[CMAKE] Add CMake script to find or fetch Microsoft.GSL

CMakeLists.txt

@@ -275,6 +275,10 @@ if(WITH_EXAMPLES_HTTP AND NOT WITH_EXAMPLES)
   message(FATAL_ERROR "WITH_EXAMPLES_HTTP=ON requires WITH_EXAMPLES=ON")
 endif()
 
+if(WITH_GSL)
+  include("${opentelemetry-cpp_SOURCE_DIR}/cmake/ms-gsl.cmake")
+endif()
+
 find_package(Threads)
 
 function(set_target_version target_name)
@@ -635,7 +639,9 @@ message(STATUS "CMake: ${CMAKE_VERSION}")
 message(STATUS "GTest: ${GTest_VERSION} (${GTest_PROVIDER})")
 message(STATUS "benchmark: ${benchmark_VERSION} (${benchmark_PROVIDER})")
 if(WITH_GSL)
-  message(STATUS "GSL: ${GSL_VERSION}")
+  message(
+    STATUS "Microsoft.GSL: ${Microsoft.GSL_VERSION} (${Microsoft.GSL_PROVIDER})"
+  )
 endif()
 if(absl_FOUND)
   message(STATUS "Abseil: ${absl_VERSION}")

api/CMakeLists.txt

@@ -9,22 +9,7 @@ target_include_directories(
 
 set_target_properties(opentelemetry_api PROPERTIES EXPORT_NAME api)
 
-otel_add_component(
-  COMPONENT
-  api
-  TARGETS
-  opentelemetry_api
-  FILES_DIRECTORY
-  "include/opentelemetry"
-  FILES_DESTINATION
-  "include"
-  FILES_MATCHING
-  PATTERN
-  "*.h")
-
-if(OPENTELEMETRY_INSTALL)
-  unset(TARGET_DEPS)
-endif()
+unset(TARGET_DEPS)
 
 if(BUILD_TESTING)
   add_subdirectory(test)
@@ -74,18 +59,8 @@ endif()
 
 if(WITH_GSL)
   target_compile_definitions(opentelemetry_api INTERFACE HAVE_GSL)
-
-  # Guidelines Support Library path. Used if we are not on not get C++20.
-  #
-  find_package(Microsoft.GSL QUIET)
-  if(TARGET Microsoft.GSL::GSL)
-    target_link_libraries(opentelemetry_api INTERFACE Microsoft.GSL::GSL)
-    list(APPEND TARGET_DEPS "gsl")
-  else()
-    set(GSL_DIR third_party/ms-gsl)
-    target_include_directories(
-      opentelemetry_api INTERFACE "$<BUILD_INTERFACE:${GSL_DIR}/include>")
-  endif()
+  target_link_libraries(opentelemetry_api INTERFACE Microsoft.GSL::GSL)
+  list(APPEND TARGET_DEPS "gsl")
 endif()
 
 if(WITH_NO_GETENV)
@@ -140,6 +115,19 @@ if(APPLE)
   target_link_libraries(opentelemetry_api INTERFACE "-framework CoreFoundation")
 endif()
 
+otel_add_component(
+  COMPONENT
+  api
+  TARGETS
+  opentelemetry_api
+  FILES_DIRECTORY
+  "include/opentelemetry"
+  FILES_DESTINATION
+  "include"
+  FILES_MATCHING
+  PATTERN
+  "*.h")
+
 include(${PROJECT_SOURCE_DIR}/cmake/pkgconfig.cmake)
 
 if(OPENTELEMETRY_INSTALL)

ci/do_ci.ps1

@@ -344,6 +344,7 @@ switch ($action) {
       "-DCMAKE_INSTALL_PREFIX=$INSTALL_TEST_DIR" `
       -DWITH_ABI_VERSION_1=OFF `
       -DWITH_ABI_VERSION_2=ON `
+      -DWITH_GSL=ON `
       -DWITH_THREAD_INSTRUMENTATION_PREVIEW=ON `
       -DWITH_METRICS_EXEMPLAR_PREVIEW=ON `
       -DWITH_ASYNC_EXPORT_PREVIEW=ON `

cmake/ms-gsl.cmake

@@ -0,0 +1,35 @@
+# Copyright The OpenTelemetry Authors
+# SPDX-License-Identifier: Apache-2.0
+
+find_package(Microsoft.GSL CONFIG QUIET)
+set(Microsoft.GSL_PROVIDER "find_package")
+
+if(NOT Microsoft.GSL_FOUND)
+  set(_Microsoft.GSL_SUBMODULE_DIR "${opentelemetry-cpp_SOURCE_DIR}/third_party/ms-gsl")
+  if(EXISTS "${_Microsoft.GSL_SUBMODULE_DIR}/.git")
+    FetchContent_Declare(
+       "gsl"
+       SOURCE_DIR "${_Microsoft.GSL_SUBMODULE_DIR}"
+       )
+    set(Microsoft.GSL_PROVIDER "fetch_source")
+  else()
+    FetchContent_Declare(
+      "gsl"
+      GIT_REPOSITORY  "https://github.com/microsoft/GSL.git"
+      GIT_TAG "${ms-gsl_GIT_TAG}"
+      )
+    set(Microsoft.GSL_PROVIDER "fetch_repository")
+  endif()
+
+  set(GSL_TEST OFF CACHE BOOL "" FORCE)
+  set(GSL_INSTALL ${OPENTELEMETRY_INSTALL} CACHE BOOL "" FORCE)
+
+  FetchContent_MakeAvailable(gsl)
+
+  # Set the Microsoft.GSL_VERSION variable from the git tag.
+  string(REGEX REPLACE "^v([0-9]+\\.[0-9]+\\.[0-9]+)$" "\\1" Microsoft.GSL_VERSION "${ms-gsl_GIT_TAG}")
+endif()
+
+if(NOT TARGET Microsoft.GSL::GSL)
+  message(FATAL_ERROR "A required Microsoft.GSL target Microsoft.GSL::GSL was not imported")
+endif()

cmake/thirdparty-dependency-config.cmake

@@ -8,6 +8,7 @@
 #-----------------------------------------------------------------------
 set(OTEL_THIRDPARTY_DEPENDENCIES_SUPPORTED
      Threads
+     Microsoft.GSL
      ZLIB
      CURL
      nlohmann_json
@@ -29,6 +30,7 @@ set(OTEL_Protobuf_TARGET_NAMESPACE "protobuf")
 # # set(OTEL_<dependency>_SEARCH_MODE "<search mode>")
 #-----------------------------------------------------------------------
 set(OTEL_Threads_SEARCH_MODE "")
+set(OTEL_Microsoft.GSL_SEARCH_MODE "CONFIG")
 set(OTEL_ZLIB_SEARCH_MODE "")
 set(OTEL_CURL_SEARCH_MODE "")
 set(OTEL_nlohmann_json_SEARCH_MODE "CONFIG")