Improve `@babel/generator` typings #14644

JLHwung · 2022-06-06T14:53:41Z

Q	A
License	MIT

See #14601 for more info. This PR improves @babel/generator typings with small refactors for more effective type inference.

JLHwung · 2022-06-06T14:54:47Z

packages/babel-generator/src/printer.ts

+          | "RegexLiteral"
+          | "RestProperty"
+          | "SpreadProperty"
+        >


Now the type checker will throw if we add a new AST node without a printer method.

babel-bot · 2022-06-06T14:56:18Z

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/52227/

babel-bot · 2022-06-06T14:56:18Z

Build successful! You can test your changes in the REPL here: https://babeljs.io/repl/build/52165/

armano2 · 2022-06-08T17:44:01Z

packages/babel-generator/src/buffer.ts

@@ -1,12 +1,11 @@
 import type SourceMap from "./source-map";
-import type * as t from "@babel/types";
 import * as charcodes from "charcodes";

 type Pos = {


if you are exporting Loc, you should make sure to export Pos to

armano2 · 2022-06-08T18:01:35Z

packages/babel-generator/src/generators/types.ts

@@ -185,7 +185,7 @@ export function NullLiteral(this: Printer) {
 }

 export function NumericLiteral(this: Printer, node: t.NumericLiteral) {
-  const raw = this.getPossibleRaw(node);
+  const raw = this.getPossibleRaw(node) as string | undefined;


q: if we know that this is always going to be a string or undefined, why not change getPossibleRaw instead of doing casting everywhere?

in some cases you are casting it to string in some to undefined or string, and in other you are casting them when you are using it

this.token(raw as string);

i understand that extra can't be strongly typed for now, but maybe that is going to change in feature

packages/babel-generator/src/generators/statements.ts

nicolo-ribaudo · 2022-06-10T19:31:04Z

packages/babel-generator/src/generators/statements.ts

@@ -89,11 +100,11 @@ export function WhileStatement(this: Printer, node: t.WhileStatement) {
  this.printBlock(node);
 }

-const buildForXStatement = function (op) {
-  return function (this: Printer, node: any) {
+const buildForXStatement = function (op: "in" | "of") {


It's a small refactor, but can we remove this parameter and just check node.type === "ForOfStatement" ? "of" : "in"?

nicolo-ribaudo · 2022-06-10T19:31:53Z

packages/babel-generator/src/generators/statements.ts

-  return function (this: Printer, node: any) {
-    this.word(prefix);
+function printStatementAfterKeyword(
+  this: Printer,


We can make the printer a normal parameter (instead of this) so that we don't need to .call to use this function.

nicolo-ribaudo · 2022-06-10T19:32:50Z

packages/babel-generator/src/generators/types.ts

@@ -202,7 +202,7 @@ export function NumericLiteral(this: Printer, node: t.NumericLiteral) {
 export function StringLiteral(this: Printer, node: t.StringLiteral) {
  const raw = this.getPossibleRaw(node);
  if (!this.format.minified && raw != null) {
-    this.token(raw);
+    this.token(raw as string);


Doesn't the != null check above help TS with this? Maybe if we make the return type of getPossibleRaw string | undefined instead of string | void it works?

We haven't enabled strictNullChecks so string | undefined will be considered as string by TS currently, which renders raw as string useless even without the null guard. With that said, I agree that string | undefined is more proper than string | void.

nicolo-ribaudo · 2022-06-10T19:35:29Z

packages/babel-generator/src/generators/typescript.ts

@@ -347,7 +351,11 @@ export function TSIntersectionType(this: Printer, node: t.TSIntersectionType) {
  this.tsPrintUnionOrIntersectionType(node, "&");
 }

-export function tsPrintUnionOrIntersectionType(this: Printer, node: any, sep) {
+export function tsPrintUnionOrIntersectionType(


We don't need to export this, or tsPrintBraced

Yes, and there are many other internal printer methods, too. I will take care of them in another PR.

liuxingbaoyu · 2022-06-12T08:18:34Z

packages/babel-generator/src/node/index.ts

-export function needsWhitespace(node, parent, type) {
+export function needsWhitespace(
+  node: t.Node,
+  parent: t.Node,
+  type: "before" | "after",
+): boolean | 0 {


