rpath: use new DTAGS if available

this allows LD_LIBRARY_PATH to take precedence over the hard-coded
rpath, which is the only sane thing to do (which is also why i'm not
adding an option to disable it).
this behavior is consistent with non-linux systems.

the windows version has no auto-detection, just like for gold linker
usage.

Task-number: QTBUG-3069
Change-Id: Ief9ba032291c898d75d76ecc740390954382a804
Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com>

configure

@@ -728,6 +728,7 @@ CFG_EVENTFD=auto
 CFG_RPATH=yes
 CFG_FRAMEWORK=auto
 CFG_USE_GOLD_LINKER=auto
+CFG_ENABLE_NEW_DTAGS=auto
 DEFINES=
 INCLUDES=
 D_FLAGS=
@@ -3442,6 +3443,13 @@ if [ "$CFG_USE_GOLD_LINKER" != "no" ]; then
     fi
 fi
 
+# auto-detect --enable-new-dtags support
+if linkerSupportsFlag $TEST_COMPILER --enable-new-dtags; then
+    CFG_ENABLE_NEW_DTAGS=yes
+else
+    CFG_ENABLE_NEW_DTAGS=no
+fi
+
 # auto-detect -fstack-protector-strong support (for QNX only currently)
 if [ "$XPLATFORM_QNX" = "yes" ]; then
     if compilerSupportsFlag $TEST_COMPILER -fstack-protector-strong; then
@@ -6067,6 +6075,7 @@ fi
 [ "$CFG_STRIP" = "no" ] && QMAKE_CONFIG="$QMAKE_CONFIG nostrip"
 [ "$CFG_PRECOMPILE" = "yes" ] && QMAKE_CONFIG="$QMAKE_CONFIG precompile_header"
 [ "$CFG_USE_GOLD_LINKER" = "yes" ] && QMAKE_CONFIG="$QMAKE_CONFIG use_gold_linker"
+[ "$CFG_ENABLE_NEW_DTAGS" = "yes" ] && QMAKE_CONFIG="$QMAKE_CONFIG enable_new_dtags"
 if [ "$CFG_SEPARATE_DEBUG_INFO" = "yes" ]; then
     QT_CONFIG="$QT_CONFIG separate_debug_info"
 fi
@@ -6980,6 +6989,7 @@ unset build_mode release
 echo "  Using sanitizer(s)...... $CFG_SANITIZERS"
 echo "  Using C++11 ............ $CFG_CXX11"
 echo "  Using gold linker....... $CFG_USE_GOLD_LINKER"
+echo "  Using new DTAGS ........ $CFG_ENABLE_NEW_DTAGS"
 echo "  Using PCH .............. $CFG_PRECOMPILE"
 echo "  Target compiler supports:"
 if [ "$CFG_ARCH" = "i386" -o "$CFG_ARCH" = "x86_64" ]; then

mkspecs/common/gcc-base-unix.conf

@@ -16,6 +16,7 @@ QMAKE_LFLAGS_SONAME    += -Wl,-soname,
 QMAKE_LFLAGS_THREAD    +=
 QMAKE_LFLAGS_RPATH      = -Wl,-rpath,
 QMAKE_LFLAGS_RPATHLINK  = -Wl,-rpath-link,
+QMAKE_LFLAGS_NEW_DTAGS  = -Wl,--enable-new-dtags
 QMAKE_LFLAGS_USE_GOLD   = -fuse-ld=gold
 
 # -Bsymbolic-functions (ld) support

mkspecs/features/default_post.prf

@@ -63,6 +63,7 @@ debug {
 }
 
 use_gold_linker: QMAKE_LFLAGS += $$QMAKE_LFLAGS_USE_GOLD
+enable_new_dtags: QMAKE_LFLAGS += $$QMAKE_LFLAGS_NEW_DTAGS
 
 dll:win32: QMAKE_LFLAGS += $$QMAKE_LFLAGS_DLL
 static:mac: QMAKE_LFLAGS += $$QMAKE_LFLAGS_STATIC_LIB

tools/configure/configureapp.cpp

@@ -244,6 +244,8 @@ Configure::Configure(int& argc, char** argv)
 
     dictionary[ "USE_GOLD_LINKER" ] = "no";
 
+    dictionary[ "ENABLE_NEW_DTAGS" ] = "no";
+
     dictionary[ "SHARED" ]          = "yes";
 
     dictionary[ "STATIC_RUNTIME" ]  = "no";
@@ -471,6 +473,10 @@ void Configure::parseCmdLine()
             dictionary[ "USE_GOLD_LINKER" ] = "yes";
         else if (configCmdLine.at(i) == "-no-use-gold-linker")
             dictionary[ "USE_GOLD_LINKER" ] = "no";
+        else if (configCmdLine.at(i) == "-enable-new-dtags")
+            dictionary[ "ENABLE_NEW_DTAGS" ] = "yes";
+        else if (configCmdLine.at(i) == "-disable-new-dtags")
+            dictionary[ "ENABLE_NEW_DTAGS" ] = "no";
         else if (configCmdLine.at(i) == "-shared")
             dictionary[ "SHARED" ] = "yes";
         else if (configCmdLine.at(i) == "-static")
@@ -1793,6 +1799,9 @@ bool Configure::displayHelp()
         desc("USE_GOLD_LINKER", "yes", "-use-gold-linker",                  "Link using the GNU gold linker (gcc only).");
         desc("USE_GOLD_LINKER", "no", "-no-use-gold-linker",                "Do not link using the GNU gold linker.\n");
 
+        desc("ENABLE_NEW_DTAGS", "yes", "-enable-new-dtags", "Use new DTAGS for RPATH (Linux only).");
+        desc("ENABLE_NEW_DTAGS", "no", "-disable-new-dtags", "Do not use new DTAGS for RPATH.\n");
+
         desc("SHARED", "yes",   "-shared",              "Create and use shared Qt libraries.");
         desc("SHARED", "no",    "-static",              "Create and use static Qt libraries.\n");
 
@@ -2675,6 +2684,9 @@ void Configure::generateOutputVars()
     if (dictionary[ "USE_GOLD_LINKER" ] == "yes")
         qmakeConfig += "use_gold_linker";
 
+    if (dictionary[ "ENABLE_NEW_DTAGS" ] == "yes")
+        qmakeConfig += "enable_new_dtags";
+
     if (dictionary[ "SHARED" ] == "no")
         qtConfig += "static";
     else