cleanup: simplify examples/ CMake files (#11932)

coryan · web-flow · commit b8e063fd3585 · 2023-06-21T13:33:59.000-04:00
Always `add_subdirectory(examples)` and let that directory decide what
it can build.
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -240,15 +240,7 @@ endif ()
 add_subdirectory(google/cloud)
 google_cloud_cpp_enable_features()
 
-# The examples are more readable if we use exceptions for error handling. We had
-# to tradeoff readability vs. "making them compile everywhere".
-if (GOOGLE_CLOUD_CPP_ENABLE_EXAMPLES
-    AND bigtable IN_LIST GOOGLE_CLOUD_CPP_ENABLE
-    AND iam IN_LIST GOOGLE_CLOUD_CPP_ENABLE
-    AND spanner IN_LIST GOOGLE_CLOUD_CPP_ENABLE
-    AND storage IN_LIST GOOGLE_CLOUD_CPP_ENABLE)
-    add_subdirectory(examples)
-endif ()
+add_subdirectory(examples)
 
 # Obsolete / retired flags and options. Removing them just cleans up a bit of
 # our code at the cost of breaking customers, while putting them here makes them
diff --git a/examples/CMakeLists.txt b/examples/CMakeLists.txt
@@ -14,18 +14,29 @@
 # limitations under the License.
 # ~~~
 
+# The examples are more readable if we use exceptions for error handling. We had
+# to tradeoff readability vs. "making them compile everywhere".
+if (NOT GOOGLE_CLOUD_CPP_ENABLE_EXAMPLES)
+    return()
+endif ()
+
 # Pick the right MSVC runtime libraries.
 include(SelectMSVCRuntime)
 
-add_executable(gcs2cbt gcs2cbt.cc)
-target_link_libraries(gcs2cbt google-cloud-cpp::bigtable
-                      google-cloud-cpp::storage google-cloud-cpp::grpc_utils)
-google_cloud_cpp_add_common_options(gcs2cbt)
+if (bigtable IN_LIST GOOGLE_CLOUD_CPP_ENABLE AND storage IN_LIST
+                                                 GOOGLE_CLOUD_CPP_ENABLE)
+    add_executable(gcs2cbt gcs2cbt.cc)
+    target_link_libraries(
+        gcs2cbt google-cloud-cpp::bigtable google-cloud-cpp::storage
+        google-cloud-cpp::grpc_utils)
+    google_cloud_cpp_add_common_options(gcs2cbt)
+endif ()
 
-if (BUILD_TESTING)
-    include(FindCurlWithTargets)
-    include(FindgRPC)
+include(FindCurlWithTargets)
+include(FindgRPC)
 
+if (spanner IN_LIST GOOGLE_CLOUD_CPP_ENABLE AND iam IN_LIST
+                                                GOOGLE_CLOUD_CPP_ENABLE)
     google_cloud_cpp_grpcpp_library(
         hello_world_protos "hello_world_grpc/hello_world.proto"
         PROTO_PATH_DIRECTORIES ${CMAKE_CURRENT_SOURCE_DIR})
@@ -38,11 +49,19 @@ if (BUILD_TESTING)
         PRIVATE hello_world_protos google_cloud_cpp_testing
                 google-cloud-cpp::iam google-cloud-cpp::spanner CURL::libcurl)
     google_cloud_cpp_add_common_options(grpc_credential_types)
+endif ()
 
-    foreach (test gcs2cbt grpc_credential_types)
-        add_test(NAME ${test} COMMAND ${test})
-        set_tests_properties(
-            ${test} PROPERTIES LABELS
-                               "integration-test;integration-test-production")
-    endforeach ()
+# Label all the binaries as "tests", so they run in our CI builds.
+if (NOT BUILD_TESTING)
+    return()
 endif ()
+
+foreach (test gcs2cbt grpc_credential_types)
+    if (NOT TARGET "${test}")
+        continue()
+    endif ()
+    add_test(NAME ${test} COMMAND ${test})
+    set_tests_properties(
+        ${test} PROPERTIES LABELS
+                           "integration-test;integration-test-production")
+endforeach ()
