Rollup of 11 pull requests

src/libcore/fmt/float.rs

@@ -12,10 +12,11 @@ fn float_to_decimal_common_exact<T>(fmt: &mut Formatter<'_>, num: &T,
     unsafe {
         let mut buf = MaybeUninit::<[u8; 1024]>::uninit(); // enough for f32 and f64
         let mut parts = MaybeUninit::<[flt2dec::Part<'_>; 4]>::uninit();
-        // FIXME(#53491): Technically, this is calling `get_mut` on an uninitialized
-        // `MaybeUninit` (here and elsewhere in this file).  Revisit this once
+        // FIXME(#53491): This is calling `get_mut` on an uninitialized
+        // `MaybeUninit` (here and elsewhere in this file). Revisit this once
         // we decided whether that is valid or not.
-        // Using `freeze` is *not enough*; `flt2dec::Part` is an enum!
+        // We can do this only because we are libstd and coupled to the compiler.
+        // (FWIW, using `freeze` would not be enough; `flt2dec::Part` is an enum!)
         let formatted = flt2dec::to_exact_fixed_str(flt2dec::strategy::grisu::format_exact,
                                                     *num, sign, precision,
                                                     false, buf.get_mut(), parts.get_mut());

src/libcore/ptr/unique.rs

@@ -26,8 +26,8 @@ use crate::ptr::NonNull;
 /// Unlike `*mut T`, `Unique<T>` is covariant over `T`. This should always be correct
 /// for any type which upholds Unique's aliasing requirements.
 #[unstable(feature = "ptr_internals", issue = "0",
-           reason = "use NonNull instead and consider PhantomData<T> \
-                     (if you also use #[may_dangle]), Send, and/or Sync")]
+           reason = "use `NonNull` instead and consider `PhantomData<T>` \
+                     (if you also use `#[may_dangle]`), `Send`, and/or `Sync`")]
 #[doc(hidden)]
 #[repr(transparent)]
 #[rustc_layout_scalar_valid_range_start(1)]

src/libfmt_macros/Cargo.toml

@@ -7,7 +7,6 @@ edition = "2018"
 [lib]
 name = "fmt_macros"
 path = "lib.rs"
-crate-type = ["dylib"]
 
 [dependencies]
 syntax_pos = { path = "../libsyntax_pos" }

src/librustc_incremental/assert_dep_graph.rs

@@ -190,7 +190,7 @@ fn check_paths<'tcx>(tcx: TyCtxt<'tcx>, if_this_changed: &Sources, then_this_wou
         for &(target_span, _, _, _) in then_this_would_need {
             tcx.sess.span_err(
                 target_span,
-                "no #[rustc_if_this_changed] annotation detected");
+                "no `#[rustc_if_this_changed]` annotation detected");
 
         }
         return;

src/librustc_incremental/persist/dirty_clean.rs

@@ -610,7 +610,7 @@ impl FindAllAttrs<'tcx> {
         for attr in &self.found_attrs {
             if !checked_attrs.contains(&attr.id) {
                 self.tcx.sess.span_err(attr.span, &format!("found unchecked \
-                    #[rustc_dirty]/#[rustc_clean] attribute"));
+                    `#[rustc_dirty]` / `#[rustc_clean]` attribute"));
             }
         }
     }

src/librustc_incremental/persist/fs.rs

@@ -538,7 +538,7 @@ fn find_source_directory_in_iter<I>(iter: I,
         if source_directories_already_tried.contains(&session_dir) ||
            !is_session_directory(&directory_name) ||
            !is_finalized(&directory_name) {
-            debug!("find_source_directory_in_iter - ignoring.");
+            debug!("find_source_directory_in_iter - ignoring");
             continue
         }
 
@@ -693,7 +693,7 @@ pub fn garbage_collect_session_directories(sess: &Session) -> io::Result<()> {
             let timestamp = match extract_timestamp_from_session_dir(lock_file_name) {
                 Ok(timestamp) => timestamp,
                 Err(()) => {
-                    debug!("Found lock-file with malformed timestamp: {}",
+                    debug!("found lock-file with malformed timestamp: {}",
                         crate_directory.join(&lock_file_name).display());
                     // Ignore it
                     continue
@@ -746,7 +746,7 @@ pub fn garbage_collect_session_directories(sess: &Session) -> io::Result<()> {
         let timestamp = match extract_timestamp_from_session_dir(directory_name) {
             Ok(timestamp) => timestamp,
             Err(()) => {
-                debug!("Found session-dir with malformed timestamp: {}",
+                debug!("found session-dir with malformed timestamp: {}",
                         crate_directory.join(directory_name).display());
                 // Ignore it
                 continue

