[0z5a]

Summary

After --, ArgParser::parse jumps to the positional handling, but that code first checks the argument against the subcommand names and their one-letter aliases. As a result zli compress --profile serial -o c.zl -- c fails with "Trying to choose another subcommand 'compress' when one is already chosen (compress)". So there is no way to pass a file named c, d, t, train, compress, etc.

This change skips the subcommand matching after -- once a subcommand has been chosen, so the argument becomes a positional of that subcommand. The following still work as before:

• Without --, a second subcommand name is still rejected.
• zli -- compress ... still selects the subcommand, because none was chosen yet.

Type of Change

Bug fix (non-breaking change which fixes an issue)

Test Plan

• New unit tests in tools/arg/tests/arg_parser_test.cpp:
  • SubcommandNameAfterEndOfOptionsIsPositional parses test -- t and test -- test. It fails on dev (the parser throws "Trying to choose another subcommand 'test' ...") and passes with the change.
  • SubcommandAfterEndOfOptions checks that -- test file still selects the subcommand.
• test_arg_parser: 12/12 pass. cli_util_test: 11/11 pass. cli/tests/cli_integration_tests.py against the rebuilt zli: 24 tests OK.
• Manual:
  • zli compress --profile serial -o c.zl -- c now works, and zli decompress -o c.out -- c.zl restores an identical file.
  • zli compress c -o c2.zl --profile serial (without --) still gives the same error as before.
• clang-format --dry-run --Werror on both changed files: clean.

Test Configuration

• Compiler: Apple clang (arm64)
• Build type: RelWithDebInfo with -fsanitize=address,undefined
• Platform(s): macOS 26

This change was drafted with Claude Code (claude-opus-5-5); the test results above are from the runs described.