Auto merge of #67419 - Centril:rollup-v7b0ypv, r=Centril

Rollup of 8 pull requests

Successful merges:

 - #67189 (Unify binop wording)
 - #67270 (std: Implement `LineWriter::write_vectored`)
 - #67286 (Fix the configure.py TOML field for a couple LLVM options)
 - #67321 (make htons const fn)
 - #67382 (Remove some unnecessary `ATTR_*` constants.)
 - #67389 (Remove `SO_NOSIGPIPE` dummy variable on platforms that don't use it.)
 - #67394 (Remove outdated references to @t from comments)
 - #67406 (Suggest associated type when the specified one cannot be found)

Failed merges:

r? @ghost

src/bootstrap/configure.py

@@ -59,13 +59,13 @@ def v(*args):
 o("lld", "rust.lld", "build lld")
 o("lldb", "rust.lldb", "build lldb")
 o("missing-tools", "dist.missing-tools", "allow failures when building tools")
-o("use-libcxx", "llvm.use_libcxx", "build LLVM with libc++")
+o("use-libcxx", "llvm.use-libcxx", "build LLVM with libc++")
 
 o("cflags", "llvm.cflags", "build LLVM with these extra compiler flags")
 o("cxxflags", "llvm.cxxflags", "build LLVM with these extra compiler flags")
 o("ldflags", "llvm.ldflags", "build LLVM with these extra linker flags")
 
-o("llvm-libunwind", "rust.llvm_libunwind", "use LLVM libunwind")
+o("llvm-libunwind", "rust.llvm-libunwind", "use LLVM libunwind")
 
 # Optimization and debugging options. These may be overridden by the release
 # channel, etc.

src/librustc/ich/mod.rs

@@ -12,21 +12,13 @@ mod impls_hir;
 mod impls_ty;
 mod impls_syntax;
 
-pub const ATTR_DIRTY: Symbol = sym::rustc_dirty;
-pub const ATTR_CLEAN: Symbol = sym::rustc_clean;
-pub const ATTR_IF_THIS_CHANGED: Symbol = sym::rustc_if_this_changed;
-pub const ATTR_THEN_THIS_WOULD_NEED: Symbol = sym::rustc_then_this_would_need;
-pub const ATTR_PARTITION_REUSED: Symbol = sym::rustc_partition_reused;
-pub const ATTR_PARTITION_CODEGENED: Symbol = sym::rustc_partition_codegened;
-pub const ATTR_EXPECTED_CGU_REUSE: Symbol = sym::rustc_expected_cgu_reuse;
-
 pub const IGNORED_ATTRIBUTES: &[Symbol] = &[
     sym::cfg,
-    ATTR_IF_THIS_CHANGED,
-    ATTR_THEN_THIS_WOULD_NEED,
-    ATTR_DIRTY,
-    ATTR_CLEAN,
-    ATTR_PARTITION_REUSED,
-    ATTR_PARTITION_CODEGENED,
-    ATTR_EXPECTED_CGU_REUSE,
+    sym::rustc_if_this_changed,
+    sym::rustc_then_this_would_need,
+    sym::rustc_dirty,
+    sym::rustc_clean,
+    sym::rustc_partition_reused,
+    sym::rustc_partition_codegened,
+    sym::rustc_expected_cgu_reuse,
 ];

src/librustc_incremental/assert_dep_graph.rs

@@ -44,11 +44,10 @@ use rustc_data_structures::graph::implementation::{
 };
 use rustc::hir;
 use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
-use rustc::ich::{ATTR_IF_THIS_CHANGED, ATTR_THEN_THIS_WOULD_NEED};
 use std::env;
 use std::fs::{self, File};
 use std::io::Write;
-use syntax::ast;
+use syntax::{ast, symbol::sym};
 use syntax_pos::Span;
 
 pub fn assert_dep_graph(tcx: TyCtxt<'_>) {
@@ -78,7 +77,7 @@ pub fn assert_dep_graph(tcx: TyCtxt<'_>) {
             assert!(tcx.sess.opts.debugging_opts.query_dep_graph,
                     "cannot use the `#[{}]` or `#[{}]` annotations \
                     without supplying `-Z query-dep-graph`",
-                    ATTR_IF_THIS_CHANGED, ATTR_THEN_THIS_WOULD_NEED);
+                    sym::rustc_if_this_changed, sym::rustc_then_this_would_need);
         }
 
