Let LDFLAGS specify rpath.

Fixes #2567

mesonbuild/backend/backends.py

@@ -444,6 +444,21 @@ class Backend:
                 return True
         return False
 
+    def get_external_rpath_dirs(self, target):
+        dirs = set()
+        args = []
+        # FIXME: is there a better way?
+        for lang in ['c', 'cpp']:
+            try:
+                args.extend(self.environment.coredata.get_external_link_args(target.for_machine, lang))
+            except Exception:
+                pass
+        for arg in args:
+            if arg.startswith('-Wl,-rpath='):
+                for dir in arg.replace('-Wl,-rpath=','').split(':'):
+                    dirs.add(dir)
+        return dirs
+
     def rpaths_for_bundled_shared_libraries(self, target, exclude_system=True):
         paths = []
         for dep in target.external_deps:
@@ -458,6 +473,9 @@ class Backend:
             if exclude_system and self._libdir_is_system(libdir, target.compilers, self.environment):
                 # No point in adding system paths.
                 continue
+            # Don't remove rpaths specified in LDFLAGS.
+            if libdir in self.get_external_rpath_dirs(target):
+                continue
             # Windows doesn't support rpaths, but we use this function to
             # emulate rpaths by setting PATH, so also accept DLLs here
             if os.path.splitext(libpath)[1] not in ['.dll', '.lib', '.so', '.dylib']:

run_unittests.py

@@ -6079,6 +6079,39 @@ class LinuxlikeTests(BasePlatformTests):
         install_rpath = get_rpath(os.path.join(self.installdir, 'usr/bin/progcxx'))
         self.assertEqual(install_rpath, 'baz')
 
+    def test_global_rpath(self):
+        if is_cygwin():
+            raise unittest.SkipTest('Windows PE/COFF binaries do not use RPATH')
+        if is_osx():
+            raise unittest.SkipTest('Global RPATHs via LDFLAGS not yet supported on MacOS (does anybody need it?)')
+
+        testdir = os.path.join(self.unit_test_dir, '77 global-rpath')
+        oldinstalldir = self.installdir
+
+        # Build and install an external library without DESTDIR.
+        # The external library generates a .pc file without an rpath.
+        yonder_dir = os.path.join(testdir, 'yonder')
+        yonder_prefix = os.path.join(oldinstalldir, 'yonder')
+        yonder_libdir = os.path.join(yonder_prefix, self.libdir)
+        self.prefix = yonder_prefix
+        self.installdir = yonder_prefix
+        self.init(yonder_dir)
+        self.build()
+        self.install(use_destdir=False)
+        self.new_builddir()
+
+        # Build an app that uses that installed library.
+        # Supply the rpath to the installed library via LDFLAGS
+        # (as systems like buildroot and guix are wont to do)
+        # and verify install preserves that rpath.
+        env = {'LDFLAGS': '-Wl,-rpath=' + yonder_libdir,
+               'PKG_CONFIG_PATH': os.path.join(yonder_libdir, 'pkgconfig')}
+        self.init(testdir, override_envvars=env)
+        self.build()
+        self.install(use_destdir=False)
+        got_rpath = get_rpath(os.path.join(yonder_prefix, 'bin/rpathified'))
+        self.assertEqual(got_rpath, yonder_libdir)
+
     @skip_if_not_base_option('b_sanitize')
     def test_pch_with_address_sanitizer(self):
         if is_cygwin():

test cases/unit/77 global-rpath/meson.build

@@ -0,0 +1,3 @@
+project('global-rpath', 'cpp')
+yonder_dep = dependency('yonder')
+executable('rpathified', 'rpathified.cpp', dependencies: [yonder_dep], install: true)

test cases/unit/77 global-rpath/rpathified.cpp

@@ -0,0 +1,6 @@
+#include <yonder.h>
+#include <string.h>
+int main(int argc, char **argv)
+{
+    return strcmp(yonder(), "AB54 6BR");
+}

test cases/unit/77 global-rpath/yonder/meson.build

@@ -0,0 +1,5 @@
+project('yonder', 'cpp')
+yonder = shared_library('yonder', 'yonder.cpp', install: true)
+install_headers('yonder.h')
+pkgconfig = import('pkgconfig')
+pkgconfig.generate(yonder)

test cases/unit/77 global-rpath/yonder/yonder.cpp

@@ -0,0 +1,3 @@
+#include "yonder.h"
+
+char *yonder(void) { return "AB54 6BR"; }

test cases/unit/77 global-rpath/yonder/yonder.h

@@ -0,0 +1 @@
+char *yonder(void);