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From: "phdiv at fastmail dot fm" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug middle-end/106559] New: Spurious warning format-truncation (regression from 9) Date: Mon, 08 Aug 2022 15:10:58 +0000 [thread overview] Message-ID: <bug-106559-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106559 Bug ID: 106559 Summary: Spurious warning format-truncation (regression from 9) Product: gcc Version: 10.3.1 Status: UNCONFIRMED Severity: normal Priority: P3 Component: middle-end Assignee: unassigned at gcc dot gnu.org Reporter: phdiv at fastmail dot fm Target Milestone: --- Created attachment 53426 --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=53426&action=edit Reproducer. > cat w.cpp extern char buffer[64]; extern unsigned int number[16]; void f(){ static const char string[16][3]={ "01","02","03","04","05","06","07","08", "09","10","11","12","13","14","15","16"}; for(unsigned int i=0; i<16; ++i) __builtin_snprintf(buffer,sizeof(buffer),"%u (%s): %8x", i,string[i],number[i]); } > g++ -O1 -Wformat-truncation -c w.cpp w.cpp: In function 'void f()': w.cpp:10:61: warning: '__builtin_snprintf' output may be truncated before the last format character [-Wformat-truncation=] 10 | __builtin_snprintf(buffer,sizeof(buffer),"%u (%s): %8x", | ^ w.cpp:10:23: note: '__builtin_snprintf' output between 17 and 65 bytes into a destination of size 64 10 | __builtin_snprintf(buffer,sizeof(buffer),"%u (%s): %8x", | ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 11 | i,string[i],number[i]); | ~~~~~~~~~~~~~~~~~~~~~~ Granted, the documentation of Wformat-truncation mentions possible false positives, but this is a regression in GCC 10 with respect to GCC 9 (and present up to trunk). For some more variations which do or do not exhibit this bug, see https://godbolt.org/z/PvfrchP7E .
next reply other threads:[~2022-08-08 15:10 UTC|newest] Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-08-08 15:10 phdiv at fastmail dot fm [this message] 2022-08-09 7:37 ` [Bug tree-optimization/106559] [10/11/12/13 Regression] Spurious warning -Wformat-truncation " rguenth at gcc dot gnu.org 2022-08-16 16:00 ` msebor at gcc dot gnu.org 2022-12-14 2:28 ` pinskia at gcc dot gnu.org 2023-07-07 10:43 ` [Bug tree-optimization/106559] [11/12/13/14 " rguenth at gcc dot gnu.org
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