From 0084354ba917f712ce293e06df5d300f9094d86e Mon Sep 17 00:00:00 2001
From: Andrew Stitcher <astitcher@apache.org>
Date: Mon, 8 Jul 2024 12:36:49 -0400
Subject: [PATCH] PROTON-2810: Make standalone C++ examples build work
 correctly

---
 cpp/CMakeLists.txt          |  2 +-
 cpp/examples/CMakeLists.txt | 11 ++++++++++-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/cpp/CMakeLists.txt b/cpp/CMakeLists.txt
index 93b42424e..c65cc8723 100644
--- a/cpp/CMakeLists.txt
+++ b/cpp/CMakeLists.txt
@@ -33,7 +33,7 @@ enable_language(CXX)
 # So leave this here for a few more years!
 set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
 find_package(Threads)
-link_libraries(Threads::Threads)
+list(APPEND PLATFORM_LIBS Threads::Threads)
 
 include(versions.cmake)
 
diff --git a/cpp/examples/CMakeLists.txt b/cpp/examples/CMakeLists.txt
index cbaefbe3c..587edfc52 100644
--- a/cpp/examples/CMakeLists.txt
+++ b/cpp/examples/CMakeLists.txt
@@ -25,6 +25,15 @@ find_package(ProtonCpp REQUIRED)
 set(CMAKE_CXX_STANDARD 17)
 set(CMAKE_CXX_EXTENSIONS OFF)
 
+# This is not needed for modern versions of Linux using glibc 2.34 or later
+# However RHEL before RHEL 9; Ubuntu before 22.04; Debian before 12 and FreeBSD
+# with clang (its system compiler) all still need to link the threads library
+# explicitly even though thread support is now included in C++17.
+#
+# So leave this here for a few more years!
+set(CMAKE_THREAD_PREFER_PTHREAD TRUE)
+find_package(Threads)
+
 # Single-threaded examples
 foreach(example
     broker
@@ -53,7 +62,7 @@ foreach(example
     multithreaded_client
     multithreaded_client_flow_control)
   add_executable(${example} ${example}.cpp)
-  target_link_libraries(${example} Proton::cpp)
+  target_link_libraries(${example} Proton::cpp Threads::Threads)
 endforeach()
 
 # Tracing examples