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module: add --preserve-symlinks-main
Add `--preserve-symlinks-main` option which behaves like `--preserve-symlinks` but for `require.main`. PR-URL: nodejs#19911 Reviewed-By: James M Snell <jasnell@gmail.com>
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Lines changed: 124 additions & 4 deletions

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‎doc/api/cli.md‎

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@@ -217,6 +217,29 @@ are linked from more than one location in the dependency tree (Node.js would
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see those as two separate modules and would attempt to load the module multiple
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times, causing an exception to be thrown).
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The `--preserve-symlinks` flag does not apply to the main module, which allows
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`node --preserve-symlinks node_module/.bin/<foo>` to work. To apply the same
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behavior for the main module, also use `--preserve-symlinks-main`.
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### `--preserve-symlinks-main`
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<!-- YAML
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added: REPLACEME
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-->
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Instructs the module loader to preserve symbolic links when resolving and
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caching the main module (`require.main`).
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This flag exists so that the main module can be opted-in to the same behavior
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that `--preserve-symlinks` gives to all other imports; they are separate flags,
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however, for backward compatibility with older Node.js versions.
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Note that `--preserve-symlinks-main` does not imply `--preserve-symlinks`; it
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is expected that `--preserve-symlinks-main` will be used in addition to
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`--preserve-symlinks` when it is not desirable to follow symlinks before
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resolving relative paths.
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See `--preserve-symlinks` for more information.
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### `--prof-process`
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<!-- YAML
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added: v5.2.0

‎doc/node.1‎

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@@ -143,7 +143,10 @@ Among other uses, this can be used to enable FIPS-compliant crypto if Node.js is
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Emit pending deprecation warnings.
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.
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.It Fl -preserve-symlinks
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Instructs the module loader to preserve symbolic links when resolving and caching modules.
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Instructs the module loader to preserve symbolic links when resolving and caching modules other than the main module.
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.
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.It F1 -preserve-symlinks-main
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Instructs the module loader to preserve symbolic links when resolving and caching the main module.
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.
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.It Fl -prof-process
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Process V8 profiler output generated using the V8 option

‎lib/internal/modules/cjs/loader.js‎

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@@ -42,6 +42,7 @@ const {
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stripShebang
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} = require('internal/modules/cjs/helpers');
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const preserveSymlinks = !!process.binding('config').preserveSymlinks;
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const preserveSymlinksMain = !!process.binding('config').preserveSymlinksMain;
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const experimentalModules = !!process.binding('config').experimentalModules;
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const {
@@ -239,7 +240,21 @@ Module._findPath = function(request, paths, isMain) {
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var rc = stat(basePath);
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if (!trailingSlash) {
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if (rc === 0) { // File.
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if (preserveSymlinks && !isMain) {
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if (!isMain) {
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if (preserveSymlinks) {
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filename = path.resolve(basePath);
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} else {
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filename = toRealPath(basePath);
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}
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} else if (preserveSymlinksMain) {
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// For the main module, we use the preserveSymlinksMain flag instead
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// mainly for backward compatibility, as the preserveSymlinks flag
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// historically has not applied to the main module. Most likely this
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// was intended to keep .bin/ binaries working, as following those
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// symlinks is usually required for the imports in the corresponding
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// files to resolve; that said, in some use cases following symlinks
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// causes bigger problems which is why the preserveSymlinksMain option
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// is needed.
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filename = path.resolve(basePath);
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} else {
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filename = toRealPath(basePath);

‎lib/internal/modules/esm/default_resolve.js‎

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@@ -7,6 +7,7 @@ const { NativeModule, internalBinding } = require('internal/bootstrap/loaders');
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const { extname } = require('path');
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const { realpathSync } = require('fs');
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const preserveSymlinks = !!process.binding('config').preserveSymlinks;
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const preserveSymlinksMain = !!process.binding('config').preserveSymlinksMain;
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const {
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ERR_MISSING_MODULE,
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ERR_MODULE_RESOLUTION_LEGACY,
@@ -71,7 +72,7 @@ function resolve(specifier, parentURL) {
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const isMain = parentURL === undefined;
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if (!preserveSymlinks || isMain) {
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if (isMain ? !preserveSymlinksMain : !preserveSymlinks) {
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const real = realpathSync(getPathFromURL(url), {
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[internalFS.realpathCacheKey]: realpathCache
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});

