refactor(core): use const for descriptor in LegacyMigrationResolver (#4292)

Author: trivikr

.yarn/versions/0856ca1a.yml

@@ -0,0 +1,34 @@
+releases:
+  "@yarnpkg/core": patch
+
+declined:
+  - "@yarnpkg/plugin-compat"
+  - "@yarnpkg/plugin-constraints"
+  - "@yarnpkg/plugin-dlx"
+  - "@yarnpkg/plugin-essentials"
+  - "@yarnpkg/plugin-exec"
+  - "@yarnpkg/plugin-file"
+  - "@yarnpkg/plugin-git"
+  - "@yarnpkg/plugin-github"
+  - "@yarnpkg/plugin-http"
+  - "@yarnpkg/plugin-init"
+  - "@yarnpkg/plugin-interactive-tools"
+  - "@yarnpkg/plugin-link"
+  - "@yarnpkg/plugin-nm"
+  - "@yarnpkg/plugin-npm"
+  - "@yarnpkg/plugin-npm-cli"
+  - "@yarnpkg/plugin-pack"
+  - "@yarnpkg/plugin-patch"
+  - "@yarnpkg/plugin-pnp"
+  - "@yarnpkg/plugin-pnpm"
+  - "@yarnpkg/plugin-stage"
+  - "@yarnpkg/plugin-typescript"
+  - "@yarnpkg/plugin-version"
+  - "@yarnpkg/plugin-workspace-tools"
+  - "@yarnpkg/builder"
+  - "@yarnpkg/cli"
+  - "@yarnpkg/doctor"
+  - "@yarnpkg/extensions"
+  - "@yarnpkg/nm"
+  - "@yarnpkg/pnpify"
+  - "@yarnpkg/sdks"

packages/yarnpkg-core/sources/LegacyMigrationResolver.ts

@@ -53,15 +53,16 @@ export class LegacyMigrationResolver implements Resolver {
     const resolutions = this.resolutions = new Map();
 
     for (const key of Object.keys(parsed)) {
-      let descriptor = structUtils.tryParseDescriptor(key);
+      const parsedDescriptor = structUtils.tryParseDescriptor(key);
 
-      if (!descriptor) {
+      if (!parsedDescriptor) {
         report.reportWarning(MessageName.YARN_IMPORT_FAILED, `Failed to parse the string "${key}" into a proper descriptor`);
         continue;
       }
 
-      if (semverUtils.validRange(descriptor.range))
-        descriptor = structUtils.makeDescriptor(descriptor, `npm:${descriptor.range}`);
+      const descriptor = semverUtils.validRange(parsedDescriptor.range)
+        ? structUtils.makeDescriptor(parsedDescriptor, `npm:${parsedDescriptor.range}`)
+        : parsedDescriptor;
 
       const {version, resolved} = (parsed as any)[key];