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feat(eslint-plugin): [prefer-nullish-coalescing][prefer-optional-chai…
…n] remove unsafe fixers

These fixers are very unsafe and even providing default options for them are a bad idea.
This ensures that they are suggestion fixers in all cases, and removes the options that allow them not to be.
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bradzacher committed May 21, 2020
1 parent ae82ea4 commit 52b6085
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Showing 7 changed files with 271 additions and 215 deletions.
4 changes: 2 additions & 2 deletions packages/eslint-plugin/README.md
Expand Up @@ -146,8 +146,8 @@ Pro Tip: For larger codebases you may want to consider splitting our linting int
| [`@typescript-eslint/prefer-function-type`](./docs/rules/prefer-function-type.md) | Use function types instead of interfaces with call signatures | | :wrench: | |
| [`@typescript-eslint/prefer-includes`](./docs/rules/prefer-includes.md) | Enforce `includes` method over `indexOf` method | | :wrench: | :thought_balloon: |
| [`@typescript-eslint/prefer-namespace-keyword`](./docs/rules/prefer-namespace-keyword.md) | Require the use of the `namespace` keyword instead of the `module` keyword to declare custom TypeScript modules | :heavy_check_mark: | :wrench: | |
| [`@typescript-eslint/prefer-nullish-coalescing`](./docs/rules/prefer-nullish-coalescing.md) | Enforce the usage of the nullish coalescing operator instead of logical chaining | | :wrench: | :thought_balloon: |
| [`@typescript-eslint/prefer-optional-chain`](./docs/rules/prefer-optional-chain.md) | Prefer using concise optional chain expressions instead of chained logical ands | | :wrench: | |
| [`@typescript-eslint/prefer-nullish-coalescing`](./docs/rules/prefer-nullish-coalescing.md) | Enforce the usage of the nullish coalescing operator instead of logical chaining | | | :thought_balloon: |
| [`@typescript-eslint/prefer-optional-chain`](./docs/rules/prefer-optional-chain.md) | Prefer using concise optional chain expressions instead of chained logical ands | | | |
| [`@typescript-eslint/prefer-readonly`](./docs/rules/prefer-readonly.md) | Requires that private members are marked as `readonly` if they're never modified outside of the constructor | | :wrench: | :thought_balloon: |
| [`@typescript-eslint/prefer-readonly-parameter-types`](./docs/rules/prefer-readonly-parameter-types.md) | Requires that function parameters are typed as readonly to prevent accidental mutation of inputs | | | :thought_balloon: |
| [`@typescript-eslint/prefer-reduce-type-parameter`](./docs/rules/prefer-reduce-type-parameter.md) | Prefer using type parameter when calling `Array#reduce` instead of casting | | :wrench: | :thought_balloon: |
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Expand Up @@ -46,15 +46,13 @@ type Options = [
{
ignoreConditionalTests?: boolean;
ignoreMixedLogicalExpressions?: boolean;
forceSuggestionFixer?: boolean;
},
];
const defaultOptions = [
{
ignoreConditionalTests: true,
ignoreMixedLogicalExpressions: true,
forceSuggestionFixer: false,
},
];
```
Expand Down Expand Up @@ -133,12 +131,6 @@ a ?? (b && c && d);

**_NOTE:_** Errors for this specific case will be presented as suggestions (see below), instead of fixes. This is because it is not always safe to automatically convert `||` to `??` within a mixed logical expression, as we cannot tell the intended precedence of the operator. Note that by design, `??` requires parentheses when used with `&&` or `||` in the same expression.

### `forceSuggestionFixer`

Setting this option to `true` will cause the rule to use ESLint's "suggested fix" mode for all fixes. _This option is provided as to aid in transitioning your codebase onto this rule_.

Suggestion fixes cannot be automatically applied via the `--fix` CLI command, but can be _manually_ chosen to be applied one at a time via an IDE or similar. This makes it safe to run autofixers on an existing codebase without worrying about potential runtime behavior changes from this rule's fixer.

## When Not To Use It

If you are not using TypeScript 3.7 (or greater), then you will not be able to use this rule, as the operator is not supported.
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15 changes: 1 addition & 14 deletions packages/eslint-plugin/docs/rules/prefer-optional-chain.md
Expand Up @@ -70,20 +70,7 @@ foo?.a?.b?.method?.();
foo?.a?.b?.c?.d?.e;
```

## Options

The rule accepts an options object with the following properties:

```ts
type Options = {
// if true, the rule will only provide suggested fixes instead of automatically modifying code
suggestInsteadOfAutofix?: boolean;
};
const defaults = {
suggestInsteadOfAutofix: false,
};
```
**Note:** there are a few edge cases where this rule will false positive. Use your best judgement when evaluating reported errors.

