Add Relacy tests to the build

Author: ccotter

CMakeLists.txt

@@ -91,6 +91,7 @@ else()
     set(STDEXEC_BUILD_TESTS_DEFAULT OFF)
 endif()
 option(STDEXEC_BUILD_TESTS "Build stdexec tests" ${STDEXEC_BUILD_TESTS_DEFAULT})
+option(STDEXEC_BUILD_RELACY_TESTS "Build stdexec relacy tests" ${STDEXEC_BUILD_TESTS_DEFAULT})
 
 # STDEXEC_BUILD_TESTS is used solely to configure CTest's BUILD_TESTING option,
 # which is CMake's preferred option for enabling testing when using CTest.

include/stdexec/__detail/__atomic.hpp

@@ -61,7 +61,7 @@ namespace STDEXEC::__std {
   using std::atomic_thread_fence;
   using std::atomic_signal_fence;
 
-#  if __cpp_lib_atomic_ref >= 2018'06L && !defined(STDEXEC_RELACY)
+#  if __cpp_lib_atomic_ref >= 2018'06L
   using std::atomic_ref;
 #  else
   inline constexpr int __atomic_flag_map[] = {

test/CMakeLists.txt

@@ -138,6 +138,10 @@ icm_add_build_failure_test(
     FOLDER test
 )
 
+if(STDEXEC_BUILD_RELACY_TESTS)
+    add_subdirectory(rrd)
+endif()
+
 # # Adding multiple tests with a glob
 # icm_glob_build_failure_tests(
 #     PATTERN *_fail*.cpp

test/rrd/CMakeLists.txt

@@ -0,0 +1,44 @@
+include(FetchContent)
+
+FetchContent_Declare(
+  relacy
+  GIT_REPOSITORY https://github.com/dvyukov/relacy
+  GIT_TAG master
+)
+
+FetchContent_Populate(relacy)
+
+add_library(relacy INTERFACE)
+target_include_directories(relacy INTERFACE
+  $<BUILD_INTERFACE:${relacy_SOURCE_DIR}/relacy/fakestd>
+  $<BUILD_INTERFACE:${relacy_SOURCE_DIR}>
+  $<INSTALL_INTERFACE:include>
+)
+
+function(add_relacy_test target_name)
+  add_executable(${target_name} ${target_name}.cpp)
+
+  target_link_libraries(${target_name} PRIVATE relacy)
+  target_include_directories(${target_name} PRIVATE ../../include)
+  target_include_directories(${target_name} PRIVATE ${CMAKE_CURRENT_SOURCE_DIR})
+  set_target_properties(${target_name} PROPERTIES
+      CXX_STANDARD 20
+      CXX_STANDARD_REQUIRED ON
+      CXX_EXTENSIONS OFF)
+
+  add_test(NAME relacy-${target_name} COMMAND ${target_name})
+endfunction()
+
+set(relacy_tests
+  async_scope
+  intrusive_mpsc_queue
+  split
+  sync_wait
+)
+
+foreach(test ${relacy_tests})
+  add_relacy_test(${test})
+endforeach()
+
+# Target to build all relacy tests
+add_custom_target(relacy-tests DEPENDS ${relacy_tests})

test/rrd/README.md

@@ -15,13 +15,20 @@ STDEXEC library could needs to use `x.fetch_add(1)` to be compatible with Relacy
 
 ## Instructions
 
-Run the following commands from within this directory (`./tests/rrd`).
+Configure and build stdexec following the build instructions in the top level
+[README.md](../../README.md). There are a couple relacy specific build and ctest
+targets, though they are part of the standard build and ctest and will be run
+automatically if cmake is configured with `-DSTDEXEC_BUILD_RELACY_TESTS=1`.
+`STDEXEC_BUILD_RELACY_TESTS` is set by default for GCC today.
+
+Run the following on a Linux machine with GCC as the toolchain.
 
 ```
-git clone -b STDEXEC https://github.com/dvyukov/relacy
-CXX=g++-11 make -j 4
-./build/split
-./build/async_scope
+mkdir build && cd build
+cmake ..
+make relacy-tests -j 4
+ctest -R relacy # Run all relacy tests
+./test/rrd/sync_wait # Run a specific relacy test directly
 ```
 
 ## Recommended use
@@ -35,8 +42,16 @@ out a more stable build on all environments/compilers, we should revisit this.
 ## Supported platforms
 
