From 38c28ad2420542d795a27c5359226260c886b112 Mon Sep 17 00:00:00 2001
From: Thiago Macieira <thiago.macieira@intel.com>
Date: Tue, 2 Jun 2015 11:10:22 -0700
Subject: [PATCH] Add a linker version script to Qt libraries

This linker script is only enabled for systems with GCC or GCC-like
compilers, though technically it should work on the BSDs too (will
enable after testing). For regular modules, this declares one ELF
version "Qt_5" and places all QtCore symbols inside, then it declares
unused ELF versions "Qt_5.x" for each older minor release. For modules
declared "internal_module", all symbols are placed in version
Qt_5_PRIVATE_API.

The big advantage of an ELF version is that, when we do Qt 6, both
versions of QtCore could be loaded in memory without conflicts and all
symbols would be resolved to the correct library. No module can talk to
both at the same time, but this avoids mistakes of loading them
indirectly by plugins.

The extra Qt_5.x versions will be used in the next commit.

Change-Id: I049a653beeb5454c9539ffff13e3fe6f050fdf31
---
 mkspecs/common/gcc-base-unix.conf             |  1 +
 mkspecs/common/qcc-base-qnx.conf              |  1 +
 mkspecs/features/qt_module.prf                | 22 ++++++++++++++++++++++
 mkspecs/linux-icc/qmake.conf                  |  1 +
 mkspecs/unsupported/linux-host-g++/qmake.conf |  1 +
 5 files changed, 26 insertions(+)

diff --git a/mkspecs/common/gcc-base-unix.conf b/mkspecs/common/gcc-base-unix.conf
index f82c8a843062d6591713160d865b51264cc9cb5b..0178bda75a97398d6ca78b2bb8f04ca3fe8b9455 100644
--- a/mkspecs/common/gcc-base-unix.conf
+++ b/mkspecs/common/gcc-base-unix.conf
@@ -22,3 +22,4 @@ QMAKE_LFLAGS_USE_GOLD   = -fuse-ld=gold
 # -Bsymbolic-functions (ld) support
 QMAKE_LFLAGS_BSYMBOLIC_FUNC = -Wl,-Bsymbolic-functions
 QMAKE_LFLAGS_DYNAMIC_LIST   = -Wl,--dynamic-list,
+QMAKE_LFLAGS_VERSION_SCRIPT = -Wl,--version-script,
diff --git a/mkspecs/common/qcc-base-qnx.conf b/mkspecs/common/qcc-base-qnx.conf
index a0a88b9605412e9c316a2ab831f71740245fbf20..cebbe06661196834701938cff84127667f9ddb35 100644
--- a/mkspecs/common/qcc-base-qnx.conf
+++ b/mkspecs/common/qcc-base-qnx.conf
@@ -19,6 +19,7 @@ QMAKE_LFLAGS_RPATHLINK  = -Wl,-rpath-link,
 # -Bsymbolic-functions (ld) support
 QMAKE_LFLAGS_BSYMBOLIC_FUNC = -Wl,-Bsymbolic-functions
 QMAKE_LFLAGS_DYNAMIC_LIST   = -Wl,--dynamic-list,
+QMAKE_LFLAGS_VERSION_SCRIPT = -Wl,--version-script,
 
 # Generic options for all BlackBerry/QNX qcc mkspecs
 QMAKE_CFLAGS_THREAD     = -D_REENTRANT
diff --git a/mkspecs/features/qt_module.prf b/mkspecs/features/qt_module.prf
index c89b6d2793bcaef69102c51c4433b304bf6fb769..5206691a17949eab630632f05d0f91d0e56d27b6 100644
--- a/mkspecs/features/qt_module.prf
+++ b/mkspecs/features/qt_module.prf
@@ -185,6 +185,28 @@ equals(QT_ARCH, i386):contains(QT_CPU_FEATURES.$$QT_ARCH, sse2):compiler_support
     QMAKE_CXXFLAGS += -mfpmath=sse
 }
 
+unix:!isEmpty(QMAKE_LFLAGS_VERSION_SCRIPT):!no_linker_version_script:!static {
+    verscript = $$OUT_PWD/$${TARGET}.version
+    QMAKE_LFLAGS += $${QMAKE_LFLAGS_VERSION_SCRIPT}$$verscript
+
+    internal_module {
+        verscript_content = "Qt_$${QT_MAJOR_VERSION}_PRIVATE_API { *; };"
+    } else {
+        current = Qt_$$QT_MAJOR_VERSION
+        verscript_content = "$$current { *; };"
+        for(i, 0..$$section(VERSION, ., 1, 1)) {
+            previous = $$current
+            current = Qt_$${QT_MAJOR_VERSION}.$$i
+            verscript_content += "$$current {} $$previous;"
+        }
+    }
+    write_file($$verscript, verscript_content)|error("Aborting.")
+    unset(current)
+    unset(previous)
+    unset(verscript)
+    unset(verscript_content)
+}
+
 android: CONFIG += qt_android_deps
 
 #install directives
diff --git a/mkspecs/linux-icc/qmake.conf b/mkspecs/linux-icc/qmake.conf
index 9190aa9f28cf6b38455a718afd6851d341ca57b5..4b10d42d44dd0cb8d788c6247099b42ba25c33a6 100644
--- a/mkspecs/linux-icc/qmake.conf
+++ b/mkspecs/linux-icc/qmake.conf
@@ -97,6 +97,7 @@ QMAKE_CXXFLAGS_PRECOMPILE = -c -pch-create ${QMAKE_PCH_OUTPUT} -include ${QMAKE_
 # -Bsymbolic-functions (ld) support
 QMAKE_LFLAGS_BSYMBOLIC_FUNC = -Wl,-Bsymbolic-functions
 QMAKE_LFLAGS_DYNAMIC_LIST = -Wl,--dynamic-list,
+QMAKE_LFLAGS_VERSION_SCRIPT = -Wl,--version-script,
 
 # Symbol visibility control
 QMAKE_CFLAGS_HIDESYMS   += -fvisibility=hidden
diff --git a/mkspecs/unsupported/linux-host-g++/qmake.conf b/mkspecs/unsupported/linux-host-g++/qmake.conf
index 1523126eaaa4761708fe58e449f8b43f6c3b8c14..546ff213498c80649d5a40810f068aca1c598494 100644
--- a/mkspecs/unsupported/linux-host-g++/qmake.conf
+++ b/mkspecs/unsupported/linux-host-g++/qmake.conf
@@ -71,6 +71,7 @@ QMAKE_PCH_OUTPUT_EXT    = .gch
 # -Bsymbolic-functions (ld) support
 QMAKE_LFLAGS_BSYMBOLIC_FUNC = -Wl,-Bsymbolic-functions
 QMAKE_LFLAGS_DYNAMIC_LIST = -Wl,--dynamic-list,
+QMAKE_LFLAGS_VERSION_SCRIPT = -Wl,--version-script,
 
 #
 # qmake configuration for common linux
-- 
2.6.0