fix(cli): parse inline values for optional short flags

[sjh9714]

What does this PR do?

Fixes #21431.

Short optional CLI flags such as -c=custom.toml were parsed as bare flags before the short-option parser checked the inline = value. This makes the Values::OneOptional short-flag path return the value after = while preserving the existing DoesntTakeValue error for no-value flags like -a=value.

The regression test covers the reported config forms:

• bun -c=custom.toml index.ts
• bun -c=custom.toml run index.ts
• bun run -c=custom.toml index.ts

How did you verify your code works?

• USE_SYSTEM_BUN=1 bun test test/cli/bun.test.ts -t "-c=path loads bunfig" (fails on system Bun 1.3.14 with missing, confirming the regression)
• git diff --check
• PATH="$HOME/.cargo/bin:$PATH" SDKROOT="$(xcrun --show-sdk-path)" DEVELOPER_DIR=/Applications/Xcode.app/Contents/Developer RUSTFLAGS="-C link-arg=-isysroot -C link-arg=$(xcrun --show-sdk-path)" cargo test -p bun_clap short_params
• build/debug/bun-debug test test/cli/bun.test.ts -t "-c=path loads bunfig"

Local caveat: my Homebrew LLVM 21 config points at a missing CommandLineTools MacOSX26.sdk, so the full bun bd test ... command needed local generated-build env fixes to use the installed Xcode SDK/Apple clang for host/Rust build edges. No generated files are included in this PR.

Note: I used Codex to help inspect the issue/code path and draft the tests, then reviewed the final diff and ran the listed verification commands locally.

[claude]

Claude Code Review

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📥 Commits

Reviewing files that changed from the base of the PR and between 3dfca30 and 34cc82c.

📒 Files selected for processing (2)

• src/clap/streaming.rs
• test/cli/bun.test.ts

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Walkthrough

The PR fixes short option argument parsing to handle optional values with = syntax. The parser is updated so that -c=path extracts path as the option value, and unit and integration tests verify both the parser change and its real-world behavior for the config flag.

Changes

Short option parsing with optional values

Layer / File(s)	Summary
Parser logic and unit tests src/clap/streaming.rs	When parsing a chained short option with OneOptional value semantics, the parser now extracts the substring after = and returns it as the argument value. Unit test fixture and assertions are extended to exercise -e=1 (parsed value) and -e (no value) cases.
Integration test for short config flag test/cli/bun.test.ts	New test verifies -c=path works equivalently to --config=path by running Bun with a temporary config that preloads a side effect, checking both argument orderings produce correct output and exit code.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'fix(cli): parse inline values for optional short flags' directly and clearly describes the main code change in the PR, which modifies the short option parser to handle inline values with = for optional flags.
Description check	✅ Passed	The description follows the template with both required sections completed: 'What does this PR do?' explains the fix and links the issue, and 'How did you verify your code works?' lists comprehensive verification steps including tests and cargo commands.
Linked Issues check	✅ Passed	The PR successfully addresses the linked issue #21431 by fixing the short flag -c= parsing to work with optional values, enabling forms like -c=custom.toml to properly set the config file as documented.
Out of Scope Changes check	✅ Passed	All changes are directly scoped to fixing the reported issue: the streaming.rs modification handles the inline value parsing, and the test addition verifies the fix covers the reported use cases.

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[robobun]

Thanks for tracking this down, and sorry for the slow response here.

This overlaps with #34983, which fixes the same -c=path case in StreamingClap::chainging and also covers the attached form (-cpath) and the space-separated forms (-c path, --config path) by making -c, --config a required-value flag in both the runtime and install param tables, so the path is no longer treated as a script to run or a package to install. Since it is the superset, we are keeping that one and closing this PR.

The argv shapes from your test (-c=... index.ts, -c=... run index.ts, run -c=... index.ts) are now part of the test matrix over there, with you credited as co-author on that commit.