dev-lang/swift-bootstrap: new package, add 1.0

Signed-off-by: Itai Ferber <itai@itaiferber.net>

dev-lang/swift-bootstrap/metadata.xml

@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE pkgmetadata SYSTEM "https://www.gentoo.org/dtd/metadata.dtd">
+<pkgmetadata>
+  <maintainer type="person">
+    <email>itai@itaiferber.net</email>
+    <name>Itai Ferber</name>
+  </maintainer>
+  <longdescription>
+    A virtual package which provides a base version of Swift to bootstrap
+    ">=dev-lang/swift-6*" with. Swift 6 and later require an earlier Swift
+    compiler to bootstrap with; "dev-lang/swift" can depend on earlier versions
+    of itself, but to avoid arbitrarily long dependency chains on a first
+    install of Swift on a new machine, this package vends a base version of
+    Swift that newer versions can BDEPEND on.
+  </longdescription>
+  <upstream>
+    <remote-id type="github">swiftlang/swift</remote-id>
+  </upstream>
+  <slots>
+    <slot name="5">
+      The Swift 5 language, compiler, and tooling, used to bootstrap future versions of Swift.
+    </slot>
+    <subslots>
+      Minor Swift versions.
+    </subslots>
+  </slots>
+</pkgmetadata>

dev-lang/swift-bootstrap/swift-bootstrap-1.0.ebuild

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+# Copyright 1999-2024 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+DESCRIPTION="A virtual package providing a base Swift to bootstrap future versions with."
+HOMEPAGE="https://www.swift.org"
+
+S="${WORKDIR}"
+
+LICENSE="GPL-2"
+SLOT="5/10"
+KEYWORDS="~amd64"
+
+# `dev-lang/swift` BDEPENDS on either this package or `dev-lang/swift` itself. When any version of `dev-lang/swift` is
+# installed, it will be preferred over this package; when no version of `dev-lang/swift` is installed, `emerge` will
+# fall back to installing this.
+#
+# Because `dev-lang/swift` is versioned by SLOT, any updates to newer versions of Swift will record the current version
+# in the @world set, leaving them around; this allows `swift-bootstrap` to eventually get cleaned up.
+RDEPEND="dev-lang/swift:5/10"