Rollup of 16 pull requests

compiler/rustc_ast/src/util/literal.rs

@@ -23,7 +23,7 @@ pub enum LitError {
 
 impl LitKind {
     /// Converts literal token into a semantic literal.
-    fn from_lit_token(lit: token::Lit) -> Result<LitKind, LitError> {
+    pub fn from_lit_token(lit: token::Lit) -> Result<LitKind, LitError> {
         let token::Lit { kind, symbol, suffix } = lit;
         if suffix.is_some() && !kind.may_have_suffix() {
             return Err(LitError::InvalidSuffix);

compiler/rustc_ast_passes/src/ast_validation.rs

@@ -64,8 +64,8 @@ struct AstValidator<'a> {
     /// certain positions.
     is_assoc_ty_bound_banned: bool,
 
-    /// Used to allow `let` expressions in certain syntactic locations.
-    is_let_allowed: bool,
+    /// See [ForbiddenLetReason]
+    forbidden_let_reason: Option<ForbiddenLetReason>,
 
     lint_buffer: &'a mut LintBuffer,
 }
@@ -103,20 +103,28 @@ impl<'a> AstValidator<'a> {
         self.is_tilde_const_allowed = old;
     }
 
-    fn with_let_allowed(&mut self, allowed: bool, f: impl FnOnce(&mut Self, bool)) {
-        let old = mem::replace(&mut self.is_let_allowed, allowed);
+    fn with_let_management(
+        &mut self,
+        forbidden_let_reason: Option<ForbiddenLetReason>,
+        f: impl FnOnce(&mut Self, Option<ForbiddenLetReason>),
+    ) {
+        let old = mem::replace(&mut self.forbidden_let_reason, forbidden_let_reason);
         f(self, old);
-        self.is_let_allowed = old;
+        self.forbidden_let_reason = old;
     }
 
     /// Emits an error banning the `let` expression provided in the given location.
-    fn ban_let_expr(&self, expr: &'a Expr) {
+    fn ban_let_expr(&self, expr: &'a Expr, forbidden_let_reason: ForbiddenLetReason) {
         let sess = &self.session;
         if sess.opts.unstable_features.is_nightly_build() {
-            sess.struct_span_err(expr.span, "`let` expressions are not supported here")
-                .note("only supported directly in conditions of `if`- and `while`-expressions")
-                .note("as well as when nested within `&&` and parentheses in those conditions")
-                .emit();
+            let err = "`let` expressions are not supported here";
+            let mut diag = sess.struct_span_err(expr.span, err);
+            diag.note("only supported directly in conditions of `if` and `while` expressions");
+            diag.note("as well as when nested within `&&` and parentheses in those conditions");
+            if let ForbiddenLetReason::ForbiddenWithOr(span) = forbidden_let_reason {
+                diag.span_note(span, "`||` operators are not allowed in let chain expressions");
+            }
+            diag.emit();
         } else {
             sess.struct_span_err(expr.span, "expected expression, found statement (`let`)")
                 .note("variable declaration using `let` is a statement")
@@ -988,39 +996,48 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
     }
 
