On 05/08/2017 11:37 AM, Martin Sebor wrote:
The -Wformat-overflow warning newly enhanced in GCC 8.0 to detect reading past the end of the source sequence misinterprets the size argument to stpncpy as a request to read that many bytes from the source sequence, rather than the number of bytes to write. Like strncpy, the function never reads past the end of the source string.This constraint is already handled correctly for strncpy by the check_sizes function so the fix is to simply remove the wrong length handling from expand_builtin_stpncpy and let check_sizes do the right thing. The attached patch passes bootstrap and regression test on x86_64. Martin gcc-80669.diff PR middle-end/80669 - Bad -Wstringop-overflow warnings for stpncpy gcc/ChangeLog: PR middle-end/80669 * builtins.c (expand_builtin_stpncpy): Simplify. gcc/testsuite/ChangeLog: PR middle-end/80669 * gcc.dg/builtin-stpncpy.c: New test.
OK. jeff
