C++11 supports thread-safe initialization of statics

A static local variable is guaranteed to be initialized only once, and in time.

Lambda expressions can be used to perform complex initialization of those static
variables on the spot.

(starting from: gcc >= 4.8, msvc >= 2015)

src/ConverterCache.cpp

@@ -223,7 +223,6 @@ ConverterCache::~ConverterCache()
 }
 
 
-// FIXME THREAD
 ConverterCache & ConverterCache::get()
 {
 	// Now return the cache

src/CutAndPaste.cpp

@@ -486,16 +486,18 @@ Buffer * copyToTempBuffer(ParagraphList const & paragraphs, DocumentClassConstPt
 	// to be so, but the alternative is to construct a new one of these (with a
 	// new temporary directory, etc) every time, and then to destroy it. So maybe
 	// it's worth just keeping this one around.
-	// FIXME THREAD
 	static TempFile tempfile("clipboard.internal");
 	tempfile.setAutoRemove(false);
-	static Buffer * staticbuffer = theBufferList().newInternalBuffer(
-			tempfile.name().absFileName());
-
-	// These two things only really need doing the first time.
-	staticbuffer->setUnnamed(true);
-	staticbuffer->inset().setBuffer(*staticbuffer);
-
+	// The initialization of staticbuffer is thread-safe. Using a lambda
+	// guarantees that the properties are set only once.
+	static Buffer * staticbuffer = [&](){
+		Buffer * b =
+			theBufferList().newInternalBuffer(tempfile.name().absFileName());
+		b->setUnnamed(true);
+		b->inset().setBuffer(*b);
+		//initialize staticbuffer with b
+		return b;
+	}();
 	// Use a clone for the complicated stuff so that we do not need to clean
 	// up in order to avoid a crash.
 	Buffer * buffer = staticbuffer->cloneBufferOnly();

src/frontends/qt4/GuiWorkArea.cpp

@@ -1251,7 +1251,7 @@ void GuiWorkArea::inputMethodEvent(QInputMethodEvent * e)
 		stopBlinkingCursor();
 
 	// last_width : for checking if last preedit string was/wasn't empty.
-	// FIXME THREAD
+	// FIXME THREAD && FIXME
 	// We could have more than one work area, right?
 	static bool last_width = false;
 	if (!last_width && preedit_string.empty()) {

src/graphics/GraphicsCache.cpp

@@ -44,7 +44,6 @@ public:
 };
 
 
-// FIXME THREAD
 Cache & Cache::get()
 {
 	// Now return the cache

src/graphics/GraphicsLoader.cpp

@@ -78,7 +78,6 @@ static int const s_numimages_ = 10;
 static int const s_millisecs_ = 500;
 
 
-// FIXME THREAD
 LoaderQueue & LoaderQueue::get()
 {
 	static LoaderQueue singleton;

src/support/os.cpp

@@ -64,9 +64,9 @@ int timeout_min()
 
 string const python(bool reset)
 {
-	// FIXME THREAD
 	// Check whether the first python in PATH is the right one.
 	static string command = python23("python -tt");
+	// FIXME THREAD
 	if (reset) {
 		command = python23("python -tt");
 	}