fix: linking optional dependencies (#7949)

close #7943

.changeset/gold-cars-protect.md

@@ -0,0 +1,6 @@
+---
+"@pnpm/resolve-dependencies": patch
+"pnpm": patch
+---
+
+Fixed an issue where optional dependencies were not linked into the dependent's node_modules [#7943](https://github.com/pnpm/pnpm/issues/7943).

pkg-manager/core/test/install/optionalDependencies.ts

@@ -689,3 +689,12 @@ test('optional dependency is hardlinked to the store if it does not require a bu
     })
   )
 })
+
+// Covers https://github.com/pnpm/pnpm/issues/7943
+test('complex scenario with same optional dependencies appearing in many places of the dependency graph', async () => {
+  prepareEmpty()
+  await addDependenciesToPackage({}, ['@storybook/addon-essentials@7.6.17', 'storybook@7.6.17', 'vite@5.2.8'], testDefaults())
+
+  expect(fs.readdirSync('node_modules/.pnpm/esbuild@0.18.20/node_modules/@esbuild').length).toEqual(1)
+  expect(fs.readdirSync('node_modules/.pnpm/esbuild@0.20.2/node_modules/@esbuild').length).toEqual(1)
+})

pkg-manager/resolve-dependencies/src/resolveDependencyTree.ts

@@ -277,7 +277,7 @@ function buildTree (
     }
     const childNodeId = createNodeId(parentNodeId, child.depPath)
     childrenNodeIds[child.alias] = childNodeId
-    installable = installable && !ctx.skipped.has(child.depPath)
+    installable = installable || !ctx.skipped.has(child.depPath)
     ctx.dependenciesTree.set(childNodeId, {
       children: () => buildTree(ctx,
         childNodeId,