Auto merge of #29383 - petrochenkov:empstr, r=pnkfelix

Fixes #28692
Fixes #28992
Fixes some other similar issues (see the tests)

[breaking-change], needs crater run (cc @brson or @alexcrichton )

The pattern with parens `UnitVariant(..)` for unit variants seems to be popular in rustc (see the second commit), but mostly used by one person (@nikomatsakis), according to git blame. If it causes breakage on crates.io I'll add an exceptional case for it.

Author: bors

src/librustc/middle/intrinsicck.rs

@@ -225,11 +225,10 @@ impl<'a, 'tcx, 'v> Visitor<'v> for IntrinsicCheckingVisitor<'a, 'tcx> {
                 intravisit::walk_fn(self, fk, fd, b, s);
                 self.param_envs.pop();
             }
-            FnKind::Closure(..) => {
+            FnKind::Closure => {
                 intravisit::walk_fn(self, fk, fd, b, s);
             }
         }
-
     }
 
     fn visit_expr(&mut self, expr: &hir::Expr) {

src/librustc/middle/mem_categorization.rs

@@ -1424,7 +1424,7 @@ impl<'tcx> cmt_<'tcx> {
                 NonAliasable
             }
 
-            Categorization::StaticItem(..) => {
+            Categorization::StaticItem => {
                 if self.mutbl.is_mutable() {
                     FreelyAliasable(AliasableStaticMut)
                 } else {

src/librustc/middle/resolve_lifetime.rs

@@ -184,7 +184,7 @@ impl<'a, 'v> Visitor<'v> for LifetimeContext<'a> {
                     this.walk_fn(fk, fd, b, s)
                 })
             }
-            FnKind::Closure(..) => {
+            FnKind::Closure => {
                 self.walk_fn(fk, fd, b, s)
             }
         }
@@ -479,7 +479,7 @@ impl<'a> LifetimeContext<'a> {
                 self.visit_generics(&sig.generics);
                 self.visit_explicit_self(&sig.explicit_self);
             }
-            FnKind::Closure(..) => {
+            FnKind::Closure => {
                 intravisit::walk_fn_decl(self, fd);
             }
         }

src/librustc/middle/traits/coherence.rs

@@ -300,7 +300,7 @@ fn ty_is_local_constructor<'tcx>(tcx: &ty::ctxt<'tcx>,
         ty::TyInt(..) |
         ty::TyUint(..) |
         ty::TyFloat(..) |
-        ty::TyStr(..) |
+        ty::TyStr |
         ty::TyBareFn(..) |
         ty::TyArray(..) |
         ty::TySlice(..) |

src/librustc/middle/traits/select.rs

@@ -1563,7 +1563,7 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
         }
 
         match other {
-            &ObjectCandidate(..) |
+            &ObjectCandidate |
             &ParamCandidate(_) | &ProjectionCandidate => match victim {
                 &DefaultImplCandidate(..) => {
                     self.tcx().sess.bug(
@@ -1572,16 +1572,16 @@ impl<'cx, 'tcx> SelectionContext<'cx, 'tcx> {
                 }
                 &ImplCandidate(..) |
                 &ClosureCandidate(..) |
-                &FnPointerCandidate(..) |
-                &BuiltinObjectCandidate(..) |
-                &BuiltinUnsizeCandidate(..) |
+                &FnPointerCandidate |
+                &BuiltinObjectCandidate |
+                &BuiltinUnsizeCandidate |
                 &DefaultImplObjectCandidate(..) |
                 &BuiltinCandidate(..) => {
                     // We have a where-clause so don't go around looking
                     // for impls.
                     true
                 }
-                &ObjectCandidate(..) |
+                &ObjectCandidate |
                 &ProjectionCandidate => {
                     // Arbitrarily give param candidates priority
                     // over projection and object candidates.