     fn visit_expr(&mut self, expr: &'a Expr) {
-        self.with_let_allowed(false, |this, let_allowed| match &expr.kind {
-            ExprKind::If(cond, then, opt_else) => {
-                this.visit_block(then);
-                walk_list!(this, visit_expr, opt_else);
-                this.with_let_allowed(true, |this, _| this.visit_expr(cond));
-                return;
-            }
-            ExprKind::Let(..) if !let_allowed => this.ban_let_expr(expr),
-            ExprKind::Match(expr, arms) => {
-                this.visit_expr(expr);
-                for arm in arms {
-                    this.visit_expr(&arm.body);
-                    this.visit_pat(&arm.pat);
-                    walk_list!(this, visit_attribute, &arm.attrs);
-                    if let Some(ref guard) = arm.guard {
-                        if let ExprKind::Let(_, ref expr, _) = guard.kind {
-                            this.with_let_allowed(true, |this, _| this.visit_expr(expr));
+        self.with_let_management(Some(ForbiddenLetReason::GenericForbidden), |this, forbidden_let_reason| {
+            match &expr.kind {
+                ExprKind::Binary(Spanned { node: BinOpKind::Or, span }, lhs, rhs) => {
+                    let forbidden_let_reason = Some(ForbiddenLetReason::ForbiddenWithOr(*span));
+                    this.with_let_management(forbidden_let_reason, |this, _| this.visit_expr(lhs));
+                    this.with_let_management(forbidden_let_reason, |this, _| this.visit_expr(rhs));
+                }
+                ExprKind::If(cond, then, opt_else) => {
+                    this.visit_block(then);
+                    walk_list!(this, visit_expr, opt_else);
+                    this.with_let_management(None, |this, _| this.visit_expr(cond));
+                    return;
+                }
+                ExprKind::Let(..) if let Some(elem) = forbidden_let_reason => {
+                    this.ban_let_expr(expr, elem);
+                },
+                ExprKind::Match(scrutinee, arms) => {
+                    this.visit_expr(scrutinee);
+                    for arm in arms {
+                        this.visit_expr(&arm.body);
+                        this.visit_pat(&arm.pat);
+                        walk_list!(this, visit_attribute, &arm.attrs);
+                        if let Some(guard) = &arm.guard && let ExprKind::Let(_, guard_expr, _) = &guard.kind {
+                            this.with_let_management(None, |this, _| {
+                                this.visit_expr(guard_expr)
+                            });
                             return;
                         }
                     }
                 }
+                ExprKind::Paren(_) | ExprKind::Binary(Spanned { node: BinOpKind::And, .. }, ..) => {
+                    this.with_let_management(forbidden_let_reason, |this, _| visit::walk_expr(this, expr));
+                    return;
+                }
+                ExprKind::While(cond, then, opt_label) => {
+                    walk_list!(this, visit_label, opt_label);
+                    this.visit_block(then);
+                    this.with_let_management(None, |this, _| this.visit_expr(cond));
+                    return;
+                }
+                _ => visit::walk_expr(this, expr),
             }
-            ExprKind::Paren(_) | ExprKind::Binary(Spanned { node: BinOpKind::And, .. }, ..) => {
-                this.with_let_allowed(let_allowed, |this, _| visit::walk_expr(this, expr));
-                return;
-            }
-            ExprKind::While(cond, then, opt_label) => {
-                walk_list!(this, visit_label, opt_label);
-                this.visit_block(then);
-                this.with_let_allowed(true, |this, _| this.visit_expr(cond));
-                return;
-            }
-            _ => visit::walk_expr(this, expr),
         });
     }
 
@@ -1772,10 +1789,19 @@ pub fn check_crate(session: &Session, krate: &Crate, lints: &mut LintBuffer) ->
         is_tilde_const_allowed: false,
         is_impl_trait_banned: false,
         is_assoc_ty_bound_banned: false,
-        is_let_allowed: false,
+        forbidden_let_reason: Some(ForbiddenLetReason::GenericForbidden),
         lint_buffer: lints,
     };
     visit::walk_crate(&mut validator, krate);
 
     validator.has_proc_macro_decls
 }
+
+/// Used to forbid `let` expressions in certain syntactic locations.
+#[derive(Clone, Copy)]
+enum ForbiddenLetReason {
+    /// A let chain with the `||` operator
+    ForbiddenWithOr(Span),
+    /// `let` is not valid and the source environment is not important
+    GenericForbidden,
+}

compiler/rustc_ast_passes/src/lib.rs

@@ -4,11 +4,13 @@
 //!
 //! The crate also contains other misc AST visitors, e.g. `node_count` and `show_span`.
 
-#![feature(iter_is_partitioned)]
+#![allow(rustc::potential_query_instability)]
 #![feature(box_patterns)]
+#![feature(if_let_guard)]
+#![feature(iter_is_partitioned)]
+#![feature(let_chains)]
 #![feature(let_else)]
 #![recursion_limit = "256"]
-#![allow(rustc::potential_query_instability)]
 
 pub mod ast_validation;
 pub mod feature_gate;

compiler/rustc_const_eval/src/interpret/eval_context.rs

@@ -164,7 +164,7 @@ pub enum StackPopCleanup {
 }
 
 /// State of a local variable including a memoized layout
-#[derive(Clone, PartialEq, Eq, HashStable)]
+#[derive(Clone, Debug, PartialEq, Eq, HashStable)]
 pub struct LocalState<'tcx, Tag: Provenance = AllocId> {
     pub value: LocalValue<Tag>,
     /// Don't modify if `Some`, this is only used to prevent computing the layout twice
@@ -714,13 +714,15 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         self.size_and_align_of(&mplace.meta, &mplace.layout)
     }
 
