From 8df827075f5ac2c570d2cfa7695547132d347fbe Mon Sep 17 00:00:00 2001
From: Martijn Otto <git@martijnotto.nl>
Date: Wed, 10 Apr 2019 11:37:02 +0200
Subject: [PATCH] Fix linker issues using easylogging

---
 cmake/FindBacktrace.cmake             | 90 +++++++++++++++++++++++++++
 external/easylogging++/CMakeLists.txt |  4 +-
 2 files changed, 93 insertions(+), 1 deletion(-)
 create mode 100644 cmake/FindBacktrace.cmake

diff --git a/cmake/FindBacktrace.cmake b/cmake/FindBacktrace.cmake
new file mode 100644
index 000000000..89bbad07c
--- /dev/null
+++ b/cmake/FindBacktrace.cmake
@@ -0,0 +1,90 @@
+# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+# file Copyright.txt or https://cmake.org/licensing for details.
+
+#.rst:
+# FindBacktrace
+# -------------
+#
+# Find provider for backtrace(3).
+#
+# Checks if OS supports backtrace(3) via either libc or custom library.
+# This module defines the following variables:
+#
+# ``Backtrace_HEADER``
+#   The header file needed for backtrace(3). Cached.
+#   Could be forcibly set by user.
+# ``Backtrace_INCLUDE_DIRS``
+#   The include directories needed to use backtrace(3) header.
+# ``Backtrace_LIBRARIES``
+#   The libraries (linker flags) needed to use backtrace(3), if any.
+# ``Backtrace_FOUND``
+#   Is set if and only if backtrace(3) support detected.
+#
+# The following cache variables are also available to set or use:
+#
+# ``Backtrace_LIBRARY``
+#   The external library providing backtrace, if any.
+# ``Backtrace_INCLUDE_DIR``
+#   The directory holding the backtrace(3) header.
+#
+# Typical usage is to generate of header file using configure_file() with the
+# contents like the following::
+#
+#  #cmakedefine01 Backtrace_FOUND
+#  #if Backtrace_FOUND
+#  # include <${Backtrace_HEADER}>
+#  #endif
+#
+# And then reference that generated header file in actual source.
+
+include(CMakePushCheckState)
+include(CheckSymbolExists)
+include(FindPackageHandleStandardArgs)
+
+# List of variables to be provided to find_package_handle_standard_args()
+set(_Backtrace_STD_ARGS Backtrace_INCLUDE_DIR)
+
+if(Backtrace_HEADER)
+  set(_Backtrace_HEADER_TRY "${Backtrace_HEADER}")
+else(Backtrace_HEADER)
+  set(_Backtrace_HEADER_TRY "execinfo.h")
+endif(Backtrace_HEADER)
+
+find_path(Backtrace_INCLUDE_DIR "${_Backtrace_HEADER_TRY}")
+set(Backtrace_INCLUDE_DIRS ${Backtrace_INCLUDE_DIR})
+
+if (NOT DEFINED Backtrace_LIBRARY)
+  # First, check if we already have backtrace(), e.g., in libc
+  cmake_push_check_state(RESET)
+  set(CMAKE_REQUIRED_INCLUDES ${Backtrace_INCLUDE_DIRS})
+  set(CMAKE_REQUIRED_QUIET ${Backtrace_FIND_QUIETLY})
+  check_symbol_exists("backtrace" "${_Backtrace_HEADER_TRY}" _Backtrace_SYM_FOUND)
+  cmake_pop_check_state()
+endif()
+
+if(_Backtrace_SYM_FOUND)
+  # Avoid repeating the message() call below each time CMake is run.
+  if(NOT Backtrace_FIND_QUIETLY AND NOT DEFINED Backtrace_LIBRARY)
+    message(STATUS "backtrace facility detected in default set of libraries")
+  endif()
+  set(Backtrace_LIBRARY "" CACHE FILEPATH "Library providing backtrace(3), empty for default set of libraries")
+else()
+  # Check for external library, for non-glibc systems
+  if(Backtrace_INCLUDE_DIR)
+    # OpenBSD has libbacktrace renamed to libexecinfo
+    find_library(Backtrace_LIBRARY "execinfo")
+  elseif()     # respect user wishes
+    set(_Backtrace_HEADER_TRY "backtrace.h")
+    find_path(Backtrace_INCLUDE_DIR ${_Backtrace_HEADER_TRY})
+    find_library(Backtrace_LIBRARY "backtrace")
+  endif()
+
+  # Prepend list with library path as it's more common practice
+  set(_Backtrace_STD_ARGS Backtrace_LIBRARY ${_Backtrace_STD_ARGS})
+endif()
+
+set(Backtrace_LIBRARIES ${Backtrace_LIBRARY})
+set(Backtrace_HEADER "${_Backtrace_HEADER_TRY}" CACHE STRING "Header providing backtrace(3) facility")
+
+find_package_handle_standard_args(Backtrace FOUND_VAR Backtrace_FOUND REQUIRED_VARS ${_Backtrace_STD_ARGS})
+mark_as_advanced(Backtrace_HEADER Backtrace_INCLUDE_DIR Backtrace_LIBRARY)
diff --git a/external/easylogging++/CMakeLists.txt b/external/easylogging++/CMakeLists.txt
index 8287024c2..35fb86552 100644
--- a/external/easylogging++/CMakeLists.txt
+++ b/external/easylogging++/CMakeLists.txt
@@ -33,6 +33,7 @@ project(easylogging CXX)
 SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -std=c++11")
 
 find_package(Threads)
+find_package(Backtrace)
 
 add_library(easylogging
   easylogging++.cc)
@@ -41,7 +42,8 @@ include_directories("${CMAKE_CURRENT_SOURCE_DIR}")
 include_directories("${CMAKE_CURRENT_BINARY_DIR}")
 target_link_libraries(easylogging
   PRIVATE
-    ${CMAKE_THREAD_LIBS_INIT})
+    ${CMAKE_THREAD_LIBS_INIT}
+    ${Backtrace_LIBRARIES})
 
 # GUI/libwallet install target
 if (BUILD_GUI_DEPS)