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From 0821df518b264e754d698d399f98be1a62945e32 Mon Sep 17 00:00:00 2001 From: Longjun Luo <luolongjuna@gmail.com> Date: Thu, 12 Jan 2023 23:59:54 +0800 Subject: [PATCH] libcpp: suppress builtin macro redefined warnings for __LINE__ As implied in gcc.gnu.org/legacy-ml/gcc-patches/2008-09/msg00076.html, gcc provides -Wno-builtin-macro-redefined to suppress warning when redefining builtin macro. However, at that time, there was no scenario for __LINE__ macro. But, when we try to build a live-patch, we compare sections by using -ffunction-sections. Some same functions are considered changed because of __LINE__ macro. At present, to detect such a changed caused by __LINE__ macro, we have to analyse code and maintain a function list. For example, in kpatch, check this commit github.com/dynup/kpatch/commit/0e1b95edeafa36edb7bcf11da6d1c00f76d7e03d. So, in this scenario, when we try to compared sections, it would be better to support suppress builtin macro redefined warnings for __LINE__ macro. libcpp: * init.cc (builtin_array): Do not always warn for a redefinition of __LINE__. gcc/testsuite * gcc.dg/builtin-redefine.c: Test for redefintion warnings for __LINE__. * gcc.dg/builtin-redefine-1.c: New test.