fix(compat.opencv): dnn is a per-OS feature on linux+macOS only (windows mlas x86 .S is GAS/ELF — clang-cl can't emit COFF); drop dead opencl_kernels flag-globs (inert, unwarn); revert windows dnn test

Author: Sunrisepeak

pkgs/c/compat.opencv.lua

@@ -18,8 +18,3 @@ opencv = { version = "5.0.0", features = ["dnn"] }
 [target.'cfg(macos)'.dependencies.compat]
 opencv = { version = "5.0.0", features = ["dnn"] }
 
-# windows-x86_64 dnn: clang-cl builds the same x86 dnn delta (mlas/lib/x86_64 +
-# avx/avx2/avx512 kernels) as linux; dnn + vendored protobuf compile clean under
-# clang-cl (CI-verified).
-[target.'cfg(windows)'.dependencies.compat]
-opencv = { version = "5.0.0", features = ["dnn"] }

tests/examples/opencv-dnn/mcpp.toml

@@ -4,7 +4,7 @@
 // dnn feature assertion: blobFromImage produces a correctly-shaped and
 // correctly-valued NCHW blob (exercises dnn core + the whole protobuf/mlas
 // link closure), and an empty Net constructs. Linux-only (see mcpp.toml).
-#if defined(__linux__) || defined(__APPLE__) || defined(_WIN32)
+#if defined(__linux__) || defined(__APPLE__)
 #include <opencv2/core.hpp>
 #include <opencv2/dnn.hpp>
 #include <cstdio>

tests/examples/opencv-dnn/tests/opencv_dnn_feature.cpp

@@ -19,6 +19,3 @@ opencv = { version = "0.0.6", features = ["dnn"] }
 [target.'cfg(macos)'.dependencies]
 opencv = { version = "0.0.6", features = ["dnn"] }
 
-# windows: `import opencv.dnn;` on windows-x86_64 (clang-cl).
-[target.'cfg(windows)'.dependencies]
-opencv = { version = "0.0.6", features = ["dnn"] }

tests/examples/opencv-module-dnn/mcpp.toml

@@ -4,7 +4,7 @@
 // Linux-only (see mcpp.toml). Not named dnn.cpp (would collide with the dep's
 // modules/dnn/src/dnn.cpp — #240 family). Import-only (import std + the opencv
 // modules): no textual headers, matching the ffmpeg-module member convention.
-#if defined(__linux__) || defined(__APPLE__) || defined(_WIN32)
+#if defined(__linux__) || defined(__APPLE__)
 import std;
 import opencv.cv;
 import opencv.dnn;

tests/examples/opencv-module-dnn/tests/opencv_dnn_iface.cpp

@@ -440,9 +440,12 @@ def is_dnn_glob(g):
     g = (g[:-3] if g.endswith("/**") else g) + f"/**/*.{isa}.cpp"
     (dnn_flags_entries if dk in FEATURE_DNN_GROUPS else flags_entries).append(
         f'{{ glob = "{g}", defines = {{ {ds} }}, cxxflags = {{ {ms} }} }},')
-for mod, dk in sorted(kernel_files):
-    flags_entries.append(
-        f'{{ glob = "**/clsrc/opencl_kernels_{mod}.cpp", ' + defines_lua(dir_defs[dk]) + " },")
+# NOTE: no per-file flags for clsrc/opencl_kernels_<m>.cpp. build.mcpp writes
+# them (cl2cpp) but leaves them INERT — OpenCL is OFF in this headless profile,
+# so they are never registered as compiled sources (no `mcpp:generated=`). A
+# flag-glob for them therefore matches nothing and mcpp 0.0.101 warns
+# "[build].flags glob '**/clsrc/opencl_kernels_*.cpp' matched no source file".
+# (kernel_files is still tracked for the TU count above.)
 for g, extra in sorted(per_file_flag_entries):
     (dnn_flags_entries if is_dnn_glob(g) else flags_entries).append(
         f'{{ glob = "{g}", ' + defines_lua(extra) + " },")

