On Mon, Apr 29, 2019 at 08:39:57AM -0600, Jeff Law wrote: > On 4/29/19 8:24 AM, Thomas Koenig wrote: > > Hi! > > > > Is there a way to mark a TREE statement (or a variable) so that > > a warning is issued at a later stage if the statement has not been > > removed in the meantime? > > > > I am thinking, for example, of Fortran's -Warray-temporaries, which > > issues a warning in the front end even though the whole temporary > > array may be optimized away later. We could, for example, mark > > a call to malloc in such a way. > I'm not aware of one, but I recently suggested the concept of > __builtin_warning which would allow us to effectively delay a warning. > > The goal was to have the warning explicitly in the IL so that if the > path to the warning was later determined infeasible the warning would > just get removed by the standard unreachable code elimination optimization. > > This would allow us to avoid false positives due to the IL not being > well enough optimized at the point where we discover something is > potentially amiss.
FYI, I also raised the idea of delayed warnings in the C FE some time ago: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68193#c3 Marek
