From 133e989cee5b4e3b32afa10618d700c0590a9c63 Mon Sep 17 00:00:00 2001
From: Christophe Giboudeaux <christophe@krop.fr>
Date: Tue, 12 Jan 2021 12:31:10 +0100
Subject: CMake: Fix build with GCC and ltcg

The porting script could not handle this special case.
To achieve the same thing, we'll use an intermediate 'OBJECT' library
which will get the '-fno-lto' build flag if the conditions are met.

Fixes: QTBUG-89426
Change-Id: Ied62502ce9c7f7fd6b89fab166f7bccfcd6e7433
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>
(cherry picked from commit 2d4a40f93fd3f0fd31110ef7d19a12fc56c00967)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
---
 src/corelib/CMakeLists.txt | 31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

(limited to 'src/corelib/CMakeLists.txt')

diff --git a/src/corelib/CMakeLists.txt b/src/corelib/CMakeLists.txt
index 6389e9f09b..c4461da6b5 100644
--- a/src/corelib/CMakeLists.txt
+++ b/src/corelib/CMakeLists.txt
@@ -54,7 +54,6 @@ qt_internal_add_module(Core
         global/qsysinfo.h
         global/qsystemdetection.h
         global/qtypeinfo.h
-        global/qversiontagging.cpp global/qversiontagging.h  # special case
         io/qabstractfileengine.cpp io/qabstractfileengine_p.h
         io/qbuffer.cpp io/qbuffer.h
         io/qdataurl.cpp io/qdataurl_p.h
@@ -599,22 +598,28 @@ qt_internal_extend_target(Core CONDITION QT_FEATURE_journald
         PkgConfig::Libsystemd
 )
 
-#### Keys ignored in scope 39:.:global:global/global.pri:GCC AND ltcg:
-# QMAKE_EXTRA_COMPILERS = "versiontagging_compiler"
-# versiontagging_compiler.commands = "$$QMAKE_CXX" "-c" "$(CXXFLAGS)" "$(INCPATH)" "-fno-lto" "-o" "${QMAKE_FILE_OUT}" "${QMAKE_FILE_IN}"
-# versiontagging_compiler.dependency_type = "TYPE_C"
-# versiontagging_compiler.input = "VERSIONTAGGING_SOURCES"
-# versiontagging_compiler.name = "compiling[versiontagging]" "${QMAKE_FILE_IN}"
-# versiontagging_compiler.output = "${QMAKE_VAR_OBJECTS_DIR}${QMAKE_FILE_BASE}$${firstQMAKE_EXT_OBJ}"
-# versiontagging_compiler.variable_out = "OBJECTS"
+# special case begin
+add_library(Core_versiontagging OBJECT
+    global/qversiontagging.cpp global/qversiontagging.h
+)
 
-#### Keys ignored in scope 40:.:global:global/global.pri:silent:
-# versiontagging_compiler.commands = "@echo" "compiling[versiontagging]" "${QMAKE_FILE_IN}" "&&"
+set_target_properties(Core_versiontagging PROPERTIES
+    COMPILE_OPTIONS $<TARGET_PROPERTY:Core,COMPILE_OPTIONS>
+    COMPILE_DEFINITIONS $<TARGET_PROPERTY:Core,COMPILE_DEFINITIONS>
+    INCLUDE_DIRECTORIES $<TARGET_PROPERTY:Core,INCLUDE_DIRECTORIES>
+)
+
+# Disable LTO, as the symbols disappear somehow under GCC
+# (https://gcc.gnu.org/bugzilla/show_bug.cgi?id=48200)
+if(GCC AND FEATURE_ltcg)
+    target_compile_options(Core_versiontagging PRIVATE "-fno-lto")
+endif()
 
-qt_internal_extend_target(Core CONDITION NOT GCC OR NOT ltcg
+qt_internal_extend_target(Core
     SOURCES
-        global/qversiontagging.cpp
+        $<TARGET_OBJECTS:Core_versiontagging>
 )
+# special case end
 
 qt_internal_extend_target(Core CONDITION UNIX
     SOURCES
-- 
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