Describe the bug

Three argument checks in math.log differ from CPython. With a base, a zero x returns -inf instead of raising ValueError. A None base is treated as a missing base, so the natural logarithm is returned instead of a TypeError. A non-positive x with a base that cannot be converted raises the base's TypeError instead of the ValueError for x.

Operating system

macOS

CPU architecture

ARM64

GraalPy version

master a3009f9 (Python 3.13.14); also reproduced on 25.0.2 (Python 3.12.8) and 25.4.4.1.1 (Python 3.13.14)

JDK version

No response

Context configuration

No response

Steps to reproduce

import math
for args in [(0, 2), (10, None), (-1, object())]:
    try:
        print(math.log(*args))
    except Exception as e:
        print(type(e).__name__, e)

GraalPy master a3009f9:

-inf
2.302585092994046
TypeError must be real number, not object

Expected behavior

CPython 3.13.14 (same on 3.12.13):

ValueError math domain error
TypeError must be real number, not NoneType
ValueError math domain error

Stack trace

Additional context

The zero case also covers math.log(0.0, 2.0), math.log(-0.0, 2), math.log(0, MyInt(2)) and the one-argument math.log(MyInt(0)) for an int subclass; math.log(0, 1) raises ZeroDivisionError instead. The None case depends on call history: once math.log(-1, object()) has run in the process, math.log(10, None) raises TypeError like CPython, while math.log(10.0, None) still returns 2.302585092994046.

Root Cause

The two-argument specializations of LogNode test the value with value < 0 (MathModuleBuiltins.java#L1733-L1742 and four more, plus logPIN at #L1702), so zero reaches Math.log. The one-argument specializations take the base as PNone without an isNoValue guard (#L1678-L1704, #L1806-L1811), so they also match None. logOO, logLO, logDO and logPIO convert the base before the recursive call that checks the value (#L1813-L1839). CPython's math_log computes log(x) first, rejecting any x <= 0, and converts a second argument only after that, whatever it is (mathmodule.c#L2269-L2273, #L2227-L2232).

Fix Suggestion

Use <= 0 for the value in the six specializations, add isNoValue(novalue) to the four PNone specializations, and in logOO, logLO, logDO and logPIO check the value's domain before converting the base and exclude a missing base. The guard change needs the last one, or math.log(-1, None) would start raising TypeError.