gen_descriptor: route dnn-group flag-globs into features.dnn.flags (mcpp 0.0.101 per-feature flags — clears feature-off dead-glob warnings; per-OS deltas land via merge)

Author: Sunrisepeak

tools/compat-opencv/gen_descriptor.py

@@ -404,7 +404,18 @@ def lua_list(items, ind):
 def defines_lua(defset):
     return "defines = { " + ", ".join(f'"{D(f)}"' for f in sorted(defset)) + " }"
 
+# base flag-globs vs dnn-feature flag-globs. Flag-globs for the dnn groups
+# (mlas/mlasgemm/protobuf/dnn) only match a source when the `dnn` feature is
+# on; kept in the base `flags` they glob nothing in the default (feature-off)
+# profile -> mcpp 0.0.101 warns "[build].flags glob matched no source file".
+# mcpp#253 per-feature flags let them ride WITH the feature (features.dnn.flags),
+# so they resolve exactly when their sources do.  (dnn-group flag-globs are
+# arch-specific for the per-ISA entries -> they land per-OS via merge_opencv.lua.)
 flags_entries = []
+dnn_flags_entries = []
+def is_dnn_glob(g):
+    return any(m in g for m in ("3rdparty/mlas", "3rdparty/protobuf",
+                                "modules/dnn", "tu/mlasgemm"))
 # curated exception: mlas/lib/platform.cpp calls syscall(2); glibc hides it
 # under __STRICT_ANSI__ (-std=c++NN). The reference build's gcc13 tolerated
 # this only because ninja -k discards the object; consumers must compile it,
@@ -416,7 +427,8 @@ def defines_lua(defset):
     key = "cflags" if dk in ("zlib", "png", "jpeg", "jpeg12", "jpeg16") else "cxxflags"
     parts = [f'glob = "{GROUP_GLOB[dk]}"']
     if dir_defs[dk]: parts.append(defines_lua(dir_defs[dk]))
-    flags_entries.append("{ " + ", ".join(parts) + " },")
+    (dnn_flags_entries if dk in FEATURE_DNN_GROUPS else flags_entries).append(
+        "{ " + ", ".join(parts) + " },")
 if ("jpeg-asm", None) in groups:
     cs = groups[("jpeg-asm", None)]
     common = frozenset.intersection(*[c[2] for c in cs])
@@ -426,17 +438,18 @@ def defines_lua(defset):
     ms = ", ".join(f'"{m}"' for m in isa_m[(dk, isa)])
     g = GROUP_GLOB[dk]
     g = (g[:-3] if g.endswith("/**") else g) + f"/**/*.{isa}.cpp"
-    flags_entries.append(
+    (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]) + " },")
 for g, extra in sorted(per_file_flag_entries):
-    flags_entries.append(f'{{ glob = "{g}", ' + defines_lua(extra) + " },")
+    (dnn_flags_entries if is_dnn_glob(g) else flags_entries).append(
+        f'{{ glob = "{g}", ' + defines_lua(extra) + " },")
 # curated exception #2: mlas/lib/platform.cpp calls syscall(2) but includes
 # only <sys/syscall.h> (the prototype lives in <unistd.h>; upstream
 # toolchains leak it transitively, the hermetic glibc does not).
-flags_entries.append('{ glob = "*/3rdparty/mlas/lib/platform.cpp", cxxflags = { "-include", "unistd.h" } },')
+dnn_flags_entries.append('{ glob = "*/3rdparty/mlas/lib/platform.cpp", cxxflags = { "-include", "unistd.h" } },')
 
 # upstream reference uses -std=c++17; the index floor is c++23 and the whole
 # TU set builds green under gcc16 -std=c++23 (validated by the O0 spike).
@@ -464,6 +477,7 @@ def defines_lua(defset):
 sources_dnn_out.append("mcpp_generated/mlas_hgemm_stub.cpp")
 
 dnn_sources_lua = lua_list(sources_dnn_out, " " * 20)
+dnn_flags_lua = ("\n" + " " * 20).join(dnn_flags_entries)
 n_dnn = len(sources_dnn)
 L = []
 L.append(f"""-- Auto-generated by tools/compat-opencv/gen_descriptor.py — do not edit by hand.
@@ -530,6 +544,9 @@ def defines_lua(defset):
             }},
             ["dnn"] = {{
                 defines = {{ "HAVE_OPENCV_DNN" }},
+                flags = {{
+                    {dnn_flags_lua}
+                }},
                 sources = {{
                     {dnn_sources_lua}
                 }},