feat: add noUselessStringConcat rule

[michellocana]

Implementation of the no-useless-concat ESLint rule in Biome.
Closes #2622

Summary

The rule handle many ways to express an useless concatenation and tries to fix the problem when the fix is safe to apply.

Invalid case	Fix suggestion
const a = 'a' + 'b'	const·a·=·"ab"
const a = 'a' + 'b' + 'c'	const·a·=·"abc"
const a = 'a' + ('b' + 'c')	const·a·=·"abc"
const a = ('a' + 'b') + 'c'	const·a·=·"abc"
const a = 'a' + `b`	const·a·=·"ab"
const a = `a` + 'b'	const·a·=·"ab"
const a = `a` + `b`	const·a·=·"ab"
const a = 'a' + 1	const·a·=·"a1"
const a = 1 + '1'	const·a·=·"11"
const a = 1 + `1`	const·a·=·"11"
const a = `1` + 1	const·a·=·"11"

Special case 1: foo + 'a' + 'b' + 'c'

The expression foo + 'a' might result in different string values depending of the value of foo, so we don't merge 'a' with 'bc' to preserve the expression result.

Invalid case	Fix suggestion
const a = foo + 'a' + 'b' + 'c'	const·a·=·foo·+·'a'·+·"bc"
const a = (foo + 'a') + ('b' + 'c')	const·a·=·(foo·+·'a')·+·("bc")
const a = ((foo + 'a') + ('b' + 'c') + 1)	const·a·=·((foo·+·'a')·+·("bc")·+·1)

Special case 2: const a = 1 + 1 + ""

We can't automatically infer the value of all expressions, so we don't suggest a fix unless we are sure of the expression result.

Test Plan

Added snapshots, for valid and invalid cases according to the no-useless-concat ESLint tests.

[codspeed-hq]

CodSpeed Performance Report

Merging #2720 will not alter performance

_{Comparing michellocana:feat/no-useless-concat (37408c9) with main (b9f90b7)}

Summary

✅ 85 untouched benchmarks

[ematipico]

I haven't checked the code yet, but my first feedback is to change the name of the rule. At that beginning I thought it was about array concat: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/concat

What about noUselessConcatenation?

[Conaclos]

What about noUselessConcatenation?

Or noUselessStringConcat

[arendjr]

Nice work!

Just left some questions and nits. As for the rule name itself, I think my vote would also be for noUselessStringConcatenation.

[arendjr]

Why is the fix unsafe?

[michellocana]

While implemented this rule, I realized string concatenations can get very weird sometimes in JS, so I decided to consider the fix "unsafe" because there's a small chance that a weird concatenation pattern can result in an incorrect fix that I didn't anticipate. However, I don't know the correct approach of fix categorization in these cases, so let me know if you want me to change to safe.

[Conaclos]

This is a safe assumption :) We could re-assess the fix category once many users have tested the rule.

[arendjr]

I’m not sure I fully understand the reason we can’t merge 'a' with the other strings. Regardless of the value of foo, wouldn’t the end result always end in "abc"?

[michellocana]

I was sure of that too, until I realized that {} + 'abc' is different from {} + 'a' + 'bc' in browser environments:
Browsers:

{} + 'abc' // NaN
{} + 'a' + 'bc' // "NaNbc"

Weirdly enough, the result is totally different in Node:

{} + 'a' + 'bc' // "[object Object]abc"
{} + 'abc' // "[object Object]abc"

[michellocana]

What about noUselessConcatenation?

Or noUselessStringConcat

@ematipico @arendjr @Conaclos renamed to noUselessStringConcat

[arendjr]

Could you add a changelog entry also?

[michellocana]

Could you add a changelog entry also?

Yup, done @arendjr!

[Conaclos]

@michellocana Thanks!

[Sec-ant]

This rule lacks a fix_kind and thus fails the CI in the website repo: https://github.com/biomejs/website/actions/runs/8968865501/job/24629152214#step:8:275

[michellocana]

This rule lacks a fix_kind and thus fails the CI in the website repo: https://github.com/biomejs/website/actions/runs/8968865501/job/24629152214#step:8:275

Oh, sorry about that, fixed it here #2748

[Sec-ant]

Oh, sorry about that, fixed it here #2748

No need to apologize, thank you!