Simplify inherited attribute handling

This reduces the difference between inherited and non-inherited
attribute handling to the choice of which env to use (in recs and lets)
by setting the AttrDef::e to a new ExprVar in the parser rather than
carrying a separate AttrDef::v VarRef member.

As an added bonus, this allows inherited attributes that inherit from a
with to delay forcing evaluation of the with's attributes.

Signed-off-by: Shea Levy <shea@shealevy.com>

1 files changed, 3 insertions, 6 deletions

diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc
index 9b75bb644..72bc0a14b 100644
--- a/src/libexpr/nixexpr.cc
+++ b/src/libexpr/nixexpr.cc
@@ -230,14 +230,12 @@ void ExprAttrs::bindVars(const StaticEnv & env)
             newEnv.vars[i->first] = i->second.displ = displ++;
         
         foreach (AttrDefs::iterator, i, attrs)
-            if (i->second.inherited) i->second.var.bind(env);
-            else i->second.e->bindVars(newEnv);
+            i->second.e->bindVars(i->second.inherited ? env : newEnv);
     }
 
     else
         foreach (AttrDefs::iterator, i, attrs)
-            if (i->second.inherited) i->second.var.bind(env);
-            else i->second.e->bindVars(env);
+            i->second.e->bindVars(env);
 }
 
 void ExprList::bindVars(const StaticEnv & env)
@@ -274,8 +272,7 @@ void ExprLet::bindVars(const StaticEnv & env)
         newEnv.vars[i->first] = i->second.displ = displ++;
     
     foreach (ExprAttrs::AttrDefs::iterator, i, attrs->attrs)
-        if (i->second.inherited) i->second.var.bind(env);
-        else i->second.e->bindVars(newEnv);
+        i->second.e->bindVars(i->second.inherited ? env : newEnv);
     
     body->bindVars(newEnv);
 }