

@@ -710,6 +710,12 @@ impl Pat {
     }
 }
 
+impl From<P<Pat>> for Pat {
+    fn from(value: P<Pat>) -> Self {
+        *value
+    }
+}
+
 /// A single field in a struct pattern.
 ///
 /// Patterns like the fields of `Foo { x, ref y, ref mut z }`
@@ -1553,17 +1559,23 @@ impl Expr {
         )
     }
 
-    /// Creates a dummy `P<Expr>`.
+    /// Creates a dummy `Expr`.
     ///
     /// Should only be used when it will be replaced afterwards or as a return value when an error was encountered.
-    pub fn dummy() -> P<Expr> {
-        P(Expr {
+    pub fn dummy() -> Expr {
+        Expr {
             id: DUMMY_NODE_ID,
             kind: ExprKind::Dummy,
             span: DUMMY_SP,
             attrs: ThinVec::new(),
             tokens: None,
-        })
+        }
+    }
+}
+
+impl From<P<Expr>> for Expr {
+    fn from(value: P<Expr>) -> Self {
+        *value
     }
 }
 
@@ -2374,6 +2386,12 @@ impl Clone for Ty {
     }
 }
 
+impl From<P<Ty>> for Ty {
+    fn from(value: P<Ty>) -> Self {
+        *value
+    }
+}
+
 impl Ty {
     pub fn peel_refs(&self) -> &Self {
         let mut final_ty = self;

compiler/rustc_ast/src/mut_visit.rs

@@ -168,15 +168,15 @@ pub trait MutVisitor: Sized + MutVisitorResult<Result = ()> {
         walk_flat_map_arm(self, arm)
     }
 
-    fn visit_pat(&mut self, p: &mut P<Pat>) {
+    fn visit_pat(&mut self, p: &mut Pat) {
         walk_pat(self, p);
     }
 
     fn visit_anon_const(&mut self, c: &mut AnonConst) {
         walk_anon_const(self, c);
     }
 
-    fn visit_expr(&mut self, e: &mut P<Expr>) {
+    fn visit_expr(&mut self, e: &mut Expr) {
         walk_expr(self, e);
     }
 
@@ -194,7 +194,7 @@ pub trait MutVisitor: Sized + MutVisitorResult<Result = ()> {
         walk_generic_arg(self, arg);
     }
 
-    fn visit_ty(&mut self, t: &mut P<Ty>) {
+    fn visit_ty(&mut self, t: &mut Ty) {
         walk_ty(self, t);
     }
 

compiler/rustc_ast_lowering/messages.ftl

@@ -179,6 +179,8 @@ ast_lowering_underscore_expr_lhs_assign =
     in expressions, `_` can only be used on the left-hand side of an assignment
     .label = `_` not allowed here
 
+ast_lowering_union_default_field_values = unions cannot have default field values
+
 ast_lowering_unstable_inline_assembly = inline assembly is not stable yet on this architecture
 ast_lowering_unstable_inline_assembly_label_operand_with_outputs =
     using both label and output operands for inline assembly is unstable

compiler/rustc_ast_lowering/src/errors.rs

@@ -475,3 +475,10 @@ pub(crate) struct UseConstGenericArg {
     #[suggestion_part(code = "{other_args}")]
     pub call_args: Span,
 }
+
+#[derive(Diagnostic)]
+#[diag(ast_lowering_union_default_field_values)]
+pub(crate) struct UnionWithDefault {
+    #[primary_span]
+    pub span: Span,
+}

compiler/rustc_ast_lowering/src/item.rs

@@ -17,6 +17,7 @@ use tracing::instrument;
 
