fix #3131, fix #3663: yarnpnp + windows + D drive

Author: evanw

CHANGELOG.md

@@ -2,6 +2,18 @@
 
 ## Unreleased
 
+* Better support building projects that use Yarn on Windows ([#3131](https://github.com/evanw/esbuild/issues/3131), [#3663](https://github.com/evanw/esbuild/issues/3663))
+
+    With this release, you can now use esbuild to bundle projects that use Yarn Plug'n'Play on Windows on drives other than the `C:` drive. The problem was as follows:
+
+    1. Yarn in Plug'n'Play mode on Windows stores its global module cache on the `C:` drive
+    2. Some developers put their projects on the `D:` drive
+    3. Yarn generates relative paths that use `../..` to get from the project directory to the cache directory
+    4. Windows-style paths don't support directory traversal between drives via `..` (so `D:\..` is just `D:`)
+    5. I didn't have access to a Windows machine for testing this edge case
+
+    Yarn works around this edge case by pretending Windows-style paths beginning with `C:\` are actually Unix-style paths beginning with `/C:/`, so the `../..` path segments are able to navigate across drives inside Yarn's implementation. This was broken for a long time in esbuild but I finally got access to a Windows machine and was able to debug and fix this edge case. So you should now be able to bundle these projects with esbuild.
+
 * Preserve parentheses around function expressions ([#4252](https://github.com/evanw/esbuild/issues/4252))
 
     The V8 JavaScript VM uses parentheses around function expressions as an optimization hint to immediately compile the function. Otherwise the function would be lazily-compiled, which has additional overhead if that function is always called immediately as lazy compilation involves parsing the function twice. You can read [V8's blog post about this](https://v8.dev/blog/preparser) for more details.

internal/bundler_tests/bundler_yarnpnp_test.go

@@ -150,3 +150,57 @@ func TestTsconfigStackOverflowYarnPnP(t *testing.T) {
 		},
 	})
 }
+func TestWindowsCrossVolumeReferenceYarnPnP(t *testing.T) {
+	yarnpnp_suite.expectBundledWindows(t, bundled{
+		files: map[string]string{
+			"D:\\project\\entry.jsx": `
+				import * as React from 'react'
+				console.log(<div />)
+			`,
+			"C:\\Users\\user\\AppData\\Local\\Yarn\\Berry\\cache\\react.zip\\node_modules\\react\\index.js": `
+				export function createElement() {}
+			`,
+			"D:\\project\\.pnp.data.json": `
+				{
+					"packageRegistryData": [
+						[null, [
+							[null, {
+								"packageLocation": "./",
+								"packageDependencies": [
+									["react", "npm:19.1.1"],
+									["project", "workspace:."]
+								],
+								"linkType": "SOFT"
+							}]
+						]],
+						["react", [
+							["npm:19.1.1", {
+								"packageLocation": "../../C:/Users/user/AppData/Local/Yarn/Berry/cache/react.zip/node_modules/react/",
+								"packageDependencies": [
+									["react", "npm:19.1.1"]
+								],
+								"linkType": "HARD"
+							}]
+						]],
+						["project", [
+							["workspace:.", {
+								"packageLocation": "./",
+								"packageDependencies": [
+									["react", "npm:19.1.1"],
+									["project", "workspace:."]
+								],
+								"linkType": "SOFT"
+							}]
+						]]
+					]
+				}
+			`,
+		},
+		entryPaths:    []string{"D:\\project\\entry.jsx"},
+		absWorkingDir: "D:\\project",
+		options: config.Options{
+			Mode:          config.ModeBundle,
+			AbsOutputFile: "D:\\project\\out.js",
+		},
+	})
+}

internal/bundler_tests/snapshots/snapshots_yarnpnp.txt

@@ -8,3 +8,13 @@ TestTsconfigStackOverflowYarnPnP
 ---------- /Users/user/project/out.js ----------
 // entry.jsx
 console.log(/* @__PURE__ */ success("div", null));
+
+================================================================================
+TestWindowsCrossVolumeReferenceYarnPnP
+---------- D:/project/out.js ----------
+// C:/Users/user/AppData/Local/Yarn/Berry/cache/react.zip/node_modules/react/index.js
+function createElement() {
+}
+
+// entry.jsx
+console.log(/* @__PURE__ */ createElement("div", null));

internal/resolver/yarnpnp.go

@@ -4,6 +4,7 @@ package resolver
 
 import (
 	"fmt"
+	"path"
 	"regexp"
 	"strings"
 	"syscall"
@@ -278,7 +279,25 @@ func (r resolverQuery) resolveToUnqualified(specifier string, parentURL string,
 	}
 
 	// Return path.resolve(manifest.dirPath, dependencyPkg.packageLocation, modulePath)
-	pkgDirPath := r.fs.Join(manifest.absDirPath, dependencyPkg.packageLocation)
+	absDirPath := manifest.absDirPath
+	isWindows := !strings.HasPrefix(absDirPath, "/")
+	if isWindows {
+		// Yarn converts Windows-style paths with volume labels into Unix-style
+		// paths with a "/" prefix for the purpose of joining them together here.
+		// So "C:\foo\bar.txt" becomes "/C:/foo/bar.txt". This is very important
+		// because Yarn also stores a single global cache on the "C:" drive, many
+		// developers do their work on the "D:" drive, and Yarn uses "../C:" to
+		// traverse between the "D:" drive and the "C:" drive. Windows doesn't
+		// allow you to do that ("D:\.." is just "D:\") so without temporarily
+		// swapping to Unix-style paths here, esbuild would otherwise fail in this
+		// case while Yarn itself would succeed.
+		absDirPath = "/" + strings.ReplaceAll(absDirPath, "\\", "/")
+	}
+	pkgDirPath := path.Join(absDirPath, dependencyPkg.packageLocation)
+	if isWindows && strings.HasPrefix(pkgDirPath, "/") {
+		// Convert the Unix-style path back into a Windows-style path afterwards
+		pkgDirPath = strings.ReplaceAll(pkgDirPath[1:], "\\", "//")
+	}
 	if r.debugLogs != nil {
 		r.debugLogs.addNote(fmt.Sprintf("  Resolved %q via Yarn PnP to %q with subpath %q", specifier, pkgDirPath, modulePath))
 	}