diff --git a/src/librustc/ty/sty.rs b/src/librustc/ty/sty.rs
index 962b115f1877a..ea547c592d048 100644
--- a/src/librustc/ty/sty.rs
+++ b/src/librustc/ty/sty.rs
@@ -1458,7 +1458,7 @@ impl RegionKind {
 
 /// Type utilities
 impl<'a, 'gcx, 'tcx> TyS<'tcx> {
-    pub fn is_nil(&self) -> bool {
+    pub fn is_unit(&self) -> bool {
         match self.sty {
             Tuple(ref tys) => tys.is_empty(),
             _ => false,
diff --git a/src/librustc/util/ppaux.rs b/src/librustc/util/ppaux.rs
index ddcc0fa9c9280..3d7117dd46a21 100644
--- a/src/librustc/util/ppaux.rs
+++ b/src/librustc/util/ppaux.rs
@@ -234,7 +234,7 @@ impl PrintContext {
             }
         }
         write!(f, ")")?;
-        if !output.is_nil() {
+        if !output.is_unit() {
             print!(f, self, write(" -> "), print_display(output))?;
         }
 
diff --git a/src/librustc_codegen_llvm/debuginfo/type_names.rs b/src/librustc_codegen_llvm/debuginfo/type_names.rs
index 95a094bf909e1..f9eb80a1988af 100644
--- a/src/librustc_codegen_llvm/debuginfo/type_names.rs
+++ b/src/librustc_codegen_llvm/debuginfo/type_names.rs
@@ -160,7 +160,7 @@ pub fn push_debuginfo_type_name<'a, 'tcx>(cx: &CodegenCx<'a, 'tcx>,
 
             output.push(')');
 
-            if !sig.output().is_nil() {
+            if !sig.output().is_unit() {
                 output.push_str(" -> ");
                 push_debuginfo_type_name(cx, sig.output(), true, output);
             }
diff --git a/src/librustc_codegen_llvm/mir/rvalue.rs b/src/librustc_codegen_llvm/mir/rvalue.rs
index e301e5ae70be8..c3ec347f60876 100644
--- a/src/librustc_codegen_llvm/mir/rvalue.rs
+++ b/src/librustc_codegen_llvm/mir/rvalue.rs
@@ -566,7 +566,7 @@ impl FunctionCx<'a, 'll, 'tcx> {
     ) -> &'ll Value {
         let is_float = input_ty.is_fp();
         let is_signed = input_ty.is_signed();
-        let is_nil = input_ty.is_nil();
+        let is_unit = input_ty.is_unit();
         match op {
             mir::BinOp::Add => if is_float {
                 bx.fadd(lhs, rhs)
@@ -604,7 +604,7 @@ impl FunctionCx<'a, 'll, 'tcx> {
             mir::BinOp::Shl => common::build_unchecked_lshift(bx, lhs, rhs),
             mir::BinOp::Shr => common::build_unchecked_rshift(bx, input_ty, lhs, rhs),
             mir::BinOp::Ne | mir::BinOp::Lt | mir::BinOp::Gt |
-            mir::BinOp::Eq | mir::BinOp::Le | mir::BinOp::Ge => if is_nil {
+            mir::BinOp::Eq | mir::BinOp::Le | mir::BinOp::Ge => if is_unit {
                 C_bool(bx.cx, match op {
                     mir::BinOp::Ne | mir::BinOp::Lt | mir::BinOp::Gt => false,
                     mir::BinOp::Eq | mir::BinOp::Le | mir::BinOp::Ge => true,
diff --git a/src/librustc_lint/types.rs b/src/librustc_lint/types.rs
index 33181bd80e937..2bec9203e9ee5 100644
--- a/src/librustc_lint/types.rs
+++ b/src/librustc_lint/types.rs
@@ -691,7 +691,7 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
                 }
 
                 let sig = cx.erase_late_bound_regions(&sig);
-                if !sig.output().is_nil() {
+                if !sig.output().is_unit() {
                     let r = self.check_type_for_ffi(cache, sig.output());
                     match r {
                         FfiSafe => {}
@@ -767,7 +767,7 @@ impl<'a, 'tcx> ImproperCTypesVisitor<'a, 'tcx> {
 
         if let hir::Return(ref ret_hir) = decl.output {
             let ret_ty = sig.output();
-            if !ret_ty.is_nil() {
+            if !ret_ty.is_unit() {
                 self.check_type_for_ffi_and_report_errors(ret_hir.span, ret_ty);
             }
         }
diff --git a/src/librustc_mir/build/block.rs b/src/librustc_mir/build/block.rs
index c3637a5abebdc..50d4944d7c242 100644
--- a/src/librustc_mir/build/block.rs
+++ b/src/librustc_mir/build/block.rs
@@ -177,7 +177,7 @@ impl<'a, 'gcx, 'tcx> Builder<'a, 'gcx, 'tcx> {
             // the case of `!`, no return value is required, as the block will never return.
             let tcx = this.hir.tcx();
             let ty = destination.ty(&this.local_decls, tcx).to_ty(tcx);
-            if ty.is_nil() {
+            if ty.is_unit() {
                 // We only want to assign an implicit `()` as the return value of the block if the
                 // block does not diverge. (Otherwise, we may try to assign a unit to a `!`-type.)
                 this.cfg.push_assign_unit(block, source_info, destination);
diff --git a/src/librustc_mir/monomorphize/item.rs b/src/librustc_mir/monomorphize/item.rs
index dc437ee8510d7..3f5a05f9d0ed8 100644
--- a/src/librustc_mir/monomorphize/item.rs
+++ b/src/librustc_mir/monomorphize/item.rs
@@ -368,7 +368,7 @@ impl<'a, 'tcx> DefPathBasedNames<'a, 'tcx> {
 
                 output.push(')');
 
