Remove the discarded message argument of MA0080

[meziantou]

What changed

One line in UseAnOverloadThatHasCancellationTokenAnalyzer.AnalyzeLoop: MA0080 (FlowCancellationTokenInAwaitForEachRule) no longer passes string.Join(", ", availableCancellationTokens) as a message argument.

Why

The argument was already being discarded:

• In that branch availableCancellationTokens is always empty (it is the else of if (availableCancellationTokens.Length > 0)), so the join always produced "".
• The rule's messageFormat is "Specify a CancellationToken" — no {0} placeholder — so the argument was formatted into nothing.

Notes for the reviewer

This is a cleanup, not a bug fix, and no test changes because nothing observable changes. The diagnostic ID, severity, location and message text are all identical before and after. If you'd rather not carry a no-op diff, this is a reasonable thing to close.

This started from a report that also suggested passing CreateProperties(...) on this branch, for symmetry with AnalyzeInvocation and for a hypothetical future MA0080 fixer. I tried that and backed it out, because the properties would carry no information: in the loop case every value is a constant (ParameterIndex="-1", ParameterName=null, IsEnumeratorCancellation="False", CancellationTokens=""). Worse, the existing fixer's only use of them is cancellationTokens.Split(','), and "".Split(',') yields a single empty string — so an MA0080 fixer reading those properties would offer a bogus Use CancellationToken: action over an empty expression. Such a fixer would have to synthesize CancellationToken.None itself and ignore the properties. The asymmetry with AnalyzeInvocation looks intentional rather than an oversight: the loop case has nothing meaningful to pass.

Testing

• dotnet build src/Meziantou.Analyzer/Meziantou.Analyzer.roslyn5.9.csproj — succeeded, 0 warnings.
• UseAnOverloadThatHasCancellationTokenAnalyzerTests — 64/64 pass on roslyn5.9. The same class passed 64/64 on roslyn4.8, 4.14, 5.0 and 5.6 earlier in the session; the final one-line diff is Roslyn-version independent, and CI covers all five.
• dotnet run --project src/DocumentationGenerator — exit 0, no markdown changes (no descriptor or message-format change).