         // Check paths.
@@ -114,7 +113,7 @@ impl IfThisChanged<'tcx> {
         let def_id = self.tcx.hir().local_def_id(hir_id);
         let def_path_hash = self.tcx.def_path_hash(def_id);
         for attr in attrs {
-            if attr.check_name(ATTR_IF_THIS_CHANGED) {
+            if attr.check_name(sym::rustc_if_this_changed) {
                 let dep_node_interned = self.argument(attr);
                 let dep_node = match dep_node_interned {
                     None => def_path_hash.to_dep_node(DepKind::Hir),
@@ -130,7 +129,7 @@ impl IfThisChanged<'tcx> {
                     }
                 };
                 self.if_this_changed.push((attr.span, def_id, dep_node));
-            } else if attr.check_name(ATTR_THEN_THIS_WOULD_NEED) {
+            } else if attr.check_name(sym::rustc_then_this_would_need) {
                 let dep_node_interned = self.argument(attr);
                 let dep_node = match dep_node_interned {
                     Some(n) => {

src/librustc_incremental/assert_module_sources.rs

@@ -28,8 +28,6 @@ use rustc::ty::TyCtxt;
 use std::collections::BTreeSet;
 use syntax::ast;
 use syntax::symbol::{Symbol, sym};
-use rustc::ich::{ATTR_PARTITION_REUSED, ATTR_PARTITION_CODEGENED,
-                 ATTR_EXPECTED_CGU_REUSE};
 
 pub fn assert_module_sources(tcx: TyCtxt<'_>) {
     tcx.dep_graph.with_ignore(|| {
@@ -62,11 +60,11 @@ struct AssertModuleSource<'tcx> {
 
 impl AssertModuleSource<'tcx> {
     fn check_attr(&self, attr: &ast::Attribute) {
-        let (expected_reuse, comp_kind) = if attr.check_name(ATTR_PARTITION_REUSED) {
+        let (expected_reuse, comp_kind) = if attr.check_name(sym::rustc_partition_reused) {
             (CguReuse::PreLto, ComparisonKind::AtLeast)
-        } else if attr.check_name(ATTR_PARTITION_CODEGENED) {
+        } else if attr.check_name(sym::rustc_partition_codegened) {
             (CguReuse::No, ComparisonKind::Exact)
-        } else if attr.check_name(ATTR_EXPECTED_CGU_REUSE) {
+        } else if attr.check_name(sym::rustc_expected_cgu_reuse) {
             match &*self.field(attr, sym::kind).as_str() {
                 "no" => (CguReuse::No, ComparisonKind::Exact),
                 "pre-lto" => (CguReuse::PreLto, ComparisonKind::Exact),

src/librustc_incremental/persist/dirty_clean.rs

@@ -22,7 +22,6 @@ use rustc::hir::Node as HirNode;
 use rustc::hir::def_id::DefId;
 use rustc::hir::itemlikevisit::ItemLikeVisitor;
 use rustc::hir::intravisit;
-use rustc::ich::{ATTR_DIRTY, ATTR_CLEAN};
 use rustc::ty::TyCtxt;
 use rustc_data_structures::fingerprint::Fingerprint;
 use rustc_data_structures::fx::FxHashSet;
@@ -224,7 +223,7 @@ pub fn check_dirty_clean_annotations(tcx: TyCtxt<'_>) {
 
