[eddyb]

You could look at Cranelift, which I believe uses integer indices, and several datastructures for control-flow vs dataflow.

There is no SSA IR in rustc itself (MIR, regrettably, only lowers control-flow, but uses variables instead of representing dataflow).

[jhgb]

> which I believe uses integer indices

So basically it sidesteps the type system issues in a similar way that an inconvenient car trip instead of taking a flight sidesteps the TSA issues? ;)

[aarchi]

Adjacency matrices would make ownership clear and solve the single-writer/multiple-reader issue because nodes wouldn't directly reference each other, but it keeps the exact same relationship between nodes, so any memory leaks are still possible (e.g. not cleaning up dead code because it is cyclic and appears to have references). If I'm going to defeat the type system, it seems like raw pointers would be easier.