GCC caps LLM-generated contributions at 15 lines

GCC's steering committee adopted a policy on July 29 that rejects any legally significant contribution containing or derived from LLM-generated content, per LWN.

That puts real weight on GNU's existing copyright threshold: about 15 lines of code or text is enough to make a contribution legally significant. Cross that line with LLM-derived work and GCC won't take the patch, no matter how a maintainer reviewed it afterward.

Small, disclosed LLM-assisted changes under that 15-line mark are still fine. The committee also carved out an exception for legally significant test cases: maintainers can accept those even when an LLM wrote them.

The test-case carve-out is easy to miss, and it's what separates this from a blanket ban. It reads like a policy about where copyright risk actually lives in a codebase, not a rejection of the tools themselves.

Research, bug hunting, and patch review done with LLMs stay allowed under the policy. The restriction is only about what actually lands in the tree.