From 7e58af4eafc11c2b0f92abf111b0e198c9aa0dc7 Mon Sep 17 00:00:00 2001
From: Victor Zverovich <viz@meta.com>
Date: Fri, 12 Jan 2024 06:47:59 -0800
Subject: [PATCH] Fix an ICE on clang <= 15

---
 include/fmt/base.h | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/include/fmt/base.h b/include/fmt/base.h
index 0eab2feebf82..e39580849f99 100644
--- a/include/fmt/base.h
+++ b/include/fmt/base.h
@@ -1487,8 +1487,14 @@ constexpr unsigned long long make_descriptor() {
                                      : is_unpacked_bit | NUM_ARGS;
 }
 
-// This type is intentionally undefined, only used for errors
-template <typename T, typename Char> struct type_is_unformattable_for;
+// This type is intentionally undefined, only used for errors.
+template <typename T, typename Char>
+#if FMT_CLANG_VERSION && FMT_CLANG_VERSION <= 1500
+// https://github.com/fmtlib/fmt/issues/3796
+struct type_is_unformattable_for {};
+#else
+struct type_is_unformattable_for;
+#endif
 
 template <bool PACKED, typename Context, typename T, FMT_ENABLE_IF(PACKED)>
 FMT_CONSTEXPR auto make_arg(T& val) -> value<Context> {