disable ThreadLocal.SharedLibrary when not building shared libs

Summary:
The `ThreadLocal.SharedLibrary` test depends on building a separate
`thread_local_test_lib.so`.  This can only be built when folly was compiled
with PIC.

This also fixes the test to fail normally rather than segfaulting if it cannot
load `thread_local_test_lib.so`.

Reviewed By: yfeldblum

Differential Revision: D6805683

fbshipit-source-id: b451b94c2a4b3184a8f61de3b7f83e69169205f0

CMakeLists.txt

@@ -337,6 +337,20 @@ if (BUILD_TESTS)
   include(GoogleTest OPTIONAL RESULT_VARIABLE HAVE_CMAKE_GTEST)
   enable_testing()
 
+  # The ThreadLocalTest code uses a helper shared library for one of its tests.
+  # This can only be built if folly itself was built as a shared library.
+  if (BUILD_SHARED_LIBS)
+    add_library(thread_local_test_lib MODULE
+      ${FOLLY_DIR}/test/ThreadLocalTestLib.cpp
+    )
+    set_target_properties(thread_local_test_lib PROPERTIES PREFIX "")
+    apply_folly_compile_options_to_target(thread_local_test_lib)
+    target_link_libraries(thread_local_test_lib PUBLIC folly)
+    target_include_directories(
+      thread_local_test_lib
+      PUBLIC ${CMAKE_CURRENT_BINARY_DIR})
+  endif()
+
   add_library(folly_test_support
     ${FOLLY_DIR}/test/common/TestMain.cpp
     ${FOLLY_DIR}/test/DeterministicSchedule.cpp

folly/test/ThreadLocalTest.cpp

@@ -578,17 +578,25 @@ TEST(ThreadLocal, Fork2) {
   }
 }
 
-// Elide this test when using any sanitizer. Otherwise, the dlopen'ed code
-// would end up running without e.g., ASAN-initialized data structures and
-// failing right away.
-#if !defined FOLLY_SANITIZE_ADDRESS && !defined UNDEFINED_SANITIZER && \
-    !defined FOLLY_SANITIZE_THREAD
+// Disable the SharedLibrary test when using any sanitizer. Otherwise, the
+// dlopen'ed code would end up running without e.g., ASAN-initialized data
+// structures and failing right away.
+//
+// We also cannot run this test unless folly was compiled with PIC support,
+// since we cannot build thread_local_test_lib.so without PIC.
+#if defined FOLLY_SANITIZE_ADDRESS || defined UNDEFINED_SANITIZER || \
+    defined FOLLY_SANITIZE_THREAD || !defined FOLLY_SUPPORT_SHARED_LIBRARY
+#define SHARED_LIBRARY_TEST_NAME DISABLED_SharedLibrary
+#else
+#define SHARED_LIBRARY_TEST_NAME SharedLibrary
+#endif
 
-TEST(ThreadLocal, SharedLibrary) {
+TEST(ThreadLocal, SHARED_LIBRARY_TEST_NAME) {
   auto exe = fs::executable_path();
   auto lib = exe.parent_path() / "thread_local_test_lib.so";
   auto handle = dlopen(lib.string().c_str(), RTLD_LAZY);
-  EXPECT_NE(nullptr, handle);
+  ASSERT_NE(nullptr, handle)
+      << "unable to load " << lib.string() << ": " << dlerror();
 
   typedef void (*useA_t)();
   dlerror();
@@ -596,6 +604,7 @@ TEST(ThreadLocal, SharedLibrary) {
 
   const char *dlsym_error = dlerror();
   EXPECT_EQ(nullptr, dlsym_error);
+  ASSERT_NE(nullptr, useA);
 
   useA();
 
@@ -625,7 +634,6 @@ TEST(ThreadLocal, SharedLibrary) {
   t2.join();
 }
 
-#endif
 #endif
 
 namespace folly { namespace threadlocal_detail {