feat: add pnpm dedupe command

.changeset/giant-crews-push.md

@@ -0,0 +1,7 @@
+---
+"@pnpm/plugin-commands-installation": minor
+"@pnpm/core": minor
+pnpm: minor
+---
+
+Add a `pnpm dedupe` command that removes dependencies from the lockfile by re-resolving the dependency graph. This work similar to yarn's [`yarn dedupe --strategy highest`](https://yarnpkg.com/cli/dedupe) command.

__fixtures__/workspace-with-lockfile-dupes/package.json

@@ -0,0 +1 @@
+{}

__fixtures__/workspace-with-lockfile-dupes/packages/bar/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "bar",
+  "dependencies": {
+    "ajv": "^6.10.2"
+  }
+}

__fixtures__/workspace-with-lockfile-dupes/packages/foo/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "foo",
+  "dependencies": {
+    "ajv": "^6.12.5"
+  }
+}

__fixtures__/workspace-with-lockfile-dupes/pnpm-workspace.yaml

@@ -0,0 +1,2 @@
+packages:
+  - 'packages/**'

pkg-manager/core/src/install/extendInstallOptions.ts

@@ -37,6 +37,7 @@ export interface StrictInstallOptions {
   linkWorkspacePackagesDepth: number
   lockfileOnly: boolean
   fixLockfile: boolean
+  dedupe: boolean
   ignoreCompatibilityDb: boolean
   ignoreDepScripts: boolean
   ignorePackageManifest: boolean

pkg-manager/core/src/install/index.ts

@@ -305,6 +305,7 @@ export async function mutateModules (
       !ctx.lockfileHadConflicts &&
       !opts.update &&
       !opts.fixLockfile &&
+      !opts.dedupe &&
       installsOnly &&
       (
         frozenLockfile && !opts.lockfileOnly ||
@@ -644,6 +645,27 @@ function forgetResolutionsOfPrevWantedDeps (importer: ProjectSnapshot, wantedDep
   }
 }
 
+function forgetResolutionsOfAllPrevWantedDeps (wantedLockfile: Lockfile) {
+  // Similar to the forgetResolutionsOfPrevWantedDeps function above, we can
+  // delete existing resolutions in importers to make sure they're resolved
+  // again.
+  if ((wantedLockfile.importers != null) && !isEmpty(wantedLockfile.importers)) {
+    wantedLockfile.importers = mapValues(
+      ({ dependencies, devDependencies, optionalDependencies, ...rest }) => rest,
+      wantedLockfile.importers)
+  }
+
+  // The resolveDependencies function looks at previous PackageSnapshot
+  // dependencies/optionalDependencies blocks and merges them with new resolved
+  // deps. Clear the previous PackageSnapshot fields so the newly resolved deps
+  // are always used.
+  if ((wantedLockfile.packages != null) && !isEmpty(wantedLockfile.packages)) {
+    wantedLockfile.packages = mapValues(
+      ({ dependencies, optionalDependencies, ...rest }) => rest,
+      wantedLockfile.packages)
+  }
+}
+
 export async function addDependenciesToPackage (
   manifest: ProjectManifest,
   dependencySelectors: string[],
@@ -798,6 +820,15 @@ const _installInContext: InstallFunction = async (projects, ctx, opts) => {
     }), ctx.wantedLockfile.packages)
   }
 
+  if (opts.dedupe) {
+    // Deleting recorded version resolutions from importers and packages. These
+    // fields will be regenerated using the preferred versions computed above.
+    //
+    // This is a bit different from a "full resolution", which completely
+    // ignores preferred versions from the lockfile.
+    forgetResolutionsOfAllPrevWantedDeps(ctx.wantedLockfile)
+  }
+
   let {
     dependenciesGraph,
     dependenciesByProjectId,

pkg-manager/plugin-commands-installation/src/dedupe.ts

@@ -0,0 +1,37 @@
+import { docsUrl } from '@pnpm/cli-utils'
+import { UNIVERSAL_OPTIONS } from '@pnpm/common-cli-options-help'
+import renderHelp from 'render-help'
+import * as install from './install'
+
+export const rcOptionsTypes = cliOptionsTypes
+
+export function cliOptionsTypes () {
+  return {}
+}
+
+export const commandNames = ['dedupe']
+
+export function help () {
+  return renderHelp({
+    description: 'Perform an install removing older dependencies in the lockfile if a newer version can be used.',
+    descriptionLists: [
+      {
+        title: 'Options',
+        list: [
+          ...UNIVERSAL_OPTIONS,
+        ],
+      },
+    ],
+    url: docsUrl('dedupe'),
+    usages: ['pnpm dedupe'],
+  })
+}
+
+export async function handler (
+  opts: install.InstallCommandOptions
+) {
+  return install.handler({
+    ...opts,
+    dedupe: true,
+  })
+}

pkg-manager/plugin-commands-installation/src/index.ts

@@ -1,4 +1,5 @@
 import * as add from './add'
+import * as dedupe from './dedupe'
 import * as install from './install'
 import * as fetch from './fetch'
 import * as link from './link'
@@ -8,4 +9,4 @@ import * as unlink from './unlink'
 import * as update from './update'
 import * as importCommand from './import'
 
-export { add, fetch, install, link, prune, remove, unlink, update, importCommand }
+export { add, dedupe, fetch, install, link, prune, remove, unlink, update, importCommand }

pkg-manager/plugin-commands-installation/src/install.ts

@@ -293,6 +293,7 @@ export type InstallCommandOptions = Pick<Config,
   pruneDirectDependencies?: boolean
   pruneStore?: boolean
   recursive?: boolean
+  dedupe?: boolean
   saveLockfile?: boolean
   workspace?: boolean
 } & Partial<Pick<Config, 'modulesCacheMaxAge' | 'pnpmHomeDir' | 'preferWorkspacePackages'>>

pkg-manager/plugin-commands-installation/src/installDeps.ts

@@ -90,6 +90,7 @@ export type InstallDepsOptions = Pick<Config,
   updatePackageManifest?: boolean
   useBetaCli?: boolean
   recursive?: boolean
+  dedupe?: boolean
   workspace?: boolean
 } & Partial<Pick<Config, 'pnpmHomeDir'>>