Properly scope label resolution

src/librustc/hir/lowering.rs

@@ -103,7 +103,6 @@ pub struct LoweringContext<'a> {
     loop_scopes: Vec<NodeId>,
     is_in_loop_condition: bool,
     is_in_trait_impl: bool,
-    is_in_anon_const: bool,
 
     /// What to do when we encounter either an "anonymous lifetime
     /// reference". The term "anonymous" is meant to encompass both
@@ -231,7 +230,6 @@ pub fn lower_crate(
         node_id_to_hir_id: IndexVec::new(),
         is_generator: false,
         is_in_trait_impl: false,
-        is_in_anon_const: false,
         lifetimes_to_define: Vec::new(),
         is_collecting_in_band_lifetimes: false,
         in_scope_lifetimes: Vec::new(),
@@ -970,26 +968,22 @@ impl<'a> LoweringContext<'a> {
     }
 
     fn lower_loop_destination(&mut self, destination: Option<(NodeId, Label)>) -> hir::Destination {
-        let target_id = if self.is_in_anon_const {
-            Err(hir::LoopIdError::OutsideLoopScope)
-        } else {
-            match destination {
-                Some((id, _)) => {
-                    if let Def::Label(loop_id) = self.expect_full_def(id) {
-                        Ok(self.lower_node_id(loop_id).node_id)
-                    } else {
-                        Err(hir::LoopIdError::UnresolvedLabel)
-                    }
-                }
-                None => {
-                    self.loop_scopes
-                        .last()
-                        .map(|innermost_loop_id| *innermost_loop_id)
-                        .map(|id| Ok(self.lower_node_id(id).node_id))
-                        .unwrap_or(Err(hir::LoopIdError::OutsideLoopScope))
-                        .into()
+        let target_id = match destination {
+            Some((id, _)) => {
+                if let Def::Label(loop_id) = self.expect_full_def(id) {
+                    Ok(self.lower_node_id(loop_id).node_id)
+                } else {
+                    Err(hir::LoopIdError::UnresolvedLabel)
                 }
             }
+            None => {
+                self.loop_scopes
+                    .last()
+                    .map(|innermost_loop_id| *innermost_loop_id)
+                    .map(|id| Ok(self.lower_node_id(id).node_id))
+                    .unwrap_or(Err(hir::LoopIdError::OutsideLoopScope))
+                    .into()
+            }
         };
         hir::Destination {
             label: self.lower_label(destination.map(|(_, label)| label)),
@@ -3448,22 +3442,14 @@ impl<'a> LoweringContext<'a> {
     }
 
     fn lower_anon_const(&mut self, c: &AnonConst) -> hir::AnonConst {
-        let was_in_loop_condition = self.is_in_loop_condition;
-        self.is_in_loop_condition = false;
-        let was_in_anon_const = self.is_in_anon_const;
-        self.is_in_anon_const = true;
-
-        let LoweredNodeId { node_id, hir_id } = self.lower_node_id(c.id);
-        let anon_const = hir::AnonConst {
-            id: node_id,
-            hir_id,
-            body: self.lower_body(None, |this| this.lower_expr(&c.value)),
-        };
-
-        self.is_in_anon_const = was_in_anon_const;
-        self.is_in_loop_condition = was_in_loop_condition;
-
-        anon_const
+        self.with_new_scopes(|this| {
+            let LoweredNodeId { node_id, hir_id } = this.lower_node_id(c.id);
+            hir::AnonConst {
+                id: node_id,
+                hir_id,
+                body: this.lower_body(None, |this| this.lower_expr(&c.value)),
+            }
+        })
     }
 
     fn lower_expr(&mut self, e: &Expr) -> hir::Expr {

src/librustc_resolve/lib.rs

@@ -2358,7 +2358,9 @@ impl<'a> Resolver<'a> {
         where F: FnOnce(&mut Resolver)
     {
         self.ribs[ValueNS].push(Rib::new(ConstantItemRibKind));
+        self.label_ribs.push(Rib::new(ConstantItemRibKind));
         f(self);
+        self.label_ribs.pop();
         self.ribs[ValueNS].pop();
     }
 

src/test/ui/const-eval/issue-52442.rs

@@ -0,0 +1,13 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    [();  { &loop { break } as *const _ as usize } ]; //~ ERROR unimplemented expression type
+}

src/test/ui/const-eval/issue-52442.stderr

@@ -0,0 +1,9 @@
+error[E0019]: constant contains unimplemented expression type
+  --> $DIR/issue-52442.rs:12:14
+   |
+LL |     [();  { &loop { break } as *const _ as usize } ]; //~ ERROR unimplemented expression type
+   |              ^^^^^^^^^^^^^^
+
+error: aborting due to previous error
+
+For more information about this error, try `rustc --explain E0019`.

src/test/ui/const-eval/issue-52443.rs

@@ -0,0 +1,18 @@
+// Copyright 2018 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+fn main() {
+    [(); & { loop { continue } } ]; //~ ERROR mismatched types
+    [(); loop { break }]; //~ ERROR mismatched types
+    [(); {while true {break}; 0}]; //~ ERROR constant contains unimplemented expression type
+    [(); { for _ in 0usize.. {}; 0}]; //~ ERROR calls in constants are limited to constant functions
+    //~^ ERROR constant contains unimplemented expression type
+    //~| ERROR could not evaluate repeat length
+}

src/test/ui/const-eval/issue-52443.stderr

@@ -0,0 +1,51 @@
+error[E0308]: mismatched types
+  --> $DIR/issue-52443.rs:12:10
+   |
+LL |     [(); & { loop { continue } } ]; //~ ERROR mismatched types
+   |          ^^^^^^^^^^^^^^^^^^^^^^^
+   |          |
+   |          expected usize, found reference
+   |          help: consider removing the borrow: `{ loop { continue } }`
+   |
+   = note: expected type `usize`
+              found type `&_`
+
+error[E0308]: mismatched types
+  --> $DIR/issue-52443.rs:13:17
+   |
+LL |     [(); loop { break }]; //~ ERROR mismatched types
+   |                 ^^^^^ expected (), found usize
+   |
+   = note: expected type `()`
+              found type `usize`
+
+error[E0019]: constant contains unimplemented expression type
+  --> $DIR/issue-52443.rs:14:11
+   |
+LL |     [(); {while true {break}; 0}]; //~ ERROR constant contains unimplemented expression type
+   |           ^^^^^^^^^^^^^^^^^^
+
+error[E0015]: calls in constants are limited to constant functions, tuple structs and tuple variants
+  --> $DIR/issue-52443.rs:15:21
+   |
+LL |     [(); { for _ in 0usize.. {}; 0}]; //~ ERROR calls in constants are limited to constant functions
+   |                     ^^^^^^^^
+
+error[E0019]: constant contains unimplemented expression type
+  --> $DIR/issue-52443.rs:15:21
+   |
+LL |     [(); { for _ in 0usize.. {}; 0}]; //~ ERROR calls in constants are limited to constant functions
+   |                     ^^^^^^^^
+
+error[E0080]: could not evaluate repeat length
+  --> $DIR/issue-52443.rs:15:10
+   |
+LL |     [(); { for _ in 0usize.. {}; 0}]; //~ ERROR calls in constants are limited to constant functions
+   |          ^^^^^^^^^^^--------^^^^^^^
+   |                     |
+   |                     calling non-const fn `<I as std::iter::IntoIterator><std::ops::RangeFrom<usize>>::into_iter`
+
+error: aborting due to 6 previous errors
+
+Some errors occurred: E0015, E0019, E0080, E0308.
+For more information about an error, try `rustc --explain E0015`.