unikernel/duniverse/dune_/doc/reference/foreign-flags.rst

@@ -0,0 +1,22 @@
+Flags in Foreign Code
+---------------------
+
+Depending on the :doc:`dune-project/use_standard_c_and_cxx_flags` option,
+the base ``:standard`` set of flags for C will contain only ``ocamlc_cflags`` or
+both ``ocamlc_cflags`` and ``ocamlc_cppflags``.
+
+There are multiple levels where one can declare custom flags (using the
+:doc:`ordered-set-language`), and each level inherits the flags of the previous
+one in its `:standard` set:
+
+- In the global :doc:`dune-workspace/env` definition of a
+  :doc:`dune-workspace/index` file
+- In the :doc:`per-context env <dune-workspace/context>` definitions in a
+  :doc:`dune-workspace/index` file
+- In the :doc:`dune/env` definition of a :doc:`dune/index` file
+- In a :doc:`foreign_stubs <foreign-stubs>`, :doc:`foreign_library
+  <foreign-archives>` or :doc:`extra_objects <extra-objects>` field of an
+  executable or a library.
+
+The ``%{cc}`` :doc:`variable <../concepts/variables>` will contain the flags
+from the first three levels only.