link against hpx_core

CMakeLists.txt

@@ -1,6 +1,7 @@
 # Copyright (c)      2020 Mikael Simberg
 # Copyright (c) 2007-2024 Hartmut Kaiser
 # Copyright (c) 2011-2014 Thomas Heller
+# Copyright (c)      2024 Isidoros Tsaousis-Seiras
 # Copyright (c) 2007-2008 Chirag Dekate
 # Copyright (c)      2011 Bryce Lelbach
 # Copyright (c)      2011 Vinay C Amatya
@@ -589,25 +590,37 @@ hpx_option(
   ADVANCED
 )
 
-# if STDEXEC_ROOT was provided, HPX_WITH_STDEXEC is set to ON
-if(STDEXEC_ROOT OR HPX_WITH_FETCH_STDEXEC)
+if(Stdexec_ROOT OR HPX_WITH_FETCH_STDEXEC)
+  # explicitly enable HPX_WITH_STDEXEC
   set(HPX_WITH_STDEXEC ON)
 
-  hpx_add_config_define(HPX_HAVE_STDEXEC)
+  # prefer Stdexec_ROOT over HPX_WITH_FETCH_STDEXEC by default
+  if(Stdexec_ROOT AND HPX_WITH_FETCH_STDEXEC)
+    set(HPX_WITH_FETCH_STDEXEC OFF)
+    hpx_warn(
+      "Both Stdexec_ROOT and HPX_WITH_FETCH_STDEXEC are provided. HPX_WITH_FETCH_STDEXEC is set to OFF."
+    )
+  endif()
 elseif(HPX_WITH_STDEXEC)
   hpx_error(
-    "HPX_WITH_STDEXEC is set to ON, but STDEXEC_ROOT is not provided. Please provide STDEXEC_ROOT or set HPX_WITH_FETCH_STDEXEC to ON."
+    "HPX_WITH_STDEXEC is set to ON, but Stdexec_ROOT is not provided and HPX_WITH_FETCH_STDEXEC is not enabled. Please provide Stdexec_ROOT or set HPX_WITH_FETCH_STDEXEC to ON."
   )
 endif()
 
-if(HPX_WITH_STDEXEC)
-  # need cxx20 and over
-  if(HPX_WITH_CXX_STANDARD LESS 20)
-    hpx_error(
-      "HPX_WITH_STDEXEC is set to ON, but HPX_WITH_CXX_STANDARD is less than 20. Please set HPX_WITH_CXX_STANDARD to 20 or higher."
-    )
-  endif()
-  hpx_info("STDEXEC is enabled.")
+# STDEXEC requires C++20
+if(HPX_WITH_STDEXEC AND HPX_WITH_CXX_STANDARD LESS 20)
+  hpx_error(
+  "HPX_WITH_STDEXEC is set to ON, but HPX_WITH_CXX_STANDARD is less than 20. Please set HPX_WITH_CXX_STANDARD to 20 or higher."
+  )
+endif()
+
+if(HPX_WITH_FETCH_STDEXEC)
+  hpx_option(
+    HPX_WITH_STDEXEC_TAG
+    STRING "STDEXEC repository tag or branch"
+    "main"
+    CATEGORY "Executor"
+  )
 endif()
 
 # ##############################################################################

cmake/FindStdexec.cmake

@@ -1,3 +1,8 @@
+#  Copyright (c) 2024 Isidoros Tsaousis-Seiras
+#
+#  SPDX-License-Identifier: BSL-1.0
+#  Distributed under the Boost Software License, Version 1.0. (See accompanying
+#  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
 if(NOT TARGET STDEXEC::stdexec)
   if (STDEXEC_ROOT AND NOT Stdexec_ROOT)
@@ -29,8 +34,5 @@ if(NOT TARGET STDEXEC::stdexec)
     add_library(STDEXEC::stdexec INTERFACE IMPORTED)
     target_include_directories(STDEXEC::stdexec SYSTEM INTERFACE ${Stdexec_INCLUDE_DIR})
 