+    #[instrument(skip(self, body, return_place, return_to_block), level = "debug")]
     pub fn push_stack_frame(
         &mut self,
         instance: ty::Instance<'tcx>,
         body: &'mir mir::Body<'tcx>,
         return_place: Option<&PlaceTy<'tcx, M::PointerTag>>,
         return_to_block: StackPopCleanup,
     ) -> InterpResult<'tcx> {
+        debug!("body: {:#?}", body);
         // first push a stack frame so we have access to the local substs
         let pre_frame = Frame {
             body,
@@ -824,6 +826,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     /// `Drop` impls for any locals that have been initialized at this point.
     /// The cleanup block ends with a special `Resume` terminator, which will
     /// cause us to continue unwinding.
+    #[instrument(skip(self), level = "debug")]
     pub(super) fn pop_stack_frame(&mut self, unwinding: bool) -> InterpResult<'tcx> {
         info!(
             "popping stack frame ({})",
@@ -876,6 +879,8 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
             return Ok(());
         }
 
+        debug!("locals: {:#?}", frame.locals);
+
         // Cleanup: deallocate all locals that are backed by an allocation.
         for local in &frame.locals {
             self.deallocate_local(local.value)?;
@@ -935,6 +940,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
         Ok(())
     }
 
+    #[instrument(skip(self), level = "debug")]
     fn deallocate_local(&mut self, local: LocalValue<M::PointerTag>) -> InterpResult<'tcx> {
         if let LocalValue::Live(Operand::Indirect(MemPlace { ptr, .. })) = local {
             // All locals have a backing allocation, even if the allocation is empty

compiler/rustc_const_eval/src/interpret/intern.rs

@@ -359,6 +359,8 @@ pub fn intern_const_alloc_recursive<
     // pointers, ... So we can't intern them according to their type rules
 
     let mut todo: Vec<_> = leftover_allocations.iter().cloned().collect();
+    debug!(?todo);
+    debug!("dead_alloc_map: {:#?}", ecx.memory.dead_alloc_map);
     while let Some(alloc_id) = todo.pop() {
         if let Some((_, mut alloc)) = ecx.memory.alloc_map.remove(&alloc_id) {
             // We can't call the `intern_shallow` method here, as its logic is tailored to safe

compiler/rustc_const_eval/src/interpret/memory.rs

@@ -275,6 +275,7 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
         Ok(new_ptr)
     }
 
+    #[instrument(skip(self), level = "debug")]
     pub fn deallocate(
         &mut self,
         ptr: Pointer<Option<M::PointerTag>>,
@@ -305,6 +306,8 @@ impl<'mir, 'tcx, M: Machine<'mir, 'tcx>> Memory<'mir, 'tcx, M> {
             .into());
         };
 
+        debug!(?alloc);
+
         if alloc.mutability == Mutability::Not {
             throw_ub_format!("deallocating immutable allocation {}", alloc_id);
         }

compiler/rustc_expand/src/lib.rs

@@ -3,6 +3,7 @@
 #![feature(crate_visibility_modifier)]
 #![feature(decl_macro)]
 #![feature(if_let_guard)]
+#![feature(let_chains)]
 #![feature(let_else)]
 #![feature(proc_macro_diagnostic)]
 #![feature(proc_macro_internals)]

compiler/rustc_expand/src/mbe.rs

@@ -6,17 +6,17 @@
 crate mod macro_check;
 crate mod macro_parser;
 crate mod macro_rules;
+crate mod metavar_expr;
 crate mod quoted;
 crate mod transcribe;
 
+use metavar_expr::MetaVarExpr;
 use rustc_ast::token::{self, NonterminalKind, Token, TokenKind};
 use rustc_ast::tokenstream::DelimSpan;
-
+use rustc_data_structures::sync::Lrc;
 use rustc_span::symbol::Ident;
 use rustc_span::Span;
 
-use rustc_data_structures::sync::Lrc;
-
 /// Contains the sub-token-trees of a "delimited" token tree, such as the contents of `(`. Note
 /// that the delimiter itself might be `NoDelim`.
 #[derive(Clone, PartialEq, Encodable, Decodable, Debug)]
@@ -73,8 +73,8 @@ enum KleeneOp {
     ZeroOrOne,
 }
 
