The latest version or rstan / StanHeaders fails to build on Ubuntu 26.04: https://stan-dev.r-universe.dev/builds I think it will be fixed by including the latest RcppEigen in your universe: https://github.com/stan-dev/stan-dev.r-universe.dev/pull/1
The latest version or rstan / StanHeaders fails to build on Ubuntu 26.04: https://stan-dev.r-universe.dev/builds
I think it will be fixed by including the latest RcppEigen in your universe: stan-dev/stan-dev.r-universe.dev#1