`enum InterIntraType`: make a real enum #3773

Job	Run time
test-on-macos-latest	4m 0s
test-on-ubuntu-latest (x86_64-unknown-linux-gnu, release, --release --no-default-features --featu...	2m 3s
test-on-ubuntu-latest (x86_64-unknown-linux-gnu, release, --release --no-default-features --featu...	2m 17s
test-on-ubuntu-latest (x86_64-unknown-linux-gnu, release, --release --no-default-features --featu...	1m 53s
test-on-ubuntu-latest (x86_64-unknown-linux-gnu, opt-dev, --profile opt-dev, 2)	2m 24s
test-on-ubuntu-latest (x86_64-unknown-linux-gnu, opt-dev, --profile opt-dev, 2, -f 1)	2m 30s
test-on-ubuntu-latest (x86_64-unknown-linux-gnu, opt-dev, --profile opt-dev, 2, -f 2)	3m 28s
test-on-ubuntu-latest (i686-unknown-linux-gnu, release, --release --no-default-features --feature...	2m 27s
test-on-ubuntu-latest (i686-unknown-linux-gnu, release, --release --no-default-features --feature...	2m 29s
test-on-ubuntu-latest (i686-unknown-linux-gnu, release, --release --no-default-features --feature...	1m 53s
test-on-ubuntu-latest (i686-unknown-linux-gnu, opt-dev, --profile opt-dev, 2)	1m 58s
test-on-ubuntu-latest (i686-unknown-linux-gnu, opt-dev, --profile opt-dev, 2, -f 1)	1m 57s
test-on-ubuntu-latest (i686-unknown-linux-gnu, opt-dev, --profile opt-dev, 2, -f 2)	2m 54s
	32m 13s

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