-
-
-
     mark_as_advanced(Stdexec_INCLUDE_DIR Stdexec_ROOT)
 endif()

cmake/HPX_SetupStdexec.cmake

@@ -1,34 +1,37 @@
-if(STDEXEC_ROOT AND NOT Stdexec_ROOT)
-    set(Stdexec_ROOT
-        ${STDEXEC_ROOT}
-        CACHE PATH "STDEXEC base directory"
-    )
-    unset(STDEXEC_ROOT CACHE)
-endif()
+#  Copyright (c) 2024 Isidoros Tsaousis-Seiras
+#
+#  SPDX-License-Identifier: BSL-1.0
+#  Distributed under the Boost Software License, Version 1.0. (See accompanying
+#  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
 
-if(HPX_WITH_FETCH_STDEXEC AND NOT Stdexec_ROOT)
-    hpx_info(
-        "HPX_WITH_FETCH_STDEXEC=${HPX_WITH_FETCH_STDEXEC}, Stdexec will be fetched using CMake's FetchContent."
-    )
-    if(UNIX)
-        include(FetchContent)
-        FetchContent_Declare(
-            Stdexec
-            GIT_REPOSITORY https://github.com/NVIDIA/stdexec.git
-            GIT_TAG        main
+if(HPX_WITH_STDEXEC AND NOT TARGET STDEXEC::stdexec)
+    hpx_add_config_define(HPX_HAVE_STDEXEC)
+
+    if(HPX_WITH_FETCH_STDEXEC)
+        hpx_info(
+            "HPX_WITH_FETCH_STDEXEC=${HPX_WITH_FETCH_STDEXEC}, Stdexec will be fetched using CMake's FetchContent."
         )
-        FetchContent_MakeAvailable(Stdexec)
-    endif()
+        if(UNIX)
+            include(FetchContent)
+            message("FETCHING STDEXEC")
+            FetchContent_Declare(
+                Stdexec
+                GIT_REPOSITORY https://github.com/NVIDIA/stdexec.git
+                GIT_TAG        ${HPX_WITH_STDEXEC_TAG}
+            )
+            FetchContent_MakeAvailable(Stdexec)
+        endif()
 
-    add_library(STDEXEC::stdexec INTERFACE IMPORTED)
-    target_include_directories(STDEXEC::stdexec INTERFACE ${stdexec_SOURCE_DIR}/include)
-    target_link_libraries(STDEXEC::stdexec INTERFACE ${Stdexec_LIBRARY})
-elseif(HPX_WITH_STDEXEC)
-    find_package(Stdexec REQUIRED)
+        # add_library(STDEXEC::stdexec INTERFACE IMPORTED)
+        # target_include_directories(STDEXEC::stdexec INTERFACE ${stdexec_SOURCE_DIR})
+        # target_link_libraries(STDEXEC::stdexec INTERFACE ${Stdexec_LIBRARY})
+    else()
+        find_package(Stdexec REQUIRED)
 
-    if(NOT Stdexec_FOUND)
-        hpx_error(
-            "Stdexec could not be found, please specify Stdexec_ROOT to point to the correct location"
-        )
+        if(NOT Stdexec_FOUND)
+            hpx_error(
+                "Stdexec could not be found, please specify Stdexec_ROOT to point to the correct location"
+            )
+        endif()
     endif()
 endif()

libs/CMakeLists.txt

@@ -113,6 +113,11 @@ if(TARGET APEX::apex)
   target_link_libraries(hpx_full INTERFACE APEX::apex)
 endif()
 
+# Do I need this here?
+# if(TARGET STDEXEC::stdexec)
+#   target_link_libraries(hpx_full INTERFACE STDEXEC::stdexec)
+# endif()
+
 if(TARGET Gperftools::gperftools)
   target_link_libraries(hpx_full PRIVATE Gperftools::gperftools)
 endif()
@@ -376,6 +381,10 @@ if(HPX_WITH_ITTNOTIFY)
   target_link_libraries(hpx_core PUBLIC Amplifier::amplifier)
 endif()
 
+if(TARGET STDEXEC::stdexec)
+  target_link_libraries(hpx_core INTERFACE STDEXEC::stdexec)
+endif()
+
 if(HPX_WITH_PARCELPORT_GASNET AND GASNET_LIBRARY_DIRS)
   target_link_directories(hpx_core PUBLIC ${GASNET_LIBRARY_DIRS})
 endif()