fix #3634: crash if resolving with bad source dir

CHANGELOG.md

@@ -1,5 +1,11 @@
 # Changelog
 
+## Unreleased
+
+* Fix a crash when resolving a path from a directory that doesn't exist ([#3634](https://github.com/evanw/esbuild/issues/3634))
+
+    This release fixes a regression where esbuild could crash when resolving an absolute path if the source directory for the path resolution operation doesn't exist. While this situation doesn't normally come up, it could come up when running esbuild concurrently with another operation that mutates the file system as esbuild is doing a build (such as using `git` to switch branches). The underlying problem was a regression that was introduced in version 0.18.0.
+
 ## 0.20.0
 
 **This release deliberately contains backwards-incompatible changes.** To avoid automatically picking up releases like this, you should either be pinning the exact version of `esbuild` in your `package.json` file (recommended) or be using a version range syntax that only accepts patch upgrades such as `^0.19.0` or `~0.19.0`. See npm's documentation about [semver](https://docs.npmjs.com/cli/v6/using-npm/semver/) for more information.

internal/resolver/resolver.go

@@ -504,7 +504,6 @@ func (res *Resolver) Resolve(sourceDir string, importPath string, kind ast.Impor
 
 	r.mutex.Lock()
 	defer r.mutex.Unlock()
-	sourceDirInfo := r.dirInfoCached(sourceDir)
 
 	// Check for the Yarn PnP manifest if it hasn't already been checked for
 	if !r.pnpManifestWasChecked {
@@ -533,6 +532,12 @@ func (res *Resolver) Resolve(sourceDir string, importPath string, kind ast.Impor
 		}
 	}
 
+	sourceDirInfo := r.dirInfoCached(sourceDir)
+	if sourceDirInfo == nil {
+		// Bail if the directory is missing for some reason
+		return nil, debugMeta
+	}
+
 	result := r.resolveWithoutSymlinks(sourceDir, sourceDirInfo, importPath)
 	if result == nil {
 		// If resolution failed, try again with the URL query and/or hash removed
@@ -1006,11 +1011,6 @@ func (r resolverQuery) resolveWithoutSymlinks(sourceDir string, sourceDirInfo *d
 	}
 
 	if checkPackage {
-		if sourceDirInfo == nil {
-			// Bail if the directory is missing for some reason
-			return nil
-		}
-
 		// Support remapping one package path to another via the "browser" field
 		if remapped, ok := r.checkBrowserMap(sourceDirInfo, importPath, packagePathKind); ok {
 			if remapped == nil {

scripts/plugin-tests.js

@@ -2522,6 +2522,25 @@ var foo_default2 = "🍕";
 console.log(foo_default, foo_default2);
 `)
   },
+
+  async internalCrashIssue3634({ esbuild }) {
+    await esbuild.build({
+      entryPoints: [],
+      bundle: true,
+      plugins: [{
+        name: 'abc',
+        setup(build) {
+          build.onStart(async () => {
+            const result = await build.resolve('/foo', {
+              kind: 'require-call',
+              resolveDir: 'bar',
+            })
+            assert.strictEqual(result.errors.length, 1)
+          })
+        }
+      }],
+    })
+  },
 }
 
 const makeRebuildUntilPlugin = () => {