Add Windows MinGW tests (#20)

Author: alugowski

.github/workflows/tests.yml

@@ -41,6 +41,11 @@ jobs:
           - os: windows-latest
             # uses MSVC
 
+          - os: windows-latest
+            mingw-version: "13.2.0"
+            description: "MinGW 13"
+            cmake-flags: '-G "MinGW Makefiles"'
+
     steps:
       - uses: actions/checkout@v4
 
@@ -58,6 +63,12 @@ jobs:
         with:
           version: ${{ matrix.gcc-version }}
 
+      - name: Setup MinGW
+        if: contains(matrix.os, 'windows') && matrix.mingw-version != ''
+        run: |
+          choco install --no-progress mingw --version ${{ matrix.mingw-version }}
+          Add-Content $env:GITHUB_PATH "C:\ProgramData\mingw64\mingw64\bin"
+
       - name: Setup LLVM and Clang
         uses: KyleMayes/install-llvm-action@v1
         if: ${{ matrix.llvm-version != '' }}
@@ -73,7 +84,7 @@ jobs:
 
       - name: Build and Test
         run: |
-          cmake -S . -B build/ -DCMAKE_BUILD_TYPE=Debug -DPOOLSTL_TEST=ON -DPOOLSTL_TEST_COVERAGE=ON
+          cmake -S . -B build/ -DCMAKE_BUILD_TYPE=Debug -DPOOLSTL_TEST=ON -DPOOLSTL_TEST_COVERAGE=ON ${{ matrix.cmake-flags }}
           cmake --build build/ --config Debug
           cd build/tests
           ctest -C Debug --output-on-failure --verbose
@@ -85,7 +96,7 @@ jobs:
         # Earliest GCC with all benchmarked methods is 9
         if: matrix.gcc-version != '7' && matrix.gcc-version != '8'
         run: |
-          cmake -S . -B bench_build/ -DCMAKE_BUILD_TYPE=Release -DPOOLSTL_BENCH=ON
+          cmake -S . -B bench_build/ -DCMAKE_BUILD_TYPE=Release -DPOOLSTL_BENCH=ON ${{ matrix.cmake-flags }}
           cmake --build bench_build/ --config Release
           cd bench_build/benchmark/
           ./poolstl_bench || ./Release/poolstl_bench.exe
@@ -101,7 +112,7 @@ jobs:
           cp tools/poolstl.hpp include/poolstl/
           mkdir -p include/poolstl/internal
           cp tools/poolstl.hpp include/poolstl/internal/utils.hpp
-          cmake -S . -B build/ -DCMAKE_BUILD_TYPE=Debug -DPOOLSTL_TEST=ON -DPOOLSTL_TEST_COVERAGE=OFF
+          cmake -S . -B build/ -DCMAKE_BUILD_TYPE=Debug -DPOOLSTL_TEST=ON -DPOOLSTL_TEST_COVERAGE=OFF ${{ matrix.cmake-flags }}
           cmake --build build/ --config Debug
           cd build/tests
           ctest -C Debug --output-on-failure --verbose

README.md

@@ -222,5 +222,12 @@ If not found then poolSTL will alias its `poolstl::par` as `std::execution::par`
 
 Now just use `std::execution::par` as normal, and poolSTL will fill in as necessary. See [supplement_test.cpp](tests/supplement_test.cpp).
 
