Rollup of 11 pull requests

src/ci/docker/armhf-gnu/Dockerfile

@@ -71,7 +71,8 @@ COPY scripts/qemu-bare-bones-addentropy.c /tmp/addentropy.c
 RUN arm-linux-gnueabihf-gcc addentropy.c -o rootfs/addentropy -static
 
 # TODO: What is this?!
-RUN curl -O http://ftp.nl.debian.org/debian/dists/jessie/main/installer-armhf/current/images/device-tree/vexpress-v2p-ca15-tc1.dtb
+# Source of the file: https://github.com/vfdev-5/qemu-rpi2-vexpress/raw/master/vexpress-v2p-ca15-tc1.dtb
+RUN curl -O https://s3-us-west-1.amazonaws.com/rust-lang-ci2/rust-ci-mirror/vexpress-v2p-ca15-tc1.dtb
 
 COPY scripts/sccache.sh /scripts/
 RUN sh /scripts/sccache.sh

src/doc/unstable-book/src/language-features/non-exhaustive.md

@@ -7,10 +7,12 @@ The tracking issue for this feature is: [#44109]
 ------------------------
 
 The `non_exhaustive` gate allows you to use the `#[non_exhaustive]` attribute
-on structs and enums. When applied within a crate, users of the crate will need
-to use the `_` pattern when matching enums and use the `..` pattern when
-matching structs. Structs marked as `non_exhaustive` will not be able to be
-created normally outside of the defining crate. This is demonstrated below:
+on structs, enums and enum variants. When applied within a crate, users of the
+crate will need to use the `_` pattern when matching enums and use the `..`
+pattern when matching structs. Enum variants cannot be matched against.
+Structs and enum variants marked as `non_exhaustive` will not be able to
+be created normally outside of the defining crate. This is demonstrated
+below:
 
 ```rust,ignore (pseudo-Rust)
 use std::error::Error as StdError;
@@ -72,4 +74,3 @@ let config = Config { window_width: 640, window_height: 480 };
 // when marked non_exhaustive.
 let &Config { window_width, window_height, .. } = config;
 ```
-

src/libcore/iter/sources.rs

@@ -375,8 +375,8 @@ pub fn once<T>(value: T) -> Once<T> {
     Once { inner: Some(value).into_iter() }
 }
 
-/// An iterator that repeats elements of type `A` endlessly by
-/// applying the provided closure `F: FnMut() -> A`.
+/// An iterator that yields a single element of type `A` by
+/// applying the provided closure `F: FnOnce() -> A`.
 ///
 /// This `struct` is created by the [`once_with`] function.
 /// See its documentation for more.

src/librustc/ty/mod.rs

@@ -1869,6 +1869,11 @@ impl<'a, 'gcx, 'tcx> VariantDef {
         if adt_kind == AdtKind::Struct && tcx.has_attr(parent_did, "non_exhaustive") {
             debug!("found non-exhaustive field list for {:?}", parent_did);
             flags = flags | VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
+        } else if let Some(variant_did) = variant_did {
+            if tcx.has_attr(variant_did, "non_exhaustive") {
+                debug!("found non-exhaustive field list for {:?}", variant_did);
+                flags = flags | VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
+            }
         }
 
         VariantDef {
@@ -2146,6 +2151,7 @@ impl<'a, 'gcx, 'tcx> AdtDef {
             debug!("found non-exhaustive variant list for {:?}", did);
             flags = flags | AdtFlags::IS_VARIANT_LIST_NON_EXHAUSTIVE;
         }
+
         flags |= match kind {
             AdtKind::Enum => AdtFlags::IS_ENUM,
             AdtKind::Union => AdtFlags::IS_UNION,
@@ -2299,21 +2305,25 @@ impl<'a, 'gcx, 'tcx> AdtDef {
             self.variants.iter().all(|v| v.fields.is_empty())
     }
 
+    /// Return a `VariantDef` given a variant id.
     pub fn variant_with_id(&self, vid: DefId) -> &VariantDef {
         self.variants.iter().find(|v| v.def_id == vid)
             .expect("variant_with_id: unknown variant")
     }
 
