fix(version-tools): Detect bump types between RC builds and internal builds correctly (#19152)

When comparing RC and internal builds, RC builds should be considered
major bumps compared to internal builds. There may be further fixes
needed, but this enables `flub release report` to work on the RC1
version.

Author: tylerbutler

build-tools/packages/version-tools/src/semver.ts

@@ -99,16 +99,32 @@ export function detectBumpType(
 
 	const v1IsInternal = isInternalVersionScheme(v1, true, true);
 	const v2IsInternal = isInternalVersionScheme(v2, true, true);
+	let v1PrereleaseId: string = "";
+	let v2PrereleaseId: string = "";
 
 	if (v1IsInternal) {
-		const [, internalVer] = fromInternalScheme(v1, true);
+		const [, internalVer, prereleaseId] = fromInternalScheme(v1, true);
 		v1Parsed = internalVer;
+		v1PrereleaseId = prereleaseId;
 	}
 
 	// Only convert if the versions are the same scheme.
 	if (v2IsInternal && v1IsInternal) {
-		const [, internalVer] = fromInternalScheme(v2, true);
+		const [, internalVer, prereleaseId] = fromInternalScheme(v2, true);
 		v2Parsed = internalVer;
+		v2PrereleaseId = prereleaseId;
+	}
+
+	if (v1PrereleaseId === "internal" && v2PrereleaseId === "rc") {
+		// This is a special case for RC and internal builds. RC builds are always a
+		// major bump compared to an internal build.
+		return "major";
+	}
+
+	if (v1PrereleaseId !== v2PrereleaseId) {
+		throw new Error(
+			`v1 prerelease ID: ${v1PrereleaseId} cannot be compared to v2 prerelease ID: ${v2PrereleaseId}`,
+		);
 	}
 
 	if (semver.compareBuild(v1Parsed, v2Parsed) >= 0) {

build-tools/packages/version-tools/src/test/semver.test.ts

@@ -115,6 +115,14 @@ describe("semver", () => {
 		it("v1 is semver, v2 is internal but smaller than v1", () => {
 			assert.throws(() => detectBumpType("2.1.0", "2.0.0-internal.3.0.0"));
 		});
+
+		it("v1 is internal, v2 is rc", () => {
+			assert.equal(detectBumpType("2.0.0-internal.8.0.1", "2.0.0-rc.1.0.0"), "major");
+		});
+
+		it("v1 is rc, v2 is rc", () => {
+			assert.equal(detectBumpType("2.0.0-rc.1.0.0", "2.0.0-rc.1.0.1"), "patch");
+		});
 	});
 
 	describe("internal version scheme ranges", () => {