[Bug c++/99251] [11 Regression] inconsistent -Wnonnull warning behaviour with dynamic_cast
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99251 Bug 99251 depends on bug 74762, which changed state. Bug 74762 Summary: [9/10/11 Regression] missing uninitialized warning (C++, parenthesized expr, TREE_NO_WARNING) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=74762 What|Removed |Added Status|ASSIGNED|RESOLVED Resolution|--- |FIXED
[Bug c++/99251] [11 Regression] inconsistent -Wnonnull warning behaviour with dynamic_cast
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99251 Martin Sebor changed: What|Removed |Added Resolution|--- |FIXED Status|ASSIGNED|RESOLVED --- Comment #5 from Martin Sebor --- Fixed in r11-7458.
[Bug c++/99251] [11 Regression] inconsistent -Wnonnull warning behaviour with dynamic_cast
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99251 --- Comment #4 from CVS Commits --- The master branch has been updated by Martin Sebor : https://gcc.gnu.org/g:66ecb059c9d77cfcfb06cbdc3cac6a63b9e67f3d commit r11-7458-g66ecb059c9d77cfcfb06cbdc3cac6a63b9e67f3d Author: Martin Sebor Date: Tue Mar 2 11:12:50 2021 -0700 PR c++/99251 - inconsistent -Wnonnull warning behaviour with dynamic_cast gcc/cp/ChangeLog: PR c++/99251 * class.c (build_base_path): Call build_if_nonnull. * cp-tree.h (build_if_nonnull): Declare. * rtti.c (ifnonnull): Rename... (build_if_nonnull): ...to this. Set no-warning bit on COND_EXPR. (build_dynamic_cast_1): Adjust to name change. gcc/testsuite/ChangeLog: PR c++/99251 * g++.dg/warn/Wnonnull9.C: Expect no warnings. * g++.dg/warn/Wnonnull12.C: New test.
[Bug c++/99251] [11 Regression] inconsistent -Wnonnull warning behaviour with dynamic_cast
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99251 Richard Biener changed: What|Removed |Added Target Milestone|--- |11.0
[Bug c++/99251] [11 Regression] inconsistent -Wnonnull warning behaviour with dynamic_cast
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99251 Martin Sebor changed: What|Removed |Added Keywords||patch --- Comment #3 from Martin Sebor --- Patch: https://gcc.gnu.org/pipermail/gcc-patches/2021-February/565824.html
[Bug c++/99251] [11 Regression] inconsistent -Wnonnull warning behaviour with dynamic_cast
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99251 Martin Sebor changed: What|Removed |Added Depends on||74762 --- Comment #2 from Martin Sebor --- The reason why there's no warning for cl3::g() is because the result of the cast is not dereferenced in the same expression (the -Wnonnull warning is issued for the call, and the call is in the next statement). The reason why there's no warning for the parenthesized cast in cl3::h() is due to pr74762: the C++ front end sets the no-warning bit on the parenthesized expression. The warning sees this IL: cl2::h (((struct cl3 *) this)->p != 0B ? (struct cl2 *) __dynamic_cast (this->p, &_ZTI3cl1, &_ZTI3cl2, 0) : 0B) where both the COND_EXPR (?:) and the NE_EXPR (!=) have the no-warning bit set and the warning code uses the first bit to suppress it. The reason why there is a warning for cl3::i() is because the no-warning bit is set only on the NE_EXPR and not on the COND_EXPR as above, and the warning code only tests the latter. Finally, the reason why the warning is not issued for a similar static_cast (where the argument has to be checked for equality to null in order for the result to stay null) is because of the fix for pr96003 that set the no-warning bit even on the COND_EXPR but didn't make the corresponding change in ifnonnull() in cp/rtti.c. What a mess. Referenced Bugs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=74762 [Bug 74762] [8/9/10/11 Regression] missing uninitialized warning (C++, parenthesized expr, TREE_NO_WARNING)
[Bug c++/99251] [11 Regression] inconsistent -Wnonnull warning behaviour with dynamic_cast
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99251 Martin Sebor changed: What|Removed |Added Assignee|unassigned at gcc dot gnu.org |msebor at gcc dot gnu.org Status|NEW |ASSIGNED
[Bug c++/99251] [11 Regression] inconsistent -Wnonnull warning behaviour with dynamic_cast
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99251 Martin Sebor changed: What|Removed |Added Blocks||95507 Last reconfirmed||2021-02-24 Keywords||diagnostic Summary|Strange -Wnonnull warning |[11 Regression] |behaviour with dynamic_cast |inconsistent -Wnonnull ||warning behaviour with ||dynamic_cast Ever confirmed|0 |1 CC||msebor at gcc dot gnu.org Status|UNCONFIRMED |NEW --- Comment #1 from Martin Sebor --- We discussed this instance of the warning in pr98646 and decided that even though issuing it for an access to the result of dynamic_cast was strictly a false positive when the operand was guaranteed to be nonnull by a prior test, the workaround to cast to a reference rather than a pointer was simple enough and made the intent clearer: return dynamic_cast(*p).i(); But the inconsistency exhibited in this test case is not a good thing (enclosing the cast in parentheses certainly shouldn't make a difference) and suggests the decision should be revisited. The warning for the dynamic_cast should either be issued consistently or not at all. Let me look into it. Referenced Bugs: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95507 [Bug 95507] [meta-bug] bogus/missing -Wnonnull
