build: use composite builds instead of buildSrc

build-logic/src/main/kotlin/lookupversion.kt

@@ -0,0 +1,25 @@
+fun execString(vararg args: String): String {
+	val pb = ProcessBuilder(*args)
+		.redirectOutput(ProcessBuilder.Redirect.PIPE)
+		.start()
+	pb.waitFor()
+	return pb.inputStream.readAllBytes().decodeToString().trim()
+}
+
+private val tag = "([0-9.]+)(?:\\+[^-]*)?".toRegex()
+private val tagOffset = "([0-9.]+)(?:\\+.*)?-([0-9]+)-(.+)".toRegex()
+
+inline fun <T> Regex.useMatcher(string: String, block: (MatchResult) -> T): T? {
+	return matchEntire(string)?.let(block)
+}
+
+fun getGitTagInfo(mcVersion: String): String {
+	val str = execString("git", "describe", "--tags", "HEAD")
+	tag.useMatcher(str) {
+		return it.groupValues[1] + "+mc$mcVersion"
+	}
+	tagOffset.useMatcher(str) {
+		return it.groupValues[1] + "-dev+mc$mcVersion+" + it.groupValues[3]
+	}
+	return "nogitversion+mc$mcVersion"
+}