Rework default extension derivation, again

1 files changed, 5 insertions, 24 deletions

diff --git a/build2/target.txx b/build2/target.txx
index fbaa8ef..4999f61 100644
--- a/build2/target.txx
+++ b/build2/target.txx
@@ -10,14 +10,14 @@
 namespace build2
 {
   template <const char* ext>
-  const string&
+  const string*
   target_extension_fix (const target_key&, scope&)
   {
-    return extension_pool.find (ext);
+    return &extension_pool.find (ext);
   }
 
   template <const char* var, const char* def>
-  const string&
+  const string*
   target_extension_var (const target_key& tk, scope& s)
   {
     // Include target type/pattern-specific variables.
@@ -27,29 +27,10 @@ namespace build2
       // Help the user here and strip leading '.' from the extension.
       //
       const string& e (as<string> (*l));
-      return extension_pool.find (
+      return &extension_pool.find (
         !e.empty () && e.front () == '.' ? string (e, 1) : e);
     }
 
-    if (def != nullptr)
-      return extension_pool.find (def);
-
-    // Similar code to target_extension_fail().
-    //
-    {
-      diag_record dr;
-      dr << error << "no default extension in variable '" << var << "'"
-         << info << "required to derive file name for ";
-
-      if (tk.dir->absolute ())
-        dr << "target " << tk;
-      else
-        dr << "prerequisite " << prerequisite_key {nullptr, tk, &s};
-
-      dr << info << "perhaps you forgot to add "
-         << tk.type->name << "{*}: " << var << " = ...";
-    }
-
-    throw failed ();
+    return def != nullptr ? &extension_pool.find (def) : nullptr;
   }
 }