         let mut all_attrs = FindAllAttrs {
             tcx,
-            attr_names: vec![ATTR_DIRTY, ATTR_CLEAN],
+            attr_names: vec![sym::rustc_dirty, sym::rustc_clean],
             found_attrs: vec![],
         };
         intravisit::walk_crate(&mut all_attrs, krate);
@@ -246,9 +245,9 @@ impl DirtyCleanVisitor<'tcx> {
     fn assertion_maybe(&mut self, item_id: hir::HirId, attr: &Attribute)
         -> Option<Assertion>
     {
-        let is_clean = if attr.check_name(ATTR_DIRTY) {
+        let is_clean = if attr.check_name(sym::rustc_dirty) {
             false
-        } else if attr.check_name(ATTR_CLEAN) {
+        } else if attr.check_name(sym::rustc_clean) {
             true
         } else {
             // skip: not rustc_clean/dirty

src/librustc_typeck/astconv.rs

@@ -1145,11 +1145,8 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         } else {
             // Otherwise, we have to walk through the supertraits to find
             // those that do.
-            let candidates = traits::supertraits(tcx, trait_ref).filter(|r| {
-                self.trait_defines_associated_type_named(r.def_id(), binding.item_name)
-            });
             self.one_bound_for_assoc_type(
-                candidates,
+                || traits::supertraits(tcx, trait_ref),
                 &trait_ref.print_only_trait_path().to_string(),
                 binding.item_name,
                 binding.span
@@ -1531,50 +1528,48 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
 
         debug!("find_bound_for_assoc_item: predicates={:#?}", predicates);
 
-        let bounds = predicates.iter().filter_map(|(p, _)| p.to_opt_poly_trait_ref());
-
-        // Check that there is exactly one way to find an associated type with the
-        // correct name.
-        let suitable_bounds = traits::transitive_bounds(tcx, bounds)
-            .filter(|b| self.trait_defines_associated_type_named(b.def_id(), assoc_name));
-
         let param_hir_id = tcx.hir().as_local_hir_id(ty_param_def_id).unwrap();
         let param_name = tcx.hir().ty_param_name(param_hir_id);
-        self.one_bound_for_assoc_type(suitable_bounds,
-                                      &param_name.as_str(),
-                                      assoc_name,
-                                      span)
+        self.one_bound_for_assoc_type(
+            || traits::transitive_bounds(tcx, predicates
+                .iter().filter_map(|(p, _)| p.to_opt_poly_trait_ref())),
+            &param_name.as_str(),
+            assoc_name,
+            span,
+        )
     }
 
-    // Checks that `bounds` contains exactly one element and reports appropriate
-    // errors otherwise.
     fn one_bound_for_assoc_type<I>(&self,
-                                   mut bounds: I,
+                                   all_candidates: impl Fn() -> I,
                                    ty_param_name: &str,
                                    assoc_name: ast::Ident,
                                    span: Span)
         -> Result<ty::PolyTraitRef<'tcx>, ErrorReported>
         where I: Iterator<Item = ty::PolyTraitRef<'tcx>>
     {
-        let bound = match bounds.next() {
+        let mut matching_candidates = all_candidates().filter(|r| {
+            self.trait_defines_associated_type_named(r.def_id(), assoc_name)
+        });
+
+        let bound = match matching_candidates.next() {
             Some(bound) => bound,
             None => {
-                struct_span_err!(self.tcx().sess, span, E0220,
-                                 "associated type `{}` not found for `{}`",
-                                 assoc_name,
-                                 ty_param_name)
-                    .span_label(span, format!("associated type `{}` not found", assoc_name))
-                    .emit();
+                self.complain_about_assoc_type_not_found(
+                    all_candidates,
+                    ty_param_name,
+                    assoc_name,
+                    span
+                );
                 return Err(ErrorReported);
             }
         };
 
         debug!("one_bound_for_assoc_type: bound = {:?}", bound);
 
