[NFC] Update doxygen build and configuration files

BUILD.bazel

@@ -131,3 +131,9 @@ label_flag(
     build_setting_default = ":.clang-tidy",
     visibility = ["//visibility:public"],
 )
+
+# Doxygen configuration file
+exports_files(
+    ["doxyfile"],
+    visibility = ["//build/doxygen:__pkg__"],
+)

MODULE.bazel

@@ -81,6 +81,7 @@ archive_override(
 )
 
 include("//build/deps:deps.MODULE.bazel")
+include("//build/deps:doxygen.MODULE.bazel")
 include("//build/deps:nodejs.MODULE.bazel")
 include("//build/deps:python.MODULE.bazel")
 include("//build/deps:v8.MODULE.bazel")

build/deps/doxygen.MODULE.bazel

@@ -0,0 +1,22 @@
+"""Doxygen dependency configuration.
+
+This module builds doxygen from source with libclang support, enabling
+clang-assisted parsing of C++ code for accurate documentation generation.
+"""
+
+doxygen_repository = use_repo_rule("//build/doxygen:doxygen.bzl", "doxygen_repository")
+
+DOXYGEN_VERSION = "1.13.2"
+
+doxygen_repository(
+    name = "doxygen",
+    sha256 = "4c9d9c8e95c2af4163ee92bcb0f3af03b2a4089402a353e4715771e8d3701c48",
+    strip_prefix = "doxygen-Release_{version}".format(
+        version = DOXYGEN_VERSION.replace(".", "_"),
+    ),
+    urls = [
+        "https://github.com/doxygen/doxygen/archive/refs/tags/Release_{version}.tar.gz".format(
+            version = DOXYGEN_VERSION.replace(".", "_"),
+        ),
+    ],
+)

build/doxygen/BUILD.bazel

@@ -0,0 +1,8 @@
+"""Build rules for generating doxygen documentation."""
+
+# Re-export the doxygen binary from the external repository
+alias(
+    name = "doxygen",
+    actual = "@doxygen//:doxygen",
+    visibility = ["//visibility:public"],
+)

build/doxygen/doxygen.bzl

@@ -0,0 +1,109 @@
+"""Repository rule for building doxygen from source with libclang support.
+
+This rule downloads and builds doxygen from source using CMake, linking against
+the system LLVM/clang installation to enable clang-assisted parsing of C++ code.
+"""
+
+def _doxygen_repository_impl(ctx):
+    """Builds doxygen from source with libclang support."""
+
+    # Download doxygen source
+    ctx.download_and_extract(
+        url = ctx.attr.urls,
+        sha256 = ctx.attr.sha256,
+        stripPrefix = ctx.attr.strip_prefix,
+    )
+
+    # Create the build script
+    build_script = """#!/bin/bash
+set -euo pipefail
+
+cd "{src_dir}"
+mkdir -p build
+cd build
+
+# Find LLVM installation
+LLVM_DIR=""
+for v in 21 20 19 18; do
+    if [ -d "/usr/lib/llvm-$v" ]; then
+        LLVM_DIR="/usr/lib/llvm-$v"
+        break
+    fi
+done
+
+if [ -z "$LLVM_DIR" ]; then
+    echo "ERROR: No LLVM installation found" >&2
+    exit 1
+fi
+
+echo "Using LLVM from: $LLVM_DIR"
+
+# Configure with CMake
+cmake .. \\
+    -DCMAKE_BUILD_TYPE=Release \\
+    -DCMAKE_C_COMPILER=clang \\
+    -DCMAKE_CXX_COMPILER=clang++ \\
+    -DCMAKE_EXE_LINKER_FLAGS="-fuse-ld=lld" \\
+    -DCMAKE_SHARED_LINKER_FLAGS="-fuse-ld=lld" \\
+    -Duse_libclang=ON \\
+    -Duse_libc++=OFF \\
+    -DLLVM_DIR="$LLVM_DIR/lib/cmake/llvm" \\
+    -DClang_DIR="$LLVM_DIR/lib/cmake/clang" \\
+    -DCMAKE_INSTALL_PREFIX="{install_dir}"
+
+# Build
+make -j$(nproc)
+make install
+""".format(
+        src_dir = ctx.path("."),
+        install_dir = ctx.path("install"),
+    )
+
+    ctx.file("build_doxygen.sh", build_script, executable = True)
+
+    # Execute the build
+    result = ctx.execute(
+        ["bash", "build_doxygen.sh"],
+        timeout = 1800,  # 30 minutes
+        quiet = False,
+    )
+
+    if result.return_code != 0:
+        fail("Failed to build doxygen:\nstdout:\n{}\nstderr:\n{}".format(
+            result.stdout,
+            result.stderr,
+        ))
+
+    # Create BUILD file exposing the doxygen binary
+    ctx.file("BUILD.bazel", """
+package(default_visibility = ["//visibility:public"])
+
+filegroup(
+    name = "doxygen_bin",
+    srcs = ["install/bin/doxygen"],
+)
+
+filegroup(
+    name = "doxygen",
+    srcs = ["install/bin/doxygen"],
+)
+""")
+
+doxygen_repository = repository_rule(
+    implementation = _doxygen_repository_impl,
+    attrs = {
+        "urls": attr.string_list(
+            mandatory = True,
+            doc = "URLs to download doxygen source archive",
+        ),
+        "sha256": attr.string(
+            mandatory = True,
+            doc = "SHA256 checksum of the archive",
+        ),
+        "strip_prefix": attr.string(
+            mandatory = True,
+            doc = "Prefix to strip from the archive",
+        ),
+    },
+    doc = "Downloads and builds doxygen from source with libclang support",
+)