‎src/node.cc‎

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@@ -237,6 +237,11 @@ bool trace_warnings = false;
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// that is used by lib/module.js
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bool config_preserve_symlinks = false;
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// Set in node.cc by ParseArgs when --preserve-symlinks-main is used.
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// Used in node_config.cc to set a constant on process.binding('config')
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// that is used by lib/module.js
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bool config_preserve_symlinks_main = false;
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// Set in node.cc by ParseArgs when --experimental-modules is used.
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// Used in node_config.cc to set a constant on process.binding('config')
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// that is used by lib/module.js
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" --pending-deprecation emit pending deprecation warnings\n"
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#if defined(NODE_HAVE_I18N_SUPPORT)
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" --preserve-symlinks preserve symbolic links when resolving\n"
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" --preserve-symlinks-main preserve symbolic links when resolving\n"
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" the main module\n"
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#endif
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" --prof-process process v8 profiler output generated\n"
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" using --prof\n"
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" -r, --require module to preload (option can be "
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"repeated)\n"
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" -v, --version print Node.js version\n"
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"\n"
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"Environment variables:\n"
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"NODE_DEBUG ','-separated list of core modules\n"
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Revert(cve);
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} else if (strcmp(arg, "--preserve-symlinks") == 0) {
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config_preserve_symlinks = true;
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} else if (strcmp(arg, "--preserve-symlinks-main") == 0) {
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config_preserve_symlinks_main = true;
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} else if (strcmp(arg, "--experimental-modules") == 0) {
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config_experimental_modules = true;
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new_v8_argv[new_v8_argc] = "--harmony-dynamic-import";
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SafeGetenv("NODE_PRESERVE_SYMLINKS", &text) && text[0] == '1';
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}
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{
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std::string text;
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config_preserve_symlinks_main =
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SafeGetenv("NODE_PRESERVE_SYMLINKS_MAIN", &text) && text[0] == '1';
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}
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if (config_warning_file.empty())
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SafeGetenv("NODE_REDIRECT_WARNINGS", &config_warning_file);
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‎src/node_config.cc‎

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@@ -72,6 +72,8 @@ static void Initialize(Local<Object> target,
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if (config_preserve_symlinks)
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READONLY_BOOLEAN_PROPERTY("preserveSymlinks");
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if (config_preserve_symlinks_main)
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READONLY_BOOLEAN_PROPERTY("preserveSymlinksMain");
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if (config_experimental_modules) {
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READONLY_BOOLEAN_PROPERTY("experimentalModules");

‎src/node_internals.h‎

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@@ -173,6 +173,11 @@ extern std::string openssl_config;
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// that is used by lib/module.js
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extern bool config_preserve_symlinks;
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// Set in node.cc by ParseArgs when --preserve-symlinks-main is used.
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// Used in node_config.cc to set a constant on process.binding('config')
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// that is used by lib/module.js
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extern bool config_preserve_symlinks_main;
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// Set in node.cc by ParseArgs when --experimental-modules is used.
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// Used in node_config.cc to set a constant on process.binding('config')
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// that is used by lib/module.js

‎test/es-module/test-esm-preserve-symlinks-main.js‎

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@@ -0,0 +1,57 @@
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'use strict';
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const common = require('../common');
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const { spawn } = require('child_process');
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const assert = require('assert');
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const path = require('path');
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const fs = require('fs');
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const tmpdir = require('../common/tmpdir');
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tmpdir.refresh();
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const tmpDir = tmpdir.path;
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fs.mkdirSync(path.join(tmpDir, 'nested'));
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fs.mkdirSync(path.join(tmpDir, 'nested2'));
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const entry = path.join(tmpDir, 'nested', 'entry.js');
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const entry_link_absolute_path = path.join(tmpDir, 'link.js');
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const submodule = path.join(tmpDir, 'nested2', 'submodule.js');
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const submodule_link_absolute_path = path.join(tmpDir, 'submodule_link.js');
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fs.writeFileSync(entry, `
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const assert = require('assert');
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// this import only resolves with --preserve-symlinks-main set
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require('./submodule_link.js');
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`);
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fs.writeFileSync(submodule, '');
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try {
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fs.symlinkSync(entry, entry_link_absolute_path);
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fs.symlinkSync(submodule, submodule_link_absolute_path);
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} catch (err) {
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if (err.code !== 'EPERM') throw err;
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common.skip('insufficient privileges for symlinks');
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}
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function doTest(flags, done) {
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// invoke the main file via a symlink. In this case --preserve-symlinks-main
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// dictates that it'll resolve relative imports in the main file relative to
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// the symlink, and not relative to the symlink target; the file structure set
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// up above requires this to not crash when loading ./submodule_link.js
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spawn(process.execPath,
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flags.concat([
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'--preserve-symlinks',
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'--preserve-symlinks-main', entry_link_absolute_path
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]),
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{ stdio: 'inherit' }).on('exit', (code) => {
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assert.strictEqual(code, 0);
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done();
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});
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}
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// first test the commonjs module loader
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doTest([], () => {
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// now test the new loader
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doTest(['--experimental-modules'], () => {});
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});

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