Detect non-v8 snapshotable systems

Author: jakebailey

src/tscSnapshot/tsc.ts

@@ -1,13 +1,30 @@
 import fs = require("fs");
 import path = require("path");
-import crypto = require("crypto");
 import cp = require("child_process");
 
+let v8: typeof import("v8") | undefined;
+try {
+    if (!process.versions.bun) {
+        v8 = require("v8");
+    }
+}
+catch {
+    // do nothing
+}
+
+const exe = path.join(__dirname, "tscReal.js");
+
+if (!(v8 as any)?.startupSnapshot) {
+    require(exe);
+    throw new Error("unreachable");
+}
+
 const args = process.argv.slice(2);
 
 const doBuildSnapshot = process.env.TYPESCRIPT_BUILD_SNAPSHOT === "true";
 
 function checksumFile(path: string) {
+    const crypto = require("crypto") as typeof import("crypto");
     // Benchmarking shows that sha1 is the fastest hash.
     // It is theoretically insecure, but we're just using it to detect file mismatches.
     // TODO(jakebailey): If sha1 is ever removed, this will fail; we should try catch
@@ -18,10 +35,8 @@ function checksumFile(path: string) {
     return hash.digest("hex");
 }
 
-const exe = path.join(__dirname, "tscReal.js");
 const exeHash = checksumFile(exe);
 const blobName = `${exe}.${process.version}.${exeHash}.blob`;
-// const blobName = `${exe}.${process.version}.blob`;
 
 if (doBuildSnapshot) {
     // Build and atomic rename.