From 3720e811fa2883bca1a2698543146070e4d8d32c Mon Sep 17 00:00:00 2001
From: Robert Hensing <robert@roberthensing.nl>
Date: Tue, 12 Sep 2023 13:21:55 +0200
Subject: [PATCH] libexpr: Add nrExprs to NIX_SHOW_STATS

---
 src/libexpr/eval.cc    | 1 +
 src/libexpr/nixexpr.hh | 4 ++++
 src/libexpr/parser.y   | 1 +
 3 files changed, 6 insertions(+)

diff --git a/src/libexpr/eval.cc b/src/libexpr/eval.cc
index 6d445fd96..afa864730 100644
--- a/src/libexpr/eval.cc
+++ b/src/libexpr/eval.cc
@@ -2506,6 +2506,7 @@ void EvalState::printStats()
             {"elements", nrValuesInEnvs},
             {"bytes", bEnvs},
         };
+        topObj["nrExprs"] = Expr::nrExprs;
         topObj["list"] = {
             {"elements", nrListElems},
             {"bytes", bLists},
diff --git a/src/libexpr/nixexpr.hh b/src/libexpr/nixexpr.hh
index 5ca3d1fa6..b80c07f46 100644
--- a/src/libexpr/nixexpr.hh
+++ b/src/libexpr/nixexpr.hh
@@ -155,6 +155,10 @@ std::string showAttrPath(const SymbolTable & symbols, const AttrPath & attrPath)
 
 struct Expr
 {
+    static unsigned long nrExprs;
+    inline Expr() {
+        nrExprs++;
+    }
     virtual ~Expr() { };
     virtual void show(const SymbolTable & symbols, std::ostream & str) const;
     virtual void bindVars(EvalState & es, const std::shared_ptr<const StaticEnv> & env);
diff --git a/src/libexpr/parser.y b/src/libexpr/parser.y
index 792f51fde..a3d3c7041 100644
--- a/src/libexpr/parser.y
+++ b/src/libexpr/parser.y
@@ -653,6 +653,7 @@ formal
 
 namespace nix {
 
+unsigned long Expr::nrExprs = 0;
 
 Expr * EvalState::parse(
     char * text,