Rollup merge of #38006 - frewsxcv:libstd-debug, r=alexcrichton

Implement `fmt::Debug` for all structures in libstd.

Part of https://github.com/rust-lang/rust/issues/31869.

Also turn on the `missing_debug_implementations` lint at the crate
level.

4 files changed, 12 insertions, 2 deletions

diff --git a/src/libstd/sys/unix/fast_thread_local.rs b/src/libstd/sys/unix/fast_thread_local.rs
index 0c625e7add9..f4f73646e1b 100644
--- a/src/libstd/sys/unix/fast_thread_local.rs
+++ b/src/libstd/sys/unix/fast_thread_local.rs
@@ -12,6 +12,7 @@
 #![unstable(feature = "thread_local_internals", issue = "0")]
 
 use cell::{Cell, UnsafeCell};
+use fmt;
 use intrinsics;
 use ptr;
 
@@ -24,6 +25,12 @@ pub struct Key<T> {
     dtor_running: Cell<bool>,
 }
 
+impl<T> fmt::Debug for Key<T> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.pad("Key { .. }")
+    }
+}
+
 unsafe impl<T> ::marker::Sync for Key<T> { }
 
 impl<T> Key<T> {
diff --git a/src/libstd/sys/unix/fd.rs b/src/libstd/sys/unix/fd.rs
index 61eb60da486..2384d959881 100644
--- a/src/libstd/sys/unix/fd.rs
+++ b/src/libstd/sys/unix/fd.rs
@@ -18,6 +18,7 @@ use sys::cvt;
 use sys_common::AsInner;
 use sys_common::io::read_to_end_uninitialized;
 
+#[derive(Debug)]
 pub struct FileDesc {
     fd: c_int,
 }
diff --git a/src/libstd/sys/unix/fs.rs b/src/libstd/sys/unix/fs.rs
index 9ee0458b5da..8b5c0c04276 100644
--- a/src/libstd/sys/unix/fs.rs
+++ b/src/libstd/sys/unix/fs.rs
@@ -66,7 +66,7 @@ pub struct DirEntry {
     name: Box<[u8]>
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct OpenOptions {
     // generic
     read: bool,
@@ -86,6 +86,7 @@ pub struct FilePermissions { mode: mode_t }
 #[derive(Copy, Clone, PartialEq, Eq, Hash, Debug)]
 pub struct FileType { mode: mode_t }
 
+#[derive(Debug)]
 pub struct DirBuilder { mode: mode_t }
 
 impl FileAttr {
diff --git a/src/libstd/sys/windows/fs.rs b/src/libstd/sys/windows/fs.rs
index 7d7d78bbd87..c410fcd1ee0 100644
--- a/src/libstd/sys/windows/fs.rs
+++ b/src/libstd/sys/windows/fs.rs
@@ -58,7 +58,7 @@ pub struct DirEntry {
     data: c::WIN32_FIND_DATAW,
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct OpenOptions {
     // generic
     read: bool,
@@ -79,6 +79,7 @@ pub struct OpenOptions {
 #[derive(Clone, PartialEq, Eq, Debug)]
 pub struct FilePermissions { attrs: c::DWORD }
 
+#[derive(Debug)]
 pub struct DirBuilder;
 
 impl fmt::Debug for ReadDir {