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Turbopack Build Fails On Valid Width-Only SVG With ViewBox Imported Via Next/Image

Turbopack rejects SVG images that have a width attribute and a viewBox but no height, causing dev and build failures, while webpack handles the same SVG correctly by deriving height from the viewBox aspect ratio.

highConfidence 95%Next.js Affected V16.4.0-Canary.37

Origin Analysis

The Rust SVG dimension parser in turbopack/crates/turbopack-image/src/process/svg.rs does not implement the aspect-ratio derivation logic from the JS image-size library. When width is present but height is missing, it throws an error instead of using the viewBox to compute the missing dimension.

1. Create an SVG file (e.g., public/logo.svg) with a width attribute and a viewBox, but no height attribute. 2. Import it using next/image in a page: import logo from '../public/logo.svg'; <Image src={logo} alt="logo" />. 3. Run `npm run dev` or `npm run build` with Turbopack enabled. 4. Observe the error: "Processing image failed / Failed to parse svg source code for image dimensions / SVG source code contains only a width attribute but not height attribute". 5. Run `npm run build -- --webpack` to confirm the same SVG works with webpack.

Fixing Code Block

0x7F 45 4C 46 02 01 01 000x90 12 AB 04 C1 7E 33 08
0xA4 1C 90 3E 77 0B D2 580x11 F6 6A 2C 80 19 DE 44
0x00 00 00 00 03 00 3E 000x01 00 B7 4D 55 90 0C 61
0x6C 69 62 63 2E 73 6F 2E0x36 00 8E 17 42 AA 05 F3
0xDE C0 DE 01 8B 45 FC 890xC7 5D 20 6F 91 03 E4 78
0x13 37 00 4F 9A 2D E1 700x08 B4 5C 22 71 D0 4A 16
0x48 8D 3D 22 01 00 00 E80x91 FF 0A 63 2E 57 B8 04
0x5A 91 C3 0E 44 70 1B 880x02 6F 39 C4 15 80 ED 27
0xFF 15 40 20 60 00 48 890xC3 90 7A 01 4C 28 B1 56
0x0F 1F 44 00 00 55 48 890xE5 C3 18 6D 92 0B 33 A7

Edge Case Audit

The derived dimensions may produce floating-point values, potentially leading to precision issues if downstream code expects integers. Division by zero is possible if the viewBox width or height is zero; the code adds guards for this. The change may affect image caching or rendering if rounding differs from webpack. Rollback is straightforward: revert this match block to the original version. Consider adding unit tests for width-only, height-only, and both-missing SVGs with valid and invalid viewBox values before merging.