Auto merge of #59293 - Centril:rollup, r=Centril

Rollup of 11 pull requests

Successful merges:

 - #56348 (Add todo!() macro)
 - #57729 (extra testing of how NLL handles wildcard type `_`)
 - #57847 (dbg!() without parameters)
 - #58778 (Implement ExactSizeIterator for ToLowercase and ToUppercase)
 - #58812 (Clarify distinction between floor() and trunc())
 - #58939 (Fix a tiny error in documentation of std::pin.)
 - #59116 (Be more discerning on when to attempt suggesting a comma in a macro invocation)
 - #59252 (add self to mailmap)
 - #59275 (Replaced self-reflective explicit types with clearer `Self` or `Self::…` in stdlib docs)
 - #59280 (Stabilize refcell_map_split feature)
 - #59290 (Run branch cleanup after copy prop)

Failed merges:

r? @ghost

4 files changed, 24 insertions, 9 deletions

diff --git a/src/libstd/f32.rs b/src/libstd/f32.rs
index a2b12d00a78..2fabe30fa93 100644
--- a/src/libstd/f32.rs
+++ b/src/libstd/f32.rs
@@ -32,11 +32,13 @@ impl f32 {
     /// # Examples
     ///
     /// ```
-    /// let f = 3.99_f32;
+    /// let f = 3.7_f32;
     /// let g = 3.0_f32;
+    /// let h = -3.7_f32;
     ///
     /// assert_eq!(f.floor(), 3.0);
     /// assert_eq!(g.floor(), 3.0);
+    /// assert_eq!(h.floor(), -4.0);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
@@ -104,11 +106,13 @@ impl f32 {
     /// # Examples
     ///
     /// ```
-    /// let f = 3.3_f32;
-    /// let g = -3.7_f32;
+    /// let f = 3.7_f32;
+    /// let g = 3.0_f32;
+    /// let h = -3.7_f32;
     ///
     /// assert_eq!(f.trunc(), 3.0);
-    /// assert_eq!(g.trunc(), -3.0);
+    /// assert_eq!(g.trunc(), 3.0);
+    /// assert_eq!(h.trunc(), -3.0);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
diff --git a/src/libstd/f64.rs b/src/libstd/f64.rs
index be5cd92d416..a471117f6d6 100644
--- a/src/libstd/f64.rs
+++ b/src/libstd/f64.rs
@@ -32,11 +32,13 @@ impl f64 {
     /// # Examples
     ///
     /// ```
-    /// let f = 3.99_f64;
+    /// let f = 3.7_f64;
     /// let g = 3.0_f64;
+    /// let h = -3.7_f64;
     ///
     /// assert_eq!(f.floor(), 3.0);
     /// assert_eq!(g.floor(), 3.0);
+    /// assert_eq!(h.floor(), -4.0);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
@@ -84,11 +86,13 @@ impl f64 {
     /// # Examples
     ///
     /// ```
-    /// let f = 3.3_f64;
-    /// let g = -3.7_f64;
+    /// let f = 3.7_f64;
+    /// let g = 3.0_f64;
+    /// let h = -3.7_f64;
     ///
     /// assert_eq!(f.trunc(), 3.0);
-    /// assert_eq!(g.trunc(), -3.0);
+    /// assert_eq!(g.trunc(), 3.0);
+    /// assert_eq!(h.trunc(), -3.0);
     /// ```
     #[stable(feature = "rust1", since = "1.0.0")]
     #[inline]
diff --git a/src/libstd/lib.rs b/src/libstd/lib.rs
index fc8ac9a0b3e..296c4c88727 100644
--- a/src/libstd/lib.rs
+++ b/src/libstd/lib.rs
@@ -301,6 +301,7 @@
 #![feature(stmt_expr_attributes)]
 #![feature(str_internals)]
 #![feature(thread_local)]
+#![feature(todo_macro)]
 #![feature(toowned_clone_into)]
 #![feature(try_reserve)]
 #![feature(unboxed_closures)]
@@ -323,7 +324,7 @@ use prelude::v1::*;
 #[stable(feature = "rust1", since = "1.0.0")]
 pub use core::{assert_eq, assert_ne, debug_assert, debug_assert_eq, debug_assert_ne};
 #[stable(feature = "rust1", since = "1.0.0")]
-pub use core::{unreachable, unimplemented, write, writeln, r#try};
+pub use core::{unreachable, unimplemented, write, writeln, r#try, todo};
 
 #[allow(unused_imports)] // macros from `alloc` are not used on all platforms
 #[macro_use]
diff --git a/src/libstd/macros.rs b/src/libstd/macros.rs
index 9d0eb2e6b1c..d5dc5f7c4f0 100644
--- a/src/libstd/macros.rs
+++ b/src/libstd/macros.rs
@@ -305,10 +305,16 @@ macro_rules! eprintln {
 /// let _ = dbg!(a); // <-- `a` is moved again; error!
 /// ```
 ///
+/// You can also use `dbg!()` without a value to just print the
+/// file and line whenever it's reached.
+///
 /// [stderr]: https://en.wikipedia.org/wiki/Standard_streams#Standard_error_(stderr)
 #[macro_export]
 #[stable(feature = "dbg_macro", since = "1.32.0")]
 macro_rules! dbg {
+    () => {
+        eprintln!("[{}:{}]", file!(), line!());
+    };
     ($val:expr) => {
         // Use of `match` here is intentional because it affects the lifetimes
         // of temporaries - https://stackoverflow.com/a/48732525/1063961