Merge branch 'master' into patch-1

README.md

@@ -35,6 +35,7 @@ Please see the [CONTRIBUTING.md] file for more details.
 
 ## Translations to other languages
 
+* [Bulgarian](https://github.com/kberov/rust-by-example-bg)
 * [Chinese](https://github.com/rust-lang-cn/rust-by-example-cn)
 * [Japanese](https://github.com/rust-lang-ja/rust-by-example-ja)
 * [French](https://github.com/Songbird0/FR_RBE)

src/error/option_unwrap/question_mark.md

@@ -8,7 +8,8 @@ function is being executed and return `None`.
 ```rust,editable
 fn next_birthday(current_age: Option<u8>) -> Option<String> {
 	// If `current_age` is `None`, this returns `None`.
-	// If `current_age` is `Some`, the inner `u8` gets assigned to `next_age`
+	// If `current_age` is `Some`, the inner `u8` value + 1
+    // gets assigned to `next_age`
     let next_age: u8 = current_age? + 1;
     Some(format!("Next year I will be {}", next_age))
 }

src/fn/closures.md

@@ -26,7 +26,7 @@ fn main() {
     // TODO: uncomment the line above and see the compiler error. The compiler
     // suggests that we define a closure instead.
 
-    // Closures are anonymous, here we are binding them to references
+    // Closures are anonymous, here we are binding them to references.
     // Annotation is identical to function annotation but is optional
     // as are the `{}` wrapping the body. These nameless functions
     // are assigned to appropriately named variables.

src/index.md

@@ -21,9 +21,9 @@ Now let's begin!
 
 - [Types](types.md) - Learn about changing and defining types.
 
-- [Conversion](conversion.md)
+- [Conversion](conversion.md) - Convert between different types, such as strings, integers, and floats.
 
-- [Expressions](expression.md)
+- [Expressions](expression.md) - Learn about Expressions & how to use them.
 
 - [Flow of Control](flow_control.md) - `if`/`else`, `for`, and others.
 
@@ -43,7 +43,7 @@ Now let's begin!
 
 - [Traits](trait.md) - A trait is a collection of methods defined for an unknown type: `Self`
 
-- [Macros](macros.md)
+- [Macros](macros.md) - Macros are a way of writing code that writes other code, which is known as metaprogramming.
 
 - [Error handling](error.md) - Learn Rust way of handling failures.
 
@@ -53,9 +53,9 @@ Now let's begin!
 
 - [Testing](testing.md) - All sorts of testing in Rust.
 
-- [Unsafe Operations](unsafe.md)
+- [Unsafe Operations](unsafe.md) - Learn about entering a block of unsafe operations.
 
-- [Compatibility](compatibility.md)
+- [Compatibility](compatibility.md) - Handling Rust's evolution and potential compatibility issues.
 
 - [Meta](meta.md) - Documentation, Benchmarking.
 

src/std/hash/alt_key_types.md

@@ -3,7 +3,7 @@
 Any type that implements the `Eq` and `Hash` traits can be a key in `HashMap`. 
 This includes:
 
-* `bool` (though not very useful since there is only two possible keys)
+* `bool` (though not very useful since there are only two possible keys)
 * `int`, `uint`, and all variations thereof
 * `String` and `&str` (protip: you can have a `HashMap` keyed by `String`
 and call `.get()` with an `&str`)

src/std_misc/file/read_lines.md

@@ -62,7 +62,7 @@ fn main() {
     }
 }
 
-// The output is wrapped in a Result to allow matching on errors
+// The output is wrapped in a Result to allow matching on errors.
 // Returns an Iterator to the Reader of the lines of the file.
 fn read_lines<P>(filename: P) -> io::Result<io::Lines<io::BufReader<File>>>
 where P: AsRef<Path>, {

src/std_misc/threads/testcase_mapreduce.md

@@ -30,7 +30,7 @@ use std::thread;
 fn main() {
 
     // This is our data to process.
-    // We will calculate the sum of all digits via a threaded  map-reduce algorithm.
+    // We will calculate the sum of all digits via a threaded map-reduce algorithm.
     // Each whitespace separated chunk will be handled in a different thread.
     //
     // TODO: see what happens to the output if you insert spaces!

src/unsafe/asm.md

@@ -139,8 +139,8 @@ can be written at any time, and can therefore not share its location with any ot
 However, to guarantee optimal performance it is important to use as few registers as possible,
 so they won't have to be saved and reloaded around the inline assembly block.
 To achieve this Rust provides a `lateout` specifier. This can be used on any output that is
-written only after all inputs have been consumed.
-There is also a `inlateout` variant of this specifier.
+written only after all inputs have been consumed. There is also an `inlateout` variant of this 
+specifier.
 
 Here is an example where `inlateout` *cannot* be used in `release` mode or other optimized cases:
 
@@ -163,11 +163,12 @@ unsafe {
 assert_eq!(a, 12);
 # }
 ```
-The above could work well in unoptimized cases (`Debug` mode), but if you want optimized performance (`release` mode or other optimized cases), it could not work.
 
-That is because in optimized cases, the compiler is free to allocate the same register for inputs `b` and `c` since it knows they have the same value. However it must allocate a separate register for `a` since it uses `inout` and not `inlateout`. If `inlateout` was used, then `a` and `c` could be allocated to the same register, in which case the first instruction to overwrite the value of `c` and cause the assembly code to produce the wrong result.
+In unoptimized cases (e.g. `Debug` mode), replacing `inout(reg) a` with `inlateout(reg) a` in the above example can continue to give the expected result. However, with `release` mode or other optimized cases, using `inlateout(reg) a` can instead lead to the final value `a = 16`, causing the assertion to fail. 
 
-However the following example can use `inlateout` since the output is only modified after all input registers have been read:
+This is because in optimized cases, the compiler is free to allocate the same register for inputs `b` and `c` since it knows that they have the same value. Furthermore, when `inlateout` is used, `a` and `c` could be allocated to the same register, in which case the first `add` instruction would overwrite the initial load from variable `c`. This is in contrast to how using `inout(reg) a` ensures a separate register is allocated for `a`. 
+
+However, the following example can use `inlateout` since the output is only modified after all input registers have been read:
 
 ```rust
 # #[cfg(target_arch = "x86_64")] {