On 08/21/2018 02:59 AM, Richard Biener wrote:
On Tue, 21 Aug 2018, Bernd Edlinger wrote:gcc -S -O2 -Wall -Wformat-overflow -ftrack-macro-expansion=0 -fshort-wchar builtin-sprintf-warn-20.c builtin-sprintf-warn-20.c: In function 'test': builtin-sprintf-warn-20.c:19:39: warning: hex escape sequence out of range 19 | ? (char*)L"\x4142\x4344" : (char*)L"\x41424344\x45464748"; | ^~~~~~~~~~~~~~~~~~~~~~~ Hmm, this test might create some noise on short-wchar targets. I would prefer a warning here, about the wrong type of the parameter. The buffer overflow is only a secondary thing. For constant objects like those, the GIMPLE type is still guaranteed to be reliable, right?TREE_TYPE of tcc_declaration and tcc_constant trees should more-or-less (minus qualifications not affecting semantics) be those set by frontends.
A warning for these cases should be relatively straightforward to add to the sprintf pass. It would require c_strlen() to return the type of the string argument to the caller. That way sprintf's format_string() function could compare the string type to the expected type of the directive. If c_strlen() fails because the types don't match as it does now there's no easy way for format_string() to know what the actual type of the string is (not without doing the same work c_strlen() would have done). Martin
