CMakeLists.txt: allow compilation without CXX support #4364

ThomasDevoogdt · ThomasDevoogdt · commit 7576aa612c7b · 2025-10-03T17:52:46.000+02:00
e.g. fluent-bit is a c-only library, so allow compilation without cxx

Signed-off-by: Thomas Devoogdt &lt;thomas.devoogdt@barco.com&gt;
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -3,7 +3,16 @@ cmake_minimum_required(VERSION 3.5)
 include("packaging/cmake/parseversion.cmake")
 parseversion("src/rdkafka.h")
 
-project(RdKafka VERSION ${RDKAFKA_VERSION})
+project(RdKafka VERSION ${RDKAFKA_VERSION} LANGUAGES C)
+
+# Check for CXX support
+include(CheckLanguage)
+check_language(CXX)
+if(CMAKE_CXX_COMPILER)
+  enable_language(CXX)
+else()
+  message(STATUS "C++ compiler not found, skipping C++ support")
+endif()
 
 set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_CURRENT_SOURCE_DIR}/packaging/cmake/Modules/")
 
@@ -279,7 +288,10 @@ install(
 )
 
 add_subdirectory(src)
-add_subdirectory(src-cpp)
+
+if(CMAKE_CXX_COMPILER)
+  add_subdirectory(src-cpp)
+endif()
 
 if(RDKAFKA_BUILD_EXAMPLES)
   add_subdirectory(examples)
diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
@@ -5,23 +5,31 @@ endif(WIN32)
 add_executable(producer producer.c ${win32_sources})
 target_link_libraries(producer PUBLIC rdkafka)
 
-add_executable(producer_cpp producer.cpp ${win32_sources})
-target_link_libraries(producer_cpp PUBLIC rdkafka++)
+if(CMAKE_CXX_COMPILER)
+    add_executable(producer_cpp producer.cpp ${win32_sources})
+    target_link_libraries(producer_cpp PUBLIC rdkafka++)
+endif()
 
 add_executable(consumer consumer.c ${win32_sources})
 target_link_libraries(consumer PUBLIC rdkafka)
 
 add_executable(rdkafka_performance rdkafka_performance.c ${win32_sources})
 target_link_libraries(rdkafka_performance PUBLIC rdkafka)
 
-add_executable(rdkafka_example_cpp rdkafka_example.cpp ${win32_sources})
-target_link_libraries(rdkafka_example_cpp PUBLIC rdkafka++)
+if(CMAKE_CXX_COMPILER)
+    add_executable(rdkafka_example_cpp rdkafka_example.cpp ${win32_sources})
+    target_link_libraries(rdkafka_example_cpp PUBLIC rdkafka++)
+endif()
 
-add_executable(rdkafka_complex_consumer_example_cpp rdkafka_complex_consumer_example.cpp ${win32_sources})
-target_link_libraries(rdkafka_complex_consumer_example_cpp PUBLIC rdkafka++)
+if(CMAKE_CXX_COMPILER)
+    add_executable(rdkafka_complex_consumer_example_cpp rdkafka_complex_consumer_example.cpp ${win32_sources})
+    target_link_libraries(rdkafka_complex_consumer_example_cpp PUBLIC rdkafka++)
+endif()
 
-add_executable(openssl_engine_example_cpp openssl_engine_example.cpp ${win32_sources})
-target_link_libraries(openssl_engine_example_cpp PUBLIC rdkafka++)
+if(CMAKE_CXX_COMPILER)
+    add_executable(openssl_engine_example_cpp openssl_engine_example.cpp ${win32_sources})
+    target_link_libraries(openssl_engine_example_cpp PUBLIC rdkafka++)
+endif()
 
 add_executable(misc misc.c ${win32_sources})
 target_link_libraries(misc PUBLIC rdkafka)
@@ -73,7 +81,8 @@ if(NOT WIN32)
     add_executable(rdkafka_complex_consumer_example rdkafka_complex_consumer_example.c)
     target_link_libraries(rdkafka_complex_consumer_example PUBLIC rdkafka)
 
