On 04/30/2017 02:02 PM, Tom de Vries wrote:
On 01/10/2017 11:16 PM, Martin Sebor wrote:+ __builtin_sprintf (d, "%32s", "x"); /* { dg-warning "directive writing 32 bytes into a region of size 12" "-Wformat-length" { xfail *-*-* } } */This xpasses for me on an older system: ... XPASS: gcc.dg/pr78768.c -Wformat-overflow (test for warnings, line 11) ... The mechanism is as follows: - the system doesn't have linker plugin support, and sets HAVE_LTO_PLUGIN to 0 - consequently, opts.c:finish_options() sets x_flag_fat_lto_objects to 1 in cc1 - cgraphunit.c:symbol_table::compile() does not return here: ... /* Do nothing else if any IPA pass found errors or if we are just streaming LTO. */ if (seen_error () || (!in_lto_p && flag_lto && !flag_fat_lto_objects)) { timevar_pop (TV_CGRAPHOPT); return; } ... and ends up calling expand_all_functions, which calls pass_sprintf_length - the warning is generated by cc1 Maybe the test needs: ... /* { dg-require-linker-plugin "" } */ ... ?
That seems possible. IIUC, without linker plugin support the pass will run when the ordinary object file is created during the first stage of compilation. I don't have a system to confirm it on but if pr78768.c xfails when you add the directive I'd say go ahead and commit the fix as obvious. Thanks Martin
