Ignore prerequisite mtimes that are not linker inputs

This makes sure, for example, that we don't unnecessarily re-link an
executable when its testscript prerequisite is changes.

1 files changed, 1 insertions, 5 deletions

diff --git a/build2/rule b/build2/rule
index 8090fa0..015cf1a 100644
--- a/build2/rule
+++ b/build2/rule
@@ -39,8 +39,7 @@ namespace build2
     apply (action, target&) const = 0;
   };
 
-  // Fallback rule that on update verifies that the file exists and is
-  // not older than any of its prerequisites.
+  // Fallback rule that only matches if the file exists.
   //
   class file_rule: public rule
   {
@@ -51,9 +50,6 @@ namespace build2
     virtual recipe
     apply (action, target&) const override;
 
-    static target_state
-    perform_update (action, target&);
-
     static file_rule instance;
   };