From 23e7b35c39810ddf308961222637461984602c46 Mon Sep 17 00:00:00 2001
From: Tulio Leao <tupaschoal@gmail.com>
Date: Wed, 19 Jun 2019 12:23:45 -0300
Subject: [PATCH] Add section about C++17 attributes (#50)

* Add section about C++17 attributes

Explains, in a single piece of code, about [[nodiscard]], [[fallthrough]] and [[maybe_unused]]
---
 CPP17.md  | 20 ++++++++++++++++++++
 README.md | 21 +++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/CPP17.md b/CPP17.md
index adbc43a..7f3b0bd 100644
--- a/CPP17.md
+++ b/CPP17.md
@@ -17,6 +17,7 @@ C++17 includes the following new language features:
 - [constexpr if](#constexpr-if)
 - [utf-8 character literals](#utf-8-character-literals)
 - [direct-list-initialization of enums](#direct-list-initialization-of-enums)
+- [New standard attributes](#new-standard-attributes)
 
 C++17 includes the following new library features:
 - [std::variant](#stdvariant)
@@ -237,6 +238,25 @@ byte d = byte{1}; // OK
 byte e = byte{256}; // ERROR
 ```
 
+### New standard attributes
+C++17 introduces three new attributes: `[[fallthrough]]`, `[[nodiscard]]` and `[[maybe_unused]]`:
+```c++
+// Will warn if return of foo() is ignored
+[[nodiscard]] int foo();
+int main() {
+  int a {1};
+  switch (a) {
+      // Indicates that falling through on case 1 is intentional
+      case 1: [[fallthrough]]
+      case 2:
+      // Indicates that b might be unused, such as on production builds
+        [[maybe_unused]] int b = foo();
+        assert(b > 0);
+        break;
+  }
+}
+```
+
 ## C++17 Library Features
 
 ### std::variant
diff --git a/README.md b/README.md
index f6a80b1..d23ef50 100644
--- a/README.md
+++ b/README.md
@@ -23,6 +23,7 @@ C++17 includes the following new language features:
 - [constexpr if](#constexpr-if)
 - [utf-8 character literals](#utf-8-character-literals)
 - [direct-list-initialization of enums](#direct-list-initialization-of-enums)
+- [New standard attributes](#new-standard-attributes)
 
 C++17 includes the following new library features:
 - [std::variant](#stdvariant)
@@ -454,6 +455,26 @@ byte d = byte{1}; // OK
 byte e = byte{256}; // ERROR
 ```
 
+### New standard attributes
+C++17 introduces three new attributes: `[[fallthrough]]`, `[[nodiscard]]` and `[[maybe_unused]]`:
+```c++
+// Will warn if return of foo() is ignored
+[[nodiscard]] int foo();
+
+int main() {
+  int a {1};
+  switch (a) {
+      // Indicates that falling through on case 1 is intentional
+      case 1: [[fallthrough]]
+      case 2:
+      // Indicates that b might be unused, such as on production builds
+        [[maybe_unused]] int b = foo();
+        assert(b > 0);
+        break;
+  }
+}
+```
+
 ## C++17 Library Features
 
 ### std::variant