From 94714307ec07f75ce97a66bf93958558bc860158 Mon Sep 17 00:00:00 2001
From: Walter Bright <WalterBright@users.noreply.github.com>
Date: Mon, 27 Jan 2025 14:25:04 -0800
Subject: [PATCH] add __builtin__popcount() for ImportC (#20790)

---
 druntime/src/__importc_builtins.di | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/druntime/src/__importc_builtins.di b/druntime/src/__importc_builtins.di
index a13aa407bc..757a34b6bd 100644
--- a/druntime/src/__importc_builtins.di
+++ b/druntime/src/__importc_builtins.di
@@ -86,6 +86,12 @@ version (DigitalMars)
         return core.bitop.bswap(value);
     }
 
+    uint  __builtin__popcount()(ulong value)
+    {
+        import core.bitop;
+        return core.bitop._popcnt(value);
+    }
+
     // Lazily imported on first use
     private alias c_long = imported!"core.stdc.config".c_long;