From 22491eb1236c8b5c1dcba2ed3a213c74ce699988 Mon Sep 17 00:00:00 2001
From: Eric Kilmer <eric.d.kilmer@gmail.com>
Date: Thu, 25 May 2023 15:26:33 -0400
Subject: [PATCH] logging: Prevent LogStream constructor from being discarded
 (#925)

Fixes linker error reported in #922
---
 CONTRIBUTORS          | 1 +
 src/glog/logging.h.in | 9 +++++++++
 2 files changed, 10 insertions(+)

diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index 05cb688..5780377 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -29,6 +29,7 @@ Andy Ying <andy@trailofbits.com>
 Bret McKee <bretmckee@google.com>
 Brian Silverman <bsilver16384@gmail.com>
 Dmitriy Arbitman <d.arbitman@gmail.com>
+Eric Kilmer <eric.d.kilmer@gmail.com>
 Fumitoshi Ukai <ukai@google.com>
 Guillaume Dumont <dumont.guillaume@gmail.com>
 Håkan L. S. Younes <hyounes@google.com>
diff --git a/src/glog/logging.h.in b/src/glog/logging.h.in
index 09f9645..26fd371 100644
--- a/src/glog/logging.h.in
+++ b/src/glog/logging.h.in
@@ -1344,6 +1344,15 @@ GLOG_MSVC_PUSH_DISABLE_WARNING(4275)
   class GLOG_EXPORT LogStream : public std::ostream {
 GLOG_MSVC_POP_WARNING()
   public:
+#if defined __has_attribute
+#  if __has_attribute (used)
+    // In some cases, like when compiling glog as a static library with GCC and
+    // linking against a Clang-built executable, this constructor will be
+    // removed by the linker. We use this attribute to prevent the linker from
+    // discarding it.
+    __attribute__ ((used))
+#  endif
+#endif
     LogStream(char *buf, int len, int64 ctr)
         : std::ostream(NULL),
           streambuf_(buf, len),