build/doxygen/doxygen_docs.bzl

@@ -0,0 +1,84 @@
+"""Rules for generating doxygen documentation."""
+
+def _doxygen_docs_impl(ctx):
+    """Generates doxygen documentation."""
+
+    # Create output directory
+    output_dir = ctx.actions.declare_directory(ctx.attr.name + "_html")
+
+    # Get the doxygen binary
+    doxygen_files = ctx.attr.doxygen[DefaultInfo].files.to_list()
+    if not doxygen_files:
+        fail("No doxygen binary found")
+    doxygen_bin = doxygen_files[0]
+
+    # Create a script to run doxygen
+    script = ctx.actions.declare_file(ctx.attr.name + "_run.sh")
+
+    script_content = """#!/bin/bash
+set -e
+
+DOXYGEN="{doxygen}"
+DOXYFILE="{doxyfile}"
+OUTPUT_DIR="{output_dir}"
+WORKSPACE="{workspace}"
+
+# Create output directory
+mkdir -p "$OUTPUT_DIR"
+
+# Run doxygen from workspace root
+cd "$WORKSPACE"
+"$DOXYGEN" "$DOXYFILE"
+
+# Move output to bazel output location
+if [ -d "docs/api/html" ]; then
+    cp -r docs/api/html/* "$OUTPUT_DIR/"
+fi
+""".format(
+        doxygen = doxygen_bin.path,
+        doxyfile = ctx.file.doxyfile.path,
+        output_dir = output_dir.path,
+        workspace = ctx.file.doxyfile.dirname,
+    )
+
+    ctx.actions.write(
+        output = script,
+        content = script_content,
+        is_executable = True,
+    )
+
+    # Collect all source files
+    srcs = []
+    for src in ctx.attr.srcs:
+        srcs.extend(src[DefaultInfo].files.to_list())
+
+    ctx.actions.run(
+        executable = script,
+        inputs = [ctx.file.doxyfile, doxygen_bin] + srcs,
+        outputs = [output_dir],
+        mnemonic = "Doxygen",
+        progress_message = "Generating doxygen documentation",
+        use_default_shell_env = True,
+    )
+
+    return [DefaultInfo(files = depset([output_dir]))]
+
+doxygen_docs = rule(
+    implementation = _doxygen_docs_impl,
+    attrs = {
+        "doxyfile": attr.label(
+            mandatory = True,
+            allow_single_file = True,
+            doc = "The Doxyfile configuration",
+        ),
+        "srcs": attr.label_list(
+            allow_files = True,
+            doc = "Source files to document",
+        ),
+        "doxygen": attr.label(
+            default = "//build/doxygen",
+            doc = "The doxygen binary",
+        ),
+    },
+    doc = "Generates doxygen documentation from source files",
+)