Define _DISABLE_CONSTEXPR_MUTEX_CONSTRUCTOR preprocessor macro to work around invalid MEX file issue on Windows. Fixes #130

Author: duncanpo

CMakeLists.txt

@@ -36,9 +36,12 @@ else()
        set(VCPKG_TARGET_TRIPLET ${VCPKG_OTEL_TRIPLET})
        set(TRIPLET_DEFINITIONS -DVCPKG_OVERLAY_TRIPLETS="${VCPKG_OVERLAY_TRIPLETS}" -DVCPKG_TARGET_TRIPLET=${VCPKG_TARGET_TRIPLET})
    elseif(WIN32)
-       # On Windows, there is a conflict between abseil_dll.dll and the version used by Simulink. 
+       # On Windows, we use a custom triplet to work around two issues.
+       # First, there is a conflict between abseil_dll.dll and the version used by Simulink. 
        # The shared library doesn't seem ABI stable and different versions cannot be used interchangeably. 
        # To sidestep the problem, use static library.
+       # Second, define a preprocessor macro _DISABLE_CONSTEXPR_MUTEX_CONSTRUCTOR to work around an invalid MEX file issue on GitHub
+       # See https://github.com/mathworks/OpenTelemetry-Matlab/issues/130
        set(VCPKG_OVERLAY_TRIPLETS ${CMAKE_SOURCE_DIR}/cmake/vcpkg_triplets)
        set(VCPKG_TARGET_TRIPLET x64-windows-otel-matlab)
        set(TRIPLET_DEFINITIONS -DVCPKG_OVERLAY_TRIPLETS="${VCPKG_OVERLAY_TRIPLETS}" -DVCPKG_TARGET_TRIPLET=${VCPKG_TARGET_TRIPLET})
@@ -184,10 +187,18 @@ if(NOT DEFINED OTEL_CPP_INSTALLED_DIR)
 
    set(OTEL_CPP_CXX_STANDARD 14)
 
-   if(NOT APPLE OR SKIP_OTEL_CPP_PATCH)
-       set(patch_command "")
+   set(PATCHES_DIR ${CMAKE_SOURCE_DIR}/patches)
+   if(SKIP_OTEL_CPP_PATCH)
+       set(patch_comand "")
+   elseif(WIN32)
+       # Windows patch to add a preprocessor definition _DISABLE_CONSTEXPR_MUTEX_CONSTRUCTOR
+       # See https://github.com/mathworks/OpenTelemetry-Matlab/issues/130
+       set(patch_command git apply ${PATCHES_DIR}/otel-cpp-windows.patch)
+   elseif(APPLE)
+       # Mac patch to fix a linker issue when including gRPC exporter 
+       set(patch_command git apply ${PATCHES_DIR}/otel-cpp-mac.patch)
    else()
-       set(patch_command git apply ${CMAKE_SOURCE_DIR}/otel-cpp.patch)
+       set(patch_command "")
    endif()
 
    ExternalProject_Add(
@@ -309,6 +320,12 @@ if(WITH_OTLP_GRPC)
     ${OTLP_EXPORTER_SOURCE_DIR}/OtlpGrpcLogRecordExporterProxy.cpp)
 endif()
 
+if(WIN32)
+    # Add a preprocessor definition _DISABLE_CONSTEXPR_MUTEX_CONSTRUCTOR to fix an invalid mex file issue on Windows.
+    # See https://github.com/mathworks/OpenTelemetry-Matlab/issues/130
+    add_compile_definitions(_DISABLE_CONSTEXPR_MUTEX_CONSTRUCTOR)
+endif()
+
 libmexclass_client_add_proxy_library(
     NAME ${OPENTELEMETRY_PROXY_LIBRARY_NAME}
     SOURCES ${OPENTELEMETRY_PROXY_SOURCES}

cmake/vcpkg_triplets/x64-windows-otel-matlab.cmake

@@ -6,4 +6,6 @@ if(${PORT} MATCHES "abseil")
 else()
     set(VCPKG_LIBRARY_LINKAGE dynamic)
 endif()
-
+# Define a preprocessor macro _DISABLE_CONSTEXPR_MUTEX_CONSTRUCTOR to work around an invalid MEX file issue
+# See https://github.com/mathworks/OpenTelemetry-Matlab/issues/130
+set(VCPKG_CXX_FLAGS "/D_DISABLE_CONSTEXPR_MUTEX_CONSTRUCTOR")

otel-cpp.patch patches/otel-cpp-mac.patchotel-cpp.patch renamed to patches/otel-cpp-mac.patch

@@ -0,0 +1,17 @@
+diff --git a/CMakeLists.txt b/CMakeLists.txt
+index cc085b1a..6c4dc0ae 100644
+--- a/CMakeLists.txt
++++ b/CMakeLists.txt
+@@ -15,6 +15,12 @@ endif()
+ 
+ project(opentelemetry-cpp)
+ 
++if(WIN32)
++  # Add a preprocessor macro _DISABLE_CONSTEXPR_MUTEX_CONSTRUCTOR to work around an invalid MEX file issue
++  # See https://github.com/mathworks/OpenTelemetry-Matlab/issues/130
++  add_compile_definitions(_DISABLE_CONSTEXPR_MUTEX_CONSTRUCTOR)
++endif()
++
+ # Mark variables as used so cmake doesn't complain about them
+ mark_as_advanced(CMAKE_TOOLCHAIN_FILE)
+