-    add_executable(kafkatest_verifiable_client kafkatest_verifiable_client.cpp)
-    target_link_libraries(kafkatest_verifiable_client PUBLIC rdkafka++)
-
+    if(CMAKE_CXX_COMPILER)
+        add_executable(kafkatest_verifiable_client kafkatest_verifiable_client.cpp)
+        target_link_libraries(kafkatest_verifiable_client PUBLIC rdkafka++)
+    endif()
 endif(NOT WIN32)
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
@@ -48,38 +48,22 @@ set(
     0050-subscribe_adds.c
     0051-assign_adds.c
     0052-msg_timestamps.c
-    0053-stats_cb.cpp
-    0054-offset_time.cpp
     0055-producer_latency.c
     0056-balanced_group_mt.c
-    0057-invalid_topic.cpp
-    0058-log.cpp
-    0059-bsearch.cpp
-    0060-op_prio.cpp
-    0061-consumer_lag.cpp
-    0062-stats_event.c
-    0063-clusterid.cpp
     0064-interceptors.c
-    0065-yield.cpp
-    0066-plugins.cpp
-    0067-empty_topic.cpp
     0068-produce_timeout.c
     0069-consumer_add_parts.c
-    0070-null_empty.cpp
     0072-headers_ut.c
     0073-headers.c
     0074-producev.c
     0075-retry.c
     0076-produce_retry.c
     0077-compaction.c
-    0078-c_from_cpp.cpp
     0079-fork.c
     0080-admin_ut.c
     0081-admin.c
-    0082-fetch_max_bytes.cpp
     0083-cb_event.c
     0084-destroy_flags.c
-    0085-headers.cpp
     0086-purge.c
     0088-produce_metadata_timeout.c
     0089-max_poll_interval.c
@@ -88,50 +72,32 @@ set(
     0092-mixed_msgver.c
     0093-holb.c
     0094-idempotence_msg_timeout.c
-    0095-all_brokers_down.cpp
-    0097-ssl_verify.cpp
-    0098-consumer-txn.cpp
-    0099-commit_metadata.c
-    0100-thread_interceptors.cpp
-    0101-fetch-from-follower.cpp
     0102-static_group_rebalance.c
     0103-transactions.c
     0104-fetch_from_follower_mock.c
     0105-transactions_mock.c
     0106-cgrp_sess_timeout.c
     0107-topic_recreate.c
-    0109-auto_create_topics.cpp
-    0110-batch_size.cpp
-    0111-delay_create_topics.cpp
     0112-assign_unknown_part.c
-    0113-cooperative_rebalance.cpp
-    0114-sticky_partitioning.cpp
-    0115-producer_auth.cpp
-    0116-kafkaconsumer_close.cpp
     0117-mock_errors.c
     0118-commit_rebalance.c
-    0119-consumer_auth.cpp
     0120-asymmetric_subscription.c
     0121-clusterid.c
     0122-buffer_cleaning_after_rebalance.c
     0123-connections_max_idle.c
     0124-openssl_invalid_engine.c
     0125-immediate_flush.c
     0126-oauthbearer_oidc.c
-    0127-fetch_queue_backoff.cpp
-    0128-sasl_callback_queue.cpp
     0129-fetch_aborted_msgs.c
     0130-store_offsets.c
     0131-connect_timeout.c
     0132-strategy_ordering.c
     0133-ssl_keys.c
     0134-ssl_provider.c
-    0135-sasl_credentials.cpp
     0136-resolve_cb.c
     0137-barrier_batch_consume.c
     0138-admin_mock.c
     0139-offset_validation_mock.c
-    0140-commit_metadata.cpp
     0142-reauthentication.c
     0143-exponential_backoff_mock.c
     0144-idempotence_mock.c
@@ -144,21 +110,66 @@ set(
     0151-purge-brokers.c
     0152-rebootstrap.c
     0153-memberid.c
-    8000-idle.cpp
     8001-fetch_from_follower_mock_manual.c
     test.c
-    testcpp.cpp
     rusage.c
 )
 
+if(CMAKE_CXX_COMPILER)
+    add_compile_definitions(_CXX=1)
+    list(APPEND sources
+        0053-stats_cb.cpp
+        0054-offset_time.cpp
+        0057-invalid_topic.cpp
+        0058-log.cpp
+        0059-bsearch.cpp
+        0060-op_prio.cpp
+        0061-consumer_lag.cpp
+        0062-stats_event.c
+        0063-clusterid.cpp
+        0065-yield.cpp
+        0066-plugins.cpp
+        0067-empty_topic.cpp
+        0070-null_empty.cpp
+        0078-c_from_cpp.cpp
+        0082-fetch_max_bytes.cpp
+        0085-headers.cpp
+        0095-all_brokers_down.cpp
+        0097-ssl_verify.cpp
+        0098-consumer-txn.cpp
+        0099-commit_metadata.c
+        0100-thread_interceptors.cpp
+        0101-fetch-from-follower.cpp
+        0109-auto_create_topics.cpp
+        0110-batch_size.cpp
+        0111-delay_create_topics.cpp
+        0113-cooperative_rebalance.cpp
+        0114-sticky_partitioning.cpp
+        0115-producer_auth.cpp
+        0116-kafkaconsumer_close.cpp
+        0119-consumer_auth.cpp
+        0127-fetch_queue_backoff.cpp
+        0128-sasl_callback_queue.cpp
+        0135-sasl_credentials.cpp
+        0140-commit_metadata.cpp
+        8000-idle.cpp
+        testcpp.cpp
+    )
+endif()
+
 if(NOT WIN32)
     list(APPEND sources sockem.c sockem_ctrl.c)
 else()
     list(APPEND sources ../src/tinycthread.c ../src/tinycthread_extra.c)
 endif()
 
 add_executable(test-runner ${sources})
-target_link_libraries(test-runner PUBLIC rdkafka++)
+
+if(CMAKE_CXX_COMPILER)
+  target_link_libraries(test-runner PUBLIC rdkafka++)
+else()
+  target_link_libraries(test-runner PUBLIC rdkafka)
+endif()
 
 add_test(NAME RdKafkaTestInParallel COMMAND test-runner -p5)
 add_test(NAME RdKafkaTestSequentially COMMAND test-runner -p1)
diff --git a/tests/test.c b/tests/test.c