+    /// Return a `VariantDef` given a constructor id.
     pub fn variant_with_ctor_id(&self, cid: DefId) -> &VariantDef {
         self.variants.iter().find(|v| v.ctor_def_id == Some(cid))
             .expect("variant_with_ctor_id: unknown variant")
     }
 
+    /// Return the index of `VariantDef` given a variant id.
     pub fn variant_index_with_id(&self, vid: DefId) -> VariantIdx {
         self.variants.iter_enumerated().find(|(_, v)| v.def_id == vid)
             .expect("variant_index_with_id: unknown variant").0
     }
 
+    /// Return the index of `VariantDef` given a constructor id.
     pub fn variant_index_with_ctor_id(&self, cid: DefId) -> VariantIdx {
         self.variants.iter_enumerated().find(|(_, v)| v.ctor_def_id == Some(cid))
             .expect("variant_index_with_ctor_id: unknown variant").0
@@ -2930,8 +2940,8 @@ impl<'a, 'gcx, 'tcx> TyCtxt<'a, 'gcx, 'tcx> {
         }
     }
 
-    // Returns `ty::VariantDef` if `def` refers to a struct,
-    // or variant or their constructors, panics otherwise.
+    /// Returns `ty::VariantDef` if `def` refers to a struct,
+    /// or variant or their constructors, panics otherwise.
     pub fn expect_variant_def(self, def: Def) -> &'tcx VariantDef {
         match def {
             Def::Variant(did) => {

src/librustc_codegen_llvm/debuginfo/metadata.rs

@@ -117,6 +117,32 @@ impl TypeMap<'ll, 'tcx> {
         }
     }
 
+    // Removes a Ty to metadata mapping
+    // This is useful when computing the metadata for a potentially
+    // recursive type (e.g. a function ptr of the form:
+    //
+    // fn foo() -> impl Copy { foo }
+    //
+    // This kind of type cannot be properly represented
+    // via LLVM debuginfo. As a workaround,
+    // we register a temporary Ty to metadata mapping
+    // for the function before we compute its actual metadata.
+    // If the metadata computation ends up recursing back to the
+    // original function, it will use the temporary mapping
+    // for the inner self-reference, preventing us from
+    // recursing forever.
+    //
+    // This function is used to remove the temporary metadata
+    // mapping after we've computed the actual metadata
+    fn remove_type(
+        &mut self,
+        type_: Ty<'tcx>,
+    ) {
+        if self.type_to_metadata.remove(type_).is_none() {
+            bug!("Type metadata Ty '{}' is not in the TypeMap!", type_);
+        }
+    }
+
     // Adds a UniqueTypeId to metadata mapping to the TypeMap. The method will
     // fail if the mapping already exists.
     fn register_unique_id_with_metadata(
@@ -597,17 +623,49 @@ pub fn type_metadata(
             }
         }
         ty::FnDef(..) | ty::FnPtr(_) => {
-            let fn_metadata = subroutine_type_metadata(cx,
-                                                       unique_type_id,
-                                                       t.fn_sig(cx.tcx),
-                                                       usage_site_span).metadata;
+
             if let Some(metadata) = debug_context(cx).type_map
                .borrow()
                .find_metadata_for_unique_id(unique_type_id)
             {
                 return metadata;
             }
 
+            // It's possible to create a self-referential
+            // type in Rust by using 'impl trait':
+            //
+            // fn foo() -> impl Copy { foo }
+            //
+            // See TypeMap::remove_type for more detals
+            // about the workaround
+
+            let temp_type = {
+                unsafe {
+                    // The choice of type here is pretty arbitrary -
+                    // anything reading the debuginfo for a recursive
+                    // type is going to see *somthing* weird - the only
+                    // question is what exactly it will see
+                    let (size, align) = cx.size_and_align_of(t);
+                    llvm::LLVMRustDIBuilderCreateBasicType(
+                        DIB(cx),
+                        SmallCStr::new("<recur_type>").as_ptr(),
+                        size.bits(),
+                        align.bits() as u32,
+                        DW_ATE_unsigned)
+                }
+            };
+
+            let type_map = &debug_context(cx).type_map;
+            type_map.borrow_mut().register_type_with_metadata(t, temp_type);
+
+            let fn_metadata = subroutine_type_metadata(cx,
+                                                       unique_type_id,
+                                                       t.fn_sig(cx.tcx),
+                                                       usage_site_span).metadata;
+
+            type_map.borrow_mut().remove_type(t);
+
+
             // This is actually a function pointer, so wrap it in pointer DI
             MetadataCreationResult::new(pointer_type_metadata(cx, t, fn_metadata), false)
 

