[cli] fallback to _start value for --exportStart if argument was skipped (#2343)

Author: MaxGraey

cli/index.js

@@ -62,6 +62,10 @@ function toUpperSnakeCase(str) {
   return str.replace(/-/g, "_").toUpperCase();
 }
 
+function isNonEmptyString(value) {
+  return typeof value === "string" && value !== "";
+}
+
 /** Ensures that an object is a wrapper class instead of just a pointer. */
 // function __wrap(ptrOrObj, wrapperClass) {
 //   if (typeof ptrOrObj === "number") {
@@ -309,7 +313,9 @@ export async function main(argv, options) {
   assemblyscript.setSharedMemory(compilerOptions, opts.sharedMemory);
   assemblyscript.setImportTable(compilerOptions, opts.importTable);
   assemblyscript.setExportTable(compilerOptions, opts.exportTable);
-  assemblyscript.setExportStart(compilerOptions, typeof opts.exportStart === "string" ? opts.exportStart : null);
+  if (opts.exportStart) {
+    assemblyscript.setExportStart(compilerOptions, isNonEmptyString(opts.exportStart) ? opts.exportStart : "_start");
+  }
   assemblyscript.setMemoryBase(compilerOptions, opts.memoryBase >>> 0);
   assemblyscript.setTableBase(compilerOptions, opts.tableBase >>> 0);
   assemblyscript.setSourceMap(compilerOptions, opts.sourceMap != null);
@@ -318,7 +324,7 @@ export async function main(argv, options) {
   assemblyscript.setLowMemoryLimit(compilerOptions, opts.lowMemoryLimit >>> 0);
   assemblyscript.setExportRuntime(compilerOptions, opts.exportRuntime);
   assemblyscript.setBundleVersion(compilerOptions, bundleMajorVersion, bundleMinorVersion, bundlePatchVersion);
-  if (!opts.stackSize && opts.runtime == "incremental") {
+  if (!opts.stackSize && runtime === 2 /* incremental */) {
     opts.stackSize = assemblyscript.DEFAULT_STACK_SIZE;
   }
   assemblyscript.setStackSize(compilerOptions, opts.stackSize);

tests/cli/options.js

@@ -1,5 +1,5 @@
 import assert from "assert";
-import * as optionsUtil from "../../cli/util/options.js";
+import * as optionsUtil from "../../util/options.js";
 
 const config = {
   "enable": {
@@ -40,10 +40,15 @@ optionsUtil.addDefaults(config, merged = { other: ["y"] });
 assert.deepStrictEqual(merged.other, ["y"]);
 
 // Complete usage test
-var result = optionsUtil.parse(["--enable", "a", "--disable", "b"], config, false);
+var result = optionsUtil.parse([
+  "--enable", "a",
+  "--disable", "b",
+], config, false);
+
 merged = optionsUtil.merge(config, result.options, { enable: ["b", "c"] });
 merged = optionsUtil.merge(config, merged, { disable: ["a", "d"] });
 optionsUtil.addDefaults(config, merged);
+
 assert.deepStrictEqual(merged.enable, ["a", "c"]);
 assert.deepStrictEqual(merged.disable, ["b", "d"]);
 assert.deepStrictEqual(merged.other, ["x"]);