IronLanguages / IronLanguages/ironpython3

Formatting issues

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Dominant language
C#
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Description

%-formatting of 999999999999998 is busted (outputs f-1) on .NET Framework (because it's rounding up to 1000000000000000 and the formatting logic fails to handle that properly).

assert "%.15g" % 999999999999998 == "999999999999998"

The "new-style" formatting is also failing, but with a ValueError:

assert f"{999999999999998:.15g}" == "999999999999998"

ValueError: Precision not allowed in integer format specifier

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  4. Open a pull request that references the issue number.

Research direction

Start by reproducing the two assertions on .NET Framework, then trace the %-formatting and new-style formatting paths for numeric values near 1000000000000000. Done means both examples produce "999999999999998" without an exception.

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Assessment

Tech stack
csharp, python
Domain
compilers
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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