-        if let Some(bound2) = bounds.next() {
+        if let Some(bound2) = matching_candidates.next() {
             debug!("one_bound_for_assoc_type: bound2 = {:?}", bound2);
 
-            let bounds = iter::once(bound).chain(iter::once(bound2)).chain(bounds);
+            let bounds = iter::once(bound).chain(iter::once(bound2)).chain(matching_candidates);
             let mut err = struct_span_err!(
                 self.tcx().sess, span, E0221,
                 "ambiguous associated type `{}` in bounds of `{}`",
@@ -1606,6 +1601,50 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
         return Ok(bound);
     }
 
+    fn complain_about_assoc_type_not_found<I>(&self,
+                                              all_candidates: impl Fn() -> I,
+                                              ty_param_name: &str,
+                                              assoc_name: ast::Ident,
+                                              span: Span)
+    where I: Iterator<Item = ty::PolyTraitRef<'tcx>> {
+        let mut err = struct_span_err!(self.tcx().sess, span, E0220,
+                                 "associated type `{}` not found for `{}`",
+                                 assoc_name,
+                                 ty_param_name);
+
+        let all_candidate_names: Vec<_> = all_candidates()
+            .map(|r| self.tcx().associated_items(r.def_id()))
+            .flatten()
+            .filter_map(|item|
+                if item.kind == ty::AssocKind::Type {
+                    Some(item.ident.name)
+                } else {
+                    None
+                }
+            )
+            .collect();
+
+        if let Some(suggested_name) = find_best_match_for_name(
+            all_candidate_names.iter(),
+            &assoc_name.as_str(),
+            None,
+        ) {
+            err.span_suggestion(
+                span,
+                "there is an associated type with a similar name",
+                suggested_name.to_string(),
+                Applicability::MaybeIncorrect,
+            );
+        } else {
+            err.span_label(
+                span,
+                format!("associated type `{}` not found", assoc_name)
+            );
+        }
+
+        err.emit();
+    }
+
     // Create a type from a path to an associated type.
     // For a path `A::B::C::D`, `qself_ty` and `qself_def` are the type and def for `A::B::C`
     // and item_segment is the path segment for `D`. We return a type and a def for
@@ -1660,10 +1699,12 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                     }
                 };
 
-                let candidates = traits::supertraits(tcx, ty::Binder::bind(trait_ref))
-                    .filter(|r| self.trait_defines_associated_type_named(r.def_id(), assoc_ident));
-
-                self.one_bound_for_assoc_type(candidates, "Self", assoc_ident, span)?
+                self.one_bound_for_assoc_type(
+                    || traits::supertraits(tcx, ty::Binder::bind(trait_ref)),
+                    "Self",
+                    assoc_ident,
+                    span
+                )?
             }
             (&ty::Param(_), Res::SelfTy(Some(param_did), None)) |
             (&ty::Param(_), Res::Def(DefKind::TyParam, param_did)) => {

