On 3/19/19 12:37 PM, Martin Sebor wrote: > On 3/19/19 12:01 PM, Martin Sebor wrote: >> On 3/19/19 8:33 AM, Jeff Law wrote: >>> 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. >> >> I just noticed some some -Wrestrict test failures that I had missed >> in the test report. The patch wasn't quite right. Sorry about that. >> I'll fix it shortly. > > The variable to use to check for nul-termination is full_string_p > rather than endptr. I've fixed that in 269809. ACK. I'll restart those targets once 269809 lands in the git mirror.
jeff
