GLM 5.2 coding test: cheaper, but not a strong Opus replacement
GLM 5.2 is being promoted as a low-cost model that could replace Opus 4.8 or GPT 5.5 for much coding work, but this firsthand benchmark did not support that idea. The test used 50 real coding tasks: 25 in Go and 25 in Rust. The tasks came from merged changes in two active projects, graphql-go-tools and sqlparser-rs.
GLM 5.2 ranked last in quality for both projects. It was also not the cheapest choice, costing about twice as much as in both languages. It needed more agent turns, changed about 1.8 times as much code as the human solution, and still often missed the real fix.
The test pass rate did not separate good answers from bad ones well, so passing tests alone was not enough proof that the result was good. The practical conclusion is to treat GLM 5.2 as a supervised first-draft tool, not as a model for unattended coding work.
Key points
- The benchmark used 50 real coding tasks from Go and Rust projects.
- GLM 5.2 came last on quality in both tested projects.
- It cost about twice as much as in this test.
- It made more code changes than the human solution while still missing key fixes.
- Test pass rate alone was not a reliable sign that the code was good.