Rollup of 8 pull requests

Cargo.lock

@@ -3736,8 +3736,6 @@ dependencies = [
 name = "rustc_const_eval"
 version = "0.0.0"
 dependencies = [
- "either",
- "gsgdt",
  "rustc_apfloat",
  "rustc_ast",
  "rustc_attr",

compiler/rustc_const_eval/Cargo.toml

@@ -7,8 +7,6 @@ edition = "2021"
 doctest = false
 
 [dependencies]
-either = "1.5.0"
-gsgdt = "0.1.2"
 tracing = "0.1"
 rustc_apfloat = { path = "../rustc_apfloat" }
 rustc_ast = { path = "../rustc_ast" }

compiler/rustc_const_eval/src/interpret/operand.rs

@@ -618,6 +618,7 @@ impl<'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> InterpCx<'mir, 'tcx, M> {
     }
 
     /// Read discriminant, return the runtime value as well as the variant index.
+    /// Can also legally be called on non-enums (e.g. through the discriminant_value intrinsic)!
     pub fn read_discriminant(
         &self,
         op: &OpTy<'tcx, M::PointerTag>,

compiler/rustc_const_eval/src/interpret/place.rs

@@ -988,10 +988,23 @@ where
         variant_index: VariantIdx,
         dest: &PlaceTy<'tcx, M::PointerTag>,
     ) -> InterpResult<'tcx> {
+        // This must be an enum or generator.
+        match dest.layout.ty.kind() {
+            ty::Adt(adt, _) => assert!(adt.is_enum()),
+            ty::Generator(..) => {}
+            _ => span_bug!(
+                self.cur_span(),
+                "write_discriminant called on non-variant-type (neither enum nor generator)"
+            ),
+        }
         // Layout computation excludes uninhabited variants from consideration
         // therefore there's no way to represent those variants in the given layout.
+        // Essentially, uninhabited variants do not have a tag that corresponds to their
+        // discriminant, so we cannot do anything here.
+        // When evaluating we will always error before even getting here, but ConstProp 'executes'
+        // dead code, so we cannot ICE here.
         if dest.layout.for_variant(self, variant_index).abi.is_uninhabited() {
-            throw_ub!(Unreachable);
+            throw_ub!(UninhabitedEnumVariantWritten)
         }
 
         match dest.layout.variants {

compiler/rustc_error_codes/src/error_codes.rs

@@ -92,6 +92,7 @@ E0164: include_str!("./error_codes/E0164.md"),
 E0165: include_str!("./error_codes/E0165.md"),
 E0170: include_str!("./error_codes/E0170.md"),
 E0178: include_str!("./error_codes/E0178.md"),
+E0183: include_str!("./error_codes/E0183.md"),
 E0184: include_str!("./error_codes/E0184.md"),
 E0185: include_str!("./error_codes/E0185.md"),
 E0186: include_str!("./error_codes/E0186.md"),
@@ -513,7 +514,6 @@ E0785: include_str!("./error_codes/E0785.md"),
 //  E0173, // manual implementations of unboxed closure traits are experimental
 //  E0174,
 //  E0182, // merged into E0229
-    E0183,
 //  E0187, // cannot infer the kind of the closure
 //  E0188, // can not cast an immutable reference to a mutable pointer
 //  E0189, // deprecated: can only cast a boxed pointer to a boxed object

compiler/rustc_error_codes/src/error_codes/E0183.md

@@ -0,0 +1,39 @@
+Manual implemetation of a `Fn*` trait.
+
+Erroneous code example:
+
+```compile_fail,E0183
+struct MyClosure {
+    foo: i32
+}
+
+impl FnOnce<()> for MyClosure {  // error
+    type Output = ();
+    extern "rust-call" fn call_once(self, args: ()) -> Self::Output {
+        println!("{}", self.foo);
+    }
+}
+```
+
+Manually implementing `Fn`, `FnMut` or `FnOnce` is unstable
+and requires `#![feature(fn_traits, unboxed_closures)]`.
+
+```
+#![feature(fn_traits, unboxed_closures)]
+
+struct MyClosure {
+    foo: i32
+}
+
+impl FnOnce<()> for MyClosure {  // ok!
+    type Output = ();
+    extern "rust-call" fn call_once(self, args: ()) -> Self::Output {
+        println!("{}", self.foo);
+    }
+}
+```
+
+The argumements must be a tuple representing the argument list.
+For more info, see the [tracking issue][iss29625]:
+
+[iss29625]: https://github.com/rust-lang/rust/issues/29625

compiler/rustc_expand/src/expand.rs

@@ -1024,12 +1024,10 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
         placeholder(fragment_kind, NodeId::placeholder_from_expn_id(expn_id), vis)
     }
 
