On 3/11/19 8:27 PM, Martin Sebor wrote: > The -Wstringop-truncation handling for strncpy/stpncpy neglects > to consider that character arrays tracked by the strlen pass > are not necessarily nul-terminated. It unconditionally adds > one when computing the size of each sequence to account for > the nul. This leads to false positive warnings when checking > the validity of indices/pointers computed by the built-ins. > > The attached patch corrects this by adding one for the nul > only when the character array is known to be nul-terminated. > > Since GCC 7 does not issue the warning this is a 8/9 regression > that I would like to fix in both releases. Is the patch okay > for trunk/gcc-8-branch? > > Tested on x86_64-linux. > > Martin > > gcc-89644.diff > > PR tree-optimization/89644 - False-positive -Warray-bounds diagnostic on > strncpy > > gcc/ChangeLog: > > PR tree-optimization/89644 > * tree-ssa-strlen.c (handle_builtin_stxncpy): Consider unterminated > arrays in determining sequence sizes in strncpy and stpncpy. > > gcc/testsuite/ChangeLog: > > PR tree-optimization/89644 > * gcc.dg/Wstringop-truncation-8.c: New test. OK for the trunk as well as the affected release branches.
jeff
