[gobject-introspection] giscanner: add a --lib-dirs-envvar option

[Christoph Reiter <creiter src gnome org>]

commit 48f41930a773bdd48b9664b2fc5b1e45d6bc5688
Author: Alexander Kanavin <alex kanavin gmail com>
Date:   Wed Jan 3 17:02:01 2018 +0200

    giscanner: add a --lib-dirs-envvar option
    
    By default LD_LIBRARY_PATH is set to the list of target library paths;
    this breaks down in cross-compilation environment, as we need to run a
    native emulation wrapper rather than the target binary itself. This patch
    allows exporting those paths to a different environment variable
    which can be picked up and used by the wrapper.
    
    Signed-off-by: Alexander Kanavin <alex kanavin gmail com>

 giscanner/ccompiler.py   | 4 ++--
 giscanner/dumper.py      | 3 ++-
 giscanner/scannermain.py | 3 +++
 3 files changed, 7 insertions(+), 3 deletions(-)
---
diff --git a/giscanner/ccompiler.py b/giscanner/ccompiler.py
index 4ad572c3..a81d4b86 100644
--- a/giscanner/ccompiler.py
+++ b/giscanner/ccompiler.py
@@ -174,7 +174,7 @@ class CCompiler(object):
 
             self._cflags_no_deprecation_warnings = "-Wno-deprecated-declarations"
 
-    def get_internal_link_flags(self, args, libtool, libraries, extra_libraries, libpaths):
+    def get_internal_link_flags(self, args, libtool, libraries, extra_libraries, libpaths, lib_dirs_envvar):
         # An "internal" link is where the library to be introspected
         # is being built in the current directory.
 
@@ -184,7 +184,7 @@ class CCompiler(object):
         if os.name == 'nt':
             runtime_path_envvar = ['LIB', 'PATH']
         else:
-            runtime_path_envvar = ['LD_LIBRARY_PATH', 'DYLD_FALLBACK_LIBRARY_PATH']
+            runtime_path_envvar = ['LD_LIBRARY_PATH', 'DYLD_FALLBACK_LIBRARY_PATH'] if not lib_dirs_envvar 
else [lib_dirs_envvar]
             # Search the current directory first
             # (This flag is not supported nor needed for Visual C++)
             args.append('-L.')
diff --git a/giscanner/dumper.py b/giscanner/dumper.py
index efa18782..61942faf 100644
--- a/giscanner/dumper.py
+++ b/giscanner/dumper.py
@@ -240,7 +240,8 @@ class DumpCompiler(object):
                                                    libtool,
                                                    self._options.libraries,
                                                    self._options.extra_libraries,
-                                                   self._options.library_paths)
+                                                   self._options.library_paths,
+                                                   self._options.lib_dirs_envvar)
             args.extend(pkg_config_libs)
 
         else:
diff --git a/giscanner/scannermain.py b/giscanner/scannermain.py
index 4aeb4172..ca9065b2 100644
--- a/giscanner/scannermain.py
+++ b/giscanner/scannermain.py
@@ -126,6 +126,9 @@ def _get_option_parser():
     parser.add_option("", "--use-ldd-wrapper",
                       action="store", dest="ldd_wrapper", default=None,
                       help="wrapper to use instead of ldd (useful when cross-compiling)")
+    parser.add_option("", "--lib-dirs-envvar",
+                      action="store", dest="lib_dirs_envvar", default=None,
+                      help="environment variable to write a list of library directories to (for running the 
transient binary), instead of standard LD_LIBRARY_PATH")
     parser.add_option("", "--program-arg",
                       action="append", dest="program_args", default=[],
                       help="extra arguments to program")