https://github.com/opencv/opencv/pull/23991

From 4ee0f212cc19f7e77483d34d4cf8378945e3da31 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E4=B8=8D=E9=B1=BC=E5=84=BF?=
 <36976072+buyuer@users.noreply.github.com>
Date: Fri, 14 Jul 2023 08:45:14 +0000
Subject: [PATCH] Eliminating compilation warnings when using lto in gcc12 and
 later versions
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use -flto=auto when use gcc12 or later

Signed-off-by: 不鱼儿 <36976072+buyuer@users.noreply.github.com>
---
 cmake/OpenCVCompilerOptions.cmake | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/cmake/OpenCVCompilerOptions.cmake b/cmake/OpenCVCompilerOptions.cmake
index d4600943fb0d..8bd86681303e 100644
--- a/cmake/OpenCVCompilerOptions.cmake
+++ b/cmake/OpenCVCompilerOptions.cmake
@@ -261,7 +261,11 @@ if(CV_GCC OR CV_CLANG)
   endif()
 
   if(ENABLE_LTO)
-    add_extra_compiler_option(-flto)
+    if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU" AND CMAKE_CXX_COMPILER_VERSION VERSION_GREATER_EQUAL 12)
+      add_extra_compiler_option(-flto=auto)
+    else()
+      add_extra_compiler_option(-flto)
+    endif()
   endif()
   if(ENABLE_THIN_LTO)
     add_extra_compiler_option(-flto=thin)