From 1b6c125cc8783de44be40dce85917edb43dc8f42 Mon Sep 17 00:00:00 2001
From: Sam Harwell <Sam.Harwell@microsoft.com>
Date: Wed, 3 Mar 2021 08:24:24 -0800
Subject: [PATCH] Update parsing of dotnet_diagnostic lines to ignore "trailing
 comments"

---
 .../Portable/CommandLine/AnalyzerConfigSet.cs | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/src/Compilers/Core/Portable/CommandLine/AnalyzerConfigSet.cs b/src/Compilers/Core/Portable/CommandLine/AnalyzerConfigSet.cs
index b6ac8fe1ab9e2..cc9df629c5257 100644
--- a/src/Compilers/Core/Portable/CommandLine/AnalyzerConfigSet.cs
+++ b/src/Compilers/Core/Portable/CommandLine/AnalyzerConfigSet.cs
@@ -337,33 +337,40 @@ static void freeKey(List<Section> sectionKey, ObjectPool<List<Section>> pool)
 
         internal static bool TryParseSeverity(string value, out ReportDiagnostic severity)
         {
+            ReadOnlySpan<char> commentStartCharacters = stackalloc char[] { ';', '#' };
+            var trimmed = value.AsSpan();
+            var commentStartIndex = trimmed.IndexOfAny(commentStartCharacters);
+            if (commentStartIndex >= 0)
+                trimmed = trimmed[0..commentStartIndex].TrimEnd();
+
             var comparer = StringComparer.OrdinalIgnoreCase;
-            if (comparer.Equals(value, "default"))
+            if (trimmed.Equals("default".AsSpan(), StringComparison.OrdinalIgnoreCase))
             {
                 severity = ReportDiagnostic.Default;
                 return true;
             }
-            else if (comparer.Equals(value, "error"))
+            else if (trimmed.Equals("error".AsSpan(), StringComparison.OrdinalIgnoreCase))
             {
                 severity = ReportDiagnostic.Error;
                 return true;
             }
-            else if (comparer.Equals(value, "warning"))
+            else if (trimmed.Equals("warning".AsSpan(), StringComparison.OrdinalIgnoreCase))
             {
                 severity = ReportDiagnostic.Warn;
                 return true;
             }
-            else if (comparer.Equals(value, "suggestion"))
+            else if (trimmed.Equals("suggestion".AsSpan(), StringComparison.OrdinalIgnoreCase))
             {
                 severity = ReportDiagnostic.Info;
                 return true;
             }
-            else if (comparer.Equals(value, "silent") || comparer.Equals(value, "refactoring"))
+            else if (trimmed.Equals("silent".AsSpan(), StringComparison.OrdinalIgnoreCase)
+                || trimmed.Equals("refactoring".AsSpan(), StringComparison.OrdinalIgnoreCase))
             {
                 severity = ReportDiagnostic.Hidden;
                 return true;
             }
-            else if (comparer.Equals(value, "none"))
+            else if (trimmed.Equals("none".AsSpan(), StringComparison.OrdinalIgnoreCase))
             {
                 severity = ReportDiagnostic.Suppress;
                 return true;