feat(builtin): linker should resolve workspace-absolute paths

Author: alexeagle

internal/linker/index.js

@@ -31,7 +31,11 @@ def register_node_modules_linker(ctx, args, inputs):
       inputs: inputs being passed to the program; a linker input will be appended
     """
 
-    mappings = {}
+    mappings = {
+        # We always map the workspace to itself to support absolute require like
+        # import from 'my_wksp/path/to/file'
+        ctx.workspace_name: ctx.workspace_name,
+    }
     node_modules_root = ""
 
     # Look through data/deps attributes to find...

internal/linker/link_node_modules.bzl

@@ -121,6 +121,10 @@ export class Runfiles {
     if (!this.manifest) return undefined;
 
     for (const [k, v] of this.manifest) {
+      // Account for Bazel --legacy_external_runfiles
+      // which pollutes the workspace with 'my_wksp/external/...'
+      if (k.startsWith(`${dir}/external`)) continue;
+
       // Entry looks like
       // k: npm/node_modules/semver/LICENSE
       // v: /path/to/external/npm/node_modules/semver/LICENSE

internal/linker/link_node_modules.ts

@@ -18,6 +18,7 @@ sh_binary(
     name = "run_program",
     srcs = ["run_program_with_node.sh"],
     data = [
+        "absolute_import/index.js",
         ":program.js",
         "//internal/linker:index.js",
         "//internal/linker/test/integration/static_linked_pkg",

internal/linker/test/integration/BUILD.bazel

@@ -0,0 +1,5 @@
+function addC(str) {
+  return `${str}_c`;
+}
+
+exports.addC = addC;

internal/linker/test/integration/absolute_import/index.js

@@ -1 +1 @@
-1.2.3_b_a
+1.2.3_c_b_a

internal/linker/test/integration/golden.txt

@@ -4,8 +4,11 @@ const a = require('static_linked');
 // First-party package from ./dynamic_linked_pkg
 // it should get resolved from the execroot
 const b = require('dynamic_linked');
+// We've always supported `require('my_workspace')` for absolute imports like Google does it
+const c = require('build_bazel_rules_nodejs/internal/linker/test/integration/absolute_import');
+
 // Third-party package installed in the root node_modules
 const semver = require('semver');
 
 // This output should match what's in the golden.txt file
-console.log(a.addA(b.addB(semver.clean(' =v1.2.3 '))));
+console.log(a.addA(b.addB(c.addC(semver.clean(' =v1.2.3 ')))));