-    fn collect_bang(
-        &mut self,
-        mac: ast::MacCall,
-        span: Span,
-        kind: AstFragmentKind,
-    ) -> AstFragment {
+    fn collect_bang(&mut self, mac: ast::MacCall, kind: AstFragmentKind) -> AstFragment {
+        // cache the macro call span so that it can be
+        // easily adjusted for incremental compilation
+        let span = mac.span();
         self.collect(kind, InvocationKind::Bang { mac, span })
     }
 
@@ -1087,25 +1085,19 @@ impl<'a, 'b> InvocationCollector<'a, 'b> {
                 let MacCallStmt { mac, style, attrs, .. } = mac.into_inner();
                 Ok((style == MacStmtStyle::Semicolon, mac, attrs.into()))
             }
-            StmtKind::Item(ref item) if matches!(item.kind, ItemKind::MacCall(..)) => {
-                match stmt.kind {
-                    StmtKind::Item(item) => match item.into_inner() {
-                        ast::Item { kind: ItemKind::MacCall(mac), attrs, .. } => {
-                            Ok((mac.args.need_semicolon(), mac, attrs))
-                        }
-                        _ => unreachable!(),
-                    },
+            StmtKind::Item(item) if matches!(item.kind, ItemKind::MacCall(..)) => {
+                match item.into_inner() {
+                    ast::Item { kind: ItemKind::MacCall(mac), attrs, .. } => {
+                        Ok((mac.args.need_semicolon(), mac, attrs))
+                    }
                     _ => unreachable!(),
                 }
             }
-            StmtKind::Semi(ref expr) if matches!(expr.kind, ast::ExprKind::MacCall(..)) => {
-                match stmt.kind {
-                    StmtKind::Semi(expr) => match expr.into_inner() {
-                        ast::Expr { kind: ast::ExprKind::MacCall(mac), attrs, .. } => {
-                            Ok((mac.args.need_semicolon(), mac, attrs.into()))
-                        }
-                        _ => unreachable!(),
-                    },
+            StmtKind::Semi(expr) if matches!(expr.kind, ast::ExprKind::MacCall(..)) => {
+                match expr.into_inner() {
+                    ast::Expr { kind: ast::ExprKind::MacCall(mac), attrs, .. } => {
+                        Ok((mac.args.need_semicolon(), mac, attrs.into()))
+                    }
                     _ => unreachable!(),
                 }
             }
@@ -1222,7 +1214,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
 
             if let ast::ExprKind::MacCall(mac) = expr.kind {
                 self.check_attributes(&expr.attrs, &mac);
-                self.collect_bang(mac, expr.span, AstFragmentKind::Expr).make_expr().into_inner()
+                self.collect_bang(mac, AstFragmentKind::Expr).make_expr().into_inner()
             } else {
                 assign_id!(self, &mut expr.id, || {
                     ensure_sufficient_stack(|| noop_visit_expr(&mut expr, self));
@@ -1318,7 +1310,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
 
             if let ast::ExprKind::MacCall(mac) = expr.kind {
                 self.check_attributes(&expr.attrs, &mac);
-                self.collect_bang(mac, expr.span, AstFragmentKind::OptExpr)
+                self.collect_bang(mac, AstFragmentKind::OptExpr)
                     .make_opt_expr()
                     .map(|expr| expr.into_inner())
             } else {
@@ -1339,9 +1331,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
         }
 
         visit_clobber(pat, |mut pat| match mem::replace(&mut pat.kind, PatKind::Wild) {
-            PatKind::MacCall(mac) => {
-                self.collect_bang(mac, pat.span, AstFragmentKind::Pat).make_pat()
-            }
+            PatKind::MacCall(mac) => self.collect_bang(mac, AstFragmentKind::Pat).make_pat(),
             _ => unreachable!(),
         });
     }
@@ -1360,12 +1350,10 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
                     .make_stmts();
             }
 
-            let span = stmt.span;
             match self.take_stmt_bang(stmt) {
                 Ok((add_semicolon, mac, attrs)) => {
                     self.check_attributes(&attrs, &mac);
-                    let mut stmts =
-                        self.collect_bang(mac, span, AstFragmentKind::Stmts).make_stmts();
+                    let mut stmts = self.collect_bang(mac, AstFragmentKind::Stmts).make_stmts();
 
