sisl: ship stdexec as a real conan dependency (3rd_party recipe)

3rd_party/stdexec/conandata.yml

@@ -0,0 +1,7 @@
+sources:
+  # NVIDIA stdexec, commit ea0d8788 (release nvhpc-25.09) -- the exact revision the in-tree
+  # FetchContent blocks (iomgr/nuraft_mesg/homestore) pin, so the conan-provided headers and the
+  # in-tree headers are byte-identical.
+  "25.09":
+    url: "https://github.com/NVIDIA/stdexec/archive/ea0d8788da51a1671daa00b88bf238725f0844a8.tar.gz"
+    sha256: "aa68f58be9854305fa09e7310ca3f4d79efb948c3df93b8904d3645be9a34751"

3rd_party/stdexec/conanfile.py

@@ -0,0 +1,52 @@
+import os
+
+from conan import ConanFile
+from conan.tools.files import copy, get
+from conan.tools.layout import basic_layout
+
+required_conan_version = ">=2.0"
+
+
+class StdexecConan(ConanFile):
+    name = "stdexec"
+    description = "NVIDIA reference implementation of std::execution (P2300): senders/receivers + coroutines"
+    license = "Apache-2.0 WITH LLVM-exception"
+    url = "https://github.com/NVIDIA/stdexec"
+    homepage = "https://github.com/NVIDIA/stdexec"
+    topics = ("execution", "p2300", "senders", "coroutines", "header-only")
+
+    # Header-only: the package is one binary for all settings (see package_id), but we keep
+    # settings so package_info() can branch on the consumer's compiler for warning flags.
+    package_type = "header-library"
+    settings = "os", "arch", "compiler", "build_type"
+    no_copy_source = True
+
+    def layout(self):
+        basic_layout(self, src_folder="src")
+
+    def package_id(self):
+        self.info.clear()
+
+    def source(self):
+        get(self, **self.conan_data["sources"][self.version], strip_root=True)
+
+    def package(self):
+        copy(self, "LICENSE*", src=self.source_folder,
+             dst=os.path.join(self.package_folder, "licenses"))
+        copy(self, "*", src=os.path.join(self.source_folder, "include"),
+             dst=os.path.join(self.package_folder, "include"))
+
+    def package_info(self):
+        self.cpp_info.bindirs = []
+        self.cpp_info.libdirs = []
+        # stdexec's <execution> include pulls libstdc++'s PSTL, which defaults to the TBB backend;
+        # force the serial backend so consumers don't have to link TBB. Mirrors the in-tree
+        # stdexec_iface targets in iomgr/nuraft_mesg/homestore.
+        self.cpp_info.defines = ["_PSTL_PAR_BACKEND_SERIAL"]
+        # stdexec internals trip a couple of warnings; suppress so -Werror consumers still build.
+        # -Wsubobject-linkage is gcc-only -- clang rejects it as an unknown warning option.
+        compiler = str(self.settings.compiler)
+        if compiler == "gcc":
+            self.cpp_info.cxxflags = ["-Wno-empty-body", "-Wno-subobject-linkage"]
+        elif compiler == "clang":
+            self.cpp_info.cxxflags = ["-Wno-empty-body"]

conanfile.py

@@ -3,13 +3,14 @@
 from conan.tools.build import check_min_cppstd
 from conan.tools.cmake import CMakeToolchain, CMakeDeps, CMake
 from conan.tools.files import copy
+from conan.tools.scm import Version
 from os.path import join
 
 required_conan_version = ">=2.0"
 
 class SISLConan(ConanFile):
     name = "sisl"
-    version = "14.4.0"
+    version = "14.4.1"
 
     homepage = "https://github.com/eBay/sisl"
     description = "Library for fast data structures, utilities"
@@ -52,6 +53,15 @@ class SISLConan(ConanFile):
     def _min_cppstd(self):
         return 23
 
