fix(codegen): escape backticks and ${} in template literal raw values

[CompuIves]

We're using OXC pretty extensively these days for custom transforms, lints and now also for code edits where users make edits in a UI and we update code. I'm a big fan of OXC, it's super fast, easy to use and also works great in the browser!

When manually injecting AST, or e.g. editing AST, I noticed that it's possible to inject backticks in template literals, leading to syntax errors. It seems like we already have escaping logic (single/double quotes, etc) for strings, so I thought it could be valuable to also add escaping to template literals in codegen.

[Copilot]

Pull request overview

This PR fixes a codegen bug where backticks and template literal interpolation syntax (${}) in template literal raw values could cause syntax errors when generating code. The fix adds proper escaping logic for template literals, handling backticks, ${} sequences, and </script> tags.

Changes:

• Added print_template_literal_str method to escape special sequences in template literals
• Added helper function is_preceded_by_odd_backslashes to detect already-escaped characters
• Updated TemplateLiteral code generation to use the new escaping method
• Added comprehensive unit tests for the escaping logic

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
crates/oxc_codegen/src/lib.rs	Implements new template literal escaping function with unit tests
crates/oxc_codegen/src/gen.rs	Updates TemplateLiteral to use new escaping method instead of script-tag-only escaping

Comments suppressed due to low confidence (1)

crates/oxc_codegen/src/gen.rs:3281

• TSTemplateLiteralType should also use print_template_literal_str instead of print_str to properly escape backticks, ${}, and </script> sequences, consistent with the runtime TemplateLiteral handling.

            p.print_str(item.value.raw.as_str());

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[codspeed-hq]

Merging this PR will not alter performance

✅ 42 untouched benchmarks
⏩ 3 skipped benchmarks¹

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_{Comparing flitsinc:template-literal-escaping (848f273) with main (b6a065e)}

Footnotes

1. 3 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[Boshen]

Superseded by #18121 - instead of escaping in codegen, we add an escape_raw: bool parameter to the template_element builder methods. This makes the escaping explicit and lets users know they need to handle special characters when building template literals programmatically.

Codegen always expects valid AST - users should pass escape_raw: true when creating template elements from runtime string values.