build: switch to C++17

Change-Id: I92039300ce845de0312dceccb94c128229ed60c4
diff --git a/docs/code-style.rst b/docs/code-style.rst
index 63bd327..2baac21 100644
--- a/docs/code-style.rst
+++ b/docs/code-style.rst
@@ -180,7 +180,7 @@
         switch (condition) {
           case ABC:        // 2 space indent
             statements;    // 4 space indent
-            NDN_CXX_FALLTHROUGH;
+            [[fallthrough]];
 
           case DEF:
             statements;
@@ -211,7 +211,7 @@
           // Correct style
           case A1: {
             statements;
-            NDN_CXX_FALLTHROUGH;
+            [[fallthrough]];
           }
 
           // Incorrect style: braces should cover the entire case block
@@ -232,7 +232,7 @@
         switch (condition) {
         case ABC:        // no indent
           statements;    // 2 space indent
-          NDN_CXX_FALLTHROUGH;
+          [[fallthrough]];
 
         case DEF:
           statements;
@@ -243,11 +243,11 @@
           break;
         }
 
-    The ``NDN_CXX_FALLTHROUGH`` annotation must be included whenever there is
-    a case without a break statement. Leaving the break out is a common error,
+    The ``[[fallthrough]]`` annotation must be included whenever there is a
+    case without a break statement. Leaving the break out is a common error,
     and it must be made clear that it is intentional when it is not there.
-    Moreover, modern compilers will warn when a case that falls through is not
-    explicitly annotated.
+    Moreover, modern compilers will warn when a case that falls through is
+    not explicitly annotated.
 
 1.11. A ``try-catch`` statement should have the following form:
 
diff --git a/docs/index.rst b/docs/index.rst
index df9f084..00943d5 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -19,7 +19,7 @@
    release-notes
    releases
 
-**ndn-cxx** is a C++14 library implementing Named Data Networking (NDN) primitives
+**ndn-cxx** is a C++17 library implementing Named Data Networking (NDN) primitives
 that can be used to write various NDN applications. The library is currently being
 used by the following projects: