From 1abae91b7700da0c2d23b96915b1f368ec2fb2b6 Mon Sep 17 00:00:00 2001
From: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>
Date: Fri, 28 Jun 2024 18:17:50 +0100
Subject: [PATCH] cmake: Add `--no-undefined` linker option

---
 CMakeLists.txt                   |  5 +++++
 cmake/TryAppendLinkerFlags.cmake | 32 ++++++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)
 create mode 100644 cmake/TryAppendLinkerFlags.cmake

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7e3465a75b..9e2c5d55ad 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -269,6 +269,11 @@ if(SECP256K1_BUILD_CTIME_TESTS)
   unset(msan_enabled)
 endif()
 
+if(NOT SECP256K1_USE_EXTERNAL_DEFAULT_CALLBACKS)
+  include(TryAppendLinkerFlags)
+  try_append_linker_flags(-Wl,--no-undefined)
+endif()
+
 include(CTest)
 # We do not use CTest's BUILD_TESTING because a single toggle for all tests is too coarse for our needs.
 mark_as_advanced(BUILD_TESTING)
diff --git a/cmake/TryAppendLinkerFlags.cmake b/cmake/TryAppendLinkerFlags.cmake
new file mode 100644
index 0000000000..457549001b
--- /dev/null
+++ b/cmake/TryAppendLinkerFlags.cmake
@@ -0,0 +1,32 @@
+include_guard(GLOBAL)
+
+include(CheckCSourceCompiles)
+
+function(secp256k1_check_linker_flags_internal flags output)
+  string(MAKE_C_IDENTIFIER "${flags}" result)
+  string(TOUPPER "${result}" result)
+  set(result "LINKER_SUPPORTS_${result}")
+  set(CMAKE_REQUIRED_FLAGS "${flags}")
+  if(MSVC)
+    string(APPEND " /WX")
+  elseif(CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+    string(APPEND " -Wl,-fatal_warnings")
+  else()
+    string(APPEND " -Wl,--fatal-warnings")
+  endif()
+
+  # This ensures running a linker.
+  set(CMAKE_TRY_COMPILE_TARGET_TYPE EXECUTABLE)
+  check_c_source_compiles("int main() { return 0; }" ${result})
+
+  set(${output} ${${result}} PARENT_SCOPE)
+endfunction()
+
+# Append flags to the LINK_OPTIONS directory property if a linker accepts them.
+macro(try_append_linker_flags)
+  secp256k1_check_linker_flags_internal("${ARGV}" result)
+  if(result)
+    add_link_options(${ARGV})
+  endif()
+  unset(result)
+endmacro()