This is basically the same idea as the warning on uninitialized uses of
fields within an initializer list. As such, it is on by default and
under -Wuninitialized.
Original patch by Richard Trieu, with some massaging from me on the
wording and grouping of the diagnostics.
llvm-svn: 128376
Diagnostic pragmas are broken because we don't keep track of the diagnostic state changes and we only check the current/latest state.
Problems manifest if a diagnostic is emitted for a source line that has different diagnostic state than the current state; this can affect
a lot of places, like C++ inline methods, template instantiations, the lexer, etc.
Fix the issue by having the Diagnostic object keep track of the source location of the pragmas so that it is able to know what is the diagnostic state at any given source location.
Fixes rdar://8365684.
llvm-svn: 121873
Fangrui Song