1 files changed, 38 insertions, 6 deletions

diff --git a/src/libexpr/nixexpr.cc b/src/libexpr/nixexpr.cc
index c9d42cea5..3bcd35fef 100644
--- a/src/libexpr/nixexpr.cc
+++ b/src/libexpr/nixexpr.cc
@@ -78,7 +78,7 @@ void ExprAttrs::showBindings(const SymbolTable & symbols, std::ostream & str) co
         return sa < sb;
     });
     std::vector<Symbol> inherits;
-    std::map<Expr *, std::vector<Symbol>> inheritsFrom;
+    std::map<ExprInheritFrom *, std::vector<Symbol>> inheritsFrom;
     for (auto & i : sorted) {
         switch (i->second.kind) {
         case AttrDef::Kind::Plain:
@@ -88,7 +88,8 @@ void ExprAttrs::showBindings(const SymbolTable & symbols, std::ostream & str) co
             break;
         case AttrDef::Kind::InheritedFrom: {
             auto & select = dynamic_cast<ExprSelect &>(*i->second.e);
-            inheritsFrom[select.e].push_back(i->first);
+            auto & from = dynamic_cast<ExprInheritFrom &>(*select.e);
+            inheritsFrom[&from].push_back(i->first);
             break;
         }
         }
@@ -100,7 +101,7 @@ void ExprAttrs::showBindings(const SymbolTable & symbols, std::ostream & str) co
     }
     for (const auto & [from, syms] : inheritsFrom) {
         str << "inherit (";
-        from->show(symbols, str);
+        (*inheritFromExprs)[from->displ]->show(symbols, str);
         str << ")";
         for (auto sym : syms) str << " " << symbols[sym];
         str << "; ";
@@ -326,6 +327,12 @@ void ExprVar::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> &
     this->level = withLevel;
 }
 
+void ExprInheritFrom::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
+{
+    if (es.debugRepl)
+        es.exprEnvs.insert(std::make_pair(this, env));
+}
+
 void ExprSelect::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
     if (es.debugRepl)
@@ -349,6 +356,27 @@ void ExprOpHasAttr::bindVars(EvalState & es, const std::shared_ptr<const StaticE
             i.expr->bindVars(es, env);
 }
 
+std::shared_ptr<const StaticEnv> ExprAttrs::bindInheritSources(
+    EvalState & es, const std::shared_ptr<const StaticEnv> & env)
+{
+    if (!inheritFromExprs)
+        return nullptr;
+
+    // the inherit (from) source values are inserted into an env of its own, which
+    // does not introduce any variable names.
+    // analysis must see an empty env, or an env that contains only entries with
+    // otherwise unused names to not interfere with regular names. the parser
+    // has already filled all exprs that access this env with appropriate level
+    // and displacement, and nothing else is allowed to access it. ideally we'd
+    // not even *have* an expr that grabs anything from this env since it's fully
+    // invisible, but the evaluator does not allow for this yet.
+    auto inner = std::make_shared<StaticEnv>(nullptr, env.get(), 0);
+    for (auto from : *inheritFromExprs)
+        from->bindVars(es, env);
+
+    return inner;
+}
+
 void ExprAttrs::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env)
 {
     if (es.debugRepl)
@@ -366,8 +394,9 @@ void ExprAttrs::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv>
 
         // No need to sort newEnv since attrs is in sorted order.
 
+        auto inheritFromEnv = bindInheritSources(es, newEnv);
         for (auto & i : attrs)
-            i.second.e->bindVars(es, i.second.chooseByKind(newEnv, env, newEnv));
+            i.second.e->bindVars(es, i.second.chooseByKind(newEnv, env, inheritFromEnv));
 
         for (auto & i : dynamicAttrs) {
             i.nameExpr->bindVars(es, newEnv);
@@ -375,8 +404,10 @@ void ExprAttrs::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv>
         }
     }
     else {
+        auto inheritFromEnv = bindInheritSources(es, env);
+
         for (auto & i : attrs)
-            i.second.e->bindVars(es, i.second.chooseByKind(env, env, env));
+            i.second.e->bindVars(es, i.second.chooseByKind(env, env, inheritFromEnv));
 
         for (auto & i : dynamicAttrs) {
             i.nameExpr->bindVars(es, env);
@@ -444,8 +475,9 @@ void ExprLet::bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> &
 
     // No need to sort newEnv since attrs->attrs is in sorted order.
 
+    auto inheritFromEnv = attrs->bindInheritSources(es, newEnv);
     for (auto & i : attrs->attrs)
-        i.second.e->bindVars(es, i.second.chooseByKind(newEnv, env, newEnv));
+        i.second.e->bindVars(es, i.second.chooseByKind(newEnv, env, inheritFromEnv));
 
     if (es.debugRepl)
         es.exprEnvs.insert(std::make_pair(this, newEnv));