1 files changed, 57 insertions, 0 deletions
diff --git a/scripts/linters/no_use_as_alias.rb b/scripts/linters/no_use_as_alias.rb
new file mode 100644
index 0000000..8e0c86b
--- /dev/null
+++ b/scripts/linters/no_use_as_alias.rb
@@ -0,0 +1,57 @@
+def no_use_as_alias(root_dir, excludes = [])
+  pattern = root_dir.join('crates', '**', '*.rs').to_s
+  errors = Dir.glob(pattern).sort.flat_map do |path|
+    relative = Pathname.new(path).relative_path_from(root_dir).to_s
+    next [] if excludes.include?(relative)
+
+    find_use_aliases(path, relative)
+  end
+
+  return true if errors.empty?
+
+  puts 'Found `use ... as name` aliases.'
+  puts 'Aliasing imports merely to shorten a namespace is forbidden.'
+  puts 'Only `as _` (e.g. `use std::io::Write as _;`) and PascalCase renames'
+  puts '(for collision avoidance, e.g. `use foo::Error as FooError;`) are allowed:'
+  errors.each do |err|
+    puts "  #{err}"
+  end
+  false
+end
+
+USE_ALIAS_START_RE = /\A(?:pub(?:\([^)]*\))?\s+)?use\b/
+PASCAL_CASE_RE = /\A[A-Z][A-Za-z0-9]*\z/
+
+def find_use_aliases(path, relative)
+  errors = []
+  in_use = false
+  brace_depth = 0
+
+  File.readlines(path).each_with_index do |raw, idx|
+    code = raw.split('//', 2).first || raw
+    stripped = code.strip
+
+    unless in_use
+      next unless stripped =~ USE_ALIAS_START_RE
+
+      in_use = true
+      brace_depth = 0
+    end
+
+    code.scan(/\bas\s+([A-Za-z_][A-Za-z0-9_]*)/) do |m|
+      name = m[0]
+      next if name == '_'
+      next if name =~ PASCAL_CASE_RE
+
+      errors << "#{relative}:#{idx + 1}: `as #{name}` aliasing in `use` statement"
+    end
+
+    brace_depth += code.count('{') - code.count('}')
+    if brace_depth <= 0 && code.rstrip.end_with?(';')
+      in_use = false
+      brace_depth = 0
+    end
+  end
+
+  errors
+end