[CMAKE] Set the project version through the cmake project macro

CMakeLists.txt

@@ -15,7 +15,14 @@ if(CMAKE_VERSION VERSION_GREATER_EQUAL "3.20.0")
   cmake_policy(SET CMP0117 NEW)
 endif()
 
-project(opentelemetry-cpp)
+# Read the opentelemetry-cpp project and abi version from the api version header
+# file and set the third-party version tags
+include("${CMAKE_CURRENT_LIST_DIR}/cmake/version.cmake")
+
+project(
+  opentelemetry-cpp
+  VERSION ${OPENTELEMETRY_VERSION}
+  LANGUAGES CXX)
 
 # Mark variables as used so cmake doesn't complain about them
 mark_as_advanced(CMAKE_TOOLCHAIN_FILE)
@@ -56,9 +63,6 @@ endif()
 option(WITH_ABI_VERSION_1 "ABI version 1" ON)
 option(WITH_ABI_VERSION_2 "EXPERIMENTAL: ABI version 2 preview" OFF)
 
-file(READ "${CMAKE_CURRENT_LIST_DIR}/api/include/opentelemetry/version.h"
-     OPENTELEMETRY_CPP_HEADER_VERSION_H)
-
 #
 # We do not want to have WITH_ABI_VERSION = "1" or "2", and instead prefer two
 # distinct flags, WITH_ABI_VERSION_1 and WITH_ABI_VERSION_2.
@@ -88,31 +92,9 @@ if(WITH_ABI_VERSION_2)
 elseif(WITH_ABI_VERSION_1)
   set(OPENTELEMETRY_ABI_VERSION_NO "1")
 else()
-  if(OPENTELEMETRY_CPP_HEADER_VERSION_H MATCHES
-     "OPENTELEMETRY_ABI_VERSION_NO[ \t\r\n]+\"?([0-9]+)\"?")
-    math(EXPR OPENTELEMETRY_ABI_VERSION_NO ${CMAKE_MATCH_1})
-  else()
-    message(
-      FATAL_ERROR
-        "OPENTELEMETRY_ABI_VERSION_NO not found on ${CMAKE_CURRENT_LIST_DIR}/api/include/opentelemetry/version.h"
-    )
-  endif()
-endif()
-
-message(STATUS "OPENTELEMETRY_ABI_VERSION_NO=${OPENTELEMETRY_ABI_VERSION_NO}")
-
-if(OPENTELEMETRY_CPP_HEADER_VERSION_H MATCHES
-   "OPENTELEMETRY_VERSION[ \t\r\n]+\"?([^\"]+)\"?")
-  set(OPENTELEMETRY_VERSION ${CMAKE_MATCH_1})
-else()
-  message(
-    FATAL_ERROR
-      "OPENTELEMETRY_VERSION not found on ${CMAKE_CURRENT_LIST_DIR}/api/include/opentelemetry/version.h"
-  )
+  set(OPENTELEMETRY_ABI_VERSION_NO ${OPENTELEMETRY_ABI_VERSION_DEFAULT})
 endif()
 
-message(STATUS "OPENTELEMETRY_VERSION=${OPENTELEMETRY_VERSION}")
-
 option(WITH_NO_DEPRECATED_CODE "Do not include deprecated code" OFF)
 
 set(WITH_STL
@@ -662,3 +644,13 @@ if(OPENTELEMETRY_INSTALL)
     include(CPack)
   endif()
 endif()
+
+# Make the version and ABI version available to the user for in-tree builds
+# These are the same variables that are cached with
+# find_package(opentelemetry-cpp CONFIG)
+set(OPENTELEMETRY_ABI_VERSION_NO
+    "${OPENTELEMETRY_ABI_VERSION_NO}"
+    CACHE STRING "opentelemetry-cpp ABI version" FORCE)
+set(OPENTELEMETRY_VERSION
+    "${OPENTELEMETRY_VERSION}"
+    CACHE STRING "opentelemetry-cpp version" FORCE)

cmake/otel-install-functions.cmake

@@ -487,13 +487,11 @@ function(otel_install_cmake_config)
     "${PROJECT_SOURCE_DIR}/cmake/templates/opentelemetry-cpp-config.cmake.in"
     "${CMAKE_CURRENT_BINARY_DIR}/cmake/${PROJECT_NAME}/${PROJECT_NAME}-config.cmake"
     INSTALL_DESTINATION "${CMAKE_INSTALL_LIBDIR}/cmake/${PROJECT_NAME}"
-    PATH_VARS OPENTELEMETRY_ABI_VERSION_NO OPENTELEMETRY_VERSION PROJECT_NAME
-              INCLUDE_INSTALL_DIR CMAKE_INSTALL_LIBDIR)
+    PATH_VARS INCLUDE_INSTALL_DIR CMAKE_INSTALL_LIBDIR)
 
