support relative paths in QMAKE_RPATHDIR

... and make use of it in qt.prf.

[ChangeLog][qmake][Unix] Added support for relative paths in
QMAKE_RPATHDIR.

Note that this technically breaks backwards compatibility, as relative
paths were previously silently resolved against $$_PRO_FILE_PWD_. This
was not documented and seems rather useless, so i'm not worried.

Change-Id: I855042a8962ab34ad4617899a5b9825af0087f8a
Reviewed-by: Joerg Bornemann <joerg.bornemann@theqtcompany.com>
Reviewed-by: Jake Petroules <jake.petroules@theqtcompany.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>

mkspecs/common/linux.conf

@@ -10,6 +10,9 @@ QMAKE_CFLAGS_THREAD    += -D_REENTRANT
 QMAKE_CXXFLAGS_THREAD  += $$QMAKE_CFLAGS_THREAD
 QMAKE_LFLAGS_GCSECTIONS = -Wl,--gc-sections
 
+QMAKE_LFLAGS_REL_RPATH  = -Wl,-z,origin
+QMAKE_REL_RPATH_BASE    = $ORIGIN
+
 QMAKE_INCDIR            =
 QMAKE_LIBDIR            =
 QMAKE_INCDIR_X11        =

mkspecs/common/mac.conf

@@ -22,6 +22,9 @@ QMAKE_FIX_RPATH         = install_name_tool -id
 QMAKE_LFLAGS_RPATH      = -Wl,-rpath,
 QMAKE_LFLAGS_GCSECTIONS = -Wl,-dead_strip
 
+QMAKE_LFLAGS_REL_RPATH  =
+QMAKE_REL_RPATH_BASE    = @loader_path
+
 QMAKE_LIBS_DYNLOAD      =
 QMAKE_LIBS_OPENGL       = -framework OpenGL -framework AGL
 QMAKE_LIBS_THREAD       =

mkspecs/features/qt.prf

@@ -167,17 +167,11 @@ qt_module_deps = $$resolve_depends(qt_module_deps, "QT.")
             } else {
                 binpath = $$target.path
             }
-            rpath = @loader_path
         } else {
-            QMAKE_LFLAGS += -Wl,-z,origin
             binpath = $$target.path
-            rpath = $ORIGIN
         }
         # NOT the /dev property, as INSTALLS use host paths
-        relpath = $$relative_path($$[QT_INSTALL_LIBS], $$binpath)
+        QMAKE_RPATHDIR += $$relative_path($$[QT_INSTALL_LIBS], $$binpath)
-        !equals(relpath, .): \
-            rpath = $$rpath/$$relpath
-        QMAKE_RPATHDIR += $$rpath
     } else {
         QMAKE_RPATHDIR += $$[QT_INSTALL_LIBS/dev]
     }

qmake/doc/src/qmake-manual.qdoc

@@ -1845,6 +1845,22 @@
     The value of this variable is typically handled by
     qmake or \l{#QMAKESPEC}{qmake.conf} and rarely needs to be modified.
 
+    \section1 QMAKE_LFLAGS_REL_RPATH
+
+    Specifies the linker flags needed to enable relative paths in
+    \l{QMAKE_RPATHDIR}.
+
+    The value of this variable is typically handled by
+    qmake or \l{#QMAKESPEC}{qmake.conf} and rarely needs to be modified.
+
+    \section1 QMAKE_REL_RPATH_BASE
+
+    Specifies the string the dynamic linker understands to be the
+    location of the referring executable or library.
+
+    The value of this variable is typically handled by
+    qmake or \l{#QMAKESPEC}{qmake.conf} and rarely needs to be modified.
+
     \section1 QMAKE_LFLAGS_RPATHLINK
 
     Specifies the linker flags needed to use the values from
@@ -2095,6 +2111,13 @@
     executable at link time so that the paths will be preferentially
     searched at runtime.
 
+    When relative paths are specified, qmake will mangle them into a form
+    understood by the dynamic linker to be relative to the location of
+    the referring executable or library.
+    This is supported only by some platforms (currently Linux and
+    Darwin-based ones) and is detectable by checking whether
+    \l{QMAKE_REL_RPATH_BASE} is set.
+
     \section1 QMAKE_RPATHLINKDIR
 
     Specifies a list of library paths for the static linker to search for implicit

qmake/generators/unix/unixmake.cpp

@@ -125,10 +125,23 @@ UnixMakefileGenerator::init()
         const ProStringList &rpathdirs = project->values("QMAKE_RPATHDIR");
         for (int i = 0; i < rpathdirs.size(); ++i) {
             QString rpathdir = rpathdirs[i].toQString();
-            if (rpathdir.length() > 1 && rpathdir.at(0) == '$' && rpathdir.at(1) != '(')
+            if (rpathdir.length() > 1 && rpathdir.at(0) == '$' && rpathdir.at(1) != '(') {
                 rpathdir.replace(0, 1, "\\$$");  // Escape from make and the shell
-            else if (!rpathdir.startsWith('@'))
+            } else if (!rpathdir.startsWith('@') && fileInfo(rpathdir).isRelative()) {
-                rpathdir = QFileInfo(rpathdir).absoluteFilePath();
+                QString rpathbase = project->first("QMAKE_REL_RPATH_BASE").toQString();
+                if (rpathbase.isEmpty()) {
+                    fprintf(stderr, "Error: This platform does not support relative paths in QMAKE_RPATHDIR (%s)\n",
+                                    rpathdir.toLatin1().constData());
+                    continue;
+                }
+                if (rpathbase.startsWith('$'))
+                    rpathbase.replace(0, 1, "\\$$");  // Escape from make and the shell
+                if (rpathdir == ".")
+                    rpathdir = rpathbase;
+                else
+                    rpathdir.prepend(rpathbase + '/');
+                project->values("QMAKE_LFLAGS").insertUnique(project->values("QMAKE_LFLAGS_REL_RPATH"));
+            }
             project->values("QMAKE_LFLAGS") += var("QMAKE_LFLAGS_RPATH") + escapeFilePath(rpathdir);
         }
     }