 use super::errors::{
     InvalidAbi, InvalidAbiSuggestion, MisplacedRelaxTraitBound, TupleStructWithDefault,
+    UnionWithDefault,
 };
 use super::stability::{enabled_names, gate_unstable_abi};
 use super::{
@@ -316,7 +317,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
                     |this| {
                         this.arena.alloc_from_iter(
-                            enum_definition.variants.iter().map(|x| this.lower_variant(x)),
+                            enum_definition.variants.iter().map(|x| this.lower_variant(i, x)),
                         )
                     },
                 );
@@ -328,7 +329,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     generics,
                     id,
                     ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
-                    |this| this.lower_variant_data(hir_id, struct_def),
+                    |this| this.lower_variant_data(hir_id, i, struct_def),
                 );
                 hir::ItemKind::Struct(ident, generics, struct_def)
             }
@@ -338,7 +339,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
                     generics,
                     id,
                     ImplTraitContext::Disallowed(ImplTraitPosition::Generic),
-                    |this| this.lower_variant_data(hir_id, vdata),
+                    |this| this.lower_variant_data(hir_id, i, vdata),
                 );
                 hir::ItemKind::Union(ident, generics, vdata)
             }
@@ -714,13 +715,13 @@ impl<'hir> LoweringContext<'_, 'hir> {
         }
     }
 
-    fn lower_variant(&mut self, v: &Variant) -> hir::Variant<'hir> {
+    fn lower_variant(&mut self, item_kind: &ItemKind, v: &Variant) -> hir::Variant<'hir> {
         let hir_id = self.lower_node_id(v.id);
         self.lower_attrs(hir_id, &v.attrs, v.span);
         hir::Variant {
             hir_id,
             def_id: self.local_def_id(v.id),
-            data: self.lower_variant_data(hir_id, &v.data),
+            data: self.lower_variant_data(hir_id, item_kind, &v.data),
             disr_expr: v.disr_expr.as_ref().map(|e| self.lower_anon_const_to_anon_const(e)),
             ident: self.lower_ident(v.ident),
             span: self.lower_span(v.span),
@@ -730,15 +731,36 @@ impl<'hir> LoweringContext<'_, 'hir> {
     fn lower_variant_data(
         &mut self,
         parent_id: hir::HirId,
+        item_kind: &ItemKind,
         vdata: &VariantData,
     ) -> hir::VariantData<'hir> {
         match vdata {
-            VariantData::Struct { fields, recovered } => hir::VariantData::Struct {
-                fields: self
+            VariantData::Struct { fields, recovered } => {
+                let fields = self
                     .arena
-                    .alloc_from_iter(fields.iter().enumerate().map(|f| self.lower_field_def(f))),
-                recovered: *recovered,
-            },
+                    .alloc_from_iter(fields.iter().enumerate().map(|f| self.lower_field_def(f)));
+
+                if let ItemKind::Union(..) = item_kind {
+                    for field in &fields[..] {
+                        if let Some(default) = field.default {
+                            // Unions cannot derive `Default`, and it's not clear how to use default
+                            // field values of unions if that was supported. Therefore, blanket reject
+                            // trying to use field values with unions.
+                            if self.tcx.features().default_field_values() {
+                                self.dcx().emit_err(UnionWithDefault { span: default.span });
+                            } else {
+                                let _ = self.dcx().span_delayed_bug(
+                                default.span,
+                                "expected union default field values feature gate error but none \
+                                was produced",
+                            );
+                            }
+                        }
+                    }
+                }
+
+                hir::VariantData::Struct { fields, recovered: *recovered }
+            }
             VariantData::Tuple(fields, id) => {
                 let ctor_id = self.lower_node_id(*id);
                 self.alias_attrs(ctor_id, parent_id);

compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs

@@ -342,10 +342,7 @@ impl<'tcx> BorrowExplanation<'tcx> {
                                 }
                             }
                         } else if let LocalInfo::BlockTailTemp(info) = local_decl.local_info() {
-                            let sp = info
-                                .span
-                                .find_ancestor_in_same_ctxt(local_decl.source_info.span)
-                                .unwrap_or(info.span);
+                            let sp = info.span.find_oldest_ancestor_in_same_ctxt();
                             if info.tail_result_is_ignored {
                                 // #85581: If the first mutable borrow's scope contains
                                 // the second borrow, this suggestion isn't helpful.

