Remove support for gcc 4.6

This was kept so long because of Ubuntu 12.04 LTS, but having a
not-really-c++11 compiler is not nice.

INSTALL

@@ -47,9 +47,8 @@ You will also probably need GNU m4 (perhaps installed as gm4).
 Requirements
 ------------
 
-First of all, you will need a recent C++ compiler, where recent means
+First of all, you will need a C++11 standard conforming compiler, like gcc (at
-that the compilers are close to C++11 standard conforming like gcc (at
+least 4.7) or clang.
-least 4.6) or clang.
 
 LyX makes great use of the C++ Standard Template Library (STL).
 This means that gcc users will have to install the relevant libstdc++

config/lyxinclude.m4

@@ -170,7 +170,7 @@ selects C++11 mode; gives an error when C++11 mode is not found.
 AC_DEFUN([LYX_CXX_CXX11_FLAGS],
 [AC_CACHE_CHECK([for at least C++11 mode], [lyx_cv_cxx11_flags],
  [lyx_cv_cxx11_flags=none
-  for flag in -std=c++14 -std=c++11 "" -std=c++0x -std=gnu++14 -std=gnu++11 -std=gnu++0x ; do
+  for flag in -std=c++14 -std=c++11 "" -std=gnu++14 -std=gnu++11 ; do
     save_CPPFLAGS=$CPPFLAGS
     CPPFLAGS="$AM_CPPFLAGS $CPPFLAGS"
     save_CXXFLAGS=$CXXFLAGS
@@ -413,8 +413,7 @@ if test x$GXX = xyes; then
       AM_CPPFLAGS="$AM_CPPFLAGS -Wall -Wextra"
   fi
   case $gxx_version in
-      2.*|3.*) AC_ERROR([gcc >= 4.6 is required]);;
+      2.*|3.*|4.@<:@0-6@:>@) AC_ERROR([gcc >= 4.7 is required]);;
-      4.0*|4.1*|4.2*|4.3*|4.4*|4.5*) AC_ERROR([gcc >= 4.6 is required]);;
   esac
   if test x$enable_stdlib_debug = xyes ; then
     dnl FIXME: for clang/libc++, one should define _LIBCPP_DEBUG2=0

src/TexRow.h

@@ -119,7 +119,6 @@ public:
 	///
 	TexRow();
 
-#if !(defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ == 6))
 	/// Copy can be expensive and is not usually useful for TexRow.
 	/// Force explicit copy, prefer move instead. This also prevents
 	/// move()s from being converted into copy silently.
@@ -127,10 +126,6 @@ public:
 	TexRow(TexRow && other) = default;
 	TexRow & operator=(TexRow const & other) = default;
 	TexRow & operator=(TexRow && other) = default;
-# else
-	//for gcc 4.6, nothing to do: it's enough to disable implicit copy during
-	// dev with more recent versions of gcc.
-#endif
 
 	/// Clears structure.
 	void reset();
@@ -241,7 +236,6 @@ struct TexString {
 	docstring str;
 	///
 	TexRow texrow;
-#if !(defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ == 6))
 	/// Copy can be expensive and is not usually useful for TexString.
 	/// Force explicit copy, prefer move instead. This also prevents
 	/// move()s from being converted into copy silently.
@@ -249,10 +243,6 @@ struct TexString {
 	TexString(TexString && other) = default;
 	TexString & operator=(TexString const & other) = default;
 	TexString & operator=(TexString && other) = default;
-# else
-	//for gcc 4.6, nothing to do: it's enough to disable implicit copy during
-	// dev with more recent versions of gcc.
-#endif
 	/// Empty TexString
 	TexString() = default;
 	/// Texstring containing str and TexRow with enough lines which are empty

src/support/Cache.h

@@ -33,15 +33,11 @@ namespace lyx {
  */
 template <class Key, class Val>
 class Cache : private QCache<Key, Val> {
-#if !(defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ == 6))
 	static_assert(std::is_copy_constructible<Val>::value,
 	              "lyx::Cache only stores copyable objects!");
 	static_assert(std::is_default_constructible<Val>::value,
 	              "lyx::Cache only stores default-constructible objects!");
 	using Q = QCache<Key, Val>;
-#else
-	typedef QCache<Key, Val> Q;
-#endif
 
 public:
 	///

src/support/Changer.h

@@ -24,9 +24,7 @@ struct Revertible {
 	virtual void keep() {}
 };
 
-//for gcc 4.6
+using Changer = unique_ptr<Revertible>;
-//using Changer = unique_ptr<Revertible>;
-typedef unique_ptr<Revertible> Changer;
 
 
 } // namespace lyx

src/support/RefChanger.h

@@ -46,18 +46,7 @@ private:
 };
 
 
-//for gcc 4.6
-#if defined(__GNUC__) && (__GNUC__ == 4) && (__GNUC_MINOR__ == 6)
-template <typename X>
-struct RefChanger : unique_ptr<RevertibleRef<X>>
-{
-	RefChanger(unique_ptr<RevertibleRef<X>> p)
-		: unique_ptr<RevertibleRef<X>>(move(p))
-		{}
-};
-#else
 template <typename X> using RefChanger = unique_ptr<RevertibleRef<X>>;
-#endif
 
 
 /// Saves the value of \param ref in a movable object

src/support/unicode.cpp

@@ -66,13 +66,6 @@ IconvProcessor::IconvProcessor(string tocode, string fromcode)
 {}
 
 
-// for gcc 4.6
-IconvProcessor::IconvProcessor(IconvProcessor && other)
-	: tocode_(move(other.tocode_)), fromcode_(move(other.fromcode_)),
-	  h_(move(other.h_))
-{}
-
-
 bool IconvProcessor::init()
 {
 	if (h_)

src/support/unicode.h

@@ -62,8 +62,8 @@ public:
 		char * out_buffer, size_t max_out_size);
 	/// target encoding
 	std::string to() const { return tocode_; }
-	// required by g++ 4.6
+	// required by g++ 4.7
-	IconvProcessor(IconvProcessor && other);
+	IconvProcessor(IconvProcessor &&) = default;
 };
 
 /// Get the global IconvProcessor instance of the current thread for