src/librustc_metadata/creader.rs

@@ -938,14 +938,14 @@ impl<'a> CrateLoader<'a> {
             }
             match global_allocator {
                 Some(Some(other_crate)) => {
-                    self.sess.err(&format!("the #[global_allocator] in {} \
+                    self.sess.err(&format!("the `#[global_allocator]` in {} \
                                             conflicts with this global \
                                             allocator in: {}",
                                            other_crate,
                                            data.root.name));
                 }
                 Some(None) => {
-                    self.sess.err(&format!("the #[global_allocator] in this \
+                    self.sess.err(&format!("the `#[global_allocator]` in this \
                                             crate conflicts with global \
                                             allocator in: {}", data.root.name));
                 }
@@ -971,7 +971,7 @@ impl<'a> CrateLoader<'a> {
         if !has_default {
             self.sess.err("no global memory allocator found but one is \
                            required; link to std or \
-                           add #[global_allocator] to a static item \
+                           add `#[global_allocator]` to a static item \
                            that implements the GlobalAlloc trait.");
         }
         self.sess.allocator_kind.set(Some(AllocatorKind::DefaultLib));

src/librustc_metadata/error_codes.rs

@@ -7,7 +7,8 @@ E0454: r##"
 A link name was given with an empty name. Erroneous code example:
 
 ```ignore (cannot-test-this-because-rustdoc-stops-compile-fail-before-codegen)
-#[link(name = "")] extern {} // error: #[link(name = "")] given with empty name
+#[link(name = "")] extern {}
+// error: `#[link(name = "")]` given with empty name
 ```
 
 The rust compiler cannot link to an external library if you don't give it its
@@ -61,7 +62,7 @@ A link was used without a name parameter. Erroneous code example:
 
 ```ignore (cannot-test-this-because-rustdoc-stops-compile-fail-before-codegen)
 #[link(kind = "dylib")] extern {}
-// error: #[link(...)] specified without `name = "foo"`
+// error: `#[link(...)]` specified without `name = "foo"`
 ```
 
 Please add the name parameter to allow the rust compiler to find the library

src/librustc_metadata/native_libs.rs

@@ -102,7 +102,7 @@ impl ItemLikeVisitor<'tcx> for Collector<'tcx> {
                     match item.value_str() {
                         Some(s) => lib.wasm_import_module = Some(s),
                         None => {
-                            let msg = "must be of the form #[link(wasm_import_module = \"...\")]";
+                            let msg = "must be of the form `#[link(wasm_import_module = \"...\")]`";
                             self.tcx.sess.span_err(item.span(), msg);
                         }
                     }
@@ -117,7 +117,7 @@ impl ItemLikeVisitor<'tcx> for Collector<'tcx> {
             let requires_name = kind_specified || lib.wasm_import_module.is_none();
             if lib.name.is_none() && requires_name {
                 struct_span_err!(self.tcx.sess, m.span, E0459,
-                                 "#[link(...)] specified without \
+                                 "`#[link(...)]` specified without \
                                   `name = \"foo\"`")
                     .span_label(m.span, "missing `name` argument")
                     .emit();
@@ -136,7 +136,7 @@ impl Collector<'tcx> {
             match span {
                 Some(span) => {
                     struct_span_err!(self.tcx.sess, span, E0454,
-                                     "#[link(name = \"\")] given with empty name")
+                                     "`#[link(name = \"\")]` given with empty name")
                         .span_label(span, "empty name given")
                         .emit();
                 }
@@ -187,7 +187,7 @@ impl Collector<'tcx> {
                         &format!("an empty renaming target was specified for library `{}`",name));
                 } else if !any_duplicate {
                     self.tcx.sess.err(&format!("renaming of the library `{}` was specified, \
-                                                however this crate contains no #[link(...)] \
+                                                however this crate contains no `#[link(...)]` \
                                                 attributes referencing this library.", name));
                 } else if renames.contains(name) {
                     self.tcx.sess.err(&format!("multiple renamings were \

src/librustc_target/spec/x86_64_unknown_linux_gnux32.rs

@@ -5,8 +5,7 @@ pub fn target() -> TargetResult {
     base.cpu = "x86-64".to_string();
     base.max_atomic_width = Some(64);
     base.pre_link_args.get_mut(&LinkerFlavor::Gcc).unwrap().push("-mx32".to_string());
-    // BUG: temporarily workaround #59674
-    base.stack_probes = false;
+    base.stack_probes = true;
     base.has_elf_tls = false;
     // BUG(GabrielMajeri): disabling the PLT on x86_64 Linux with x32 ABI
     // breaks code gen. See LLVM bug 36743

src/librustc_typeck/check/method/suggest.rs

@@ -643,13 +643,15 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
         }
     }
 
