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fix(eslint-plugin): support BigInt in restrict-plus-operands rule #344

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Merged
merged 6 commits into from
Apr 11, 2019
Merged

fix(eslint-plugin): support BigInt in restrict-plus-operands rule #344

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719c905
fix(eslint-plugin): support BigInt in restrict-plus-operands rule (#309)
webschik Mar 9, 2019
6d58d97
Merge branch 'master' into issue-309
webschik Mar 11, 2019
fd0dad6
Merge branch 'master' into issue-309
bradzacher Apr 7, 2019
c76059b
Merge branch 'master' into issue-309
JamesHenry Apr 7, 2019
5b2f89a
Merge branch 'master' into issue-309
bradzacher Apr 11, 2019
0498060
Merge branch 'master' into issue-309
bradzacher Apr 11, 2019
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6 changes: 5 additions & 1 deletion packages/eslint-plugin/src/rules/restrict-plus-operands.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -54,7 +54,11 @@ export default util.createRule({

const stringType = typeChecker.typeToString(type);

if (stringType === 'number' || stringType === 'string') {
if (
stringType === 'number' ||
stringType === 'string' ||
stringType === 'bigint'
) {
return stringType;
}
return 'invalid';
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2 changes: 1 addition & 1 deletion packages/eslint-plugin/tests/fixtures/tsconfig.json
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Expand Up @@ -4,6 +4,6 @@
"module": "commonjs",
"strict": true,
"esModuleInterop": true,
"lib": ["es2015", "es2017"]
"lib": ["es2015", "es2017", "esnext"]
}
}
22 changes: 22 additions & 0 deletions packages/eslint-plugin/tests/rules/restrict-plus-operands.test.ts
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Expand Up @@ -23,6 +23,8 @@ ruleTester.run('restrict-plus-operands', rule, {
`var foo = parseInt("5.5", 10) + 10;`,
`var foo = parseFloat("5.5", 10) + 10;`,
`var foo = 1n + 1n;`,
`var foo = BigInt(1) + 1n`,
`var foo = 1n; foo + 2n`,
`
function test () : number { return 2; }
var foo = test("5.5", 10) + 10;
Expand Down Expand Up @@ -283,5 +285,25 @@ var foo = pair + pair;
},
],
},
{
code: `var foo = 1n; foo + 1`,
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@mohsen1 mohsen1 Mar 10, 2019 •
edited
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This is already an error thrown by TypeScript. Why you need a lint rule for it?

Operator '+' cannot be applied to types 'bigint' and '1'.

https://www.typescriptlang.org/play/index.html#src=var%20foo%20%3D%201n%3B%20foo%20%2B%201

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@mohsen1 , good point. Maybe it's really an overhead and this rule makes sense only for strings and numbers.

I've implemented this to fix issue #309, but you're right that TypeScript does the same check already.

@novemberborn , @j-f1 , what do you think?

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Ah yes, it would do that. However the rule then needs to ensure either operand is actually a string or number before complaining (or any / unknown). The problem in #309 was that it complained about bigint even though bigints can be summed.

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Agree, I'd like to propose the next behaviour for this rule:

(any or unknown) + (string or number or bigint) - rule triggers an error, as it does now
all other cases - let TS decide what error to show

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That seems reasonable. You may want to pull that suggestion into its own issue for wider discussion, if you haven't already.

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I made a table to show the cases this rule should cover in my opinion:

+ number string BigInt any unknown
number rpo TS nua TS
string rpo rpo nua TS
BigInt TS rpo nua TS
any nua nua nua nua TS
unknown TS TS TS TS TS

Legend:

  • rpo: The behavior is invalid and should be caught by restrict-plus-operands.
  • TS: The behavior is invalid and is already caught by Typescript.
  • nua: The behavior coerces any into a stricter type and should thus be caught by no-unsafe-any.
  • An empty cell means valid behavior.

errors: [
{
messageId: 'notBigInts',
line: 1,
column: 15,
},
],
},
{
code: `var foo = 1; foo + 1n`,
errors: [
{
messageId: 'notBigInts',
line: 1,
column: 14,
},
],
},
],
});