fix #2462: convert \ to / in windows paths

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+* Fix Yarn PnP resolution failures due to backslashes in paths on Windows ([#2462](https://github.com/evanw/esbuild/issues/2462))
+
+    Previously dependencies of a Yarn PnP virtual dependency failed to resolve on Windows. This was because Windows uses `\` instead of `/` as a path separator, and the path manipulation algorithms used for Yarn PnP expected `/`. This release converts `\` into `/` in Windows paths, which fixes this issue.
+
 ## 0.15.2
 
 * Fix Yarn PnP issue with packages containing `index.js` ([#2455](https://github.com/evanw/esbuild/issues/2455), [#2461](https://github.com/evanw/esbuild/issues/2461))

internal/resolver/yarnpnp.go

@@ -277,6 +277,10 @@ func (r resolverQuery) findLocator(manifest *pnpData, moduleUrl string) (pnpIden
 	relativeUrl, ok := r.fs.Rel(manifest.absDirPath, moduleUrl)
 	if !ok {
 		return pnpIdentAndReference{}, false
+	} else {
+		// Relative URLs on Windows will use \ instead of /, which will break
+		// everything we do below. Use normal slashes to keep things working.
+		relativeUrl = strings.ReplaceAll(relativeUrl, "\\", "/")
 	}
 
 	// The relative path must not start with ./; trim it if needed

scripts/js-api-tests.js

@@ -3171,6 +3171,84 @@ require("/assets/file.png");
   // scripts/.js-api-tests/yarnPnP_indexJs/entry.js
   foo_default();
 })();
+`)
+  },
+
+  async yarnPnP_depOfVirtual({ esbuild, testDir }) {
+    const entry = path.join(testDir, 'entry.js')
+    const pkg = path.join(testDir, '.yarn', 'cache', 'pkg', 'index.js')
+    const dep = path.join(testDir, '.yarn', 'cache', 'dep', 'index.js')
+    const manifest = path.join(testDir, '.pnp.data.json')
+
+    await writeFileAsync(entry, `import 'pkg'`)
+
+    await mkdirAsync(path.dirname(pkg), { recursive: true })
+    await writeFileAsync(pkg, `import 'dep'`)
+
+    await mkdirAsync(path.dirname(dep), { recursive: true })
+    await writeFileAsync(dep, `success()`)
+
+    await writeFileAsync(manifest, `{
+      "packageRegistryData": [
+        [null, [
+          [null, {
+            "packageLocation": "./",
+            "packageDependencies": [
+              ["pkg", "virtual:some-path"]
+            ],
+            "linkType": "SOFT"
+          }]
+        ]],
+        ["demo", [
+          ["workspace:.", {
+            "packageLocation": "./",
+            "packageDependencies": [
+              ["demo", "workspace:."],
+              ["pkg", "virtual:some-path"]
+            ],
+            "linkType": "SOFT"
+          }]
+        ]],
+        ["pkg", [
+          ["npm:1.0.0", {
+            "packageLocation": "./.yarn/cache/pkg/",
+            "packageDependencies": [
+              ["pkg", "npm:1.0.0"]
+            ],
+            "linkType": "SOFT"
+          }],
+          ["virtual:some-path", {
+            "packageLocation": "./.yarn/__virtual__/pkg-virtual/0/cache/pkg/",
+            "packageDependencies": [
+              ["pkg", "virtual:some-path"],
+              ["dep", "npm:1.0.0"]
+            ],
+            "linkType": "HARD"
+          }]
+        ]],
+        ["dep", [
+          ["npm:1.0.0", {
+            "packageLocation": "./.yarn/cache/dep/",
+            "packageDependencies": [
+              ["dep", "npm:1.0.0"]
+            ],
+            "linkType": "HARD"
+          }]
+        ]]
+      ]
+    }`)
+
+    const value = await esbuild.build({
+      entryPoints: [entry],
+      bundle: true,
+      write: false,
+    })
+
+    assert.strictEqual(value.outputFiles.length, 1)
+    assert.strictEqual(value.outputFiles[0].text, `(() => {
+  // scripts/.js-api-tests/yarnPnP_depOfVirtual/.yarn/cache/dep/index.js
+  success();
+})();
 `)
   },
 }