   # Write version file for find_package(opentelemetry-cpp CONFIG)
   write_basic_package_version_file(
     "${CMAKE_CURRENT_BINARY_DIR}/cmake/${PROJECT_NAME}/${PROJECT_NAME}-config-version.cmake"
-    VERSION ${OPENTELEMETRY_VERSION}
     COMPATIBILITY ExactVersion)
 
   install(

cmake/templates/opentelemetry-cpp-config.cmake.in

@@ -211,10 +211,13 @@ endforeach()
 # handle the QUIETLY and REQUIRED arguments and set opentelemetry-cpp_FOUND to
 # TRUE if all variables listed contain valid results, e.g. valid file paths.
 include("FindPackageHandleStandardArgs")
+
+set(${CMAKE_FIND_PACKAGE_NAME}_CONFIG ${CMAKE_CURRENT_LIST_FILE})
+
 find_package_handle_standard_args(
-  ${CMAKE_FIND_PACKAGE_NAME}
-  FOUND_VAR ${CMAKE_FIND_PACKAGE_NAME}_FOUND
-  REQUIRED_VARS OPENTELEMETRY_CPP_INCLUDE_DIRS OPENTELEMETRY_CPP_LIBRARIES)
+   ${CMAKE_FIND_PACKAGE_NAME}
+   CONFIG_MODE
+   REQUIRED_VARS OPENTELEMETRY_CPP_INCLUDE_DIRS OPENTELEMETRY_CPP_LIBRARIES)
 
 if(${CMAKE_FIND_PACKAGE_NAME}_FOUND)
   set(OPENTELEMETRY_CPP_FOUND

cmake/version.cmake

@@ -0,0 +1,35 @@
+# Copyright The OpenTelemetry Authors
+# SPDX-License-Identifier: Apache-2.0
+
+set(OTELCPP_SOURCE_DIR "${CMAKE_CURRENT_LIST_DIR}/..")
+get_filename_component(OTELCPP_SOURCE_DIR "${OTELCPP_SOURCE_DIR}" ABSOLUTE)
+set(OTELCPP_API_VERSION_FILE "${OTELCPP_SOURCE_DIR}/api/include/opentelemetry/version.h")
+
+file(READ "${OTELCPP_API_VERSION_FILE}"
+     OPENTELEMETRY_CPP_HEADER_VERSION_H)
+
+if(NOT DEFINED OPENTELEMETRY_CPP_HEADER_VERSION_H)
+      message(FATAL_ERROR "${OTELCPP_API_VERSION_FILE} not found")
+endif()
+
+if(OPENTELEMETRY_CPP_HEADER_VERSION_H MATCHES
+   "OPENTELEMETRY_VERSION[ \t\r\n]+\"?([^\"]+)\"?")
+  set(OPENTELEMETRY_VERSION ${CMAKE_MATCH_1})
+else()
+  message(
+    FATAL_ERROR
+      "OPENTELEMETRY_VERSION not found on ${OTELCPP_API_VERSION_FILE}"
+ )
+endif()
+
+if(OPENTELEMETRY_CPP_HEADER_VERSION_H MATCHES "OPENTELEMETRY_ABI_VERSION_NO[ \t\r\n]+\"?([0-9]+)\"?")
+   math(EXPR OPENTELEMETRY_ABI_VERSION_DEFAULT ${CMAKE_MATCH_1})
+endif()
+
+if(NOT OPENTELEMETRY_VERSION OR OPENTELEMETRY_VERSION VERSION_LESS_EQUAL "0.0.0")
+  message(FATAL_ERROR "Failed to extract OpenTelemetry C++ version (${OPENTELEMETRY_VERSION}) from ${OTELCPP_API_VERSION_FILE}")
+endif()
+
+if(NOT OPENTELEMETRY_ABI_VERSION_DEFAULT)
+  message(FATAL_ERROR "Failed to extract OpenTelemetry C++ ABI version from ${OTELCPP_API_VERSION_FILE}")
+endif()

install/test/cmake/fetch_content_test/CMakeLists.txt

@@ -30,6 +30,27 @@ FetchContent_Declare(
 FetchContent_Declare(opentelemetry-cpp SOURCE_DIR ${OPENTELEMETRY_CPP_SRC_DIR})
 FetchContent_MakeAvailable(googletest opentelemetry-cpp)
 
+if(NOT DEFINED OPENTELEMETRY_VERSION OR OPENTELEMETRY_VERSION
+                                        VERSION_LESS_EQUAL 0.0.0)
+  message(
+    FATAL_ERROR
+      "OpenTelemetry C++ version not set after FetchContent_MakeAvailable(opentelemetry-cpp)."
+  )
+endif()
+
+if(NOT DEFINED OPENTELEMETRY_ABI_VERSION_NO OR OPENTELEMETRY_ABI_VERSION_NO
+                                               LESS 1)
+  message(
+    FATAL_ERROR
+      "OpenTelemetry C++ ABI version number not defined in the source directory"
+  )
+endif()
+
+message(
+  STATUS
+    "OpenTelemetry C++ version: ${OPENTELEMETRY_VERSION}, ABI version: ${OPENTELEMETRY_ABI_VERSION_NO}"
+)
+
 add_executable(
   fetch_content_src_test
   ${OPENTELEMETRY_CPP_SRC_DIR}/install/test/src/test_api.cc