[modules] Minor documentation clarification for behavior of requires-declaration.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@304253 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/docs/Modules.rst b/docs/Modules.rst
index b8841c0a5cec6660730fb9db1220333affcd3236..7bd2adf8af5233297619089564ddbe402e8ff7b0 100644 (file)
--- a/docs/Modules.rst
+++ b/docs/Modules.rst
@@ -403,7 +403,7 @@ A *requires-declaration* specifies the requirements that an importing translatio
   *feature*:
     ``!``:sub:`opt` *identifier*
 
-The requirements clause allows specific modules or submodules to specify that they are only accessible with certain language dialects or on certain platforms. The feature list is a set of identifiers, defined below. If any of the features is not available in a given translation unit, that translation unit shall not import the module. The optional ``!`` indicates that a feature is incompatible with the module.
+The requirements clause allows specific modules or submodules to specify that they are only accessible with certain language dialects or on certain platforms. The feature list is a set of identifiers, defined below. If any of the features is not available in a given translation unit, that translation unit shall not import the module. When building a module for use by a compilation, submodules requiring unavailable features are ignored. The optional ``!`` indicates that a feature is incompatible with the module.
 
 The following features are defined: