refactor(bazel): patch the kernel defines with a stock Bazel action

.bazelrc

@@ -1,10 +1,8 @@
 # Global options
 
-common  
-
 build -c opt \
       --incompatible_enable_cc_toolchain_resolution \
-      --incompatible_require_linker_input_cc_api 
+      --incompatible_require_linker_input_cc_api
 
 # Aliases for user-defined flags
 build --flag_alias=backend_config=@config//:backend_config

MODULE.bazel

@@ -32,12 +32,6 @@ sh_config_ext = use_extension("@onedal//dev/bazel/toolchains:cc_toolchain_extens
 use_repo(sh_config_ext, "onedal_cc_toolchain")
 register_toolchains("@{}//:all".format("onedal_cc_toolchain"))
 
-
-extra_toolchain_ext = use_extension("@onedal//dev/bazel/toolchains:extra_toolchain_extension.bzl", "onedal_extra_toolchain_extension")
-use_repo(extra_toolchain_ext, "onedal_extra_toolchain")
-register_toolchains("@{}//:all".format("onedal_extra_toolchain"))
-
-
 http_archive = use_repo_rule("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
 http_archive(
     name = "catch2",

dev/bazel/cc.bzl

@@ -15,7 +15,6 @@
 #===============================================================================
 
 load("@onedal//dev/bazel:utils.bzl",
-    "utils",
     "paths",
     "sets",
 )
@@ -317,31 +316,39 @@ cc_static_lib = rule(
 )
 
 
-def _copy_dynamic_release_file(ctx, src, out_name, is_windows = False, extra_inputs = []):
+def _copy_windows_release_file(ctx, src, out_name, extra_inputs = []):
+    """Copy a linker output under the file name the release layout expects.
+
+    Windows only: the Linux release names come straight out of the link action,
+    while a DLL and its import library have to be renamed afterwards (see
+    `_cc_dynamic_lib_impl`). A symlink is not enough, because creating one
+    requires developer mode on Windows.
+
+    Args:
+        ctx: rule context.
+        src: the file produced by the link action.
+        out_name: base name of the copy, declared in the current package.
+        extra_inputs: further link outputs to declare as inputs, so that the
+                      copy cannot run before the whole link action completed.
+
+    Returns:
+        The declared copy.
+    """
     out = ctx.actions.declare_file(out_name)
-    if is_windows:
-        ctx.actions.run(
-            executable = "cmd.exe",
-            inputs = [src] + extra_inputs,
-            outputs = [out],
-            arguments = [
-                "/d",
-                "/c",
-                'copy /Y "{}" "{}"'.format(
-                    src.path.replace("/", "\\"),
-                    out.path.replace("/", "\\"),
-                ),
-            ],
-            use_default_shell_env = True,
-        )
-    else:
-        ctx.actions.run(
-            executable = "cp",
-            inputs = [src] + extra_inputs,
-            outputs = [out],
-            arguments = [src.path, out.path],
-            use_default_shell_env = True,
-        )
+    ctx.actions.run(
+        executable = "cmd.exe",
+        inputs = [src] + extra_inputs,
+        outputs = [out],
+        arguments = [
+            "/d",
+            "/c",
+            'copy /Y "{}" "{}"'.format(
+                src.path.replace("/", "\\"),
+                out.path.replace("/", "\\"),
+            ),
+        ],
+        use_default_shell_env = True,
+    )
     return out
 
 
@@ -407,19 +414,17 @@ def _cc_dynamic_lib_impl(ctx):
             if dynamic_outputs.dynamic_library.basename == dynamic_release_name:
                 default_files.append(dynamic_outputs.dynamic_library)
             else:
-                default_files.append(_copy_dynamic_release_file(
+                default_files.append(_copy_windows_release_file(
                     ctx,
                     dynamic_outputs.dynamic_library,
                     dynamic_release_name,
-                    is_windows = is_windows,
                     extra_inputs = [dynamic_outputs.interface_library] if dynamic_outputs.interface_library else [],
                 ))
         if dynamic_outputs.interface_library:
-            default_files.append(_copy_dynamic_release_file(
+            default_files.append(_copy_windows_release_file(
                 ctx,
                 dynamic_outputs.interface_library,
                 "{}_dll.lib".format(rt_name),
-                is_windows = is_windows,
             ))
     default_info = DefaultInfo(
         files = depset(default_files),

dev/bazel/cc/common.bzl

@@ -19,7 +19,6 @@ load("@rules_cc//cc/common:cc_info.bzl", "CcInfo")
 
 load("@onedal//dev/bazel:utils.bzl",
     "utils",
-    "paths",
     "sets",
 )
 

dev/bazel/cc/link.bzl

@@ -20,7 +20,6 @@ load("@rules_cc//cc:action_names.bzl", "ACTION_NAMES")
 load("@onedal//dev/bazel:utils.bzl",
     "utils",
     "paths",
-    "sets",
 )
 
 load("@onedal//dev/bazel/toolchains:action_names.bzl",

dev/bazel/daal.bzl

@@ -162,10 +162,6 @@ daal_generate_version = rule(
     },
 )
 
-def _get_tool_for_kernel_defines_patching(ctx):
-    return ctx.toolchains["@onedal//dev/bazel/toolchains:extra"] \
-        .extra_toolchain_info.patch_daal_kernel_defines
-
 def _get_disabled_cpus(ctx):
     cpu_info = ctx.attr._cpus[CpuInfo]
     all_cpus = sets.make(cpu_info.allowed)
@@ -178,17 +174,37 @@ def _declare_patched_kernel_defines(ctx):
     return ctx.actions.declare_file(patched_path)
 
 def _daal_patch_kernel_defines_impl(ctx):
-    disabled_cpus = _get_disabled_cpus(ctx)
+    """Comment out the `DAAL_KERNEL_<ISA>` defines of the disabled ISAs.
+
+    `cpp/daal/include/services/internal/daal_kernel_defines.h` enables every
+    CPU dispatch variant oneDAL can build; the ones `--cpu` leaves out have to
+    be removed from the header before it is compiled or released. The Makefile
+    does it with
+
+        sed -b -i -E -e 's/^#define DAAL_KERNEL_<ISA>\\b/$(sed.eol)/'
+
+    where `sed.eol` is empty on Linux and a lone CR on Windows, so that a
+    disabled define leaves behind an empty line with the platform's own line
+    ending while every other line is untouched. `expand_template` does exactly
+    that substitution, without a helper script: it rewrites the file at
+    execution time, so nothing has to read its contents during analysis.
+
+    The substitution is literal, not anchored like sed's `^...\\b`, which is
+    equivalent here because the header holds one bare `#define DAAL_KERNEL_*`
+    per line and mentions those macros nowhere else.
+    """
+    disabled_cpus = sets.to_list(_get_disabled_cpus(ctx))
     kernel_defines = _declare_patched_kernel_defines(ctx)
-    ctx.actions.run(
-        executable = _get_tool_for_kernel_defines_patching(ctx),
-        arguments = [
-            ctx.file.src.path,
-            kernel_defines.path,
-            " ".join(sets.to_list(disabled_cpus)),
-        ],
-        inputs = [ctx.file.src],
-        outputs = [kernel_defines],
+    is_windows = ctx.target_platform_has_constraint(
+        ctx.attr._windows_constraint[platform_common.ConstraintValueInfo],
+    )
+    ctx.actions.expand_template(
+        template = ctx.file.src,
+        output = kernel_defines,
+        substitutions = {
+            "#define DAAL_KERNEL_{}".format(cpu.upper()): "\r" if is_windows else ""
+            for cpu in disabled_cpus
+        },
     )
     return [ DefaultInfo(files=depset([ kernel_defines ])) ]
 
@@ -200,6 +216,8 @@ daal_patch_kernel_defines = rule(
         "_cpus": attr.label(
             default = "@config//:cpu",
         ),
+        "_windows_constraint": attr.label(
+            default = "@platforms//os:windows",
+        ),
     },
-    toolchains = ["@onedal//dev/bazel/toolchains:extra"],
 )

dev/bazel/release.bzl

@@ -558,7 +558,6 @@ def _copy_data(ctx, prefix):
     return dst_files
 
 def _copy_to_release_impl(ctx):
-    extra_toolchain = ctx.toolchains["@onedal//dev/bazel/toolchains:extra"]
     prefix = ctx.attr.name + "/daal/latest"
     version_info = ctx.attr._version_info[VersionInfo] if ctx.attr._version_info else None
     files = []
@@ -641,9 +640,6 @@ _release = rule(
             default = "@bazel_tools//tools/allowlists/function_transition_allowlist",
         ),
     },
-    toolchains = [
-        "@onedal//dev/bazel/toolchains:extra"
-    ],
 )
 
 def _headers_filter_impl(ctx):

dev/bazel/toolchains/BUILD

@@ -15,5 +15,3 @@
 #===============================================================================
 
 package(default_visibility = ["//visibility:public"])
-
-toolchain_type(name = "extra")