Clarify parallel scheduler build

CMakeLists.txt

@@ -260,6 +260,10 @@ if (NOT STDEXEC_NAMESPACE STREQUAL "stdexec")
   target_compile_definitions(stdexec INTERFACE STDEXEC_NAMESPACE=${STDEXEC_NAMESPACE})
 endif()
 
+if (NOT STDEXEC_BUILD_PARALLEL_SCHEDULER)
+  target_compile_definitions(stdexec INTERFACE STDEXEC_PARALLEL_SCHEDULER_HEADER_ONLY)
+endif()
+
 option(STDEXEC_ENABLE_EXTRA_TYPE_CHECKING "Enable extra type checking that is costly at compile-time" OFF)
 if (STDEXEC_ENABLE_EXTRA_TYPE_CHECKING)
   target_compile_definitions(stdexec INTERFACE STDEXEC_ENABLE_EXTRA_TYPE_CHECKING)
@@ -455,12 +459,15 @@ if(STDEXEC_BUILD_PARALLEL_SCHEDULER)
       $<$<COMPILE_LANG_AND_ID:CXX,MSVC>:/Zc:__cplusplus /Zc:preprocessor /Zc:externConstexpr>
       )
   target_link_libraries(parallel_scheduler PUBLIC stdexec)
-
-  add_library(STDEXEC::parallel_scheduler ALIAS parallel_scheduler)
-  add_library(system_context ALIAS parallel_scheduler)
-  add_library(STDEXEC::system_context ALIAS parallel_scheduler)
+else()
+  add_library(parallel_scheduler INTERFACE)
+  target_link_libraries(parallel_scheduler INTERFACE stdexec)
 endif()
 
+add_library(STDEXEC::parallel_scheduler ALIAS parallel_scheduler)
+add_library(system_context ALIAS parallel_scheduler)
+add_library(STDEXEC::system_context ALIAS parallel_scheduler)
+
 option(STDEXEC_ENABLE_IO_URING "Enable the use of the io_uring scheduler on Linux" OFF)
 
 if(STDEXEC_ENABLE_IO_URING)

examples/CMakeLists.txt

@@ -32,6 +32,9 @@ function(def_example example)
         $<$<CXX_COMPILER_ID:GNU>:-Wno-maybe-uninitialized> # warnings being emitted from stdlib headers, why?
         $<$<CXX_COMPILER_ID:Clang>:-Wno-gnu-line-marker>
     )
+    target_compile_definitions(${target} PRIVATE
+        $<$<PLATFORM_ID:Windows>:NOMINMAX>
+    )
     target_link_libraries(${target}
         PRIVATE STDEXEC::stdexec
                 stdexec_executable_flags
@@ -72,11 +75,7 @@ foreach(example ${stdexec_examples})
   def_example(${example})
 endforeach()
 
-if (STDEXEC_BUILD_PARALLEL_SCHEDULER)
-  target_link_libraries(example.sudoku PRIVATE STDEXEC::parallel_scheduler)
-else()
-  target_compile_definitions(example.sudoku PRIVATE STDEXEC_PARALLEL_SCHEDULER_HEADER_ONLY)
-endif()
+target_link_libraries(example.sudoku PRIVATE STDEXEC::parallel_scheduler)
 
 if(STDEXEC_ENABLE_CUDA)
   add_subdirectory(nvexec)

examples/scope.cpp

@@ -100,7 +100,7 @@ auto main() -> int
 
   {
     sender auto nest = scope.nest(begin);
-    auto        op   = connect(std::move(nest), noop_receiver{});
+    auto        op   = stdexec::connect(std::move(nest), noop_receiver{});
     (void) op;
   }
   sync_wait(scope.on_empty());

include/exec/libdispatch_queue.hpp

@@ -16,8 +16,6 @@
 
 #pragma once
 
-#if __has_include(<dispatch/dispatch.h>)
-
 // TODO: This is needed for libdispatch to compile with GCC. Need to look for
 // workaround.
 #  ifndef __has_feature
@@ -524,5 +522,3 @@ namespace experimental::execution
 }  // namespace experimental::execution
 
 namespace exec = experimental::execution;
-
-#endif  // __has_include(<dispatch/dispatch.h>)

include/stdexec/__detail/__env.hpp

@@ -241,8 +241,8 @@ namespace STDEXEC
       noexcept(__nothrow_queryable_with<__1st_env_t<_Query, _Args...>, _Query, _Args...>)
         -> __query_result_t<__1st_env_t<_Query, _Args...>, _Query, _Args...>
     {
-      auto const &__env = __detail::__get_1st_env<_Query, _Args...>()(*this);
-      return __query<_Query>()(__env, static_cast<_Args &&>(__args)...);
+      return __query<_Query>()(__detail::__get_1st_env<_Query, _Args...>()(*this),
+                               static_cast<_Args &&>(__args)...);
     }
   };
 

include/stdexec/__detail/__parallel_scheduler_replacement_api.hpp

@@ -27,7 +27,6 @@ namespace STDEXEC::parallel_scheduler_replacement
 {
   /// Get the backend for the parallel scheduler.
   /// Users might replace this function.
-  STDEXEC_ATTRIBUTE(weak)
   auto query_parallel_scheduler_backend() -> std::shared_ptr<parallel_scheduler_backend>;
 
   /// The type of a factory that can create `parallel_scheduler_backend` instances.

test/CMakeLists.txt

@@ -96,7 +96,6 @@ set_target_properties(common_test_settings PROPERTIES
     )
 target_include_directories(common_test_settings INTERFACE "${CMAKE_CURRENT_LIST_DIR}")
 target_compile_definitions(common_test_settings INTERFACE
-    STDEXEC_NAMESPACE=std::execution
     $<$<PLATFORM_ID:Windows>:NOMINMAX>
     )
 target_compile_options(common_test_settings INTERFACE
@@ -114,6 +113,7 @@ add_compile_diagnostics(test.stdexec)
 target_link_libraries(test.stdexec
     PUBLIC
     STDEXEC::stdexec
+    STDEXEC::parallel_scheduler
     stdexec_executable_flags
     Catch2::Catch2WithMain
     PRIVATE

test/stdexec/schedulers/test_parallel_scheduler.cpp

@@ -16,10 +16,10 @@
 
 #include <thread>
 
-#define STDEXEC_PARALLEL_SCHEDULER_HEADER_ONLY 1
-
 #include <stdexec/execution.hpp>
 
+#include <stdexec/__detail/__parallel_scheduler_default_impl.hpp>
+
 #include <exec/async_scope.hpp>
 #include <exec/inline_scheduler.hpp>
 #include <exec/static_thread_pool.hpp>