Build on Windows with MSVC

.github/workflows/ci.yml

@@ -75,6 +75,60 @@ jobs:
           retention-days: 1
           if-no-files-found: error
 
+  # -----------------------------------------------------------------------
+  # build-windows: the same build under MSVC.
+  #
+  # Everything else in this file is ubuntu-only, so nothing here has ever
+  # compiled with MSVC, and portability breaks land silently: __attribute__,
+  # naming an automatic constexpr from a captureless lambda, and POSIX-only
+  # calls all build clean on gcc and stop MSVC on the first file.
+  #
+  # CPU only, no model downloads — this guards the compile, not the numbers,
+  # which the ubuntu smoke-test job already covers. GGML_NATIVE=ON matches the
+  # ubuntu build job: CI only has to run on its own runner.
+  # -----------------------------------------------------------------------
+  build-windows:
+    name: Build & unit tests (MSVC)
+    runs-on: windows-2022
+    timeout-minutes: 30
+    steps:
+      - name: Checkout (with submodules)
+        uses: actions/checkout@v4
+        with:
+          submodules: recursive
+
+      # The CMake configure-time hook shells out to bash, which is not on PATH
+      # in the MSVC environment; run it explicitly first.
+      - name: Apply ggml patches (Git Bash)
+        shell: bash
+        run: bash scripts/apply_ggml_patches.sh
+
+      - name: MSVC environment
+        uses: ilammy/msvc-dev-cmd@v1
+
+      - name: Configure CMake
+        shell: bash
+        run: |
+          cmake -B build -G Ninja \
+            -DCMAKE_BUILD_TYPE=Release \
+            -DRFDETR_BUILD_TESTS=ON \
+            -DRFDETR_BUILD_CLI=ON \
+            -DGGML_NATIVE=ON
+
+      - name: Build
+        shell: bash
+        run: cmake --build build -j
+
+      - name: Run unit tests
+        shell: bash
+        run: ctest --test-dir build --output-on-failure
+
+      - name: Usage banner
+        shell: bash
+        run: |
+          out=$(./build/bin/rfdetr-cli.exe 2>&1 || true)
+          grep -qi usage <<<"$out"
+
   # -----------------------------------------------------------------------
   # smoke-test: download nano (all 4 quants) + base-f16 from HF, run detect
   # on a committed test image, compare JSON output against committed refs.

examples/cli/main.cpp

@@ -11,7 +11,9 @@
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
+#include <filesystem>
 #include <fstream>
+#include <system_error>
 #include <sstream>
 #include <string>
 #include <sys/stat.h>
@@ -131,13 +133,15 @@ static int cmd_detect(const rfdetr_cli::DetectArgs& a) {
 
     /* 7. Optional per-detection mask PNGs (seg models only). */
     if (!a.masks_dir.empty()) {
-        /* Create the masks directory if it doesn't exist. */
-        struct stat st_buf;
-        if (::stat(a.masks_dir.c_str(), &st_buf) != 0) {
-            if (::mkdir(a.masks_dir.c_str(), 0755) != 0) {
-                std::fprintf(stderr, "failed to create masks dir '%s'\n",
-                             a.masks_dir.c_str());
-            }
+        /* Create the masks directory if it doesn't exist. std::filesystem
+         * rather than stat + ::mkdir: MSVC has no POSIX mkdir (only _mkdir,
+         * in <direct.h>), and create_directories already succeeds silently
+         * when the directory is there, so the stat probe goes with it. */
+        std::error_code mkdir_ec;
+        std::filesystem::create_directories(a.masks_dir, mkdir_ec);
+        if (mkdir_ec) {
+            std::fprintf(stderr, "failed to create masks dir '%s'\n",
+                         a.masks_dir.c_str());
         }
         size_t n_written = 0;
         for (size_t i = 0; i < n; ++i) {

src/common.hpp

@@ -9,8 +9,19 @@
  * in tests without needing to include this header. */
 void rfdetr_internal_log(rfdetr_log_level lvl, const char* msg);
 
+/* Format-string checking where the compiler offers it. MSVC does not
+ * understand __attribute__, and MinGW's printf is the gnu_printf dialect —
+ * the same three cases ggml.h handles with GGML_ATTRIBUTE_FORMAT. */
+#ifndef __GNUC__
+#    define RFDETR_ATTRIBUTE_FORMAT(...)
+#elif defined(__MINGW32__) && !defined(__clang__)
+#    define RFDETR_ATTRIBUTE_FORMAT(...) __attribute__((format(gnu_printf, __VA_ARGS__)))
+#else
+#    define RFDETR_ATTRIBUTE_FORMAT(...) __attribute__((format(printf, __VA_ARGS__)))
+#endif
+
 /* printf-style wrapper. Builds the string then dispatches. */
 void rfdetr_logf(rfdetr_log_level lvl, const char* fmt, ...)
-    __attribute__((format(printf, 2, 3)));
+    RFDETR_ATTRIBUTE_FORMAT(2, 3);
 
 #endif

src/model_loader.cpp

@@ -116,7 +116,10 @@ bool get_bool(gguf_context* g, const char* key, bool& out) {
  * with A = -0.5 for antialias=True. */
 void bicubic_resample_patch_grid(const float* src, int src_side, int dim,
                                  float* dst, int dst_side) {
-    constexpr float A = -0.5f;  // antialias=True path uses Keys, not Catmull-Rom
+    /* `static` so the captureless lambda below can name it: MSVC rejects an
+     * automatic constexpr there (C3493) where gcc/clang accept it. Static
+     * storage duration needs no capture, and is portable. */
+    static constexpr float A = -0.5f;  // antialias=True path uses Keys, not Catmull-Rom
     auto kernel = [](float x) -> float {
         const float ax = std::fabs(x);
         if (ax < 1.0f) {

tests/CMakeLists.txt

@@ -38,7 +38,10 @@ rfdetr_add_test(test_visualize)
 
 rfdetr_add_test(test_cli_smoke)
 
-if(TARGET rfdetr-cli)
+# test_cli_integration drives the CLI as a child process through <sys/wait.h>,
+# so it is POSIX-only. Everything else in this directory is portable; excluding
+# just this one keeps the rest of the suite running under MSVC.
+if(TARGET rfdetr-cli AND NOT WIN32)
     rfdetr_add_test(test_cli_integration)
     target_compile_definitions(test_cli_integration PRIVATE
         RFDETR_CLI_BINARY="$<TARGET_FILE:rfdetr-cli>")