Add --module node18

[andrewbranch]

Identical to nodenext, except implies --target es2022 like node16 does.

I validated the new baselines with

for f in tests/baselines/reference/*module=node18*; do
  [[ -e ${f/module=node18/module=node16} ]] && echo "$f" && diff "$f" "${f/module=node18/module=node16}";
done

and

for f in tests/baselines/reference/*module=node18*; do
  [[ -e ${f/module=node18/module=nodenext} ]] && echo "$f" && diff "$f" "${f/module=node18/module=nodenext}";
done

Closes #60705

[typescript-bot]

Thanks for the PR! It looks like you've changed the TSServer protocol in some way. Please ensure that any changes here don't break consumers of the current TSServer API. For some extra review, we'll ping @sheetalkamat, @mjbvz, @zkat, and @joj for you. Feel free to loop in other consumers/maintainers if necessary.

[typescript-bot]

Looks like you're introducing a change to the public API surface area. If this includes breaking changes, please document them on our wiki's API Breaking Changes page.

Also, please make sure @DanielRosenwasser and @RyanCavanaugh are aware of the changes, just as a heads up.

[andrewbranch]

Compare this file...

[andrewbranch]

...with this one to see the point of this PR

[jakebailey]

The example you gave has a diff like:

diff --git a/tests/baselines/reference/nodeModulesJson(module=node16).errors.txt b/tests/baselines/reference/nodeModulesJson(module=node18).errors.txt
index b3f36d73fa..033a1c9f7c 100644
--- a/tests/baselines/reference/nodeModulesJson(module=node16).errors.txt
+++ b/tests/baselines/reference/nodeModulesJson(module=node18).errors.txt
@@ -1,10 +1,9 @@
-/loosey.cts(1,36): error TS2823: Import attributes are only supported when the '--module' option is set to 'esnext', 'node18', 'nodenext', or 'preserve'.
+/loosey.cts(1,36): error TS2856: Import attributes are not allowed on statements that compile to CommonJS 'require' calls.
 /loosey.cts(6,9): error TS2339: Property 'default' does not exist on type '{ version: number; }'.
-/main.mts(5,36): error TS2823: Import attributes are only supported when the '--module' option is set to 'esnext', 'node18', 'nodenext', or 'preserve'.
-/main.mts(6,52): error TS2823: Import attributes are only supported when the '--module' option is set to 'esnext', 'node18', 'nodenext', or 'preserve'.
-/main.mts(8,10): error TS1544: Named imports from a JSON file into an ECMAScript module are not allowed when 'module' is set to 'Node16'.
-/main.mts(8,41): error TS2823: Import attributes are only supported when the '--module' option is set to 'esnext', 'node18', 'nodenext', or 'preserve'.
-/main.mts(9,42): error TS2823: Import attributes are only supported when the '--module' option is set to 'esnext', 'node18', 'nodenext', or 'preserve'.
+/main.mts(2,22): error TS1543: Importing a JSON file into an ECMAScript module requires a 'type: "json"' import attribute when 'module' is set to 'Node18'.
+/main.mts(3,19): error TS1543: Importing a JSON file into an ECMAScript module requires a 'type: "json"' import attribute when 'module' is set to 'Node18'.
+/main.mts(7,21): error TS1543: Importing a JSON file into an ECMAScript module requires a 'type: "json"' import attribute when 'module' is set to 'Node18'.
+/main.mts(8,10): error TS1544: Named imports from a JSON file into an ECMAScript module are not allowed when 'module' is set to 'Node18'.
 /main.mts(10,9): error TS2339: Property 'version' does not exist on type '{ default: { version: number; }; }'.
 
