Don't silently eat a certain class of analyzer-thrown exceptions

If an analyzer threw an exception, we generate a message that tells you what diagnostic IDs the analzyer produces, so you know what to disable so you can work around the analyzer. If the analyzer then also were to throw exceptions while we ask it for it's SupportedDiagnostics, we were eating that exception. This includes that as well.
dotnet · Feb 3, 2022 · 496d572 · 496d572
1 parent d23fe1e
commit 496d572
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Showing 3 changed files with 21 additions and 8 deletions.
diff --git a/src/Compilers/CSharp/Test/CommandLine/CommandLineTests.cs b/src/Compilers/CSharp/Test/CommandLine/CommandLineTests.cs
@@ -11722,7 +11722,13 @@ public void LoadinganalyzerNetStandard13()
    at TestAnalyzer.get_SupportedDiagnostics()
    at Microsoft.CodeAnalysis.Diagnostics.AnalyzerManager.AnalyzerExecutionContext.<>c__DisplayClass20_0.<ComputeDiagnosticDescriptors>b__0(Object _)
    at Microsoft.CodeAnalysis.Diagnostics.AnalyzerExecutor.ExecuteAndCatchIfThrows_NoLock[TArg](DiagnosticAnalyzer analyzer, Action`1 analyze, TArg argument, Nullable`1 info)
------", outputWithoutPaths);
+-----
+Analyzer 'TestAnalyzer' threw the following exception:
+'System.NotImplementedException: 28
+   at TestAnalyzer.get_SupportedDiagnostics()
+   at Microsoft.CodeAnalysis.Diagnostics.AnalyzerExecutor.CreateDisablingMessage(DiagnosticAnalyzer analyzer, String analyzerName)
+-----
+'.", outputWithoutPaths);
 
             Assert.Equal(0, result.ExitCode);
         }

diff --git a/src/Compilers/Core/CodeAnalysisTest/Diagnostics/SuppressMessageAttributeCompilerTests.cs b/src/Compilers/Core/CodeAnalysisTest/Diagnostics/SuppressMessageAttributeCompilerTests.cs
@@ -154,13 +154,16 @@ public class C2
         public async Task AnalyzerExceptionFromSupportedDiagnosticsCall()
         {
             var exception = new Exception();
+            const string AnalyzerName = "Microsoft.CodeAnalysis.UnitTests.Diagnostics.SuppressMessageAttributeTests+ThrowExceptionFromSupportedDiagnostics";
 
             var diagnostic = Diagnostic("AD0001", null)
                 .WithArguments(
-                    "Microsoft.CodeAnalysis.UnitTests.Diagnostics.SuppressMessageAttributeTests+ThrowExceptionFromSupportedDiagnostics",
+                    AnalyzerName,
                     "System.Exception",
                     exception.Message,
-                    (IFormattable)$@"{new LazyToString(() => exception.ToString().Substring(0, exception.ToString().IndexOf("---")))}-----")
+                    (IFormattable)$@"{new LazyToString(() =>
+                        exception.ToString().Substring(0, exception.ToString().IndexOf("---")) + "-----" + Environment.NewLine + Environment.NewLine +
+                        string.Format(CodeAnalysisResources.CompilerAnalyzerThrowsDescription, AnalyzerName, exception.ToString() + Environment.NewLine + "-----" + Environment.NewLine))}")
                 .WithLocation(1, 1);
 
             await VerifyCSharpAsync("public class C { }",

diff --git a/src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerExecutor.cs b/src/Compilers/Core/Portable/DiagnosticAnalyzer/AnalyzerExecutor.cs
@@ -1629,7 +1629,7 @@ internal static Diagnostic CreateAnalyzerExceptionDiagnostic(DiagnosticAnalyzer
             var analyzerName = analyzer.ToString();
             var title = CodeAnalysisResources.CompilerAnalyzerFailure;
             var messageFormat = CodeAnalysisResources.CompilerAnalyzerThrows;
-            var contextInformation = string.Join(Environment.NewLine, CreateDiagnosticDescription(info, e), CreateDisablingMessage(analyzer)).Trim();
+            var contextInformation = string.Join(Environment.NewLine, CreateDiagnosticDescription(info, e), CreateDisablingMessage(analyzer, analyzerName)).Trim();
             var messageArguments = new[] { analyzerName, e.GetType().ToString(), e.Message, contextInformation };
             var description = string.Format(CodeAnalysisResources.CompilerAnalyzerThrowsDescription, analyzerName, CreateDiagnosticDescription(info, e));
             var descriptor = GetAnalyzerExceptionDiagnosticDescriptor(AnalyzerExceptionDiagnosticId, title, description, messageFormat);
@@ -1647,19 +1647,23 @@ private static string CreateDiagnosticDescription(AnalysisContextInfo? info, Exc
                 string.Format(CodeAnalysisResources.ExceptionContext, info?.GetContext()), e.CreateDiagnosticDescription());
         }
 
-        private static string CreateDisablingMessage(DiagnosticAnalyzer analyzer)
+        private static string CreateDisablingMessage(DiagnosticAnalyzer analyzer, string analyzerName)
         {
             var diagnosticIds = ImmutableSortedSet<string>.Empty.WithComparer(StringComparer.OrdinalIgnoreCase);
             try
             {
                 foreach (var diagnostic in analyzer.SupportedDiagnostics)
                 {
-                    diagnosticIds = diagnosticIds.Add(diagnostic.Id);
+                    // If a null diagnostic is returned, we would have already reported that to the user earlier; we can just skip this.
+                    if (diagnostic != null)
+                    {
+                        diagnosticIds = diagnosticIds.Add(diagnostic.Id);
+                    }
                 }
             }
-            catch (Exception)
+            catch (Exception ex)
             {
-                // Intentionally empty
+                return string.Format(CodeAnalysisResources.CompilerAnalyzerThrowsDescription, analyzerName, ex.CreateDiagnosticDescription());
             }
 
             if (diagnosticIds.IsEmpty)