icsharpcode/ILSpy

foreach expected but while used instead

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#1603 opened on Jul 29, 2019

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C#DecompilerEnhancementHelp Wanted

Description

ILSpy version 5.0.0.4970-preview3

method decompiled with while but foreach expected

protected CompositeDevices(SerializationInfo info, StreamingContext context)
	: base(info, context)
{
	SerializationInfoEnumerator enumerator = info.GetEnumerator();
	while (enumerator.MoveNext())
	{
		string name = enumerator.Current.Name;
		if (name != null && name == "AdditionalParameters")
		{
			AdditionalParameters = (Dictionary<string, string>)info.GetValue("AdditionalParameters", typeof(Dictionary<string, string>));
		}
	}
	base.CollectionChanged += OnCollectionChanged;
}

please also ref to very similar method CompositeDevices(IEnumerable col) that decompiled to foreach!

target: #1601

PS this assemlby has a lot of other locations that are decompiled to while loop instead of much more expected foreach!

Contributor guide

Tech stack
csharp
Domain
tooling
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
C#ILSpy basics
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45
Research direction
Investigate why the decompiler uses 'while' instead of 'foreach' for the given pattern (SerializationInfoEnumerator loop). Compare with the similar method that correctly uses foreach. Check issue #1601 for related context. Look at the decompiler's logic for detecting foreach patterns, possibly in ICSharpCode.Decompiler/ILAst or similar. Identify the condition that causes the decompiler to emit a while loop.