From a08bf7f00ab64fd3ae7376d8dd50ca8a37bee3e3 Mon Sep 17 00:00:00 2001
From: Alexandru Croitor <alexandru.croitor@qt.io>
Date: Fri, 12 Jun 2020 19:12:26 +0200
Subject: CMake: Fix usage of gc_binaries feature

The qt_internal_apply_gc_binaries function should apply both compile
and link flags, not just link flags.

The flags should be applied publically to all consumers of Bootstrap
regardless if the gc_binaries feature is enabled.

The flags should be applied publically to Core only in case if the
feature is enabled (aka for static builds only).

Change-Id: Id42af0d9b527004d74c04eff2c9e3c2be1e76aac
Fixes: QTBUG-84461
Task-number: QTBUG-83929
Reviewed-by: Cristian Adam <cristian.adam@qt.io>
---
 cmake/QtBuild.cmake                | 25 +++++++++++++++++++++----
 configure.cmake                    |  3 +++
 qmake/CMakeLists.txt               |  2 +-
 src/corelib/CMakeLists.txt         |  2 +-
 src/tools/bootstrap/CMakeLists.txt |  2 +-
 util/cmake/configurejson2cmake.py  |  4 +++-
 6 files changed, 30 insertions(+), 8 deletions(-)

diff --git a/cmake/QtBuild.cmake b/cmake/QtBuild.cmake
index ea0d92a7cb..0778987b6a 100644
--- a/cmake/QtBuild.cmake
+++ b/cmake/QtBuild.cmake
@@ -1409,7 +1409,15 @@ function(qt_internal_add_link_flags_no_undefined target)
     endif()
 endfunction()
 
-function(qt_internal_add_link_flags_gc_sections target visibility)
+function(qt_internal_apply_gc_binaries_conditional target visibility)
+    # Should only be applied when the feature is enabled, aka for static builds.
+    if(NOT QT_FEATURE_gc_binaries)
+        return()
+    endif()
+    qt_internal_apply_gc_binaries("${target}" "${visibility}")
+endfunction()
+
+function(qt_internal_apply_gc_binaries target visibility)
     set(possible_visibilities PRIVATE INTERFACE PUBLIC)
     list(FIND possible_visibilities "${visibility}" known_visibility)
     if (known_visibility EQUAL "-1")
@@ -1419,13 +1427,22 @@ function(qt_internal_add_link_flags_gc_sections target visibility)
     if ((GCC OR CLANG) AND NOT EMSCRIPTEN)
         if(APPLE)
             set(gc_sections_flag "-Wl,-dead_strip")
-        elseif(LINUX OR BSD OR SOLARIS OR WIN32 OR ANDROID)
+        elseif(SOLARIS)
+            set(gc_sections_flag "-Wl,-z,ignore")
+        elseif(LINUX OR BSD OR WIN32 OR ANDROID)
             set(gc_sections_flag "-Wl,--gc-sections")
-        else()
-            message(FATAL_ERROR "Platform linker doesn't support gc sections. Target:\"${target}\".")
         endif()
+    endif()
+    if(gc_sections_flag)
         target_link_options("${target}" ${visibility} "${gc_sections_flag}")
     endif()
+
+    if((GCC OR CLANG OR ICC) AND NOT EMSCRIPTEN)
+        set(split_sections_flags "-ffunction-sections" "-fdata-sections")
+    endif()
+    if(split_sections_flags)
+        target_compile_options("${target}" ${visibility} ${split_sections_flags})
+    endif()
 endfunction()
 
 function(qt_internal_add_linker_version_script target)
diff --git a/configure.cmake b/configure.cmake
index fa20b94333..3863f34285 100644
--- a/configure.cmake
+++ b/configure.cmake
@@ -355,6 +355,9 @@ qt_feature("cross_compile" PUBLIC
 )
 qt_feature_config("cross_compile" QMAKE_PUBLIC_CONFIG)
 qt_feature_config("cross_compile" QMAKE_PRIVATE_CONFIG)
+qt_feature("gc_binaries" PRIVATE
+    CONDITION NOT QT_FEATURE_shared
+)
 qt_feature("use_bfd_linker"
     LABEL "bfd"
     AUTODETECT false
diff --git a/qmake/CMakeLists.txt b/qmake/CMakeLists.txt
index c12cb03237..efc6c81da4 100644
--- a/qmake/CMakeLists.txt
+++ b/qmake/CMakeLists.txt
@@ -270,7 +270,7 @@ set_target_properties(${target_name} PROPERTIES
     AUTOUIC OFF
 )
 
-qt_internal_add_link_flags_gc_sections(${target_name} PRIVATE) # special case
+qt_internal_apply_gc_binaries(${target_name} PRIVATE) # special case
 
 qt_enable_msvc_cplusplus_define(${target_name} PUBLIC) # special case
 qt_skip_warnings_are_errors(${target_name}) # special case
diff --git a/src/corelib/CMakeLists.txt b/src/corelib/CMakeLists.txt
index 9f22828fbf..2b1cd8c837 100644
--- a/src/corelib/CMakeLists.txt
+++ b/src/corelib/CMakeLists.txt
@@ -1272,7 +1272,7 @@ if(WIN32)
     set_target_properties(Core PROPERTIES COMPILE_DEFINITIONS "${defines}")
 endif()
 
-qt_internal_add_link_flags_gc_sections(Core PRIVATE)
+qt_internal_apply_gc_binaries_conditional(Core PUBLIC)
 
 if(WIN32)
     set(isExe $<STREQUAL:$<TARGET_PROPERTY:TYPE>,EXECUTABLE>)
diff --git a/src/tools/bootstrap/CMakeLists.txt b/src/tools/bootstrap/CMakeLists.txt
index b734f4fc5d..8b3a6e96d0 100644
--- a/src/tools/bootstrap/CMakeLists.txt
+++ b/src/tools/bootstrap/CMakeLists.txt
@@ -261,7 +261,7 @@ qt_extend_target(Bootstrap CONDITION MINGW AND WIN32
 # QMAKE_CFLAGS = "$$QMAKE_CFLAGS_SHSTK"
 
 # special case begin
-qt_internal_add_link_flags_gc_sections(Bootstrap PUBLIC)
+qt_internal_apply_gc_binaries(Bootstrap PUBLIC)
 set_target_properties(Bootstrap PROPERTIES AUTOMOC OFF AUTOUIC OFF AUTORCC OFF)
 qt_internal_add_target_aliases(Bootstrap)
 qt_enable_msvc_cplusplus_define(Bootstrap PUBLIC)
diff --git a/util/cmake/configurejson2cmake.py b/util/cmake/configurejson2cmake.py
index 11bb01a17a..ce032fafaf 100755
--- a/util/cmake/configurejson2cmake.py
+++ b/util/cmake/configurejson2cmake.py
@@ -863,7 +863,9 @@ def get_feature_mapping():
         "framework": {
             "condition": "APPLE AND BUILD_SHARED_LIBS AND NOT CMAKE_BUILD_TYPE STREQUAL Debug"
         },
-        "gc_binaries": None,
+        "gc_binaries": {
+            "condition" : "NOT QT_FEATURE_shared"
+        },
         "gcc-sysroot": None,
         "gcov": None,
         "gnu-libiconv": {
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