 The STDEXEC Relacy tests have been verified to build and run on
- * Linux based GCC+11 with libstdc++ (`x86_64`)
- * Mac with Apple Clang 15 with libc++ (`x86_64`)
+ * Linux based GCC+11-14 with libstdc++ (`x86_64`)
+ * Mac with Apple Clang 15 and 17 with libc++ (`x86_64`)
+
+## Caveat
+
+Relacy relies on a less than robust approach to implement its runtime: it replaces
+std:: names with its own versions, for example, std::atomic and std::mutex, as well
+as pthread_* APIs. As libstdc++/libc++ evolve, newer versions may not be compatible with
+Relacy. In these cases, changes to Relacy are needed to correctly intercept and replace
+std:: names.
 
-G++12 and newer are known to have issues that could be addressed with patches
-to Relacy.
+When the compilers and standard libraries release new versions, we will need to test the
+new versions can compile the stdexec Relacy tests before enabling the new compiler.

test/rrd/async_scope.cpp

@@ -1,17 +1,26 @@
-#include "../../relacy/relacy_cli.hpp"
-#include "../../relacy/relacy_std.hpp"
+/*
+ * Copyright (c) 2025 NVIDIA Corporation
+ *
+ * Licensed under the Apache License Version 2.0 with LLVM Exceptions
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *   https://llvm.org/LICENSE.txt
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdexec_relacy.hpp>
 
 #include <exec/async_scope.hpp>
 #include <exec/single_thread_context.hpp>
 #include <exec/static_thread_pool.hpp>
 #include <stdexec/execution.hpp>
 
-#include <stdexcept>
-
-using rl::nvar;
-using rl::nvolatile;
-using rl::mutex;
-
 namespace ex = STDEXEC;
 using exec::async_scope;
 

test/rrd/intrusive_mpsc_queue.cpp

@@ -1,4 +1,20 @@
-#include "../../relacy/relacy_std.hpp"
+/*
+ * Copyright (c) 2025 NVIDIA Corporation
+ *
+ * Licensed under the Apache License Version 2.0 with LLVM Exceptions
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *   https://llvm.org/LICENSE.txt
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdexec_relacy.hpp>
 
 #include <stdexec/__detail/__intrusive_mpsc_queue.hpp>
 
@@ -314,7 +330,7 @@ struct mpsc_five_producers_ordered : rl::test_suite<mpsc_five_producers_ordered,
 };
 
 auto main(int argc, char** argv) -> int {
-  int iterations = argc > 1 ? strtol(argv[1], nullptr, 10) : 500000;
+  int iterations = argc > 1 ? strtol(argv[1], nullptr, 10) : 250000;
   rl::test_params p;
   p.iteration_count = iterations;
   p.execution_depth_limit = 10000;
@@ -341,7 +357,7 @@ auto main(int argc, char** argv) -> int {
   CHECK(rl::simulate<mpsc_pop_from_empty_never_returns_node>(p));
 
   // Beefy test...
-  p.iteration_count = 50000;
+  p.iteration_count = 5000;
   printf("Running mpsc_five_producers_ordered...\n");
   CHECK(rl::simulate<mpsc_five_producers_ordered>(p));
 

test/rrd/split.cpp

@@ -1,13 +1,24 @@
-#include "../../relacy/relacy_cli.hpp"
-#include "../../relacy/relacy_std.hpp"
+/*
+ * Copyright (c) 2025 NVIDIA Corporation
+ *
+ * Licensed under the Apache License Version 2.0 with LLVM Exceptions
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ *   https://llvm.org/LICENSE.txt
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <stdexec_relacy.hpp>
 
 #include <exec/static_thread_pool.hpp>
 #include <stdexec/execution.hpp>
 
-using rl::nvar;
-using rl::nvolatile;
-using rl::mutex;
-
 namespace ex = STDEXEC;
 
 struct split_bug : rl::test_suite<split_bug, 1> {

test/rrd/stdexec_relacy.hpp

@@ -0,0 +1,7 @@
+#pragma once
+
+#include "../../relacy/relacy_std.hpp"
+
+namespace std {
+  template <class> struct atomic_ref;
+}

test/rrd/sync_wait.cpp

@@ -15,7 +15,7 @@
  * limitations under the License.
  */
 
-#include "../../relacy/relacy_std.hpp"
+#include <stdexec_relacy.hpp>
 
 #include <exec/static_thread_pool.hpp>
 #include <stdexec/execution.hpp>