This is a revised patch series to add warning control by group and location, updated based on feedback on the initial series.
v2 changes include: 1) Use opt_code rather than int for the option argument to the new APIs. This let me find and fix a bug in the original Ada change. 2) Use suppress_warning() and warning_suppressed_p() instead of get/set_no_warning, and also instead of warning_enabled/disabled for the names of the new functions (as requested/clarified offline by David). 3) Make the removal of the TREE_NO_WARNING macro and the gimple_get_no_warning_p() and gimple_set_no_warning() functions a standalone patch. 4) Include tests for PR 74765 and 74762 fixed by these changes. I have retested the whole patch series on x86_64-linux.