src/librustc/middle/ty/outlives.rs

@@ -188,21 +188,21 @@ fn compute_components<'a,'tcx>(infcx: &InferCtxt<'a,'tcx>,
         // the type and then visits the types that are lexically
         // contained within. (The comments refer to relevant rules
         // from RFC1214.)
-        ty::TyBool(..) |        // OutlivesScalar
-        ty::TyChar(..) |        // OutlivesScalar
+        ty::TyBool |            // OutlivesScalar
+        ty::TyChar |            // OutlivesScalar
         ty::TyInt(..) |         // OutlivesScalar
         ty::TyUint(..) |        // OutlivesScalar
         ty::TyFloat(..) |       // OutlivesScalar
         ty::TyEnum(..) |        // OutlivesNominalType
         ty::TyStruct(..) |      // OutlivesNominalType
         ty::TyBox(..) |         // OutlivesNominalType (ish)
-        ty::TyStr(..) |         // OutlivesScalar (ish)
+        ty::TyStr |             // OutlivesScalar (ish)
         ty::TyArray(..) |       // ...
         ty::TySlice(..) |       // ...
         ty::TyRawPtr(..) |      // ...
         ty::TyRef(..) |         // OutlivesReference
         ty::TyTuple(..) |       // ...
-        ty::TyError(..) => {
+        ty::TyError => {
             push_region_constraints(out, ty.regions());
             for subty in ty.walk_shallow() {
                 compute_components(infcx, subty, out);

src/librustc_borrowck/borrowck/check_loans.rs

@@ -540,14 +540,14 @@ impl<'a, 'tcx> CheckLoanCtxt<'a, 'tcx> {
                             ol, old_loan_msg)
                 }
 
-                euv::OverloadedOperator(..) |
-                euv::AddrOf(..) |
-                euv::AutoRef(..) |
-                euv::AutoUnsafe(..) |
-                euv::ClosureInvocation(..) |
-                euv::ForLoop(..) |
-                euv::RefBinding(..) |
-                euv::MatchDiscriminant(..) => {
+                euv::OverloadedOperator |
+                euv::AddrOf |
+                euv::AutoRef |
+                euv::AutoUnsafe |
+                euv::ClosureInvocation |
+                euv::ForLoop |
+                euv::RefBinding |
+                euv::MatchDiscriminant => {
                     format!("previous borrow of `{}` occurs here{}",
                             ol, old_loan_msg)
                 }

src/librustc_borrowck/borrowck/gather_loans/restrictions.rs

@@ -101,7 +101,7 @@ impl<'a, 'tcx> RestrictionsContext<'a, 'tcx> {
                 self.extend(result, &cmt, LpInterior(i.cleaned()))
             }
 
-            Categorization::StaticItem(..) => {
+            Categorization::StaticItem => {
                 Safe
             }
 

src/librustc_borrowck/borrowck/mod.rs

@@ -942,8 +942,8 @@ impl<'a, 'tcx> BorrowckCtxt<'a, 'tcx> {
                            "consider changing this closure to take self by mutable reference");
                 }
             }
-            mc::AliasableStatic(..) |
-            mc::AliasableStaticMut(..) => {
+            mc::AliasableStatic |
+            mc::AliasableStaticMut => {
                 span_err!(
                     self.tcx.sess, span, E0388,
                     "{} in a static location", prefix);
@@ -998,7 +998,7 @@ impl<'a, 'tcx> BorrowckCtxt<'a, 'tcx> {
     pub fn note_and_explain_bckerr(&self, err: BckError<'tcx>) {
         let code = err.code;
         match code {
-            err_mutbl(..) => {
+            err_mutbl => {
                 match err.cmt.note {
                     mc::NoteClosureEnv(upvar_id) | mc::NoteUpvarRef(upvar_id) => {
                         // If this is an `Fn` closure, it simply can't mutate upvars.

src/librustc_mir/build/matches/simplify.rs

@@ -66,7 +66,7 @@ impl<'a,'tcx> Builder<'a,'tcx> {
                                  candidate: &mut Candidate<'pat, 'tcx>)
                                  -> Result<BasicBlock, MatchPair<'pat, 'tcx>> {
         match *match_pair.pattern.kind {
-            PatternKind::Wild(..) => {
+            PatternKind::Wild => {
                 // nothing left to do
                 Ok(block)
             }