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Fix exponentiation precedence for compound exponents #8550

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cknitt merged 2 commits into from
Aug 15, 2026
+49 −13
Merged

Fix exponentiation precedence for compound exponents #8550

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c3a9a02
Fix exponentiation right operand precedence
cknitt Aug 15, 2026
254cb45
Update changelog for exponentiation precedence fix
cknitt Aug 15, 2026
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1 change: 1 addition & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -25,6 +25,7 @@

#### :bug: Bug fix

- Preserve parentheses around multiplication, division, and modulo expressions used as exponents. https://github.com/rescript-lang/rescript/pull/8550
- Preserve multibyte characters when wrapping long source lines in compiler code frames. https://github.com/rescript-lang/rescript/pull/8520
- Fix reanalyze optional-argument diagnostics for functions passed or returned as first-class values. https://github.com/rescript-lang/rescript/pull/8321

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2 changes: 1 addition & 1 deletion compiler/core/js_op_util.ml
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Expand Up @@ -41,7 +41,7 @@ let op_prec (op : Js_op.binop) =
| Lsl | Lsr | Asr -> (10, 10, 11)
| Bnot | Plus | Minus -> (11, 11, 12)
| Mul | Div | Mod -> (12, 12, 13)
| Pow -> (13, 14, 12)
| Pow -> (13, 14, 13)

let op_int_prec (op : Js_op.int_op) =
match op with
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48 changes: 36 additions & 12 deletions tests/tests/src/exponentiation_test.mjs
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Expand Up @@ -7,25 +7,49 @@ let intPow = ((a, b) => Math.pow(a, b) | 0);

let four = 4;

function floatPowDiv(base, numerator, denominator) {
return base ** (numerator / denominator);
}

function floatPowMul(base, left, right) {
return base ** (left * right);
}

function floatPowMod(base, value, modulus) {
return base ** (value % modulus);
}

function bigintPowMul(base, left, right) {
return base ** (left * right);
}

Mocha.describe("Exponentiation_test", () => {
Mocha.test("exponentiation operations", () => {
Test_utils.eq("File \"exponentiation_test.res\", line 11, characters 7-14", 2 ** 3 ** 2, Math.pow(2, Math.pow(3, 2)));
Test_utils.eq("File \"exponentiation_test.res\", line 12, characters 7-14", 2 ** (-3) ** 2, Math.pow(2, Math.pow(-3, 2)));
Test_utils.eq("File \"exponentiation_test.res\", line 13, characters 7-14", (2 ** 3) ** 2, Math.pow(Math.pow(2, 3), 2));
Test_utils.eq("File \"exponentiation_test.res\", line 14, characters 7-14", (-2) ** 2, Math.pow(-2, 2));
Test_utils.eq("File \"exponentiation_test.res\", line 16, characters 7-14", 512, intPow(2, intPow(3, 2)));
Test_utils.eq("File \"exponentiation_test.res\", line 17, characters 7-14", 512, intPow(2, intPow(-3, 2)));
Test_utils.eq("File \"exponentiation_test.res\", line 18, characters 7-14", 64, intPow(intPow(2, 3), 2));
Test_utils.eq("File \"exponentiation_test.res\", line 19, characters 7-14", -2147483648, intPow(-2, 31));
Test_utils.eq("File \"exponentiation_test.res\", line 20, characters 7-14", 0, intPow(2, 32));
Test_utils.eq("File \"exponentiation_test.res\", line 21, characters 7-14", 0, intPow(2147483647, 2));
Test_utils.eq("File \"exponentiation_test.res\", line 22, characters 7-14", 0, intPow(-2147483648, 2));
Test_utils.eq("File \"exponentiation_test.res\", line 24, characters 7-14", 256, four ** four | 0);
Test_utils.eq("File \"exponentiation_test.res\", line 17, characters 7-14", 2 ** 3 ** 2, Math.pow(2, Math.pow(3, 2)));
Test_utils.eq("File \"exponentiation_test.res\", line 18, characters 7-14", 2 ** (-3) ** 2, Math.pow(2, Math.pow(-3, 2)));
Test_utils.eq("File \"exponentiation_test.res\", line 19, characters 7-14", (2 ** 3) ** 2, Math.pow(Math.pow(2, 3), 2));
Test_utils.eq("File \"exponentiation_test.res\", line 20, characters 7-14", (-2) ** 2, Math.pow(-2, 2));
Test_utils.eq("File \"exponentiation_test.res\", line 22, characters 7-14", 512, intPow(2, intPow(3, 2)));
Test_utils.eq("File \"exponentiation_test.res\", line 23, characters 7-14", 512, intPow(2, intPow(-3, 2)));
Test_utils.eq("File \"exponentiation_test.res\", line 24, characters 7-14", 64, intPow(intPow(2, 3), 2));
Test_utils.eq("File \"exponentiation_test.res\", line 25, characters 7-14", -2147483648, intPow(-2, 31));
Test_utils.eq("File \"exponentiation_test.res\", line 26, characters 7-14", 0, intPow(2, 32));
Test_utils.eq("File \"exponentiation_test.res\", line 27, characters 7-14", 0, intPow(2147483647, 2));
Test_utils.eq("File \"exponentiation_test.res\", line 28, characters 7-14", 0, intPow(-2147483648, 2));
Test_utils.eq("File \"exponentiation_test.res\", line 30, characters 7-14", 256, four ** four | 0);
Test_utils.eq("File \"exponentiation_test.res\", line 32, characters 7-14", 2 ** (0 / 10000), 1);
Test_utils.eq("File \"exponentiation_test.res\", line 33, characters 7-14", 2 ** (3 * 4), 4096);
Test_utils.eq("File \"exponentiation_test.res\", line 34, characters 7-14", 2 ** (5 % 3), 4);
Test_utils.eq("File \"exponentiation_test.res\", line 35, characters 7-14", 2n ** (3n * 2n), 64n);
});
});

export {
intPow,
four,
floatPowDiv,
floatPowMul,
floatPowMod,
bigintPowMul,
}
/* Not a pure module */
11 changes: 11 additions & 0 deletions tests/tests/src/exponentiation_test.res
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Expand Up @@ -6,6 +6,12 @@ external jsPow: (float, float) => float = "Math.pow"
let intPow: (int, int) => int = %raw(`(a, b) => Math.pow(a, b) | 0`)
let four: int = %raw(`4`)

let floatPowDiv = (base: float, numerator: float, denominator: float) =>
base ** (numerator /. denominator)
let floatPowMul = (base: float, left: float, right: float) => base ** (left *. right)
let floatPowMod = (base: float, value: float, modulus: float) => base ** (value % modulus)
let bigintPowMul = (base: bigint, left: bigint, right: bigint) => base ** (left * right)

describe(__MODULE__, () => {
test("exponentiation operations", () => {
eq(__LOC__, 2. ** 3. ** 2., jsPow(2., jsPow(3., 2.)))
Expand All @@ -22,5 +28,10 @@ describe(__MODULE__, () => {
eq(__LOC__, -2147483648 ** 2, intPow(-2147483648, 2))

eq(__LOC__, 4 ** 4, four ** four)

eq(__LOC__, floatPowDiv(2., 0., 10000.), 1.)
eq(__LOC__, floatPowMul(2., 3., 4.), 4096.)
eq(__LOC__, floatPowMod(2., 5., 3.), 4.)
eq(__LOC__, bigintPowMul(2n, 3n, 2n), 64n)
})
})
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