Hacktoberfest 2026：メンテナが10月に向けて印を付けた、オープンで初心者向けの issue。 Hacktoberfest の issue を見る

Add the missing built-in constant-expression functions (`popcount`, `rotl`, `rotr`, `mod`, `exp`, `log`, `pow`, `ceiling`, `floor`)

オープン
  • 何か問題がありますか？
#390 コメント 0 件 リアクション 0 件 担当者 0 名 GitHub で見る

メンテナーはふだん 1 日以内に返信

@TheGupta2012 がすでに取り組んでいます。

2026年8月24日 から。

  • #407 @TheGupta2012 による — オープン

評価

難易度
3/5
見積もり時間
1〜2日
初心者へのやさしさ
45/100
issue の種類
機能追加
明瞭さ
おおむね明確
活発さ
静か
技術スタック
python
領域
compilers

調査の方向性

Start in src/pyqasm/maps/expressions.py, where FUNCTION_MAP is defined near line 196, and check how existing entries such as sqrt are applied in constant and gate-argument contexts. Reproduce with the pyqasm.loads(...).validate() snippets in the issue. Done means ceiling, floor, exp, log and mod validate in both const declarations and gate arguments, with tests added in tests/qasm3/test_expressions.py. Leave popcount, rotl, rotr and pow for a maintainer to scope, since they depend on a companion issue and an upstream parser problem.

索引モデルが issue の本文から書いたものです。

説明

enhancement llm-assisted qasm3 qasm3-coverage

Limitation

Table 2 — Built-in mathematical functions
lists the functions every OpenQASM 3 implementation must provide in constant expressions:

arccos, arcsin, arctan, ceiling, cos, exp, floor, log, mod, popcount,
pow, rotl, rotr, sin, sqrt, tan.

pyqasm's FUNCTION_MAP provides only abs, real, imag, sqrt, sin, cos, tan,
arccos, arcsin, arctan. Nine of the spec's functions are missing:
ceiling, floor, exp, log, mod, popcount, pow, rotl, rotr.

Example QASM failure

Every one of these is a valid constant expression per the spec:

import pyqasm

for decl in [
    "const uint c = popcount(37);",
    'const bit[8] c = rotl("00101010", 3);',
    'const bit[8] c = rotr("00101010", 3);',
    "const int c = mod(7, 2);",
    "const float[64] c = exp(1.0);",
    "const float[64] c = log(2.0);",
    "const int c = ceiling(1.2);",
    "const int c = floor(1.8);",
]:
    m = pyqasm.loads("OPENQASM 3.0;\n" + decl)
    m.validate()

ValidationError: Invalid initialization value for constant 'c'

They fail as gate arguments too, where sqrt already works:

OPENQASM 3.0;
include "stdgates.inc";
qubit[1] q;
rx(sqrt(2.0)) q[0];   // OK today
rx(exp(1.0)) q[0];    // ValidationError: Invalid parameter 'exp(1.0)' for gate 'rx'

The spec's own example under Built-in constant expression functions exercises most of them:

const float[64] f2 = 2.0 * exp(f1);
const int[8] i2 = pow(i1, u1);
const bit[8] b2 = rotl(b1, 3);

Change Requested

  1. Add ceiling, floor, exp, log, mod to FUNCTION_MAP with the spec's signatures.
  2. Add popcount, rotl, rotr, which operate on bit[n] and uint[n] and must preserve
    the input width.
  3. Add pow(a, b) as a function. Note the parser caveat below — this one is not purely a
    FUNCTION_MAP entry.
  4. Report an unknown function name and an arity or type mismatch as a ValidationError naming
    the function, rather than the current generic "Invalid initialization value" message,
    which gives the user no indication that the function was the problem.

Implementation Details

  • FUNCTION_MAP is in src/pyqasm/maps/expressions.py:196. Most additions are one line each:
    "exp": np.exp, "log": np.log, "ceiling": np.ceil, "floor": np.floor,
    "mod": np.mod.
  • popcount / rotl / rotr are defined on bit[n] and depend on a width-carrying bit
    representation — see the companion issue on bit[n] operators. Widths must be preserved:
    rotl(a, n) == rotr(a, -n), and the output width equals the input width.
  • pow has a known blocker. const int c = pow(2, 3); fails at parse time in
    openqasm3 1.0.1 because pow is also the gate-modifier keyword. Verify against the
    current upstream release and, if it still reproduces, open an issue on
    openqasm/openqasm and link it here; the pyqasm-side change can land independently for the
    other eight functions.
  • Spec overload resolution matters for the error messages: pow(int, uint) -> int is
    preferred over pow(float, float) -> float, which is preferred over the complex overload.
    exp and sqrt each have float -> float and complex -> complex forms.
  • Tests: tests/qasm3/test_expressions.py — one case per function covering a const
    declaration and a gate argument, plus arity and type-error cases.
主要言語
Python
スター
29
フォーク
33
平均マージ
2日 4時間
マージ済み PR（30日）
15

環境構築

はじめの一歩

  1. issue を最後まで読み、次にプロジェクトのコントリビューションガイドを読みます。
  2. 着手することを issue にコメントします — 二人が同じ作業をするのを防げます。
  3. リポジトリをフォークし、ブランチを切って変更します。
  4. issue 番号を参照したプルリクエストを送ります。

qBraid/pyqasm のほかの issue

qBraid/pyqasm の issue をすべて見る

似ている issue

Python の issue をもっと見る

新しい issue をメールで受け取る

初心者向けの GitHub issue を短くまとめたダイジェスト。