The Guile ebuild fails on AMD64. I downloaded the Red Hat guile source RPM, and there are a couple of patches (which I'll attach) that fix the build on AMD64.
Created attachment 21948 [details, diff] Guile patch from Red Hat source RPM Apply with: "patch -p1"
Created attachment 21949 [details, diff] Guild patch from Red Hat source RPM (#20 Apply with "patch -p1".
Created attachment 21950 [details] "spec" file for Guile patches I don't know if it matters or not, but the changelog in the spec file documents who made the fixes.
Done.