Considering that:

•     It’s best practice to do warning free builds.  Those harmless warnings you are ignoring could be hiding an important warning that’s bugging up your code.
•     Recent version of GCC support disabling of specific warnings.
•     Sometimes we use external libraries which we trust, or must accept — we don’t want to muck around with their internals — say for example the boost libraries.

Given these points, when we include a header which creates warnings, we’d like to disable just those warnings, for just those header files.  This can be done with the following statements for the GCC compiler:

#pragma GCC diagnostic ignored "-Wparentheses"
#pragma GCC diagnostic ignored "-Wswitch"
#include <tl_base_data.h>;
#pragma GCC diagnostic warning "-Wswitch"
#pragma GCC diagnostic warning "-Wparentheses"

This comes up often enough I cranked out a trivial bit of elisp so I can do this in emacs a bit more automatically:

; @todo let this work if we have a range too.
(defun insert-pragmas (pragma-name)
"Wrap the current line with a pragma to disable the warning."
(interactive "MWarning to disable: ")
(if (string= "" pragma-name)
(message "ignoring empty pragma name")
(move-beginning-of-line nil)
(insert "#pragma GCC diagnostic ignored \"-W" pragma-name "\"\n")
(move-end-of-line nil)
(insert "\n#pragma GCC diagnostic warning \"-W" pragma-name "\"\n")
)
)