rules.go

package gorules

import "github.com/quasilyte/go-ruleguard/dsl/fluent"

func useMathBits(m fluent.Matcher) {
	m.Match(`$X >> $N | $X << (8 - $N)`,
		`$X << $N | $X >> (8 - $N)`,
		`$X >> (8 - $N) | $X << $N`,
		`$X << (8 - $N) | $X >> $N`,
		`$X >> $N | $X << (16 - $N)`,
		`$X << $N | $X >> (16 - $N)`,
		`$X >> (16 - $N) | $X << $N`,
		`$X << (16 - $N) | $X >> $N`,
		`$X >> $N | $X << (32 - $N)`,
		`$X << $N | $X >> (32 - $N)`,
		`$X >> (32 - $N) | $X << $N`,
		`$X << (32 - $N) | $X >> $N`,
		`$X >> $N | $X << (64 - $N)`,
		`$X << $N | $X >> (64 - $N)`,
		`$X >> (64 - $N) | $X << $N`,
		`$X << (64 - $N) | $X >> $N`).
		Report(`Try using math/bits instead`)
}

rules_with_fix.go

package gorules

import "github.com/quasilyte/go-ruleguard/dsl/fluent"

func useMathBits(m fluent.Matcher) {
	// Suggest() is a rewrite template for a match.
	// If no Report is defined, it's also used to infer the warning text
	// when autofixing is disabled.

	m.Match(`$x << $n | $x >> (8 - $n) `,).
		Suggest(`bits.RotateLeft8($x, $n)`)
	m.Match(`$x << $n | $x >> (16 - $n) `,).
		Suggest(`bits.RotateLeft16($x, $n)`)
}