[pcwalton]

My recollection is that Brian Anderson, who came from the C# world, was an early advocate of the easily-googlable error codes that Microsoft compilers use a lot, and pushed to get them in. That was a good call. (In general Brian had a lot of behind-the-scenes positive influence on Rust: my favorite brson-ism is "if the code doesn't have a test it doesn't exist".)

[steveklabnik]

Yeah this PR cites it as explicitly a continuation of Bryan’s work. I never did any implementation work on errors, I was just a big fan of the codes concept.