Tweak function comment

diff --git a/src/ccache.cpp b/src/ccache.cpp
index 7744604ba0b91c3d611237506d1eb5afd8439468..ccae62e1c1c253228eb2369fbe56a830257f0a2a 100644 (file)
--- a/src/ccache.cpp
+++ b/src/ccache.cpp
@@ -1372,7 +1372,7 @@ option_should_be_ignored(const std::string& arg,
 
 // Update a hash sum with information specific to the direct and preprocessor
 // modes and calculate the result name. Returns the result name on success,
-// otherwise NULL.
+// otherwise nullopt.
 static optional<Digest>
 calculate_result_name(Context& ctx,
                       const Args& args,