Implement workaround to get printf("string without args") working

GCC is replacing printf("string with no args"); with puts("string with no args"); even with no optimizations enabled!

This is apparently not implemented in a usable way for us in Arduino land and results in a) no output or b) an infinitely rebooting application, depending on whether it's my lucky day or not.

Current workaround is to redefine puts() for our needs. Another option is noted in the comment along with the function, in case that bites us in the end.

Author: phillipjohnston

src/LibPrintf.cpp

@@ -25,3 +25,26 @@ extern "C" __attribute__((weak)) void putchar_(char character)
 {
 	print_instance->print(character);
 }
+
+#if __GNUC__
+/// This works around a problem where GCC is replacing
+/// printf("string with no args") with puts("string with no args"), which
+/// is not actually implemented in a way that is suitable for us, resulting
+/// in an infinite reboot loop or simply not printing that output, depending
+/// on my luck.
+///
+/// This is probably NOT the right way to go about this (expecting it to be undefined
+/// behavior, but I have fewer tools available in Arduino land, so I am
+/// sticking with this for now.
+///
+/// If this causes problems in the future, the next thing to try is
+/// NOT using the Aliasing option (currently defined in LibPrintf.h) and instead
+/// then providing definitions in the mpaland style in our LibPrintf.h header:
+/// #define printf printf_
+/// #define vprintf vprintf_
+/// etc.
+extern "C" int puts(const char * str)
+{
+	return printf("%s\n", str);
+}
+#endif //__GNUC__