## When Not To Use It

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37 changes: 9 additions & 28 deletions packages/eslint-plugin/src/rules/prefer-nullish-coalescing.ts
Expand Up @@ -10,10 +10,9 @@ export type Options = [
{
ignoreConditionalTests?: boolean;
ignoreMixedLogicalExpressions?: boolean;
forceSuggestionFixer?: boolean;
},
];
export type MessageIds = 'preferNullish';
export type MessageIds = 'preferNullish' | 'suggestNullish';

export default util.createRule<Options, MessageIds>({
name: 'prefer-nullish-coalescing',
Expand All @@ -27,10 +26,10 @@ export default util.createRule<Options, MessageIds>({
suggestion: true,
requiresTypeChecking: true,
},
fixable: 'code',
messages: {
preferNullish:
'Prefer using nullish coalescing operator (`??`) instead of a logical or (`||`), as it is a safer operator.',
suggestNullish: 'Fix to nullish coalescing operator (`??`).',
},
schema: [
{
Expand All @@ -54,19 +53,9 @@ export default util.createRule<Options, MessageIds>({
{
ignoreConditionalTests: true,
ignoreMixedLogicalExpressions: true,
forceSuggestionFixer: false,
},
],
create(
context,
[
{
ignoreConditionalTests,
ignoreMixedLogicalExpressions,
forceSuggestionFixer,
},
],
) {
create(context, [{ ignoreConditionalTests, ignoreMixedLogicalExpressions }]) {
const parserServices = util.getParserServices(context);
const sourceCode = context.getSourceCode();
const checker = parserServices.program.getTypeChecker();
Expand Down Expand Up @@ -119,23 +108,15 @@ export default util.createRule<Options, MessageIds>({
yield fixer.replaceText(barBarOperator, '??');
}

const fixer =
isMixedLogical || forceSuggestionFixer
? // suggestion instead for cases where we aren't sure if the fixer is completely safe
({
suggest: [
{
messageId: 'preferNullish',
fix,
},
],
} as const)
: { fix };

context.report({
node: barBarOperator,
messageId: 'preferNullish',
...fixer,
suggest: [
{
messageId: 'suggestNullish',
fix,
},
],
});
},
};
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63 changes: 15 additions & 48 deletions packages/eslint-plugin/src/rules/prefer-optional-chain.ts
Expand Up @@ -31,15 +31,7 @@ The AST will look like this:
}
*/

type Options = [
{
suggestInsteadOfAutofix?: boolean;
},
];

type MessageIds = 'preferOptionalChain' | 'optionalChainSuggest';

export default util.createRule<Options, MessageIds>({
export default util.createRule({
name: 'prefer-optional-chain',
meta: {
type: 'suggestion',
Expand All @@ -50,30 +42,15 @@ export default util.createRule<Options, MessageIds>({
recommended: false,
suggestion: true,
},
fixable: 'code',
messages: {
preferOptionalChain:
"Prefer using an optional chain expression instead, as it's more concise and easier to read.",
optionalChainSuggest: 'Change to an optional chain.',
},
schema: [
{
type: 'object',
properties: {
suggestInsteadOfAutofix: {
type: 'boolean',
},
},
additionalProperties: false,
},
],
schema: [],
},
defaultOptions: [
{
suggestInsteadOfAutofix: false,
},
],
create(context, [options]) {
defaultOptions: [],
create(context) {
const sourceCode = context.getSourceCode();
return {
[[
Expand Down Expand Up @@ -189,28 +166,18 @@ export default util.createRule<Options, MessageIds>({
} ${sourceCode.getText(previous.right.right)}`;
}

if (!options.suggestInsteadOfAutofix) {
context.report({
node: previous,
messageId: 'preferOptionalChain',
fix(fixer) {
return fixer.replaceText(previous, optionallyChainedCode);
context.report({
node: previous,
messageId: 'preferOptionalChain',
suggest: [
{
messageId: 'optionalChainSuggest',
fix: (fixer): TSESLint.RuleFix[] => [
fixer.replaceText(previous, optionallyChainedCode),
],
},
});
} else {
context.report({
node: previous,
messageId: 'preferOptionalChain',
suggest: [
{
messageId: 'optionalChainSuggest',
fix: (fixer): TSESLint.RuleFix[] => [
fixer.replaceText(previous, optionallyChainedCode),
],
},
],
});
}
],
});
}
},
};
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