-                if !sig.output().is_nil() {
+                if !sig.output().is_unit() {
                     output.push_str(" -> ");
                     self.push_type_name(sig.output(), output);
                 }
diff --git a/src/librustc_typeck/check/_match.rs b/src/librustc_typeck/check/_match.rs
index 2a8ee4bd8df0e..a712bce2a4c4b 100644
--- a/src/librustc_typeck/check/_match.rs
+++ b/src/librustc_typeck/check/_match.rs
@@ -677,14 +677,14 @@ https://doc.rust-lang.org/reference/types.html#trait-objects");
             // Handle the fallback arm of a desugared if-let like a missing else.
             let is_if_let_fallback = match match_src {
                 hir::MatchSource::IfLetDesugar { contains_else_clause: false } => {
-                    i == arms.len() - 1 && arm_ty.is_nil()
+                    i == arms.len() - 1 && arm_ty.is_unit()
                 }
                 _ => false
             };
 
             if is_if_let_fallback {
                 let cause = self.cause(expr.span, ObligationCauseCode::IfExpressionWithNoElse);
-                assert!(arm_ty.is_nil());
+                assert!(arm_ty.is_unit());
                 coercion.coerce_forced_unit(self, &cause, &mut |_| (), true);
             } else {
                 let cause = self.cause(expr.span, ObligationCauseCode::MatchExpressionArm {
diff --git a/src/librustc_typeck/check/coercion.rs b/src/librustc_typeck/check/coercion.rs
index 763adb007c3a4..4b09e91bdd75f 100644
--- a/src/librustc_typeck/check/coercion.rs
+++ b/src/librustc_typeck/check/coercion.rs
@@ -1146,8 +1146,8 @@ impl<'gcx, 'tcx, 'exprs, E> CoerceMany<'gcx, 'tcx, 'exprs, E>
             // `expression_ty` will be unit).
             //
             // Another example is `break` with no argument expression.
-            assert!(expression_ty.is_nil());
-            assert!(expression_ty.is_nil(), "if let hack without unit type");
+            assert!(expression_ty.is_unit());
+            assert!(expression_ty.is_unit(), "if let hack without unit type");
             fcx.at(cause, fcx.param_env)
                .eq_exp(label_expression_as_expected, expression_ty, self.merged_ty())
                .map(|infer_ok| {
diff --git a/src/librustc_typeck/check/mod.rs b/src/librustc_typeck/check/mod.rs
index 9ab269702db1c..9638b6ca6ab2d 100644
--- a/src/librustc_typeck/check/mod.rs
+++ b/src/librustc_typeck/check/mod.rs
@@ -2808,9 +2808,9 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
         } else {
             // is the missing argument of type `()`?
             let sugg_unit = if expected_arg_tys.len() == 1 && supplied_arg_count == 0 {
-                self.resolve_type_vars_if_possible(&expected_arg_tys[0]).is_nil()
+                self.resolve_type_vars_if_possible(&expected_arg_tys[0]).is_unit()
             } else if fn_inputs.len() == 1 && supplied_arg_count == 0 {
-                self.resolve_type_vars_if_possible(&fn_inputs[0]).is_nil()
+                self.resolve_type_vars_if_possible(&fn_inputs[0]).is_unit()
             } else {
                 false
             };
@@ -3958,7 +3958,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                         if let Some(ref e) = *expr_opt {
                             coerce.coerce(self, &cause, e, e_ty);
                         } else {
-                            assert!(e_ty.is_nil());
+                            assert!(e_ty.is_unit());
                             coerce.coerce_forced_unit(self, &cause, &mut |_| (), true);
                         }
                     } else {
@@ -4752,7 +4752,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                                  expression: &'gcx hir::Expr,
                                  expected: Ty<'tcx>,
                                  cause_span: Span) {
-        if expected.is_nil() {
+        if expected.is_unit() {
             // `BlockTailExpression` only relevant if the tail expr would be
             // useful on its own.
             match expression.node {
@@ -4795,7 +4795,7 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
                                    can_suggest: bool) {
         // Only suggest changing the return type for methods that
         // haven't set a return type at all (and aren't `fn main()` or an impl).
-        match (&fn_decl.output, found.is_suggestable(), can_suggest, expected.is_nil()) {
+        match (&fn_decl.output, found.is_suggestable(), can_suggest, expected.is_unit()) {
             (&hir::FunctionRetTy::DefaultReturn(span), true, true, true) => {
                 err.span_suggestion_with_applicability(
                     span,