Opt in to generate-macro-expansion when building on docs.rs

Author: dtolnay

Cargo.toml

@@ -29,6 +29,7 @@ libcxx = ["libc++"]
 targets = ["x86_64-unknown-linux-gnu"]
 rustdoc-args = [
     "--generate-link-to-definition",
+    "--generate-macro-expansion",
     "--extern-html-root-url=core=https://doc.rust-lang.org",
     "--extern-html-root-url=alloc=https://doc.rust-lang.org",
     "--extern-html-root-url=std=https://doc.rust-lang.org",