SERVER-7410 Fix SYSLIBDEPS functionality

The previous implementation was not recursively following the LIBDEPS hierarchy, looking for SYSLIBDEPS
to add.  Instead, it was trying to walk a hierachy like LIBDEPS rooted in the SYSLIBDEPS variable.  This
isn't really a meaningful behavior, since SYSLIBDEPS always list system libraries, which are always leaf
nodes in the dependency graph for our build system.

site_scons/libdeps.py

@@ -51,6 +51,9 @@
 import SCons.Scanner
 import SCons.Util
 
+libdeps_env_var = 'LIBDEPS'
+syslibdeps_env_var = 'SYSLIBDEPS'
+
 def sorted_by_str(iterable):
     """Shorthand for sorting an iterable according to its string representation.
 
@@ -71,19 +74,19 @@ def __init__(self, first_node ):
     def __str__(self):
         return " => ".join(str(n) for n in self.cycle_nodes)
 
-def __get_libdeps(node, env_var):
+def __get_libdeps(node):
     """Given a SCons Node, return its library dependencies.
 
     Computes the dependencies if they're not already cached.
     """
 
-    cached_var_name = env_var + '_cached'
+    cached_var_name = libdeps_env_var + '_cached'
 
     if not hasattr(node.attributes, cached_var_name):
-        setattr(node.attributes, cached_var_name, __compute_libdeps(node, env_var))
+        setattr(node.attributes, cached_var_name, __compute_libdeps(node))
     return getattr(node.attributes, cached_var_name)
 
-def __compute_libdeps(node, env_var):
+def __compute_libdeps(node):
     """Recursively identify all library dependencies for a node."""
 
     if getattr(node.attributes, 'libdeps_exploring', False):
@@ -94,11 +97,11 @@ def __compute_libdeps(node, env_var):
     node.attributes.libdeps_exploring = True
     try:
         try:
-            for child in env.Flatten(env.get(env_var, [])):
+            for child in env.Flatten(env.get(libdeps_env_var, [])):
                 if not child:
                     continue
                 deps.add(child)
-                deps.update(__get_libdeps(child, env_var))
+                deps.update(__get_libdeps(child))
 
         except DependencyCycleError, e:
             if len(e.cycle_nodes) == 1 or e.cycle_nodes[0] != e.cycle_nodes[-1]:
@@ -109,6 +112,20 @@ def __compute_libdeps(node, env_var):
 
     return deps
 
+def __get_syslibdeps(node):
+    """ Given a SCons Node, return its system library dependencies.
+
+    These are the depencencies listed with SYSLIBDEPS, and are linked using -l.
+    """
+    cached_var_name = syslibdeps_env_var + '_cached'
+    if not hasattr(node.attributes, cached_var_name):
+        syslibdeps = []
+        for lib in __get_libdeps(node):
+            for syslib in lib.get_env().get(syslibdeps_env_var, []):
+                syslibdeps.append(syslib)
+        setattr(node.attributes, cached_var_name, sorted(syslibdeps))
+    return getattr(node.attributes, cached_var_name)
+
 def update_scanner(builder):
     """Update the scanner for "builder" to also scan library dependencies."""
 
@@ -118,14 +135,12 @@ def update_scanner(builder):
         path_function = old_scanner.path_function
         def new_scanner(node, env, path=()):
             result = set(old_scanner.function(node, env, path))
-            result.update(__get_libdeps(node, 'LIBDEPS'))
-            result.update(__get_libdeps(node, 'SYSLIBDEPS'))
+            result.update(__get_libdeps(node))
             return sorted_by_str(result)
     else:
         path_function = None
         def new_scanner(node, env, path=()):
-            result = set(__get_libdeps(node, 'LIBDEPS'))
-            result.update(__get_libdeps(node, 'SYSLIBDEPS'))
+            result = set(__get_libdeps(node))
             return sorted_by_str(result)
 
     builder.target_scanner = SCons.Scanner.Scanner(function=new_scanner,
@@ -138,7 +153,7 @@ def get_libdeps(source, target, env, for_signature):
     """
 
     target = env.Flatten([target])
-    return sorted_by_str(__get_libdeps(target[0], 'LIBDEPS'))
+    return sorted_by_str(__get_libdeps(target[0]))
 
 def get_libdeps_objs(source, target, env, for_signature):
     objs = set()
@@ -151,8 +166,11 @@ def get_libdeps_special_sun(source, target, env, for_signature):
     return x + x + x
 
 def get_syslibdeps(source, target, env, for_signature):
-    deps = list(__get_libdeps(target[0], 'SYSLIBDEPS'))
-    return deps
+    deps = __get_syslibdeps(target[0])
+    lib_link_prefix = env.subst('$LIBLINKPREFIX')
+    lib_link_suffix = env.subst('$LIBLINKSUFFIX')
+    result = ''.join([' %s%s%s' % (lib_link_prefix, d, lib_link_suffix) for d in deps])
+    return result
 
 def libdeps_emitter(target, source, env):
     """SCons emitter that takes values from the LIBDEPS environment variable and
@@ -172,7 +190,7 @@ def libdeps_emitter(target, source, env):
     libdep_files = []
     lib_suffix = env.subst('$LIBSUFFIX', target=target, source=source)
     lib_prefix = env.subst('$LIBPREFIX', target=target, source=source)
-    for dep in env.Flatten([env.get('LIBDEPS', [])]):
+    for dep in env.Flatten([env.get(libdeps_env_var, [])]):
         full_path = env.subst(str(dep), target=target, source=source)
         dir_name = os.path.dirname(full_path)
         file_name = os.path.basename(full_path)
@@ -182,7 +200,7 @@ def libdeps_emitter(target, source, env):
             file_name += '${LIBSUFFIX}'
         libdep_files.append(env.File(os.path.join(dir_name, file_name)))
 
-    env['LIBDEPS'] = libdep_files
+    env[libdeps_env_var] = libdep_files
 
     return target, source
 
@@ -203,11 +221,11 @@ def setup_environment(env):
         env['_LIBDEPS_LIBS'] = get_libdeps
 
     env['_LIBDEPS_OBJS'] = get_libdeps_objs
-    env['_SYSLIBDEPS'] = ' ${_stripixes(LIBLINKPREFIX, SYSLIBDEPS, LIBLINKSUFFIX, LIBPREFIXES, LIBSUFFIXES, __env__)} '
+    env['_SYSLIBDEPS'] = get_syslibdeps
     env['_SHLIBDEPS'] = '$SHLIBDEP_GROUP_START ${_concat(SHLIBDEPPREFIX, __env__.subst(_LIBDEPS, target=TARGET, source=SOURCE), SHLIBDEPSUFFIX, __env__, target=TARGET, source=SOURCE)} $SHLIBDEP_GROUP_END'
 
-    env['LIBDEPS'] = SCons.Util.CLVar()
-    env['SYSLIBDEPS'] = SCons.Util.CLVar()
+    env[libdeps_env_var] = SCons.Util.CLVar()
+    env[syslibdeps_env_var] = SCons.Util.CLVar()
     env.Append(LIBEMITTER=libdeps_emitter,
                PROGEMITTER=libdeps_emitter,
                SHLIBEMITTER=libdeps_emitter)