src/librustc_typeck/check/op.rs

@@ -334,10 +334,70 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                             err.emit();
                         }
                         IsAssign::No => {
+                            let (message, missing_trait) = match op.node {
+                                hir::BinOpKind::Add    => {
+                                    (format!("cannot add `{}` to `{}`", rhs_ty, lhs_ty),
+                                    Some("std::ops::Add"))
+                                },
+                                hir::BinOpKind::Sub    => {
+                                    (format!("cannot substract `{}` from `{}`", rhs_ty, lhs_ty),
+                                    Some("std::ops::Sub"))
+                                },
+                                hir::BinOpKind::Mul    => {
+                                    (format!("cannot multiply `{}` to `{}`", rhs_ty, lhs_ty),
+                                    Some("std::ops::Mul"))
+                                },
+                                hir::BinOpKind::Div    => {
+                                    (format!("cannot divide `{}` by `{}`", lhs_ty, rhs_ty),
+                                    Some("std::ops::Div"))
+                                },
+                                hir::BinOpKind::Rem    => {
+                                    (format!("cannot mod `{}` by `{}`", lhs_ty, rhs_ty),
+                                    Some("std::ops::Rem"))
+                                },
+                                hir::BinOpKind::BitAnd => {
+                                    (format!("no implementation for `{} & {}`", lhs_ty, rhs_ty),
+                                    Some("std::ops::BitAnd"))
+                                },
+                                hir::BinOpKind::BitXor => {
+                                    (format!("no implementation for `{} ^ {}`", lhs_ty, rhs_ty),
+                                    Some("std::ops::BitXor"))
+                                },
+                                hir::BinOpKind::BitOr  => {
+                                    (format!("no implementation for `{} | {}`", lhs_ty, rhs_ty),
+                                    Some("std::ops::BitOr"))
+                                },
+                                hir::BinOpKind::Shl    => {
+                                    (format!("no implementation for `{} << {}`", lhs_ty, rhs_ty),
+                                    Some("std::ops::Shl"))
+                                },
+                                hir::BinOpKind::Shr    => {
+                                    (format!("no implementation for `{} >> {}`", lhs_ty, rhs_ty),
+                                    Some("std::ops::Shr"))
+                                },
+                                hir::BinOpKind::Eq |
+                                hir::BinOpKind::Ne     => {
+                                    (format!(
+                                            "binary operation `{}` cannot be applied to type `{}`",
+                                            op.node.as_str(), lhs_ty),
+                                    Some("std::cmp::PartialEq"))
+                                },
+                                hir::BinOpKind::Lt |
+                                hir::BinOpKind::Le |
+                                hir::BinOpKind::Gt |
+                                hir::BinOpKind::Ge     => {
+                                    (format!(
+                                            "binary operation `{}` cannot be applied to type `{}`",
+                                            op.node.as_str(), lhs_ty),
+                                    Some("std::cmp::PartialOrd"))
+                                }
+                                _ => (format!(
+                                        "binary operation `{}` cannot be applied to type `{}`",
+                                        op.node.as_str(), lhs_ty),
+                                    None)
+                            };
                             let mut err = struct_span_err!(self.tcx.sess, op.span, E0369,
-                                "binary operation `{}` cannot be applied to type `{}`",
-                                op.node.as_str(),
-                                lhs_ty);
+                                "{}", message.as_str());
 
                             let mut involves_fn = false;
                             if !lhs_expr.span.eq(&rhs_expr.span) {
@@ -382,25 +442,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
                                     }
                                 }
                             }
-                            let missing_trait = match op.node {
-                                hir::BinOpKind::Add    => Some("std::ops::Add"),
-                                hir::BinOpKind::Sub    => Some("std::ops::Sub"),
-                                hir::BinOpKind::Mul    => Some("std::ops::Mul"),
-                                hir::BinOpKind::Div    => Some("std::ops::Div"),
-                                hir::BinOpKind::Rem    => Some("std::ops::Rem"),
-                                hir::BinOpKind::BitAnd => Some("std::ops::BitAnd"),
-                                hir::BinOpKind::BitXor => Some("std::ops::BitXor"),
-                                hir::BinOpKind::BitOr  => Some("std::ops::BitOr"),
-                                hir::BinOpKind::Shl    => Some("std::ops::Shl"),
-                                hir::BinOpKind::Shr    => Some("std::ops::Shr"),
-                                hir::BinOpKind::Eq |
-                                hir::BinOpKind::Ne => Some("std::cmp::PartialEq"),
-                                hir::BinOpKind::Lt |
-                                hir::BinOpKind::Le |
-                                hir::BinOpKind::Gt |
-                                hir::BinOpKind::Ge => Some("std::cmp::PartialOrd"),
-                                _ => None
-                            };
                             if let Some(missing_trait) = missing_trait {
                                 if op.node == hir::BinOpKind::Add &&
                                     self.check_str_addition(