                     // If this is a macro invocation with a semicolon, then apply that
                     // semicolon to the final statement produced by expansion.
@@ -1433,7 +1421,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
                 item.attrs = attrs;
                 item.and_then(|item| match item.kind {
                     ItemKind::MacCall(mac) => {
-                        self.collect_bang(mac, span, AstFragmentKind::Items).make_items()
+                        self.collect_bang(mac, AstFragmentKind::Items).make_items()
                     }
                     _ => unreachable!(),
                 })
@@ -1542,9 +1530,9 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
             ast::AssocItemKind::MacCall(ref mac) => {
                 self.check_attributes(&item.attrs, &mac);
                 item.and_then(|item| match item.kind {
-                    ast::AssocItemKind::MacCall(mac) => self
-                        .collect_bang(mac, item.span, AstFragmentKind::TraitItems)
-                        .make_trait_items(),
+                    ast::AssocItemKind::MacCall(mac) => {
+                        self.collect_bang(mac, AstFragmentKind::TraitItems).make_trait_items()
+                    }
                     _ => unreachable!(),
                 })
             }
@@ -1567,9 +1555,9 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
             ast::AssocItemKind::MacCall(ref mac) => {
                 self.check_attributes(&item.attrs, &mac);
                 item.and_then(|item| match item.kind {
-                    ast::AssocItemKind::MacCall(mac) => self
-                        .collect_bang(mac, item.span, AstFragmentKind::ImplItems)
-                        .make_impl_items(),
+                    ast::AssocItemKind::MacCall(mac) => {
+                        self.collect_bang(mac, AstFragmentKind::ImplItems).make_impl_items()
+                    }
                     _ => unreachable!(),
                 })
             }
@@ -1586,9 +1574,7 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
         };
 
         visit_clobber(ty, |mut ty| match mem::replace(&mut ty.kind, ast::TyKind::Err) {
-            ast::TyKind::MacCall(mac) => {
-                self.collect_bang(mac, ty.span, AstFragmentKind::Ty).make_ty()
-            }
+            ast::TyKind::MacCall(mac) => self.collect_bang(mac, AstFragmentKind::Ty).make_ty(),
             _ => unreachable!(),
         });
     }
@@ -1613,9 +1599,9 @@ impl<'a, 'b> MutVisitor for InvocationCollector<'a, 'b> {
             ast::ForeignItemKind::MacCall(ref mac) => {
                 self.check_attributes(&foreign_item.attrs, &mac);
                 foreign_item.and_then(|item| match item.kind {
-                    ast::ForeignItemKind::MacCall(mac) => self
-                        .collect_bang(mac, item.span, AstFragmentKind::ForeignItems)
-                        .make_foreign_items(),
+                    ast::ForeignItemKind::MacCall(mac) => {
+                        self.collect_bang(mac, AstFragmentKind::ForeignItems).make_foreign_items()
+                    }
                     _ => unreachable!(),
                 })
             }

compiler/rustc_middle/src/mir/interpret/error.rs

@@ -287,6 +287,8 @@ pub enum UndefinedBehaviorInfo<'tcx> {
         target_size: u64,
         data_size: u64,
     },
+    /// A discriminant of an uninhabited enum variant is written.
+    UninhabitedEnumVariantWritten,
 }
 
 impl fmt::Display for UndefinedBehaviorInfo<'_> {
@@ -391,6 +393,9 @@ impl fmt::Display for UndefinedBehaviorInfo<'_> {
                 "scalar size mismatch: expected {} bytes but got {} bytes instead",
                 target_size, data_size
             ),
+            UninhabitedEnumVariantWritten => {
+                write!(f, "writing discriminant of an uninhabited enum")
+            }
         }
     }
 }