Can we make a small modification to make it return boolean?

packages/babel-generator/src/printer.ts

Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> Co-authored-by: liuxingbaoyu <30521560+liuxingbaoyu@users.noreply.github.com>

* generator * refactor: merge {start,end}Terminatorless to printTerminatorless * inline buildYieldAwait * inline ExportDeclaration * also export Pos * let getPossibleRaw return string | void * Apply suggestions from code review Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> Co-authored-by: liuxingbaoyu <30521560+liuxingbaoyu@users.noreply.github.com> * address review comments * do not export internal printer method * simplify needsWhitespace Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> Co-authored-by: liuxingbaoyu <30521560+liuxingbaoyu@users.noreply.github.com>

* enable noImplicitAny * codemod (#14602) * Improve preset/plugin-typescript typings (#14603) * preset-typescript * transform-typescript * Update packages/babel-plugin-transform-typescript/src/enum.ts Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> * prettier Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> * Improve transform-runtime typings (#14605) * enable noImplicitAny * codemod (#14602) * Improve preset/plugin-typescript typings (#14603) * preset-typescript * transform-typescript * Update packages/babel-plugin-transform-typescript/src/enum.ts Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> * prettier Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> * improve transform-runtime typings Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> * jsx (#14607) * Improve module transform packages typings (#14608) * improve babel-template typings (#14621) * Improve @babel/helper-* typings (#14620) * improve helper-function-name typings * helper hoist variables * helper-member-expression-to-functions * helper-simple-access * remap-async-to-generator * helper-annotate-as-pure * helper-builder-binary-assignment-operator-visitor * helper-check-duplicate-nodes * early return when export declaration is export all * split-export-declaration * helper-define-map * define-map * Update packages/babel-helper-builder-binary-assignment-operator-visitor/src/index.ts Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> * review comments Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> * improve helper-module-imports typings (#14623) * refactor: simplify ImportInjector._applyDefaults * helper-module-imports * map globals to the one used in Babel 8 * Improve fixture-test-runner typings (#14625) * plugin-test-runner * fixture-test-runner * Update packages/babel-helper-fixtures/src/index.ts Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> * Improve preset-env typings (#14606) * refactor: move shipped-proposals to ts * preset-env * address review comments * Improve pipeline-operator typings (#14629) * refactor: simplify buildOptimizedSequenceExpression * proposal-pipeline-operator * address review comments * improve standalone typings (#14630) * babel-standalone * address review comment * Improve plugins typings (Part 1) (#14633) * change AssumptionFunction return type * helper-create-regexp-features-plugin * create-class-features-plugin * transform-for-of * improve unicode-escapes typings * transform-object-super * transform-react-constant-elements * proto-to-assign * function-name * flow-comments TS cannot infer Flow visitor type because we have both Flow type and Flow virtual type. * Improve code-frame/hightlight typings (#14643) * code-frame * map js-tokens to Babel 8 * highlight * Improve `@babel/types` typings (#14645) * bump to-fast-properties to v4 * types * mark node comments as mutable * Improve babel-core typings (#14622) Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> * improve transform-classes typings (#14624) * Improve `@babel/generator` typings (#14644) * generator * refactor: merge {start,end}Terminatorless to printTerminatorless * inline buildYieldAwait * inline ExportDeclaration * also export Pos * let getPossibleRaw return string | void * Apply suggestions from code review Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> Co-authored-by: liuxingbaoyu <30521560+liuxingbaoyu@users.noreply.github.com> * address review comments * do not export internal printer method * simplify needsWhitespace Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> Co-authored-by: liuxingbaoyu <30521560+liuxingbaoyu@users.noreply.github.com> * Improve plugins typings (Part 2) (#14639) * exponentiation-operator * duplicate-keys * computed-properties * replace-supers * block-scoping * block-scoped-functions * syntax-typescript * record-and-tuple * private-property-in-object * partial-application * json-strings * function-sent * function-bind * class-static-block * async-generator-functions * Update packages/babel-plugin-transform-block-scoping/src/index.ts * address review comments * helper-replace-supers * Improve plugins typings (Part 3) (#14642) * external-helpers * bugfix * transform-parameters * object-rest-spread * destructuring-private * transform-destructuring * proposal-decorators * optional-chaining * helper-wrap-function * explode-assignable-expression * helper-compilation-targets * helper-plugin-utils * helpers * helper-validator-option * fix: allow "+" and "-" in MappedType .readonly/.optional * fixture-test-runner * remove charcodes from dependencies the charcodes transform will inline charCodes.* so we can remove it from dependencies * Improve traverse typings (#14648) * export removeProperties options * traverse * fix other packages typings * fix gatherNodeParts * downgrade to-fast-properties to v3 * fix typo * babel-core/normalize-file * add ignore comment property used by flow plugin * refine getLastStatement typings * fix babel-standalone rebase typing error * fix assert.rejects polyfill * simplify _param typings * supress Babel 7 AST errors * loosen defineType typings The AST typings are generated from defineType calls, so defineType should accept a string as type. * restore legacy code * Suppress data/core-js-compat importing errors Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> Co-authored-by: liuxingbaoyu <30521560+liuxingbaoyu@users.noreply.github.com>

