fix: static-link all dependencies into wsjtx_core.dll on Windows

Statically links MinGW runtimes (libgcc, libstdc++, libgfortran,
libquadmath, libwinpthread) and FFTW into wsjtx_core.dll so it only
depends on KERNEL32.dll and msvcrt.dll. This eliminates DLL conflicts
when the user's PATH contains a different MinGW/MSYS2 installation.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: boybook

.github/workflows/build.yml

@@ -109,11 +109,9 @@ jobs:
         if: runner.os == 'Windows'
         shell: msys2 {0}
         run: |
-          # Copy wsjtx_core.dll and MinGW runtime DLLs to build/Release
+          # All dependencies (FFTW, MinGW runtimes) are statically linked into
+          # wsjtx_core.dll — only system DLLs (KERNEL32, msvcrt) remain as imports
           cp build-core/Release/wsjtx_core.dll build/Release/
-          for dll in libgfortran-5.dll libgcc_s_seh-1.dll libstdc++-6.dll libwinpthread-1.dll libfftw3f-3.dll libfftw3f_threads-3.dll libquadmath-0.dll; do
-            [ -f "/mingw64/bin/$dll" ] && cp "/mingw64/bin/$dll" build/Release/
-          done
 
       # Test
       - name: Run tests (Linux/macOS)
@@ -180,9 +178,7 @@ jobs:
           mkdir -p "$TARGET_DIR"
           cp build/Release/wsjtx_lib_nodejs.node "$TARGET_DIR/"
           cp build/Release/wsjtx_core.dll "$TARGET_DIR/"
-          cp build/Release/*.dll "$TARGET_DIR/" 2>/dev/null || true
 
-          # build-info.json
           cat > "$TARGET_DIR/build-info.json" <<EOF
           {"platform":"${{ matrix.platform }}","arch":"${{ matrix.arch }}","build_time":"$(date -u +%Y-%m-%dT%H:%M:%SZ)"}
           EOF

CMakeLists.txt

@@ -276,27 +276,35 @@ target_include_directories(wsjtx_core PRIVATE
     ${Boost_INCLUDE_DIRS}
 )
 
-target_link_libraries(wsjtx_core PRIVATE
-    wsjtx_lib
-    ${FFTW3F_LIBRARIES}
-)
+target_link_libraries(wsjtx_core PRIVATE wsjtx_lib)
 
 # Platform-specific linking for wsjtx_core
 if(APPLE)
-    target_link_libraries(wsjtx_core PRIVATE "-framework Accelerate" gfortran gcc_s.1)
+    target_link_libraries(wsjtx_core PRIVATE
+        ${FFTW3F_LIBRARIES} "-framework Accelerate" gfortran gcc_s.1)
     if(FFTW_HAS_THREADS)
         target_link_libraries(wsjtx_core PRIVATE fftw3f_threads)
     endif()
 elseif(UNIX)
-    target_link_libraries(wsjtx_core PRIVATE gfortran gcc_s pthread)
+    target_link_libraries(wsjtx_core PRIVATE
+        ${FFTW3F_LIBRARIES} gfortran gcc_s pthread)
     if(FFTW_HAS_THREADS)
         target_link_libraries(wsjtx_core PRIVATE fftw3f_threads)
     endif()
 elseif(WIN32)
-    target_link_libraries(wsjtx_core PRIVATE gfortran gcc_s pthread)
-    if(FFTW_HAS_THREADS)
-        target_link_libraries(wsjtx_core PRIVATE fftw3f_threads)
-    endif()
+    # Static-link ALL non-system dependencies so wsjtx_core.dll only depends
+    # on Windows system DLLs (KERNEL32.dll, msvcrt.dll). This prevents DLL
+    # conflicts when the user's PATH contains a different MinGW installation.
+    target_link_options(wsjtx_core PRIVATE
+        -static-libgcc
+        -static-libstdc++
+    )
+    target_link_libraries(wsjtx_core PRIVATE
+        -Wl,-Bstatic
+        -lfftw3f -lfftw3f_threads
+        -lgfortran -lquadmath -lwinpthread
+        -Wl,-Bdynamic
+    )
 endif()
 
 # Output wsjtx_core to build/Release alongside .node