compiler/rustc_span/src/source_map.rs

@@ -653,6 +653,18 @@ impl SourceMap {
         })
     }
 
+    /// Extends the given `Span` while the next character matches the predicate
+    pub fn span_extend_while(
+        &self,
+        span: Span,
+        f: impl Fn(char) -> bool,
+    ) -> Result<Span, SpanSnippetError> {
+        self.span_to_source(span, |s, _start, end| {
+            let n = s[end..].char_indices().find(|&(_, c)| !f(c)).map_or(s.len() - end, |(i, _)| i);
+            Ok(span.with_hi(span.hi() + BytePos(n as u32)))
+        })
+    }
+
     /// Extends the given `Span` to just after the next occurrence of `c`.
     pub fn span_extend_to_next_char(&self, sp: Span, c: char, accept_newlines: bool) -> Span {
         if let Ok(next_source) = self.span_to_next_source(sp) {
@@ -1013,6 +1025,32 @@ impl SourceMap {
         let source_file = &self.files()[source_file_index];
         source_file.is_imported()
     }
+
+    /// Gets the span of a statement. If the statement is a macro expansion, the
+    /// span in the context of the block span is found. The trailing semicolon is included
+    /// on a best-effort basis.
+    pub fn stmt_span(&self, stmt_span: Span, block_span: Span) -> Span {
+        if !stmt_span.from_expansion() {
+            return stmt_span;
+        }
+        let mac_call = original_sp(stmt_span, block_span);
+        self.mac_call_stmt_semi_span(mac_call).map_or(mac_call, |s| mac_call.with_hi(s.hi()))
+    }
+
+    /// Tries to find the span of the semicolon of a macro call statement.
+    /// The input must be the *call site* span of a statement from macro expansion.
+    ///
+    ///           v output
+    ///     mac!();
+    ///     ^^^^^^ input
+    pub fn mac_call_stmt_semi_span(&self, mac_call: Span) -> Option<Span> {
+        let span = self.span_extend_while(mac_call, char::is_whitespace).ok()?;
+        let span = span.shrink_to_hi().with_hi(BytePos(span.hi().0.checked_add(1)?));
+        if self.span_to_snippet(span).as_deref() != Ok(";") {
+            return None;
+        }
+        Some(span)
+    }
 }
 
 #[derive(Clone)]

compiler/rustc_typeck/src/bounds.rs

@@ -64,16 +64,16 @@ impl<'tcx> Bounds<'tcx> {
             })
         });
 
-        sized_predicate
-            .into_iter()
-            .chain(self.region_bounds.iter().map(|&(region_bound, span)| {
+        self.region_bounds
+            .iter()
+            .map(|&(region_bound, span)| {
                 (
                     region_bound
                         .map_bound(|region_bound| ty::OutlivesPredicate(param_ty, region_bound))
                         .to_predicate(tcx),
                     span,
                 )
-            }))
+            })
             .chain(self.trait_bounds.iter().map(|&(bound_trait_ref, span, constness)| {
                 let predicate = bound_trait_ref.with_constness(constness).to_predicate(tcx);
                 (predicate, span)
@@ -83,6 +83,7 @@ impl<'tcx> Bounds<'tcx> {
                     .iter()
                     .map(|&(projection, span)| (projection.to_predicate(tcx), span)),
             )
+            .chain(sized_predicate.into_iter())
             .collect()
     }
 }

compiler/rustc_typeck/src/check/fn_ctxt/_impl.rs

@@ -1171,8 +1171,13 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         {
             return None;
         }
-        let original_span = original_sp(last_stmt.span, blk.span);
-        Some((original_span.with_lo(original_span.hi() - BytePos(1)), needs_box))
+        let span = if last_stmt.span.from_expansion() {
+            let mac_call = original_sp(last_stmt.span, blk.span);
+            self.tcx.sess.source_map().mac_call_stmt_semi_span(mac_call)?
+        } else {
+            last_stmt.span.with_lo(last_stmt.span.hi() - BytePos(1))
+        };
+        Some((span, needs_box))
     }
 
     // Instantiates the given path, which must refer to an item with the given

library/core/src/hint.rs

@@ -44,7 +44,7 @@ use crate::intrinsics;
 /// ```
 #[inline]
 #[stable(feature = "unreachable", since = "1.27.0")]
-#[rustc_const_unstable(feature = "const_unreachable_unchecked", issue = "53188")]
+#[rustc_const_stable(feature = "const_unreachable_unchecked", since = "1.57.0")]
 pub const unsafe fn unreachable_unchecked() -> ! {
     // SAFETY: the safety contract for `intrinsics::unreachable` must
     // be upheld by the caller.

library/core/src/intrinsics.rs

@@ -735,7 +735,7 @@ extern "rust-intrinsic" {
     /// reach code marked with this function.
     ///
     /// The stabilized version of this intrinsic is [`core::hint::unreachable_unchecked`].
-    #[rustc_const_unstable(feature = "const_unreachable_unchecked", issue = "53188")]
+    #[rustc_const_stable(feature = "const_unreachable_unchecked", since = "1.57.0")]
     pub fn unreachable() -> !;
 
     /// Informs the optimizer that a condition is always true.