Support serialising reserved NodeJS identifiers

[lunaris]

This commit addresses part of #11942, in which we fail to serialise closures whose code would use reserved identifiers like exports. This is due to a change we made where module imports are hoisted to avoid importing the same module multiple times. Previously, code adopted a strategy of passing all dependencies using a with statement, viz.:

function x() {
  return (function () {
    with({ fooBarBaz: require("foo/bar/baz"), ... }) {
      // Use of fooBarBaz
    }
  }).apply(...)
}

function y() {
  return (function () {
    with({ fooBarBaz: require("foo/bar/baz"), ... }) {
      // Use of fooBarBaz
    }
  }).apply(...)
}

This was changed to remove the duplicate imports, yielding code like:

const fooBarBaz = require("foo/bar/baz")

function x() {
  return (function () {
    with({ ... }) {
      // Use of fooBarBaz
    }
  }).apply(...)
}

function y() {
  return (function () {
    with({ ... }) {
      // Use of fooBarBaz
    }
  }).apply(...)
}

However, while the previous approach would work with reserved identifiers such as exports (with({ exports, ... }) { ... } is perfectly acceptable), the new one does not (const exports = ... is not acceptable since NodeJS will not allow redeclaration of the exports global).

This commit combines the two approaches. Modules are only imported once, but if an import would use a reserved identifier, we generate a fresh non-conflicting identifier and alias this using a with statement. For example:

const fooBarBaz = require("foo/bar/baz")

// __pulumi_closure_import_exports is generated to avoid shadowing the reserved "exports"
const __pulumi_closure_import_exports = require("some/other/module")

function x() {
  return (function () {
    with({ exports: __pulumi_closure_import_exports, ... }) {
      // Use of fooBarBaz and exports
    }
  }).apply(...)
}

Note that it is not expected that #11942 will be solved in its entirety. While this commit fixes code that introduces identifiers like exports, the introduction in question in that issue is caused by the use of pulumi.output(...) in the constructor of a dynamic resource provider. Since dynamic resource providers are implemented under the hood by serialising their code, we attempt to serialise pulumi.output and its dependency chain. This commit allows us to make more progress in that regard, but other things go wrong thereafter. Fixing the deeper issue that underpins #11942 (and likely other challenges with dynamic providers) is probably a more involved piece of work.

[pulumi-bot]

Changelog

[uncommitted] (2024-04-10)

Bug Fixes

• [sdk/nodejs] Correctly serialise functions whose code would make use of reserved identifiers
  #15879

[julienp]

🎉