From 955dd950f0607b0c85cdaf82391235b6710c999c Mon Sep 17 00:00:00 2001
From: Henry Fredrick Schreiner <henry.fredrick.schreiner@cern.ch>
Date: Sat, 4 Feb 2017 08:45:00 -0500
Subject: [PATCH] C++11 compliance on older compilers

---
 include/CLI.hpp   | 16 +++++++---------
 tests/CLITest.cpp |  2 +-
 2 files changed, 8 insertions(+), 10 deletions(-)

diff --git a/include/CLI.hpp b/include/CLI.hpp
index 7f6a4c25..ec8880c4 100644
--- a/include/CLI.hpp
+++ b/include/CLI.hpp
@@ -603,24 +603,22 @@ protected:
     bool parsed{false};
     App* subcommand = nullptr;
 
-    std::function<void(App*)> app_callback;
+    std::function<void()> app_callback;
 
 public:
-    /// Set a callback to run at the end of parsing 
-    App* set_callback(std::function<void(App*)> callback) {
-        app_callback = callback;
-        return this;
-    }
 
-    /// Don't have to worry about explicit App* in argument
+    /// Set a callback for the end of parsing. Due to a bug in c++11,
+    /// it is not possible to overload on std::function (fixed in c++14
+    /// and backported to c++11 on newer compilers). Use capture by reference
+    /// to get a pointer to App if needed.
     App* set_callback(std::function<void()> callback) {
-        app_callback = [callback](App*){callback();};
+        app_callback = callback;
         return this;
     }
 
     void run_callback() {
         if(app_callback)
-            app_callback(this);
+            app_callback();
     }
 
     /// Reset the parsed data
diff --git a/tests/CLITest.cpp b/tests/CLITest.cpp
index 4f98e652..d1bf22e6 100644
--- a/tests/CLITest.cpp
+++ b/tests/CLITest.cpp
@@ -383,7 +383,7 @@ TEST_F(TApp, BasicSubcommands) {
 
 TEST_F(TApp, Callbacks) {
     auto sub1 = app.add_subcommand("sub1");
-    sub1->set_callback([](CLI::App*){
+    sub1->set_callback([](){
             throw CLI::Success();
             });
     auto sub2 = app.add_subcommand("sub2");