src/librustc_codegen_llvm/debuginfo/type_names.rs

@@ -5,6 +5,7 @@ use rustc::hir::def_id::DefId;
 use rustc::ty::subst::SubstsRef;
 use rustc::ty::{self, Ty};
 use rustc_codegen_ssa::traits::*;
+use rustc_data_structures::fx::FxHashSet;
 
 use rustc::hir;
 
@@ -17,7 +18,8 @@ pub fn compute_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
                                              qualified: bool)
                                              -> String {
     let mut result = String::with_capacity(64);
-    push_debuginfo_type_name(cx, t, qualified, &mut result);
+    let mut visited = FxHashSet::default();
+    push_debuginfo_type_name(cx, t, qualified, &mut result, &mut visited);
     result
 }
 
@@ -26,7 +28,27 @@ pub fn compute_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
 pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
                                           t: Ty<'tcx>,
                                           qualified: bool,
-                                          output: &mut String) {
+                                          output: &mut String,
+                                          visited: &mut FxHashSet<Ty<'tcx>>) {
+
+    // We've encountered a weird 'recursive type'
+    // Currently, the only way to generate such a type
+    // is by using 'impl trait':
+    //
+    // fn foo() -> impl Copy { foo }
+    //
+    // There's not really a sensible name we can generate,
+    // since we don't include 'impl trait' types (e.g. ty::Opaque)
+    // in the output
+    //
+    // Since we need to generate *something*, we just
+    // use a dummy string that should make it clear
+    // that something unusual is going on
+    if !visited.insert(t) {
+        output.push_str("<recursive_type>");
+        return;
+    }
+
     // When targeting MSVC, emit C++ style type names for compatibility with
     // .natvis visualizers (and perhaps other existing native debuggers?)
     let cpp_like_names = cx.sess().target.target.options.is_like_msvc;
@@ -42,12 +64,12 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
         ty::Foreign(def_id) => push_item_name(cx, def_id, qualified, output),
         ty::Adt(def, substs) => {
             push_item_name(cx, def.did, qualified, output);
-            push_type_params(cx, substs, output);
+            push_type_params(cx, substs, output, visited);
         },
         ty::Tuple(component_types) => {
             output.push('(');
             for &component_type in component_types {
-                push_debuginfo_type_name(cx, component_type, true, output);
+                push_debuginfo_type_name(cx, component_type, true, output, visited);
                 output.push_str(", ");
             }
             if !component_types.is_empty() {
@@ -65,7 +87,7 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
                 hir::MutMutable => output.push_str("mut "),
             }
 
-            push_debuginfo_type_name(cx, inner_type, true, output);
+            push_debuginfo_type_name(cx, inner_type, true, output, visited);
 
             if cpp_like_names {
                 output.push('*');
@@ -79,15 +101,15 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
                 output.push_str("mut ");
             }
 
-            push_debuginfo_type_name(cx, inner_type, true, output);
+            push_debuginfo_type_name(cx, inner_type, true, output, visited);
 
             if cpp_like_names {
                 output.push('*');
             }
         },
         ty::Array(inner_type, len) => {
             output.push('[');
-            push_debuginfo_type_name(cx, inner_type, true, output);
+            push_debuginfo_type_name(cx, inner_type, true, output, visited);
             output.push_str(&format!("; {}", len.unwrap_usize(cx.tcx)));
             output.push(']');
         },
@@ -98,7 +120,7 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
                 output.push('[');
             }
 
