nixpkgs/pkgs/development/libraries/gobject-introspection/absolute_shlib_path.patch

--- a/giscanner/scannermain.py
+++ b/giscanner/scannermain.py
@@ -101,6 +101,39 @@
     return group
 
 
+def _get_default_fallback_libpath():
+    # Newer multiple-output-optimized stdenv has an environment variable
+    # $outputLib which in turn specifies another variable which then is used as
+    # the destination for the library contents (${!outputLib}/lib).
+    store_path = os.environ.get(os.environ.get("outputLib")) if "outputLib" in os.environ else None
+    if store_path is None:
+        outputs = os.environ.get("outputs", "out").split()
+        if "lib" in outputs:
+            # For multiple output derivations let's try whether there is a $lib
+            # environment variable and use that as the base store path.
+            store_path = os.environ.get("lib")
+        elif "out" in outputs:
+            # Otherwise we have a single output derivation, so the libraries
+            # most certainly will end up in "$out/lib".
+            store_path = os.environ.get("out")
+
+    if store_path is not None:
+        # Even if we have a $lib as output, there still should be a $lib/lib
+        # directory.
+        return os.path.join(store_path, 'lib')
+    else:
+        # If we haven't found a possible scenario, let's return an empty string
+        # so that the shared library won't be prepended with a path.
+        #
+        # Note that this doesn't mean that all hope is lost, because after all
+        # we can still use --fallback-library-path to set one.
+        #
+        # Also, we're not returning None, because that would make it very
+        # difficult to disable adding fallback paths altogether using something
+        # like: --fallback-library-path=""
+        return ""
+
+
 def _get_option_parser():
     parser = optparse.OptionParser('%prog [options] sources',
                                    version='%prog ' + giscanner.__version__)
@@ -211,6 +244,10 @@
     parser.add_option("", "--filelist",
                       action="store", dest="filelist", default=[],
                       help="file containing headers and sources to be scanned")
+    parser.add_option("", "--fallback-library-path",
+                      action="store", dest="fallback_libpath",
+                      default=_get_default_fallback_libpath(),
+                      help="Path to prepend to unknown shared libraries")
 
     group = get_preprocessor_option_group(parser)
     parser.add_option_group(group)
--- a/giscanner/shlibs.py
+++ b/giscanner/shlibs.py
@@ -62,6 +62,12 @@
     $""" % re.escape(library_name), re.VERBOSE)
 
 
+def _ldd_library_nix_pattern(library_name):
+    nix_store_dir = re.escape('@nixStoreDir@'.rstrip('/'))
+    pattern = r'(%s(?:/[^/]*)+lib%s[^A-Za-z0-9_-][^\s\(\)]*)'
+    return re.compile(pattern % (nix_store_dir, re.escape(library_name)))
+
+
 # This is a what we do for non-la files. We assume that we are on an
 # ELF-like system where ldd exists and the soname extracted with ldd is
 # a filename that can be opened with dlopen().
@@ -110,17 +116,16 @@ def _resolve_non_libtool(options, binary, libraries):
         if isinstance(output, bytes):
             output = output.decode("utf-8", "replace")
 
-        # Use absolute paths on OS X to conform to how libraries are usually
-        # referenced on OS X systems, and file names everywhere else.
-        basename = platform.system() != 'Darwin'
-        return resolve_from_ldd_output(libraries, output, basename=basename)
+        # Never strip away absolute paths in Nix
+        basename = False
+        return resolve_from_ldd_output(libraries, output, basename=basename, fallback_libpath=options.fallback_libpath)
 
 
-def resolve_from_ldd_output(libraries, output, basename=False):
+def resolve_from_ldd_output(libraries, output, basename=False, fallback_libpath=""):
     patterns = {}
     for library in libraries:
         if not os.path.isfile(library):
-            patterns[library] = _ldd_library_pattern(library)
+            patterns[library] = (_ldd_library_pattern(library), _ldd_library_nix_pattern(library))
     if len(patterns) == 0:
         return []
 
@@ -129,11 +134,14 @@ def resolve_from_ldd_output(libraries, output, basename=False):
         if line.endswith(':'):
             continue
         for word in line.split():
-            for library, pattern in patterns.items():
-                m = pattern.match(word)
+            for library, (pattern, nix_pattern) in patterns.items():
+                if line.find('@nixStoreDir@') != -1:
+                    m = nix_pattern.match(word)
+                else:
+                    m = pattern.match(word)
                 if m:
                     del patterns[library]
-                    shlibs.append(_sanitize_install_name(m.group()))
+                    shlibs.append(os.path.join(fallback_libpath, _sanitize_install_name(m.group())))
                     break
 
     if len(patterns) > 0:
--- a/giscanner/utils.py
+++ b/giscanner/utils.py
@@ -116,17 +116,11 @@
     if dlname is None:
         return None
 
-    # Darwin uses absolute paths where possible; since the libtool files never
-    # contain absolute paths, use the libdir field
-    if platform.system() == 'Darwin':
-        dlbasename = os.path.basename(dlname)
-        libdir = _extract_libdir_field(la_file)
-        if libdir is None:
-            return dlbasename
-        return libdir + '/' + dlbasename
-    # From the comments in extract_libtool(), older libtools had
-    # a path rather than the raw dlname
-    return os.path.basename(dlname)
+    dlbasename = os.path.basename(dlname)
+    libdir = _extract_libdir_field(la_file)
+    if libdir is None:
+        return dlbasename
+    return libdir + '/' + dlbasename
 
 
 def extract_libtool(la_file):