 
@@ -42,26 +41,24 @@
       "version": 1
     }
     
-==== /main.mts (6 errors) ====
+==== /main.mts (5 errors) ====
     import { oops } from "not.json"; // Ok
     import moreOops from "actually-json"; // Error in nodenext
+                         ~~~~~~~~~~~~~~~
+!!! error TS1543: Importing a JSON file into an ECMAScript module requires a 'type: "json"' import attribute when 'module' is set to 'Node18'.
     import typed from "actually-json/typed"; // Error in nodenext
+                      ~~~~~~~~~~~~~~~~~~~~~
+!!! error TS1543: Importing a JSON file into an ECMAScript module requires a 'type: "json"' import attribute when 'module' is set to 'Node18'.
     
     import config from "./config.json" with { type: "json" }; // Ok
-                                       ~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2823: Import attributes are only supported when the '--module' option is set to 'esnext', 'node18', 'nodenext', or 'preserve'.
     import { default as config1 } from "./config.json" with { type: "json" }; // Ok
-                                                       ~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2823: Import attributes are only supported when the '--module' option is set to 'esnext', 'node18', 'nodenext', or 'preserve'.
     import config2 from "./config.json"; // Error in nodenext, no attribute
+                        ~~~~~~~~~~~~~~~
+!!! error TS1543: Importing a JSON file into an ECMAScript module requires a 'type: "json"' import attribute when 'module' is set to 'Node18'.
     import { version } from "./config.json" with { type: "json" }; // Error, named import
              ~~~~~~~
-!!! error TS1544: Named imports from a JSON file into an ECMAScript module are not allowed when 'module' is set to 'Node16'.
-                                            ~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2823: Import attributes are only supported when the '--module' option is set to 'esnext', 'node18', 'nodenext', or 'preserve'.
+!!! error TS1544: Named imports from a JSON file into an ECMAScript module are not allowed when 'module' is set to 'Node18'.
     import * as config3 from "./config.json" with { type: "json" };
-                                             ~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2823: Import attributes are only supported when the '--module' option is set to 'esnext', 'node18', 'nodenext', or 'preserve'.
     config3.version; // Error
             ~~~~~~~
 !!! error TS2339: Property 'version' does not exist on type '{ default: { version: number; }; }'.
@@ -70,7 +67,7 @@
 ==== /loosey.cts (2 errors) ====
     import config from "./config.json" with { type: "json" }; // Error
                                        ~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2823: Import attributes are only supported when the '--module' option is set to 'esnext', 'node18', 'nodenext', or 'preserve'.
+!!! error TS2856: Import attributes are not allowed on statements that compile to CommonJS 'require' calls.
     import config2 from "./config.json"; // Ok
     import { version } from "./config.json"; // Ok
     import * as config3 from "./config.json";

Maybe this is preexisting, but with:

@@ -70,7 +67,7 @@
 ==== /loosey.cts (2 errors) ====
     import config from "./config.json" with { type: "json" }; // Error
                                        ~~~~~~~~~~~~~~~~~~~~~
-!!! error TS2823: Import attributes are only supported when the '--module' option is set to 'esnext', 'node18', 'nodenext', or 'preserve'.
+!!! error TS2856: Import attributes are not allowed on statements that compile to CommonJS 'require' calls.
     import config2 from "./config.json"; // Ok

If someone wants to dual emit CJS/ESM but needs to write an attribute for JSON, are they out of luck? require allows JSON so I would have sort of expected us to say "okay" to this. But maybe it was already this restrictive?

[andrewbranch]

Yeah, that is preexisting, but a good point. However, good workarounds exist (import = and fs.readFile), so I’m not sure we need to stress about it.

[jakebailey]

Well, you can't write import = if you want to be able to emit ESM, but you can of course always just read the file from the FS (ignoring potential emit path differences).

Just to be clear, is it preexisting as in "always", or preexisting in 5.7 specifically due to our added checks for attributes?

[andrewbranch]

That’s not true; import = compiles to createRequire(import.meta.url)(...) for Node.js module targets.

This looks like a new problem for us because of the new checks, but Node.js has enforced import assertions/attributes on JSON imports even while we have not, so we aren’t closing any doors with this. Anyone trying to do this previously has already had to work around it for runtime reasons, without help from TS.

[jakebailey]

Wow. I had no idea we did this:

import blah = require("react");

console.log(blah);

import { createRequire as _createRequire } from "module";
const __require = _createRequire(import.meta.url);
const blah = __require("react");
console.log(blah);

[jakebailey]

This seems like an interesting case; if the module kind is out of range, how are we ending up with CJS?

[andrewbranch]

Lol, the value is 123 which is in the Node16–NodeNext range.

[jakebailey]

This seems like a typo (not that it matters)

[jakebailey]

Otherwise I think this is good.