-    fn suggest_traits_to_import<'b>(&self,
-                                    err: &mut DiagnosticBuilder<'_>,
-                                    span: Span,
-                                    rcvr_ty: Ty<'tcx>,
-                                    item_name: ast::Ident,
-                                    source: SelfSource<'b>,
-                                    valid_out_of_scope_traits: Vec<DefId>) {
+    fn suggest_traits_to_import<'b>(
+        &self,
+        err: &mut DiagnosticBuilder<'_>,
+        span: Span,
+        rcvr_ty: Ty<'tcx>,
+        item_name: ast::Ident,
+        source: SelfSource<'b>,
+        valid_out_of_scope_traits: Vec<DefId>,
+    ) {
         if self.suggest_valid_traits(err, valid_out_of_scope_traits) {
             return;
         }
@@ -683,30 +685,96 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
             candidates.sort_by(|a, b| a.cmp(b).reverse());
             candidates.dedup();
 
-            // FIXME #21673: this help message could be tuned to the case
-            // of a type parameter: suggest adding a trait bound rather
-            // than implementing.
-            err.help("items from traits can only be used if the trait is implemented and in scope");
-            let mut msg = format!("the following {traits_define} an item `{name}`, \
-                                   perhaps you need to implement {one_of_them}:",
-                                  traits_define = if candidates.len() == 1 {
-                                      "trait defines"
-                                  } else {
-                                      "traits define"
-                                  },
-                                  one_of_them = if candidates.len() == 1 {
-                                      "it"
-                                  } else {
-                                      "one of them"
-                                  },
-                                  name = item_name);
-
-            for (i, trait_info) in candidates.iter().enumerate() {
-                msg.push_str(&format!("\ncandidate #{}: `{}`",
-                                      i + 1,
-                                      self.tcx.def_path_str(trait_info.def_id)));
+            let param_type = match rcvr_ty.sty {
+                ty::Param(param) => Some(param),
+                ty::Ref(_, ty, _) => match ty.sty {
+                    ty::Param(param) => Some(param),
+                    _ => None,
+                }
+                _ => None,
+            };
+            err.help(if param_type.is_some() {
+                "items from traits can only be used if the type parameter is bounded by the trait"
+            } else {
+                "items from traits can only be used if the trait is implemented and in scope"
+            });
+            let mut msg = format!(
+                "the following {traits_define} an item `{name}`, perhaps you need to {action} \
+                 {one_of_them}:",
+                traits_define = if candidates.len() == 1 {
+                    "trait defines"
+                } else {
+                    "traits define"
+                },
+                action = if let Some(param) = param_type {
+                    format!("restrict type parameter `{}` with", param)
+                } else {
+                    "implement".to_string()
+                },
+                one_of_them = if candidates.len() == 1 {
+                    "it"
+                } else {
+                    "one of them"
+                },
+                name = item_name,
+            );
+            // Obtain the span for `param` and use it for a structured suggestion.
+            let mut suggested = false;
+            if let (Some(ref param), Some(ref table)) = (param_type, self.in_progress_tables) {
+                let table = table.borrow();
+                if let Some(did) = table.local_id_root {
+                    let generics = self.tcx.generics_of(did);
+                    let type_param = generics.type_param(param, self.tcx);
+                    let hir = &self.tcx.hir();
+                    if let Some(id) = hir.as_local_hir_id(type_param.def_id) {
+                        // Get the `hir::Param` to verify whether it already has any bounds.
+                        // We do this to avoid suggesting code that ends up as `T: FooBar`,
+                        // instead we suggest `T: Foo + Bar` in that case.
+                        let mut has_bounds = false;
+                        if let Node::GenericParam(ref param) = hir.get(id) {
+                            has_bounds = !param.bounds.is_empty();
+                        }
+                        let sp = hir.span(id);
+                        // `sp` only covers `T`, change it so that it covers
+                        // `T:` when appropriate
+                        let sp = if has_bounds {
+                            sp.to(self.tcx
+                                .sess
+                                .source_map()
+                                .next_point(self.tcx.sess.source_map().next_point(sp)))
+                        } else {
+                            sp
+                        };
+
+                        // FIXME: contrast `t.def_id` against `param.bounds` to not suggest traits
+                        // already there. That can happen when the cause is that we're in a const
+                        // scope or associated function used as a method.
+                        err.span_suggestions(
+                            sp,
+                            &msg[..],
+                            candidates.iter().map(|t| format!(
+                                "{}: {}{}",
+                                param,
+                                self.tcx.def_path_str(t.def_id),
+                                if has_bounds { " +"} else { "" },
+                            )),
+                            Applicability::MaybeIncorrect,
+                        );
+                        suggested = true;
+                    }
+                };
+            }
+
+            if !suggested {
+                for (i, trait_info) in candidates.iter().enumerate() {
+                    msg.push_str(&format!(
+                        "\ncandidate #{}: `{}`",
+                        i + 1,
+                        self.tcx.def_path_str(trait_info.def_id),
+                    ));
+                }
+                err.note(&msg[..]);
             }
-            err.note(&msg[..]);
         }
     }
 

