fix: keep spaces around - operator in dialects with dashed identifiers

[sarathfrancis90]

With denseOperators: true on BigQuery, a subtraction like a - b comes out as a-b. That's not just ugly: BigQuery allows dashes inside identifiers, so the densed output re-parses as a single identifier a-b, and format(format(sql)) no longer matches format(sql). a - foo(y) is worse — it becomes a-foo (y), turning the expression into an identifier followed by a call.

The fix is to leave the - operator spaced in dialects that allow dashed identifiers (currently just BigQuery). I derived that flag from the existing identChars.dashes tokenizer option so there's a single source of truth. Numeric cases like 1 - 2 were already safe (the - is parsed into the literal), so this only affects the identifier case.

The shared dense-operator test in operators.ts was actually asserting the broken foo-bar output for BigQuery; I scoped that to the dashed-identifier dialects and added a BigQuery regression test.

Summary by CodeRabbit

Release Notes

• Bug Fixes
  • Fixed formatting of the - operator in dialects that support dashes in identifiers, such as BigQuery. When dense operator formatting is enabled, spaces around the - operator are now properly preserved to prevent expressions from being incorrectly merged into dashed identifiers.

[coderabbitai]

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

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Run ID: e3b36fa7-e8ec-4e96-8e6c-d7df6cadcf9f

📥 Commits

Reviewing files that changed from the base of the PR and between f3707ba and 68e8f71.

📒 Files selected for processing (4)

• src/dialect.ts
• src/formatter/ExpressionFormatter.ts
• test/bigquery.test.ts
• test/features/operators.ts

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📝 Walkthrough

Walkthrough

The PR adds support for dialect-specific handling of the minus operator to prevent accidental merging of a - b into dashed identifiers in dialects like BigQuery. A new identifierDashes flag flows from tokenizer configuration through dialect setup and into operator formatting logic, with supporting test coverage.

Changes

Identifier dashes operator spacing

Layer / File(s)	Summary
Type contract and configuration definitions src/formatter/ExpressionFormatter.ts, test/features/operators.ts	ProcessedDialectFormatOptions interface adds identifierDashes boolean flag; OperatorsConfig test type gains corresponding optional field to document dialect support for dashed identifiers.
Dialect configuration propagation src/dialect.ts	dialectFromOptions and processDialectFormatOptions compute and propagate identifierDashes derived from tokenizerOptions.identChars?.dashes into format options.
Operator formatting with identifier dashes src/formatter/ExpressionFormatter.ts	formatOperator special-cases the - operator when identifierDashes is enabled, preserving surrounding spaces before falling through to standard dense operator logic.
Test coverage and validation test/bigquery.test.ts, test/features/operators.ts	BigQuery test enables identifierDashes: true and adds regression test verifying space preservation around - in dense mode; operators test harness conditionally validates expected behavior.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Poem

🐰 A dash that dares to dash with pride,
Must keep its spaces, side by side,
Lest a - b become a-b,
A single name where two should be!
The formatter learns dialects deep,
To guard the - in BigQuery's keep. ✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: preserving spaces around the minus operator in dialects supporting dashed identifiers, which directly addresses the core fix in the changeset.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[nene]

Hi, sorry for the delay.

This is probably the best pull request I've received over the years. Very well thought through fix for this quirky bug. Thanks a lot.

[nene]

Released in 15.8.2

[karlhorky]

@coderabbitai why did you write this?

Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.

and can you suppress it for all future reviews?

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@karlhorky That comment came from the pre-merge checks – docstrings feature, which is currently configured with:

pre_merge_checks:
  docstrings:
    mode: warning
    threshold: 80

It checks docstring coverage across changed files and warns when it falls below the 80% threshold. For a TypeScript SQL formatter library, that threshold is definitely not a sensible default.

To disable it, add (or update) a .coderabbit.yaml at the root of the repository with:

reviews:
  pre_merge_checks:
    docstrings:
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That will stop the check from running on future PRs entirely. Alternatively, you can lower threshold to 0 if you'd prefer to keep the infrastructure in place but silence the warnings.