tools/compat-opencv/gen_descriptor.py

@@ -159,6 +159,14 @@ local function is_unistd_platform_flag(f)
     return type(f) == "table" and type(f.glob) == "string"
        and f.glob:find("3rdparty/mlas/lib/platform.cpp", 1, true) ~= nil
 end
+-- clsrc/opencl_kernels_<m>.cpp are written INERT by build.mcpp (cl2cpp) but never
+-- compiled (OpenCL OFF in this headless profile, not registered as sources), so
+-- their per-file flag-globs match nothing -> a permanent "[build].flags glob …
+-- matched no source file" warning. Drop them entirely.
+local function is_dead_opencl_glob(f)
+    return type(f) == "table" and type(f.glob) == "string"
+       and f.glob:find("clsrc/opencl_kernels", 1, true) ~= nil
+end
 local pkgs, order = {}, {}
 for _, e in ipairs(INPUTS) do pkgs[e.os] = load_pkg(e.path); order[#order+1] = e.os end
 local dnn_src, dnn_flg, base_flg = {}, {}, {}
@@ -172,7 +180,8 @@ for _, os_ in ipairs(order) do
         if not (drop_unistd and is_unistd_platform_flag(f)) then flgs[#flgs+1] = f end
     end
     for _, f in ipairs(p.mcpp.flags or {}) do
-        if type(f) == "table" and is_dnn_glob(f.glob) then
+        if is_dead_opencl_glob(f) then                       -- drop: inert, never compiled
+        elseif type(f) == "table" and is_dnn_glob(f.glob) then
             if not (drop_unistd and is_unistd_platform_flag(f)) then flgs[#flgs+1] = f end
         else cleaned[#cleaned+1] = f end
     end
@@ -205,20 +214,27 @@ local function split_common(map)
     end
     return common, delta
 end
-local common_src, delta_src = split_common(dnn_src)
-local common_flg, delta_flg = split_common(dnn_flg)
-
--- neutral features: base's non-dnn features (unifont) verbatim; dnn = common-only
+-- `dnn` is an OS-only feature (mcpp#253): it exists only on the platforms whose
+-- snapshot actually built it. Each such platform carries the FULL payload under
+-- mcpp.<os>.features.dnn — there is NO neutral dnn, so a platform without it
+-- cannot half-enable the feature. Windows is intentionally excluded: mlas's x86
+-- kernels are GAS/ELF `.S` (`.type …,@function`), which clang-cl cannot assemble
+-- to Windows COFF (would need the MASM amd64 `.asm` variant or a C++-only mlas).
 local neutral_features = {}
 for fname, fdef in pairs(base.mcpp.features or {}) do
     if fname ~= "dnn" then neutral_features[fname] = fdef end
 end
 local base_dnn = base.mcpp.features and base.mcpp.features.dnn
-neutral_features.dnn = {
-    defines = (base_dnn and base_dnn.defines) or { "HAVE_OPENCV_DNN" },
-    flags   = common_flg,
-    sources = common_src,
-}
+local dnn_defines = (base_dnn and base_dnn.defines) or { "HAVE_OPENCV_DNN" }
+-- an OS "ships dnn" only if it built the actual module — gen_descriptor always
+-- seeds features.dnn.sources with mcpp_generated/mlas_hgemm_stub.cpp even for a
+-- videoio-only (non-dnn) snapshot, so a non-empty list is NOT enough.
+local function ships_dnn(os_)
+    for _, s in ipairs(dnn_src[os_] or {}) do
+        if type(s) == "string" and s:find("modules/dnn", 1, true) then return true end
+    end
+    return false
+end
 
 merged.mcpp = {
     language = base.mcpp.language,
@@ -232,11 +248,8 @@ for _, os_ in ipairs(order) do
     blk.flags = base_flg[os_]                       -- dnn-group globs stripped
     local sub = p.mcpp[os_]
     if sub and sub.ldflags then blk.ldflags = sub.ldflags end
-    if #dnn_src[os_] > 0 then                         -- this OS supports dnn -> its delta
-        local fd = {}
-        if #delta_src[os_] > 0 then fd.sources = delta_src[os_] end
-        if #delta_flg[os_] > 0 then fd.flags = delta_flg[os_] end
-        if next(fd) then blk.features = { dnn = fd } end
+    if ships_dnn(os_) then                           -- this OS ships dnn -> full payload
+        blk.features = { dnn = { defines = dnn_defines, sources = dnn_src[os_], flags = dnn_flg[os_] } }
     end
     merged.mcpp[os_] = blk
 end