Some users are confused by seeing wildly different output after running
the generator, which is simply solved by running `rustfmt`. As this is
both confusing and "somewhat" slow, invoke `rustfmt` directly within the
generator by piping string contents through it before redirecting to
disk. This not only makes the output consistent, it is the fastest way
to reformat generator changes by omitting the round-trip to disk
entirely, nor having `rustfmt` recursively go through the workspace and
all files (including those that are not generated).
On a many-core machine these times are a bit skewed, but I want to
include them to prove the "speed" point nevertheless, even if simplicity
and consistency is the main reason to make this change:
Before:
time ./target/debug/generator && time cargo fmt --all
./target/debug/generator 3.51s user 1.25s system 99% cpu 4.769 total
cargo fmt --all 0.79s user 0.06s system 99% cpu 0.853 total
After:
time ./target/debug/generator
./target/debug/generator 4.51s user 0.41s system 99% cpu 4.931 total
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