[singlejar] Use gcc-style attr_packed for Clang on Windows
See #2241
Closes #6250.
PiperOrigin-RevId: 214738417
diff --git a/src/tools/singlejar/zip_headers.h b/src/tools/singlejar/zip_headers.h
index 3677a20..c76e15b 100644
--- a/src/tools/singlejar/zip_headers.h
+++ b/src/tools/singlejar/zip_headers.h
@@ -44,7 +44,7 @@
#include <string>
#include <type_traits>
-#ifdef _MSC_VER
+#if defined(_MSC_VER) && !defined(__clang__)
#pragma pack(push, 1)
#define attr_packed
#else
@@ -653,7 +653,7 @@
} attr_packed;
static_assert(56 == sizeof(ECD64), "ECD64 class fields layout is incorrect.");
-#ifdef _MSC_VER
+#if defined(_MSC_VER) && !defined(__clang__)
#pragma pack(pop)
#endif