From 4d9bd7dedf3b0615e62095659c93d68c3d6cb680 Mon Sep 17 00:00:00 2001
From: Daniel Kouchekinia <DanKouch@users.noreply.github.com>
Date: Wed, 19 Jul 2023 02:07:39 -0700
Subject: [PATCH] base: Added missing backup dummy __has_builtin definition
 (#99)

Added dummy definition of __has_builtin to bitfield.hh's hasBuiltinCtz,
which is already being done in popCount.

Change-Id: I4a1760a142209462bb807c6df4bc868284b6f5f3
---
 src/base/bitfield.hh | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/base/bitfield.hh b/src/base/bitfield.hh
index 8d3721b08a..c2eeb1fb55 100644
--- a/src/base/bitfield.hh
+++ b/src/base/bitfield.hh
@@ -310,6 +310,13 @@ namespace {
 template<typename T>
 constexpr bool
 hasBuiltinCtz() {
+// Since the defined(__has_builtin) in the subsequent #if statement
+// won't short-circuit the macro expansion of
+// __has_builtin(__builtin_ctz), we must explicitly define it as zero
+// if it's undefined to avoid a preprocessor error.
+#ifndef __has_builtin
+#   define __has_builtin(foo) 0
+#endif
 #if defined(__has_builtin) && __has_builtin(__builtin_ctz)
     return sizeof(unsigned long long) >= sizeof(T);
 #else