diff --git a/src/liballoc/collections/binary_heap.rs b/src/liballoc/collections/binary_heap.rs
index f38fe997b732c..9908a3049763a 100644
--- a/src/liballoc/collections/binary_heap.rs
+++ b/src/liballoc/collections/binary_heap.rs
@@ -536,7 +536,7 @@ impl<T: Ord> BinaryHeap<T> {
             while child < end {
                 let right = child + 1;
                 // compare with the greater of the two children
-                if right < end && !(hole.get(child) > hole.get(right)) {
+                if right < end && hole.get(child) <= hole.get(right) {
                     child = right;
                 }
                 // if we are already in order, stop.
@@ -568,7 +568,7 @@ impl<T: Ord> BinaryHeap<T> {
             while child < end {
                 let right = child + 1;
                 // compare with the greater of the two children
-                if right < end && !(hole.get(child) > hole.get(right)) {
+                if right < end && hole.get(child) <= hole.get(right) {
                     child = right;
                 }
                 hole.move_to(child);
diff --git a/src/librustc_codegen_llvm/debuginfo/metadata.rs b/src/librustc_codegen_llvm/debuginfo/metadata.rs
index d1f70ad43bd28..ab024a0265031 100644
--- a/src/librustc_codegen_llvm/debuginfo/metadata.rs
+++ b/src/librustc_codegen_llvm/debuginfo/metadata.rs
@@ -2135,7 +2135,7 @@ fn set_members_of_composite_type(
 /// Computes the type parameters for a type, if any, for the given metadata.
 fn compute_type_parameters(cx: &CodegenCx<'ll, 'tcx>, ty: Ty<'tcx>) -> Option<&'ll DIArray> {
     if let ty::Adt(def, substs) = ty.kind {
-        if !substs.types().next().is_none() {
+        if substs.types().next().is_some() {
             let generics = cx.tcx.generics_of(def.did);
             let names = get_parameter_names(cx, generics);
             let template_params: Vec<_> = substs
diff --git a/src/librustc_codegen_ssa/mir/debuginfo.rs b/src/librustc_codegen_ssa/mir/debuginfo.rs
index e5f21013ce3e3..2dc1405f4e438 100644
--- a/src/librustc_codegen_ssa/mir/debuginfo.rs
+++ b/src/librustc_codegen_ssa/mir/debuginfo.rs
@@ -48,7 +48,7 @@ pub struct DebugScope<D> {
 
 impl<D> DebugScope<D> {
     pub fn is_valid(&self) -> bool {
-        !self.scope_metadata.is_none()
+        self.scope_metadata.is_some()
     }
 }
 
@@ -304,7 +304,7 @@ impl<'a, 'tcx, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
     ) -> Option<IndexVec<mir::Local, Vec<PerLocalVarDebugInfo<'tcx, Bx::DIVariable>>>> {
         let full_debug_info = self.cx.sess().opts.debuginfo == DebugInfo::Full;
 
-        if !(full_debug_info || !self.cx.sess().fewer_names()) {
+        if !full_debug_info && self.cx.sess().fewer_names() {
             return None;
         }
 
diff --git a/src/librustc_infer/infer/freshen.rs b/src/librustc_infer/infer/freshen.rs
index 63dded3b43d10..f7141c56199d7 100644
--- a/src/librustc_infer/infer/freshen.rs
+++ b/src/librustc_infer/infer/freshen.rs
@@ -143,9 +143,9 @@ impl<'a, 'tcx> TypeFolder<'tcx> for TypeFreshener<'a, 'tcx> {
     }
 
     fn fold_ty(&mut self, t: Ty<'tcx>) -> Ty<'tcx> {
-        if !t.needs_infer()
-            && !t.has_erasable_regions()
-            && !(t.has_closure_types() && self.infcx.in_progress_tables.is_some())
+        if !(t.needs_infer()
+            || t.has_erasable_regions()
+            || (t.has_closure_types() && self.infcx.in_progress_tables.is_some()))
         {
             return t;
         }
diff --git a/src/librustc_infer/infer/mod.rs b/src/librustc_infer/infer/mod.rs
index 26998f0a33c2e..766de56913217 100644
--- a/src/librustc_infer/infer/mod.rs
+++ b/src/librustc_infer/infer/mod.rs
@@ -1484,7 +1484,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
 
         // Even if the type may have no inference variables, during
         // type-checking closure types are in local tables only.
-        if !self.in_progress_tables.is_some() || !ty.has_closure_types() {
+        if self.in_progress_tables.is_none() || !ty.has_closure_types() {
             if !(param_env, ty).has_local_value() {
                 return ty.is_copy_modulo_regions(self.tcx, param_env, span);
             }
diff --git a/src/librustc_passes/stability.rs b/src/librustc_passes/stability.rs
index 99fbac4568e4f..bab468493df53 100644
--- a/src/librustc_passes/stability.rs
+++ b/src/librustc_passes/stability.rs
@@ -551,7 +551,7 @@ impl Visitor<'tcx> for Checker<'tcx> {
                     .emit();
                 } else {
                     let param_env = self.tcx.param_env(def_id);
-                    if !can_type_implement_copy(self.tcx, param_env, ty).is_ok() {
+                    if can_type_implement_copy(self.tcx, param_env, ty).is_err() {
                         feature_err(
                             &self.tcx.sess.parse_sess,
                             sym::untagged_unions,
diff --git a/src/librustc_resolve/imports.rs b/src/librustc_resolve/imports.rs
index 55ce51e0ff057..8a07a6fe8c9ac 100644
--- a/src/librustc_resolve/imports.rs
+++ b/src/librustc_resolve/imports.rs
@@ -313,9 +313,9 @@ impl<'a> Resolver<'a> {
                             }
                         }
 
-                        if !self.is_accessible_from(binding.vis, parent_scope.module) &&
+                        if !(self.is_accessible_from(binding.vis, parent_scope.module) ||
                        // Remove this together with `PUB_USE_OF_PRIVATE_EXTERN_CRATE`
-                       !(self.last_import_segment && binding.is_extern_crate())
+                       (self.last_import_segment && binding.is_extern_crate()))
                         {
                             self.privacy_errors.push(PrivacyError {
                                 ident,
diff --git a/src/libstd/net/parser.rs b/src/libstd/net/parser.rs
index 868a7e261c497..3f38ee5471081 100644
--- a/src/libstd/net/parser.rs
+++ b/src/libstd/net/parser.rs
@@ -206,7 +206,7 @@ impl<'a> Parser<'a> {
         }
 
         // read `::` if previous code parsed less than 8 groups
-        if !self.read_given_char(':').is_some() || !self.read_given_char(':').is_some() {
+        if self.read_given_char(':').is_none() || self.read_given_char(':').is_none() {
             return None;
         }