JLHwung added 4 commits June 6, 2022 10:49

generator

6ff7d53

refactor: merge {start,end}Terminatorless to printTerminatorless

799ab8f

inline buildYieldAwait

7435a53

inline ExportDeclaration

9d51fb3

JLHwung commented Jun 6, 2022

View reviewed changes

armano2 reviewed Jun 8, 2022

View reviewed changes

also export Pos

c88056a

armano2 reviewed Jun 8, 2022

View reviewed changes

let getPossibleRaw return string | void

ab49033

nicolo-ribaudo reviewed Jun 10, 2022

View reviewed changes

packages/babel-generator/src/generators/statements.ts Outdated Show resolved Hide resolved

nicolo-ribaudo reviewed Jun 10, 2022

View reviewed changes

liuxingbaoyu reviewed Jun 12, 2022

View reviewed changes

packages/babel-generator/src/printer.ts Outdated Show resolved Hide resolved

liuxingbaoyu approved these changes Jun 12, 2022

View reviewed changes

JLHwung and others added 4 commits June 13, 2022 09:03

Apply suggestions from code review

a9e572b

Co-authored-by: Nicolò Ribaudo <nicolo.ribaudo@gmail.com> Co-authored-by: liuxingbaoyu <30521560+liuxingbaoyu@users.noreply.github.com>

address review comments

fab71ab

do not export internal printer method

1d53788

simplify needsWhitespace

50302c5

nicolo-ribaudo approved these changes Jun 13, 2022

View reviewed changes

JLHwung merged commit 9a69ece into babel:noImplicitAny Jun 13, 2022

JLHwung deleted the noImplicitAny-generator branch June 13, 2022 13:51

github-actions bot added the outdated A closed issue/PR that is archived due to age. Recommended to make a new issue label Sep 13, 2022

github-actions bot locked as resolved and limited conversation to collaborators Sep 13, 2022

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Improve `@babel/generator` typings #14644

Improve `@babel/generator` typings #14644

JLHwung commented Jun 6, 2022 •

edited by gitpod-io bot

JLHwung Jun 6, 2022

babel-bot commented Jun 6, 2022 •

edited

babel-bot commented Jun 6, 2022

armano2 Jun 8, 2022

armano2 Jun 8, 2022 •

edited

nicolo-ribaudo Jun 10, 2022

nicolo-ribaudo Jun 10, 2022

nicolo-ribaudo Jun 10, 2022

JLHwung Jun 13, 2022

nicolo-ribaudo Jun 10, 2022

JLHwung Jun 13, 2022

liuxingbaoyu Jun 12, 2022

Improve @babel/generator typings #14644

Improve @babel/generator typings #14644

Conversation

JLHwung commented Jun 6, 2022 • edited by gitpod-io bot

Choose a reason for hiding this comment

babel-bot commented Jun 6, 2022 • edited

babel-bot commented Jun 6, 2022

Choose a reason for hiding this comment

armano2 Jun 8, 2022 • edited

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Choose a reason for hiding this comment

Improve `@babel/generator` typings #14644

Improve `@babel/generator` typings #14644

JLHwung commented Jun 6, 2022 •

edited by gitpod-io bot

babel-bot commented Jun 6, 2022 •

edited

armano2 Jun 8, 2022 •

edited