src/librustc_typeck/check/mod.rs

@@ -759,40 +759,40 @@ fn adt_destructor(tcx: TyCtxt<'_>, def_id: DefId) -> Option<ty::Destructor> {
 fn primary_body_of(
     tcx: TyCtxt<'_>,
     id: hir::HirId,
-) -> Option<(hir::BodyId, Option<&hir::FnHeader>, Option<&hir::FnDecl>)> {
+) -> Option<(hir::BodyId, Option<&hir::Ty>, Option<&hir::FnHeader>, Option<&hir::FnDecl>)> {
     match tcx.hir().get(id) {
         Node::Item(item) => {
             match item.node {
-                hir::ItemKind::Const(_, body) |
-                hir::ItemKind::Static(_, _, body) =>
-                    Some((body, None, None)),
+                hir::ItemKind::Const(ref ty, body) |
+                hir::ItemKind::Static(ref ty, _, body) =>
+                    Some((body, Some(ty), None, None)),
                 hir::ItemKind::Fn(ref decl, ref header, .., body) =>
-                    Some((body, Some(header), Some(decl))),
+                    Some((body, None, Some(header), Some(decl))),
                 _ =>
                     None,
             }
         }
         Node::TraitItem(item) => {
             match item.node {
-                hir::TraitItemKind::Const(_, Some(body)) =>
-                    Some((body, None, None)),
+                hir::TraitItemKind::Const(ref ty, Some(body)) =>
+                    Some((body, Some(ty), None, None)),
                 hir::TraitItemKind::Method(ref sig, hir::TraitMethod::Provided(body)) =>
-                    Some((body, Some(&sig.header), Some(&sig.decl))),
+                    Some((body, None, Some(&sig.header), Some(&sig.decl))),
                 _ =>
                     None,
             }
         }
         Node::ImplItem(item) => {
             match item.node {
-                hir::ImplItemKind::Const(_, body) =>
-                    Some((body, None, None)),
+                hir::ImplItemKind::Const(ref ty, body) =>
+                    Some((body, Some(ty), None, None)),
                 hir::ImplItemKind::Method(ref sig, body) =>
-                    Some((body, Some(&sig.header), Some(&sig.decl))),
+                    Some((body, None, Some(&sig.header), Some(&sig.decl))),
                 _ =>
                     None,
             }
         }
-        Node::AnonConst(constant) => Some((constant.body, None, None)),
+        Node::AnonConst(constant) => Some((constant.body, None, None, None)),
         _ => None,
     }
 }
@@ -825,7 +825,7 @@ fn typeck_tables_of(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::TypeckTables<'_> {
     let span = tcx.hir().span(id);
 
     // Figure out what primary body this item has.
-    let (body_id, fn_header, fn_decl) = primary_body_of(tcx, id)
+    let (body_id, body_ty, fn_header, fn_decl) = primary_body_of(tcx, id)
         .unwrap_or_else(|| {
             span_bug!(span, "can't type-check body of {:?}", def_id);
         });
@@ -856,7 +856,10 @@ fn typeck_tables_of(tcx: TyCtxt<'_>, def_id: DefId) -> &ty::TypeckTables<'_> {
             fcx
         } else {
             let fcx = FnCtxt::new(&inh, param_env, body.value.hir_id);
-            let expected_type = tcx.type_of(def_id);
+            let expected_type = body_ty.and_then(|ty| match ty.node {
+                hir::TyKind::Infer => Some(AstConv::ast_ty_to_ty(&fcx, ty)),
+                _ => None
+            }).unwrap_or_else(|| tcx.type_of(def_id));
             let expected_type = fcx.normalize_associated_types_in(body.value.span, &expected_type);
             fcx.require_type_is_sized(expected_type, body.value.span, traits::ConstSized);