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From: "vultkayn at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug analyzer/110830] New: -Wanalyzer-use-of-uninitialized-value false negative due to use-after-free::supercedes_p. Date: Thu, 27 Jul 2023 12:41:41 +0000 [thread overview] Message-ID: <bug-110830-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110830 Bug ID: 110830 Summary: -Wanalyzer-use-of-uninitialized-value false negative due to use-after-free::supercedes_p. Product: gcc Version: 14.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: analyzer Assignee: dmalcolm at gcc dot gnu.org Reporter: vultkayn at gcc dot gnu.org Target Milestone: --- state_machine::supercedes_p is called when two diagnostics are emitted for the same statement, without regarding the path that led to this statement. See reproducer on trunk https://godbolt.org/z/GqebW5s5h #include <stdlib.h> extern int ext(); int* foo() { int *p = 0; if (ext() > 5) { p = malloc (sizeof(int)); *p = 0; free (p); return p; } else return malloc(sizeof(int)); } void test() { int *y = foo(); // (*) int x = 4 + *y; free (y); } At statement (*) both -Wanalyzer-use-of-uninitialized-value and -Wanalyzer-use-after-free should be emitted as solving the latter won't impact the former, since they result from two independent branches. But use_after_free::supercedes_p hides the other. In the case of a false positive -Wanalyzer-use-after-free, or simply one ignored by the user, the adjacent -Wanalyzer-use-of-uninitialized-value would therefore never be emitted.
next reply other threads:[~2023-07-27 12:41 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2023-07-27 12:41 vultkayn at gcc dot gnu.org [this message] 2023-07-31 22:40 ` [Bug analyzer/110830] " dmalcolm at gcc dot gnu.org 2023-07-31 22:43 ` dmalcolm at gcc dot gnu.org 2023-09-07 21:02 ` cvs-commit at gcc dot gnu.org
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