+    def _use_breakpad(self):
+        # breakpad/cci.20210521 is frozen (2021) and fails to build with gcc >= 16; keep it for the
+        # other Linux/libstdc++ toolchains it does support.
+        if self.settings.os not in ["Linux"] or self.settings.compiler.get_safe("libcxx") == "libc++":
+            return False
+        if self.settings.compiler == "gcc" and Version(self.settings.compiler.version) >= "16":
+            return False
+        return True
+
     def validate(self):
         if self.settings.compiler.get_safe("cppstd"):
             check_min_cppstd(self, self._min_cppstd())
@@ -83,8 +93,11 @@ def requirements(self):
         self.requires("nlohmann_json/3.12.0", transitive_headers=True)
         self.requires("spdlog/1.17.0", transitive_headers=True)
         self.requires("zmarok-semver/1.1.0", transitive_headers=True)
+        # Public sisl/async coroutine headers (task.hpp/when_all.hpp) include <exec/...>; ship stdexec
+        # transitively so package consumers resolve it without their own FetchContent.
+        self.requires("stdexec/25.09", transitive_headers=True)
         self.requires("lz4/1.10.0", override=True)
-        if self.settings.os in ["Linux"] and self.settings.compiler.get_safe("libcxx") != "libc++":
+        if self._use_breakpad():
             self.requires("breakpad/cci.20210521")
 
         # ARM needs unreleased versionof libunwind
@@ -237,7 +250,7 @@ def package_info(self):
                 "nlohmann_json::nlohmann_json",
                 "spdlog::spdlog",
                 ])
-        if self.settings.os in ["Linux"] and self.settings.compiler.get_safe("libcxx") != "libc++":
+        if self._use_breakpad():
             self.cpp_info.components["logging"].requires.append("breakpad::breakpad")
         self.cpp_info.components["sobject"].requires.extend([
                 "logging",
@@ -251,7 +264,9 @@ def package_info(self):
                 "logging",
                 "zmarok-semver::zmarok-semver",
                 ])
-        sisl_requires = ["sobject", "version"]
+        # sisl/async coroutine headers (task.hpp/when_all.hpp) include <exec/...>; the umbrella component
+        # carries the dependency so consumers of sisl::sisl resolve stdexec.
+        sisl_requires = ["sobject", "version", "stdexec::stdexec"]
         if self.settings.os in ["Linux"]:
             sisl_requires.append("file_watcher")
         self.cpp_info.components["sisl"].requires.extend(sisl_requires)

prepare_v2.sh

@@ -3,4 +3,6 @@ set -eu
 echo -n "Exporting custom recipes..."
 echo -n "userspace rcu."
 conan export 3rd_party/userspace-rcu --name userspace-rcu --version nu2.0.14.0 >/dev/null
+echo -n "stdexec."
+conan export 3rd_party/stdexec --name stdexec --version 25.09 >/dev/null
 echo " done."

src/async/CMakeLists.txt

@@ -1,9 +1,8 @@
 cmake_minimum_required(VERSION 3.11)
 
-# sisl_async is header-only; the tests below need stdexec available in
-# the sisl build. The wiring is up to the consumer (FetchContent in a
-# feature branch today, a Conan recipe later); this CMakeLists is
-# inert if stdexec hasn't been declared as a target yet.
+# sisl_async is header-only; the tests below need stdexec, now provided by the conan package
+# (sisl requires stdexec/25.09 -> the stdexec::stdexec target; see 3rd_party/stdexec). find_package
+# is QUIET + gated so a non-conan build without stdexec just skips these tests rather than failing.
 #
 # disk_task tests have no stdexec dependency — compile unconditionally.
 add_executable(test_disk_task)
@@ -18,13 +17,14 @@ target_sources(test_value_awaitable PRIVATE tests/test_value_awaitable.cpp)
 target_link_libraries(test_value_awaitable PRIVATE GTest::gtest GTest::gtest_main)
 add_test(NAME ValueAwaitable COMMAND test_value_awaitable)
 
-if (TARGET stdexec)
+find_package(stdexec QUIET)
+if (TARGET stdexec::stdexec)
     add_executable(test_cqe_awaitable)
     target_sources(test_cqe_awaitable PRIVATE
         tests/test_cqe_awaitable.cpp
     )
     target_link_libraries(test_cqe_awaitable PRIVATE
-        stdexec
+        stdexec::stdexec
         GTest::gtest
         GTest::gtest_main
     )
@@ -35,7 +35,7 @@ if (TARGET stdexec)
         tests/test_manual_scheduler.cpp
     )
     target_link_libraries(test_manual_scheduler PRIVATE
-        stdexec
+        stdexec::stdexec
         GTest::gtest
         GTest::gtest_main
     )