compiler/rustc_builtin_macros/src/cfg_eval.rs

@@ -155,7 +155,7 @@ impl CfgEval<'_> {
 
 impl MutVisitor for CfgEval<'_> {
     #[instrument(level = "trace", skip(self))]
-    fn visit_expr(&mut self, expr: &mut P<ast::Expr>) {
+    fn visit_expr(&mut self, expr: &mut ast::Expr) {
         self.0.configure_expr(expr, false);
         mut_visit::walk_expr(self, expr);
     }

compiler/rustc_builtin_macros/src/deriving/coerce_pointee.rs

@@ -1,5 +1,4 @@
 use ast::HasAttrs;
-use ast::ptr::P;
 use rustc_ast::mut_visit::MutVisitor;
 use rustc_ast::visit::BoundKind;
 use rustc_ast::{
@@ -378,11 +377,11 @@ struct TypeSubstitution<'a> {
 }
 
 impl<'a> ast::mut_visit::MutVisitor for TypeSubstitution<'a> {
-    fn visit_ty(&mut self, ty: &mut P<ast::Ty>) {
+    fn visit_ty(&mut self, ty: &mut ast::Ty) {
         if let Some(name) = ty.kind.is_simple_path()
             && name == self.from_name
         {
-            **ty = self.to_ty.clone();
+            *ty = self.to_ty.clone();
             self.rewritten = true;
         } else {
             ast::mut_visit::walk_ty(self, ty);

compiler/rustc_expand/src/expand.rs

@@ -1768,7 +1768,7 @@ impl InvocationCollectorNode for ast::Crate {
     }
 }
 
-impl InvocationCollectorNode for P<ast::Ty> {
+impl InvocationCollectorNode for ast::Ty {
     type OutputTy = P<ast::Ty>;
     const KIND: AstFragmentKind = AstFragmentKind::Ty;
     fn to_annotatable(self) -> Annotatable {
@@ -1791,7 +1791,7 @@ impl InvocationCollectorNode for P<ast::Ty> {
     }
 }
 
-impl InvocationCollectorNode for P<ast::Pat> {
+impl InvocationCollectorNode for ast::Pat {
     type OutputTy = P<ast::Pat>;
     const KIND: AstFragmentKind = AstFragmentKind::Pat;
     fn to_annotatable(self) -> Annotatable {
@@ -1814,11 +1814,11 @@ impl InvocationCollectorNode for P<ast::Pat> {
     }
 }
 
-impl InvocationCollectorNode for P<ast::Expr> {
+impl InvocationCollectorNode for ast::Expr {
     type OutputTy = P<ast::Expr>;
     const KIND: AstFragmentKind = AstFragmentKind::Expr;
     fn to_annotatable(self) -> Annotatable {
-        Annotatable::Expr(self)
+        Annotatable::Expr(P(self))
     }
     fn fragment_to_output(fragment: AstFragment) -> Self::OutputTy {
         fragment.make_expr()
@@ -1955,37 +1955,37 @@ impl DummyAstNode for ast::Crate {
     }
 }
 
-impl DummyAstNode for P<ast::Ty> {
+impl DummyAstNode for ast::Ty {
     fn dummy() -> Self {
-        P(ast::Ty {
+        ast::Ty {
             id: DUMMY_NODE_ID,
             kind: TyKind::Dummy,
             span: Default::default(),
             tokens: Default::default(),
-        })
+        }
     }
 }
 
-impl DummyAstNode for P<ast::Pat> {
+impl DummyAstNode for ast::Pat {
     fn dummy() -> Self {
-        P(ast::Pat {
+        ast::Pat {
             id: DUMMY_NODE_ID,
             kind: PatKind::Wild,
             span: Default::default(),
             tokens: Default::default(),
-        })
+        }
     }
 }
 
