1 files changed, 32 insertions, 0 deletions
diff --git a/third_party/systemlibs/build_defs.bzl.tpl b/third_party/systemlibs/build_defs.bzl.tpl
new file mode 100644
index 0000000000..3faa46c581
--- /dev/null
+++ b/third_party/systemlibs/build_defs.bzl.tpl
@@ -0,0 +1,32 @@
+# -*- Python -*-
+"""Skylark macros for system libraries.
+"""
+
+SYSTEM_LIBS_ENABLED = %{syslibs_enabled}
+
+SYSTEM_LIBS_LIST = [
+%{syslibs_list}
+]
+
+
+def if_any_system_libs(a, b=[]):
+  """Conditional which evaluates to 'a' if any system libraries are configured."""
+  if SYSTEM_LIBS_ENABLED:
+    return a
+  else:
+    return b
+
+
+def if_system_lib(lib, a, b=[]):
+  """Conditional which evaluates to 'a' if we're using the system version of lib"""
+
+  if SYSTEM_LIBS_ENABLED and lib in SYSTEM_LIBS_LIST:
+    return a
+  else:
+    return b
+
+
+def if_not_system_lib(lib, a, b=[]):
+  """Conditional which evaluates to 'a' if we're using the system version of lib"""
+
+  return if_system_lib(lib, b, a)