dotnet/roslyn

'Use pattern-matching' should be missing on writes from local function captures

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#29,512 建立於 2018年8月24日

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Area-IDEBughelp wanted

描述

From https://github.com/dotnet/roslyn/pull/26097#discussion_r210728805

We should look for writes that are logically within the span, but syntactically are not.

var s = field as string;
WriteField();
if (s != null) { ... }

void WriteField () => field = null;

/cc @sharwell

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csharp
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tooling
議題類型
bug
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needs investigation
前置要求
C# compiler internalspattern matching semanticslocal function scoping
新手友善度1-100 的估計分數，表示該議題對首次貢獻者的友善程度。
20
研究方向
The issue references a discussion in PR #26097. The example shows a local function WriteField that writes to a captured variable 'field', but the pattern matching analysis incorrectly does not mark the write. Investigate the data flow analysis for captured variables in local functions. Look at the compiler's implementation of pattern matching and how it handles writes that are syntactically inside local functions but logically within the enclosing method's scope. The fix likely requires updating the analysis to consider writes from local function captures.