Implement auxiliary dependency database (.d files), use in cxx.compile

This is part of the "High Fidelity Build" work.

1 files changed, 5 insertions, 0 deletions

diff --git a/build2/types b/build2/types
index 0c34efb..7c803a1 100644
--- a/build2/types
+++ b/build2/types
@@ -20,6 +20,7 @@
 #include <system_error>
 
 #include <butl/path>
+#include <butl/sha256>
 #include <butl/optional>
 #include <butl/timestamp>
 
@@ -94,6 +95,10 @@ namespace build2
   using butl::timestamp_nonexistent;
   using butl::operator<<;
 
+  // <butl/sha256>
+  //
+  using butl::sha256;
+
   // <build2/name>
   //
 }