-impl DummyAstNode for P<ast::Expr> {
+impl DummyAstNode for ast::Expr {
     fn dummy() -> Self {
         ast::Expr::dummy()
     }
 }
 
 impl DummyAstNode for AstNodeWrapper<P<ast::Expr>, MethodReceiverTag> {
     fn dummy() -> Self {
-        AstNodeWrapper::new(ast::Expr::dummy(), MethodReceiverTag)
+        AstNodeWrapper::new(P(ast::Expr::dummy()), MethodReceiverTag)
     }
 }
 
@@ -2272,7 +2272,7 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
         }
     }
 
-    fn visit_node<Node: InvocationCollectorNode<OutputTy = Node> + DummyAstNode>(
+    fn visit_node<Node: InvocationCollectorNode<OutputTy: Into<Node>> + DummyAstNode>(
         &mut self,
         node: &mut Node,
     ) {
@@ -2297,14 +2297,15 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                         *node = self
                             .collect_attr((attr, pos, derives), n.to_annotatable(), Node::KIND)
                             .make_ast::<Node>()
+                            .into()
                     }
                 },
                 None if node.is_mac_call() => {
                     let n = mem::replace(node, Node::dummy());
                     let (mac, attrs, _) = n.take_mac_call();
                     self.check_attributes(&attrs, &mac);
 
-                    *node = self.collect_bang(mac, Node::KIND).make_ast::<Node>()
+                    *node = self.collect_bang(mac, Node::KIND).make_ast::<Node>().into()
                 }
                 None if node.delegation().is_some() => unreachable!(),
                 None => {
@@ -2414,15 +2415,15 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
         self.visit_node(node)
     }
 
-    fn visit_ty(&mut self, node: &mut P<ast::Ty>) {
+    fn visit_ty(&mut self, node: &mut ast::Ty) {
         self.visit_node(node)
     }
 
-    fn visit_pat(&mut self, node: &mut P<ast::Pat>) {
+    fn visit_pat(&mut self, node: &mut ast::Pat) {
         self.visit_node(node)
     }
 
-    fn visit_expr(&mut self, node: &mut P<ast::Expr>) {
+    fn visit_expr(&mut self, node: &mut ast::Expr) {
         // FIXME: Feature gating is performed inconsistently between `Expr` and `OptExpr`.
         if let Some(attr) = node.attrs.first() {
             self.cfg().maybe_emit_expr_attr_err(attr);

compiler/rustc_expand/src/placeholders.rs

@@ -332,9 +332,9 @@ impl MutVisitor for PlaceholderExpander {
         }
     }
 
-    fn visit_expr(&mut self, expr: &mut P<ast::Expr>) {
+    fn visit_expr(&mut self, expr: &mut ast::Expr) {
         match expr.kind {
-            ast::ExprKind::MacCall(_) => *expr = self.remove(expr.id).make_expr(),
+            ast::ExprKind::MacCall(_) => *expr = *self.remove(expr.id).make_expr(),
             _ => walk_expr(self, expr),
         }
     }
@@ -399,16 +399,16 @@ impl MutVisitor for PlaceholderExpander {
         stmts
     }
 
-    fn visit_pat(&mut self, pat: &mut P<ast::Pat>) {
+    fn visit_pat(&mut self, pat: &mut ast::Pat) {
         match pat.kind {
-            ast::PatKind::MacCall(_) => *pat = self.remove(pat.id).make_pat(),
+            ast::PatKind::MacCall(_) => *pat = *self.remove(pat.id).make_pat(),
             _ => walk_pat(self, pat),
         }
     }
 
-    fn visit_ty(&mut self, ty: &mut P<ast::Ty>) {
+    fn visit_ty(&mut self, ty: &mut ast::Ty) {
         match ty.kind {
-            ast::TyKind::MacCall(_) => *ty = self.remove(ty.id).make_ty(),
+            ast::TyKind::MacCall(_) => *ty = *self.remove(ty.id).make_ty(),
             _ => walk_ty(self, ty),
         }
     }