Auto merge of #32054 - seanmonstar:impl-debug-core, r=alexcrichton

libcore: add Debug implementations to most missing types

Also adds `#![deny(missing_debug_implementations)]` to the core crate.

cc #31869

Author: bors

src/libcore/char.rs

@@ -416,14 +416,14 @@ pub fn encode_utf16_raw(mut ch: u32, dst: &mut [u16]) -> Option<usize> {
 ///
 /// [`escape_unicode()`]: ../../std/primitive.char.html#method.escape_unicode
 /// [`char`]: ../../std/primitive.char.html
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct EscapeUnicode {
     c: char,
     state: EscapeUnicodeState
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 enum EscapeUnicodeState {
     Backslash,
     Type,
@@ -496,13 +496,13 @@ impl Iterator for EscapeUnicode {
 ///
 /// [`escape_default()`]: ../../std/primitive.char.html#method.escape_default
 /// [`char`]: ../../std/primitive.char.html
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct EscapeDefault {
     state: EscapeDefaultState
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 enum EscapeDefaultState {
     Backslash(char),
     Char(char),

src/libcore/fmt/builders.rs

@@ -54,6 +54,7 @@ impl<'a, 'b: 'a> fmt::Write for PadAdapter<'a, 'b> {
 ///
 /// Constructed by the `Formatter::debug_struct` method.
 #[must_use]
+#[allow(missing_debug_implementations)]
 #[stable(feature = "debug_builders", since = "1.2.0")]
 pub struct DebugStruct<'a, 'b: 'a> {
     fmt: &'a mut fmt::Formatter<'b>,
@@ -120,6 +121,7 @@ impl<'a, 'b: 'a> DebugStruct<'a, 'b> {
 ///
 /// Constructed by the `Formatter::debug_tuple` method.
 #[must_use]
+#[allow(missing_debug_implementations)]
 #[stable(feature = "debug_builders", since = "1.2.0")]
 pub struct DebugTuple<'a, 'b: 'a> {
     fmt: &'a mut fmt::Formatter<'b>,
@@ -231,6 +233,7 @@ impl<'a, 'b: 'a> DebugInner<'a, 'b> {
 ///
 /// Constructed by the `Formatter::debug_set` method.
 #[must_use]
+#[allow(missing_debug_implementations)]
 #[stable(feature = "debug_builders", since = "1.2.0")]
 pub struct DebugSet<'a, 'b: 'a> {
     inner: DebugInner<'a, 'b>,
@@ -279,6 +282,7 @@ impl<'a, 'b: 'a> DebugSet<'a, 'b> {
 ///
 /// Constructed by the `Formatter::debug_list` method.
 #[must_use]
+#[allow(missing_debug_implementations)]
 #[stable(feature = "debug_builders", since = "1.2.0")]
 pub struct DebugList<'a, 'b: 'a> {
     inner: DebugInner<'a, 'b>,
@@ -327,6 +331,7 @@ impl<'a, 'b: 'a> DebugList<'a, 'b> {
 ///
 /// Constructed by the `Formatter::debug_map` method.
 #[must_use]
+#[allow(missing_debug_implementations)]
 #[stable(feature = "debug_builders", since = "1.2.0")]
 pub struct DebugMap<'a, 'b: 'a> {
     fmt: &'a mut fmt::Formatter<'b>,

src/libcore/fmt/mod.rs

@@ -14,7 +14,7 @@
 
 use prelude::v1::*;
 
-use cell::{Cell, RefCell, Ref, RefMut, BorrowState};
+use cell::{UnsafeCell, Cell, RefCell, Ref, RefMut, BorrowState};
 use marker::PhantomData;
 use mem;
 use num::flt2dec;
@@ -25,6 +25,7 @@ use str;
 
