[llvm] [FileCheck] --dump-input: Elide middle of underlines for no-match (PR #192908)

[Fangrui Song via llvm-commits]

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MaskRay wrote:

Thanks for the detailed comment but I don't think I get the idea of `{ ... }`.... Is this patch still acceptable without doing the `{ }` stuff? I find the underlining in the UI quite distracting, and it's something I’ve tended to overlook for years. If you have time to polish your `{ }` patch, I'll try reviewing them.

https://github.com/llvm/llvm-project/pull/192908