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Sourcemaps don't work in vm.Script scripts #52102

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@rrthomas

Description

@rrthomas

Version

v21.7.1

Platform

Linux ecls 6.5.0-25-generic #25~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Tue Feb 20 16:09:15 UTC 2 x86_64 x86_64 x86_64 GNU/Linux

Subsystem

source_map

What steps will reproduce the bug?

This example is adapted from #43047

import vm from 'node:vm';

const comment = '//#';
const code = `// Generated by CoffeeScript 2.7.0
(function() {
  throw new Error('hello');

}).call(this);

${comment} sourceMappingURL=data:application/json;base64,eyJ2ZXJzaW9uIjozLCJmaWxlIjoic2ltcGxlLmpzIiwic291cmNlUm9vdCI6IlxcIiwic291cmNlcyI6WyJzaW1wbGUuY29mZmVlIl0sIm5hbWVzIjpbXSwibWFwcGluZ3MiOiI7QUFBQTtFQUFBLE1BQU0sSUFBSSxLQUFKLENBQVUsT0FBVjtBQUFOIiwic291cmNlc0NvbnRlbnQiOlsidGhyb3cgbmV3IEVycm9yICdoZWxsbydcbiJdfQ==
${comment} sourceURL=simple.coffee
`;
// eval(code);

const script = new vm.Script(code, {filename: 'simple.js'})
console.log(script.sourceMapURL)
script.runInNewContext()

How often does it reproduce? Is there a required condition?

Always.

What is the expected behavior? Why is that the expected behavior?

The expected behavior is shown if I uncomment the eval call in foo.js and run the code:

$ node --enable-source-maps foo.js
/simple.coffee:1
throw new Error 'hello'
      ^


Error: hello
    at eval (/simple.coffee:1:7)
    at eval (/simple.coffee:1:1)
    at file:///home/rrt/Software/ursa/foo.js:13:1
    at ModuleJob.run (node:internal/modules/esm/module_job:218:25)
    at async ModuleLoader.import (node:internal/modules/esm/loader:329:24)
    at async loadESM (node:internal/process/esm_loader:28:7)
    at async handleMainPromise (node:internal/modules/run_main:113:12)

Now, the traceback shows the error in the CoffeeScript code.

What do you see instead?

Running this code from file foo.js gives:

$ node --enable-source-maps foo.js
node --enable-source-maps foo.js
data:application/json;base64,eyJ2ZXJzaW9uIjozLCJmaWxlIjoic2ltcGxlLmpzIiwic291cmNlUm9vdCI6IlxcIiwic291cmNlcyI6WyJzaW1wbGUuY29mZmVlIl0sIm5hbWVzIjpbXSwibWFwcGluZ3MiOiI7QUFBQTtFQUFBLE1BQU0sSUFBSSxLQUFKLENBQVUsT0FBVjtBQUFOIiwic291cmNlc0NvbnRlbnQiOlsidGhyb3cgbmV3IEVycm9yICdoZWxsbydcbiJdfQ==
simple.coffee:3
  throw new Error('hello');
  ^

Error: hello
    at simple.coffee:3:9
    at simple.coffee:5:4
    at Script.runInContext (node:vm:133:12)
    at Script.runInNewContext (node:vm:138:17)
    at file:///home/rrt/Software/ursa/foo.js:17:8
    at ModuleJob.run (node:internal/modules/esm/module_job:218:25)
    at async ModuleLoader.import (node:internal/modules/esm/loader:329:24)
    at async loadESM (node:internal/process/esm_loader:28:7)
    at async handleMainPromise (node:internal/modules/run_main:113:12)

Note that the traceback shows the JavaScript source, not the CoffeeScript source.

Additional information

Note that the vm.Script module correctly parses the sourceMappingURL comment, and displays its contents. This led me to believe that the source map would be supported during execution!

I'm sorry if I have overlooked other issues in this area; I have only found the issue I referred to above about adding support for source maps to eval.

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