Cpp11 (#3731)

* Enabled c++11 support (required for IO::AMF), extended Travis build to build with g++ 4.9
* ifdef guard in poly2tri/util to avoid redefinition warning
* cache local-lib

.travis.yml

@@ -11,13 +11,18 @@ branches:
     - stable
 sudo: false
 cache:
-    - apt
+  apt: true
+  directories:
+    - local-lib
 addons:
   apt:
     sources:
     - boost-latest
+    - ubuntu-toolchain-r-test
     packages:
     - libboost-thread1.55-dev
     - libboost-system1.55-dev
     - libboost-filesystem1.55-dev
     - liblocal-lib-perl
+    - g++-4.9
+env: CC=g++-4.9

xs/Build.PL

@@ -15,8 +15,13 @@ my $mswin = $^O eq 'MSWin32';
 # HAS_BOOL         : stops Perl/lib/CORE/handy.h from doing "#  define bool char" for MSVC
 # NOGDI            : prevents inclusion of wingdi.h which defines functions Polygon() and Polyline() in global namespace
 # BOOST_ASIO_DISABLE_KQUEUE : prevents a Boost ASIO bug on OS X: https://svn.boost.org/trac/boost/ticket/5339
+# std=c++11 Enforce usage of C++11 (required now). Minimum compiler supported: gcc 4.9, clang 3.3, MSVC 14.0
 my @cflags = qw(-D_GLIBCXX_USE_C99 -DHAS_BOOL -DNOGDI -DSLIC3RXS -DBOOST_ASIO_DISABLE_KQUEUE
-    -Wno-c++11-extensions);
+    -std=c++11);
+if ($cpp_guess->is_gcc)	{
+	# GCC is pedantic with c++11 std, so undefine strict ansi to get M_PI back
+	push @cflags, qw(-U__STRICT_ANSI__);
+}
 my @ldflags = ();
 if ($^O eq 'darwin') {
     push @ldflags, qw(-framework IOKit -framework CoreFoundation);

xs/src/poly2tri/common/utils.h

@@ -33,7 +33,9 @@
 #define UTILS_H
 
 // Otherwise #defines like M_PI are undeclared under Visual Studio
+#ifndef _USE_MATH_DEFINES
 #define _USE_MATH_DEFINES
+#endif
 
 #include <exception>
 #include <math.h>