gdb: initialize the data_head variable to eliminate

Signed-off-by: WizardHowl <liuwenyu7@huawei.com>

gdb-initialize-the-data_head-variable-to-eliminate-c.patch

@@ -0,0 +1,45 @@
+From 44ca285b73b68f6a8fa3e89004b510d6b7d98e91 Mon Sep 17 00:00:00 2001
+From: Enze Li <enze.li@hotmail.com>
+Date: Sat, 11 Jun 2022 18:36:48 +0800
+Subject: [PATCH] gdb: initialize the data_head variable to eliminate
+ compilation warnings
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+On a machine with gcc 12, I get this warning:
+
+  CXX    nat/linux-btrace.o
+In function ‘btrace_error linux_read_bts(btrace_data_bts*, btrace_target_info*, btrace_read_type)’,
+    inlined from ‘btrace_error linux_read_btrace(btrace_data*, btrace_target_info*, btrace_read_type)’ at ../gdb/nat/linux-btrace.c:935:29:
+../gdb/nat/linux-btrace.c:865:21: warning: ‘data_head’ may be used uninitialized [-Wmaybe-uninitialized]
+  865 |   pevent->last_head = data_head;
+      |   ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~
+../gdb/nat/linux-btrace.c: In function ‘btrace_error linux_read_btrace(btrace_data*, btrace_target_info*, btrace_read_type)’:
+../gdb/nat/linux-btrace.c:792:9: note: ‘data_head’ was declared here
+  792 |   __u64 data_head, data_tail;
+      |         ^~~~~~~~~
+
+Fix this by initializing the 'data_head' variable.
+
+Tested by rebuilding on x86_64 openSUSE Tumbleweed with gcc 12.
+---
+ gdb/nat/linux-btrace.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/gdb/nat/linux-btrace.c b/gdb/nat/linux-btrace.c
+index b0d6dcd7cf1..c31fb5ffe43 100644
+--- a/gdb/nat/linux-btrace.c
++++ b/gdb/nat/linux-btrace.c
+@@ -789,7 +789,7 @@ linux_read_bts (struct btrace_data_bts *btrace,
+   struct perf_event_buffer *pevent;
+   const uint8_t *begin, *end, *start;
+   size_t buffer_size, size;
+-  __u64 data_head, data_tail;
++  __u64 data_head = 0, data_tail;
+   unsigned int retries = 5;
+ 
+   pevent = &tinfo->variant.bts.bts;
+-- 
+2.33.0
+

gdb.spec

@@ -1,6 +1,6 @@
 Name: gdb
 Version: 12.1
-Release: 3
+Release: 4
 
 License: GPLv3+ and GPLv3+ with exceptions and GPLv2+ and GPLv2+ with exceptions and GPL+ and LGPLv2+ and LGPLv3+ and BSD and Public Domain and GFDL-1.3
 Source: https://ftp.gnu.org/gnu/gdb/gdb-%{version}.tar.xz
@@ -88,6 +88,7 @@ Patch76: gdb-sw22395-constify-target_desc.patch
 
 Patch77: 0001-set-entry-point-when-text-segment-is-missing.patch
 Patch78: 0002-Add-support-for-readline-8.2.patch
+Patch79: gdb-initialize-the-data_head-variable-to-eliminate-c.patch
 
 %global gdb_src gdb-%{version}
 %global gdb_build build-%{_target_platform}
@@ -363,6 +364,9 @@ rm -f $RPM_BUILD_ROOT%{_datadir}/gdb/python/gdb/command/backtrace.py
 %{_infodir}/ctf-spec.info.gz
 
 %changelog
+* Thu Jul 27 2023 Wenyu Liu <liuwenyu7@huawei.com> - 12.1-4
+- initialize the data_head variable to eliminate compilation warnings
+
 * Tue Feb 14 2023 Wenyu Liu <liuwenyu7@huawei.com> - 12.1-3
 - Rectify the spec file.