-Example use case: You *can* link against TBB, so you'll use native support on GCC 9+, Clang, MSVC, etc.
+**Example use case:** You *can* link against TBB, so you'll use native support on GCC 9+, Clang, MSVC, etc.
 PoolSTL will fill in automatically on GCC <9 and Apple Clang.
+
+**Example use case 2:** You'd *prefer* to use the TBB version, but don't want to fail on systems that don't have it.
+Simply use the supplement as above, but have your build system (CMake, meson, etc.) check for TBB.
+If not found define `POOLSTL_STD_SUPPLEMENT_NO_INCLUDE`.  
+
+If defined, the supplement will not `#include <execution>` (and neither should your code!),
+thus dropping the TBB link requirement. The poolSTL supplement fills in. See the supplement section of [tests/CMakeLists.txt](tests/CMakeLists.txt) for an example.

benchmark/CMakeLists.txt

@@ -6,6 +6,12 @@ if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STR
     set(CMAKE_CXX_FLAGS_RELEASE "-g -O3 -DNDEBUG")
 endif ()
 
+if (MINGW AND WIN32)
+    # MinGW on GitHub Actions requires these.
+    # If omitted the executable crashes with 'Exit code 0xc0000139' which appears to mean a missing DLL.
+    add_link_options("-static-libstdc++" "-static-libgcc")
+endif()
+
 include(FetchContent)
 
 # Add Google Benchmark
@@ -33,7 +39,7 @@ add_executable(poolstl_bench
 target_link_libraries(poolstl_bench benchmark::benchmark poolSTL::poolSTL)
 target_compile_features(poolstl_bench PUBLIC cxx_std_17)
 
-if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
+if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" OR ("${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU" AND NOT MINGW))
     # GCC and Clang require TBB for native std::execution::par
     find_package(TBB)
     if (TBB_FOUND)
@@ -42,10 +48,9 @@ if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STR
         target_compile_definitions(poolstl_bench PUBLIC POOLSTL_BENCH_STD_PAR)
     else()
         message("No TBB")
-        # No TBB means cannot use std::execution::par
-        unset(HAVE_STD_EXECUTION_PAR)
     endif()
 else()
-    # MSVC requires nothing
+    # MSVC requires nothing.
+    # MinGW also requires nothing to compile std::execution::par, but performance appears to be the same as sequential.
     target_compile_definitions(poolstl_bench PUBLIC POOLSTL_BENCH_STD_PAR)
 endif()

include/poolstl/poolstl.hpp

@@ -27,8 +27,21 @@
  *
  * To use this define POOLSTL_STD_SUPPLEMENT=1 before including poolstl.hpp.
  *
- * This aliasing will not happen if native support exists. If this autodetection fails for you,
- * define POOLSTL_ALLOW_SUPPLEMENT=0 to disable this feature.
+ * Attempts to autodetect native support by checking for <execution>, including it if it exists, and then checking for
+ * the __cpp_lib_parallel_algorithm feature macro.
+ *
+ * If native support is not found then the standard execution policies are declared as forwards to poolSTL.
+ *
+ * GCC and Clang: TBB is required if <execution> is #included. If you'd like to use the poolSTL supplement in cases
+ * that TBB is not available, have your build system define POOLSTL_STD_SUPPLEMENT_NO_INCLUDE if TBB is not found.
+ * PoolSTL will then not include <execution> and the supplement will kick in.
+ * Your code must not #include <execution>.
+ *
+ * MinGW: the compiler declares support, but actual performance is sequential (see poolSTL benchmark). To use
+ * the supplement anyway define POOLSTL_STD_SUPPLEMENT_FORCE to override the autodetection.
+ * Your code must not #include <execution>.
+ *
+ * Define POOLSTL_ALLOW_SUPPLEMENT=0 to override POOLSTL_STD_SUPPLEMENT and disable this feature.
  */
 #ifndef POOLSTL_ALLOW_SUPPLEMENT
 #define POOLSTL_ALLOW_SUPPLEMENT 1
@@ -38,11 +51,13 @@
 
 #if __cplusplus >= 201603L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201603L)
 #if __has_include(<execution>)
+#ifndef POOLSTL_STD_SUPPLEMENT_NO_INCLUDE
 #include <execution>
 #endif
 #endif
+#endif
 