-/// Similar to `tokenstream::TokenTree`, except that `$i`, `$i:ident`, and `$(...)`
-/// are "first-class" token trees. Useful for parsing macros.
+/// Similar to `tokenstream::TokenTree`, except that `$i`, `$i:ident`, `$(...)`,
+/// and `${...}` are "first-class" token trees. Useful for parsing macros.
 #[derive(Debug, Clone, PartialEq, Encodable, Decodable)]
 enum TokenTree {
     Token(Token),
@@ -85,6 +85,8 @@ enum TokenTree {
     MetaVar(Span, Ident),
     /// e.g., `$var:expr`. This is only used in the left hand side of MBE macros.
     MetaVarDecl(Span, Ident /* name to bind */, Option<NonterminalKind>),
+    /// A meta-variable expression inside `${...}`
+    MetaVarExpr(DelimSpan, MetaVarExpr),
 }
 
 impl TokenTree {
@@ -139,7 +141,9 @@ impl TokenTree {
             TokenTree::Token(Token { span, .. })
             | TokenTree::MetaVar(span, _)
             | TokenTree::MetaVarDecl(span, _, _) => span,
-            TokenTree::Delimited(span, _) | TokenTree::Sequence(span, _) => span.entire(),
+            TokenTree::Delimited(span, _)
+            | TokenTree::MetaVarExpr(span, _)
+            | TokenTree::Sequence(span, _) => span.entire(),
         }
     }
 

compiler/rustc_expand/src/mbe/macro_check.rs

@@ -278,6 +278,8 @@ fn check_binders(
                 binders.insert(name, BinderInfo { span, ops: ops.into() });
             }
         }
+        // `MetaVarExpr` can not appear in the LHS of a macro arm
+        TokenTree::MetaVarExpr(..) => {}
         TokenTree::Delimited(_, ref del) => {
             for tt in &del.tts {
                 check_binders(sess, node_id, tt, macros, binders, ops, valid);
@@ -335,6 +337,8 @@ fn check_occurrences(
             let name = MacroRulesNormalizedIdent::new(name);
             check_ops_is_prefix(sess, node_id, macros, binders, ops, span, name);
         }
+        // FIXME(c410-f3r) Check token (https://github.com/rust-lang/rust/issues/93902)
+        TokenTree::MetaVarExpr(..) => {}
         TokenTree::Delimited(_, ref del) => {
             check_nested_occurrences(sess, node_id, &del.tts, macros, binders, ops, valid);
         }

compiler/rustc_expand/src/mbe/macro_parser.rs

@@ -200,7 +200,7 @@ struct MatcherPos<'root, 'tt> {
 
 // This type is used a lot. Make sure it doesn't unintentionally get bigger.
 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
-rustc_data_structures::static_assert_size!(MatcherPos<'_, '_>, 192);
+rustc_data_structures::static_assert_size!(MatcherPos<'_, '_>, 240);
 
 impl<'root, 'tt> MatcherPos<'root, 'tt> {
     /// Generates the top-level matcher position in which the "dot" is before the first token of
@@ -321,10 +321,13 @@ pub(super) fn count_names(ms: &[TokenTree]) -> usize {
     ms.iter().fold(0, |count, elt| {
         count
             + match *elt {
-                TokenTree::Sequence(_, ref seq) => seq.num_captures,
                 TokenTree::Delimited(_, ref delim) => count_names(&delim.tts),
                 TokenTree::MetaVar(..) => 0,
                 TokenTree::MetaVarDecl(..) => 1,
+                // FIXME(c410-f3r) MetaVarExpr should be handled instead of being ignored
+                // https://github.com/rust-lang/rust/issues/9390
+                TokenTree::MetaVarExpr(..) => 0,
+                TokenTree::Sequence(_, ref seq) => seq.num_captures,
                 TokenTree::Token(..) => 0,
             }
     })
@@ -436,7 +439,9 @@ fn nameize<I: Iterator<Item = NamedMatch>>(
                 }
                 Occupied(..) => return Err((sp, format!("duplicated bind name: {}", bind_name))),
             },
-            TokenTree::MetaVar(..) | TokenTree::Token(..) => (),
+            // FIXME(c410-f3r) MetaVar and MetaVarExpr should be handled instead of being ignored
+            // https://github.com/rust-lang/rust/issues/9390
+            TokenTree::MetaVar(..) | TokenTree::MetaVarExpr(..) | TokenTree::Token(..) => {}
         }
 
         Ok(())
@@ -650,7 +655,7 @@ fn inner_parse_loop<'root, 'tt>(
                 // rules. NOTE that this is not necessarily an error unless _all_ items in
                 // `cur_items` end up doing this. There may still be some other matchers that do
                 // end up working out.
-                TokenTree::Token(..) | TokenTree::MetaVar(..) => {}
+                TokenTree::Token(..) | TokenTree::MetaVar(..) | TokenTree::MetaVarExpr(..) => {}
             }
         }
     }