-            push_debuginfo_type_name(cx, inner_type, true, output);
+            push_debuginfo_type_name(cx, inner_type, true, output, visited);
 
             if cpp_like_names {
                 output.push('>');
@@ -113,7 +135,7 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
                     &principal,
                 );
                 push_item_name(cx, principal.def_id, false, output);
-                push_type_params(cx, principal.substs, output);
+                push_type_params(cx, principal.substs, output, visited);
             } else {
                 output.push_str("dyn '_");
             }
@@ -136,7 +158,7 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
             let sig = cx.tcx.normalize_erasing_late_bound_regions(ty::ParamEnv::reveal_all(), &sig);
             if !sig.inputs().is_empty() {
                 for &parameter_type in sig.inputs() {
-                    push_debuginfo_type_name(cx, parameter_type, true, output);
+                    push_debuginfo_type_name(cx, parameter_type, true, output, visited);
                     output.push_str(", ");
                 }
                 output.pop();
@@ -155,7 +177,7 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
 
             if !sig.output().is_unit() {
                 output.push_str(" -> ");
-                push_debuginfo_type_name(cx, sig.output(), true, output);
+                push_debuginfo_type_name(cx, sig.output(), true, output, visited);
             }
         },
         ty::Closure(..) => {
@@ -200,15 +222,16 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
     // common denominator - otherwise we would run into conflicts.
     fn push_type_params<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
                                   substs: SubstsRef<'tcx>,
-                                  output: &mut String) {
+                                  output: &mut String,
+                                  visited: &mut FxHashSet<Ty<'tcx>>) {
         if substs.types().next().is_none() {
             return;
         }
 
         output.push('<');
 
         for type_parameter in substs.types() {
-            push_debuginfo_type_name(cx, type_parameter, true, output);
+            push_debuginfo_type_name(cx, type_parameter, true, output, visited);
             output.push_str(", ");
         }
 

src/librustc_metadata/encoder.rs

@@ -643,13 +643,18 @@ impl<'a, 'b: 'a, 'tcx: 'b> IsolatedEncoder<'a, 'b, 'tcx> {
             }
         };
 
-        // Variant constructors have the same visibility as the parent enums.
+        // Variant constructors have the same visibility as the parent enums, unless marked as
+        // non-exhaustive, in which case they are lowered to `pub(crate)`.
         let enum_id = tcx.hir().as_local_hir_id(enum_did).unwrap();
         let enum_vis = &tcx.hir().expect_item_by_hir_id(enum_id).vis;
+        let mut ctor_vis = ty::Visibility::from_hir(enum_vis, enum_id, tcx);
+        if variant.is_field_list_non_exhaustive() && ctor_vis == ty::Visibility::Public {
+            ctor_vis = ty::Visibility::Restricted(DefId::local(CRATE_DEF_INDEX));
+        }
 
         Entry {
             kind: EntryKind::Variant(self.lazy(&data)),
-            visibility: self.lazy(&ty::Visibility::from_hir(enum_vis, enum_id, tcx)),
+            visibility: self.lazy(&ctor_vis),
             span: self.lazy(&tcx.def_span(def_id)),
             attributes: LazySeq::empty(),
             children: LazySeq::empty(),

src/librustc_passes/ast_validation.rs

@@ -192,14 +192,6 @@ impl<'a> AstValidator<'a> {
         }
     }
 
-    fn invalid_non_exhaustive_attribute(&self, variant: &Variant) {
-        let has_non_exhaustive = attr::contains_name(&variant.node.attrs, "non_exhaustive");
-        if has_non_exhaustive {
-            self.err_handler().span_err(variant.span,
-                                        "#[non_exhaustive] is not yet supported on variants");
-        }
-    }
-
     fn invalid_visibility(&self, vis: &Visibility, note: Option<&str>) {
         if let VisibilityKind::Inherited = vis.node {
             return
@@ -608,7 +600,6 @@ impl<'a> Visitor<'a> for AstValidator<'a> {
             }
             ItemKind::Enum(ref def, _) => {
                 for variant in &def.variants {
-                    self.invalid_non_exhaustive_attribute(variant);
                     for field in variant.node.data.fields() {
                         self.invalid_visibility(&field.vis, None);
                     }