fix: expose headers/jars on system ruby

Fixes #208

Author: p0deje

.github/workflows/ci.yml

@@ -68,7 +68,7 @@ jobs:
       - if: matrix.ruby == 'system'
         uses: ruby/setup-ruby@v1
         with:
-          ruby-version: "3.1.6"
+          ruby-version: 3.1.6
       - run: bazel build ...
       - run: bazel run lib/gem:add-numbers 2
       - run: bazel run lib/gem:print-version
@@ -114,6 +114,9 @@ jobs:
         ruby:
           - 3.3.7
           - jruby-9.4.12.0
+        use-system-ruby:
+          - true
+          - false
     defaults:
       run:
         working-directory: examples/native_ext
@@ -123,7 +126,11 @@ jobs:
         with:
           bazelrc: common --announce_rc --color=yes
           repository-cache: examples/native_ext/MODULE.bazel
-      - run: echo ${{ matrix.ruby }} > .ruby-version
+      - if: matrix.use-system-ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+      - run: echo ${{ matrix.use-system-ruby && 'system' || matrix.ruby }} > .ruby-version
       - run: bazel build ...
       - if: failure() && runner.debug == '1'
         uses: mxschmitt/action-tmate@v3

ruby/private/download.bzl

@@ -85,36 +85,34 @@ def _rb_download_impl(repository_ctx):
     else:
         fail("missing value for one of mandatory attributes 'version' or 'version_file'")
 
+    engine = "ruby"
+    env = {}
+    ruby_binary_name = "ruby"
+    gem_binary_name = "gem"
     if version.startswith("jruby"):
         _install_jruby(repository_ctx, version)
-    elif version == "system":
-        _symlink_system_ruby(repository_ctx)
-    elif repository_ctx.os.name.startswith("windows"):
-        _install_via_rubyinstaller(repository_ctx, version)
-    else:
-        _install_via_ruby_build(repository_ctx, version)
 
-    if version.startswith("jruby"):
+        engine = "jruby"
         ruby_binary_name = "jruby"
         gem_binary_name = "jgem"
-    else:
-        ruby_binary_name = "ruby"
-        gem_binary_name = "gem"
-
-    env = {}
-    engine = "ruby"
-    if version.startswith("jruby"):
-        engine = "jruby"
 
         # JRuby might fail with "Errno::EACCES: Permission denied - NUL" on Windows:
         # https://github.com/jruby/jruby/issues/7182#issuecomment-1112953015
         env.update({"JAVA_OPTS": "-Djdk.io.File.enableADS=true"})
     elif version.startswith("truffleruby"):
+        _install_via_ruby_build(repository_ctx, version)
+
         engine = "truffleruby"
 
         # TruffleRuby needs explicit locale
         # https://www.graalvm.org/dev/reference-manual/ruby/UTF8Locale/
         env.update({"LANG": "en_US.UTF-8"})
+    elif version == "system":
+        engine = _symlink_system_ruby(repository_ctx)
+    elif repository_ctx.os.name.startswith("windows"):
+        _install_via_rubyinstaller(repository_ctx, version)
+    else:
+        _install_via_ruby_build(repository_ctx, version)
 
     includes = []
     if repository_ctx.path("dist/include").exists:
@@ -262,11 +260,22 @@ def _symlink_system_ruby(repository_ctx):
     result = repository_ctx.execute(["ruby", "-e", "puts RbConfig.ruby"])
     if result.return_code != 0:
         fail("Failed to determine the system Ruby path:\n%s\n%s" % (result.stdout, result.stderr))
-    ruby_path = result.stdout.strip()
-    ruby_dir = repository_ctx.path(ruby_path).dirname
-    repository_ctx.symlink(ruby_dir, "dist/bin")
-    if repository_ctx.os.name.startswith("windows"):
-        repository_ctx.symlink(ruby_dir.dirname.get_child("lib"), "dist/lib")
+
+    _symlink_system_ruby_dir("bindir", repository_ctx)
+    _symlink_system_ruby_dir("libdir", repository_ctx)
+    _symlink_system_ruby_dir("rubyhdrdir", repository_ctx)
+
+    engine = repository_ctx.execute(["ruby", "-e", "puts RbConfig::CONFIG['RUBY_BASE_NAME']"]).stdout.strip()
+    return engine
+
+def _symlink_system_ruby_dir(dirname, repository_ctx):
+    prefix = repository_ctx.execute(["ruby", "-e", "puts RbConfig::CONFIG['prefix']"]).stdout.strip()
+    path = repository_ctx.execute(["ruby", "-e", "puts RbConfig::CONFIG['{dirname}']".format(dirname = dirname)]).stdout.strip()
+    src = repository_ctx.path(path)
+    dirname = path.removeprefix(prefix).removeprefix("/")
+    dst = repository_ctx.path("dist/{dirname}".format(dirname = dirname))
+    if not dst.exists:
+        repository_ctx.symlink(src, dst)
 
 rb_download = repository_rule(
     implementation = _rb_download_impl,