-#if !defined(__cpp_lib_parallel_algorithm)
+#if !defined(__cpp_lib_parallel_algorithm) || defined(POOLSTL_STD_SUPPLEMENT_FORCE)
 namespace std {
     namespace execution {
         using ::poolstl::execution::sequenced_policy;

tests/CMakeLists.txt

@@ -2,9 +2,25 @@
 cmake_minimum_required(VERSION 3.11...3.26)
 enable_testing()
 
-# Be pedantic for clean code
-if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
-    set(CMAKE_CXX_FLAGS_DEBUG "-g -Wall -Wextra -pedantic")
+if (WIN32)
+    # Need bigobj because some tests use lots of templates
+    if (MSVC)
+        add_compile_options("/bigobj")
+    elseif(MINGW)
+        # Also add -Os to reduce maximum filesize
+        add_compile_options("-Wa,-mbig-obj" "-Os")
+    endif()
+else()
+    # Be pedantic for clean code
+    if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
+        add_compile_options("-g" "-Wall" "-Wextra" "-pedantic")
+    endif()
+endif()
+
+if (MINGW AND WIN32)
+    # The MinGW on GitHub Actions requires these.
+    # If omitted some executables crash with 'Exit code 0xc0000139' which appears to mean a missing DLL.
+    add_link_options("-static-libstdc++" "-static-libgcc")
 endif()
 
 # Code Coverage
@@ -55,19 +71,26 @@ add_executable(cpp11_test cpp11_test.cpp)
 target_link_libraries(cpp11_test PUBLIC poolSTL::poolSTL)
 target_compile_features(cpp11_test PUBLIC cxx_std_11)
 
-# Test std::execution supplementation
-# This uses only std::execution::par. On compilers with support this should result in a poolSTL no-op,
-# and on ones without support it should use fallback to poolstl::par.
+# Test std::execution supplementation.
+# The test code uses only std::execution::par, seq, and par_unseq.
+# On compilers with support poolSTL does nothing, else poolSTL creates a fallback using poolstl::par.
 add_executable(supplement_test supplement_test.cpp)
 target_link_libraries(supplement_test PUBLIC poolSTL::poolSTL)
 target_compile_features(supplement_test PUBLIC cxx_std_17)
 if ("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang" OR "${CMAKE_CXX_COMPILER_ID}" STREQUAL "GNU")
-    # GCC and Clang require TBB for std::execution::par
+    # GCC and Clang require TBB for std::execution::par.
+    # MinGW will compile std::execution::par without TBB, but performance is sequential.
     find_package(TBB)
     if (TBB_FOUND)
         target_link_libraries(supplement_test PUBLIC TBB::tbb)
     else()
         message("No TBB")
-        target_compile_definitions(supplement_test PUBLIC POOLSTL_MISSING_NEEDED_TBB)
+        # Prevent including <execution>, as doing that requires linking against TBB on newer GCC/Clang.
+        target_compile_definitions(supplement_test PUBLIC POOLSTL_STD_SUPPLEMENT_NO_INCLUDE)
+        if (MINGW)
+            # extra hack!
+            # MinGW declares support, so must override poolSTL's auto-detection to enable the supplement.
+            target_compile_definitions(supplement_test PUBLIC POOLSTL_STD_SUPPLEMENT_FORCE)
+        endif()
     endif()
 endif()

tests/supplement_test.cpp

@@ -10,7 +10,9 @@
 // The <execution> header defines compiler-provided execution policies, but is not always present.
 #if __cplusplus >= 201603L || (defined(_MSVC_LANG) && _MSVC_LANG >= 201603L)
 #if __has_include(<execution>)
-#ifndef POOLSTL_MISSING_NEEDED_TBB
+#ifndef POOLSTL_STD_SUPPLEMENT_NO_INCLUDE
+// On GCC and Clang simply including <execution> requires linking with TBB.
+// MinGW does not require TBB, but performance may be sequential. To keep parallel performance fallback to poolSTL.
 #include <execution>
 #endif
 #endif