Require -fPIC instead of just -fPIE for -reduce-relocations

GCC 5 combined with a recent binutils have a new optimization that
allows them to generate copy relocations even in -fPIE code. Clang has
the same functionality when compiling an executable with -flto. We need
to let the compilers know that they cannot use copy relocations, so they
need to use really position-independent code.

Position independent code throughout is not really required. We just
need the compilers to use position-independent access to symbols coming
from the Qt libraries, but there's currently no other way of doing that.

Task-number: QTBUG-45755
Change-Id: I0d4913955e3745b69672ffff13db5df7377398c5
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>

6 files changed, 9 insertions, 9 deletions

diff --git a/mkspecs/common/gcc-base.conf b/mkspecs/common/gcc-base.conf
index a149f4d907..e4ccbd7156 100644
--- a/mkspecs/common/gcc-base.conf
+++ b/mkspecs/common/gcc-base.conf
@@ -42,7 +42,7 @@ QMAKE_CFLAGS_RELEASE       += $$QMAKE_CFLAGS_OPTIMIZE
 QMAKE_CFLAGS_DEBUG         += -g
 QMAKE_CFLAGS_SHLIB         += -fPIC
 QMAKE_CFLAGS_STATIC_LIB    += -fPIC
-QMAKE_CFLAGS_APP           += -fPIE
+QMAKE_CFLAGS_APP           += -fPIC
 QMAKE_CFLAGS_ISYSTEM        = -isystem
 QMAKE_CFLAGS_YACC          += -Wno-unused -Wno-parentheses
 QMAKE_CFLAGS_HIDESYMS      += -fvisibility=hidden
diff --git a/mkspecs/common/qcc-base.conf b/mkspecs/common/qcc-base.conf
index f529d7fc7b..8276316c3f 100644
--- a/mkspecs/common/qcc-base.conf
+++ b/mkspecs/common/qcc-base.conf
@@ -23,7 +23,7 @@ QMAKE_CFLAGS_RELEASE_WITH_DEBUGINFO += $$QMAKE_CFLAGS_OPTIMIZE -g
 QMAKE_CFLAGS_DEBUG     += -g
 QMAKE_CFLAGS_SHLIB     += -fPIC -shared
 QMAKE_CFLAGS_STATIC_LIB += -fPIC
-QMAKE_CFLAGS_APP       += -fPIE
+QMAKE_CFLAGS_APP       += -fPIC
 QMAKE_CFLAGS_YACC      += -Wno-unused -Wno-parentheses
 QMAKE_CFLAGS_HIDESYMS  += -fvisibility=hidden
 QMAKE_CFLAGS_SSE2      += -msse2
diff --git a/mkspecs/linux-icc/qmake.conf b/mkspecs/linux-icc/qmake.conf
index 8119c8aa09..9190aa9f28 100644
--- a/mkspecs/linux-icc/qmake.conf
+++ b/mkspecs/linux-icc/qmake.conf
@@ -12,7 +12,7 @@ QMAKE_LEXFLAGS          =
 QMAKE_YACC              = yacc
 QMAKE_YACCFLAGS         = -d
 QMAKE_CFLAGS            =
-QMAKE_CFLAGS_APP        = -fPIE
+QMAKE_CFLAGS_APP        = -fPIC
 QMAKE_CFLAGS_DEPS       = -M
 QMAKE_CFLAGS_WARN_ON    = -w1 -Wall -Wcheck -wd1572,873,2259,2261
 QMAKE_CFLAGS_WARN_OFF   = -w
diff --git a/src/corelib/Qt5CoreConfigExtras.cmake.in b/src/corelib/Qt5CoreConfigExtras.cmake.in
index 7213a844f5..48d5f21447 100644
--- a/src/corelib/Qt5CoreConfigExtras.cmake.in
+++ b/src/corelib/Qt5CoreConfigExtras.cmake.in
@@ -71,7 +71,7 @@ set(_qt5_corelib_extra_includes)
 # macro to add it.
 set(Qt5_POSITION_INDEPENDENT_CODE True)
 set_property(TARGET Qt5::Core PROPERTY INTERFACE_POSITION_INDEPENDENT_CODE \"ON\")
-set(Qt5Core_EXECUTABLE_COMPILE_FLAGS \"-fPIE\")
+set(Qt5Core_EXECUTABLE_COMPILE_FLAGS \"-fPIC\")
 
 !!IF !isEmpty(QT_NAMESPACE)
 list(APPEND Qt5Core_DEFINITIONS -DQT_NAMESPACE=$$QT_NAMESPACE)
diff --git a/src/corelib/global/qglobal.h b/src/corelib/global/qglobal.h
index 455582e310..ef84662036 100644
--- a/src/corelib/global/qglobal.h
+++ b/src/corelib/global/qglobal.h
@@ -1047,9 +1047,9 @@ Q_CORE_EXPORT int qrand();
 #  define QT_NO_SHAREDMEMORY
 #endif
 
-#if !defined(QT_BOOTSTRAPPED) && defined(QT_REDUCE_RELOCATIONS) && defined(__ELF__) && !defined(__PIC__) && !defined(__PIE__)
+#if !defined(QT_BOOTSTRAPPED) && defined(QT_REDUCE_RELOCATIONS) && defined(__ELF__) && !defined(__PIC__)
 #  error "You must build your code with position independent code if Qt was built with -reduce-relocations. "\
-         "Compile your code with -fPIC or -fPIE."
+         "Compile your code with -fPIC."
 #endif
 
 namespace QtPrivate {
diff --git a/tests/auto/tools/moc/tst_moc.cpp b/tests/auto/tools/moc/tst_moc.cpp
index edb6488eaa..748cb82989 100644
--- a/tests/auto/tools/moc/tst_moc.cpp
+++ b/tests/auto/tools/moc/tst_moc.cpp
@@ -662,7 +662,7 @@ void tst_Moc::oldStyleCasts()
 
     QStringList args;
     args << "-c" << "-x" << "c++" << "-Wold-style-cast" << "-I" << "."
-         << "-I" << qtIncludePath << "-o" << "/dev/null" << "-fPIE" << "-";
+         << "-I" << qtIncludePath << "-o" << "/dev/null" << "-fPIC" << "-";
     proc.start("gcc", args);
     QVERIFY(proc.waitForStarted());
     proc.write(mocOut);
@@ -732,7 +732,7 @@ void tst_Moc::inputFileNameWithDotsButNoExtension()
 
     QStringList args;
     args << "-c" << "-x" << "c++" << "-I" << ".."
-         << "-I" << qtIncludePath << "-o" << "/dev/null" << "-fPIE" <<  "-";
+         << "-I" << qtIncludePath << "-o" << "/dev/null" << "-fPIC" <<  "-";
     proc.start("gcc", args);
     QVERIFY(proc.waitForStarted());
     proc.write(mocOut);
@@ -1011,7 +1011,7 @@ void tst_Moc::ignoreOptionClashes()
     // If -pthread wasn't ignored, it was parsed as a prefix of "thread/", which breaks compilation.
     QStringList gccArgs;
     gccArgs << "-c" << "-x" << "c++" << "-I" << ".."
-         << "-I" << qtIncludePath << "-I" << includeDir << "-o" << "/dev/null" << "-fPIE" <<  "-";
+         << "-I" << qtIncludePath << "-I" << includeDir << "-o" << "/dev/null" << "-fPIC" <<  "-";
     proc.start("gcc", gccArgs);
     QVERIFY(proc.waitForStarted());
     proc.write(mocOut);