You are correct, the technical differences are negligible for most intents and purposes.
However, the certification covers not only the source that was used to build, but rather the entire process to produce the binary for the source, that is our (Ferrous Systems) organization, our processes, the review process to ensure that requirements match the tests, the CI, the quality management, how we handle new issues (for example reporting to customers) … So even if you’d build the Ferrocene compiler from the available Ferrocene source, this would not give you a qualified compiler - because it’s not been built by our standards.
So to a large extend, the qualification does not produce better software, it „just“ documents that a certain quality baseline is fulfilled. But, as part of the qualification process we test the qualified targets to a higher standard than the rust project itself - the aarch64-unknown-none target is a tier 2 target for the rust project, it’s built as part of the compiler release but not tested. It‘s our qualification target so for us it’s tier 1. And indeed, we did discover issues as part of the certification effort, so ticking the boxes to fulfill that baseline did indeed improve the rust compiler. We wrote a little about the things that came out of the certification process in an earlier blog post: https://ferrous-systems.com/blog/how-ferrocene-improves-rust...
However, the certification covers not only the source that was used to build, but rather the entire process to produce the binary for the source, that is our (Ferrous Systems) organization, our processes, the review process to ensure that requirements match the tests, the CI, the quality management, how we handle new issues (for example reporting to customers) … So even if you’d build the Ferrocene compiler from the available Ferrocene source, this would not give you a qualified compiler - because it’s not been built by our standards.
So to a large extend, the qualification does not produce better software, it „just“ documents that a certain quality baseline is fulfilled. But, as part of the qualification process we test the qualified targets to a higher standard than the rust project itself - the aarch64-unknown-none target is a tier 2 target for the rust project, it’s built as part of the compiler release but not tested. It‘s our qualification target so for us it’s tier 1. And indeed, we did discover issues as part of the certification effort, so ticking the boxes to fulfill that baseline did indeed improve the rust compiler. We wrote a little about the things that came out of the certification process in an earlier blog post: https://ferrous-systems.com/blog/how-ferrocene-improves-rust...