 #[unstable(feature = "fmt_flags_align", issue = "27726")]
 /// Possible alignments returned by `Formatter::align`
+#[derive(Debug)]
 pub enum Alignment {
     /// Indication that contents should be left-aligned.
     Left,
@@ -152,6 +153,7 @@ impl<'a, W: Write + ?Sized> Write for &'a mut W {
 /// A struct to represent both where to emit formatting strings to and how they
 /// should be formatted. A mutable version of this is passed to all formatting
 /// traits.
+#[allow(missing_debug_implementations)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct Formatter<'a> {
     flags: u32,
@@ -175,6 +177,7 @@ enum Void {}
 /// compile time it is ensured that the function and the value have the correct
 /// types, and then this struct is used to canonicalize arguments to one type.
 #[derive(Copy)]
+#[allow(missing_debug_implementations)]
 #[unstable(feature = "fmt_internals", reason = "internal to format_args!",
            issue = "0")]
 #[doc(hidden)]
@@ -1585,7 +1588,9 @@ impl<T: ?Sized> Debug for PhantomData<T> {
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<T: Copy + Debug> Debug for Cell<T> {
     fn fmt(&self, f: &mut Formatter) -> Result {
-        write!(f, "Cell {{ value: {:?} }}", self.get())
+        f.debug_struct("Cell")
+            .field("value", &self.get())
+            .finish()
     }
 }
 
@@ -1594,9 +1599,15 @@ impl<T: ?Sized + Debug> Debug for RefCell<T> {
     fn fmt(&self, f: &mut Formatter) -> Result {
         match self.borrow_state() {
             BorrowState::Unused | BorrowState::Reading => {
-                write!(f, "RefCell {{ value: {:?} }}", self.borrow())
+                f.debug_struct("RefCell")
+                    .field("value", &self.borrow())
+                    .finish()
+            }
+            BorrowState::Writing => {
+                f.debug_struct("RefCell")
+                    .field("value", &"<borrowed>")
+                    .finish()
             }
-            BorrowState::Writing => write!(f, "RefCell {{ <borrowed> }}"),
         }
     }
 }
@@ -1615,5 +1626,12 @@ impl<'b, T: ?Sized + Debug> Debug for RefMut<'b, T> {
     }
 }
 
+#[stable(feature = "core_impl_debug", since = "1.9.0")]
+impl<T: ?Sized + Debug> Debug for UnsafeCell<T> {
+    fn fmt(&self, f: &mut Formatter) -> Result {
+        f.pad("UnsafeCell")
+    }
+}
+
 // If you expected tests to be here, look instead at the run-pass/ifmt.rs test,
 // it's a lot easier than creating all of the rt::Piece structures here.

src/libcore/fmt/rt/v1.rs

@@ -13,6 +13,7 @@
 //!
 //! These definitions are similar to their `ct` equivalents, but differ in that
 //! these can be statically allocated and are slightly optimized for the runtime
+#![allow(missing_debug_implementations)]
 
 #[derive(Copy, Clone)]
 pub struct Argument {

src/libcore/hash/mod.rs

@@ -73,6 +73,7 @@
 
 use prelude::v1::*;
 
+use fmt;
 use marker;
 use mem;
 
@@ -215,6 +216,13 @@ pub trait BuildHasher {
 #[stable(since = "1.7.0", feature = "build_hasher")]
 pub struct BuildHasherDefault<H>(marker::PhantomData<H>);
 
+#[stable(since = "1.9.0", feature = "core_impl_debug")]
+impl<H> fmt::Debug for BuildHasherDefault<H> {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        f.pad("BuildHasherDefault")
+    }
+}
+
 #[stable(since = "1.7.0", feature = "build_hasher")]
 impl<H: Default + Hasher> BuildHasher for BuildHasherDefault<H> {
     type Hasher = H;

src/libcore/hash/sip.rs

@@ -30,6 +30,7 @@ use super::Hasher;
 /// Although the SipHash algorithm is considered to be generally strong,
 /// it is not intended for cryptographic purposes. As such, all
 /// cryptographic uses of this implementation are _strongly discouraged_.
+#[derive(Debug)]
 #[stable(feature = "rust1", since = "1.0.0")]
 pub struct SipHasher {
     k0: u64,