Merge pull request #22100 from sharwell/fix-warning-level

Make analyzer diagnostics independent of the current warning level

src/Compilers/CSharp/Test/Semantic/Diagnostics/GetDiagnosticsTests.cs

@@ -120,12 +120,12 @@ public void Goo()
             var hidden = diag.WithSeverity(DiagnosticSeverity.Hidden);
             Assert.Equal(DiagnosticSeverity.Hidden, hidden.Severity);
             Assert.Equal(DiagnosticSeverity.Warning, hidden.DefaultSeverity);
-            Assert.Equal(4, hidden.WarningLevel);
+            Assert.Equal(1, hidden.WarningLevel);
 
             var info = diag.WithSeverity(DiagnosticSeverity.Info);
             Assert.Equal(DiagnosticSeverity.Info, info.Severity);
             Assert.Equal(DiagnosticSeverity.Warning, info.DefaultSeverity);
-            Assert.Equal(4, info.WarningLevel);
+            Assert.Equal(1, info.WarningLevel);
         }
 
         [Fact, WorkItem(7446, "https://github.com/dotnet/roslyn/issues/7446")]

src/Compilers/Core/Portable/Diagnostic/Diagnostic.cs

@@ -512,6 +512,19 @@ internal Diagnostic WithReportDiagnostic(ReportDiagnostic reportAction)
             }
         }
 
+        /// <summary>
+        /// Gets the default warning level for a diagnostic severity. Warning levels are used with the <c>/warn:N</c>
+        /// command line option to suppress diagnostics over a severity of interest. When N is 0, only error severity
+        /// messages are produced by the compiler. Values greater than 0 indicated that warnings up to and including
+        /// level N should also be included.
+        /// </summary>
+        /// <remarks>
+        /// <see cref="DiagnosticSeverity.Info"/> and <see cref="DiagnosticSeverity.Hidden"/> are treated as warning
+        /// level 1. In other words, these diagnostics which typically interact with editor features are enabled unless
+        /// the special <c>/warn:0</c> option is set.
+        /// </remarks>
+        /// <param name="severity">A <see cref="DiagnosticSeverity"/> value.</param>
+        /// <returns>The default compiler warning level for <paramref name="severity"/>.</returns>
         internal static int GetDefaultWarningLevel(DiagnosticSeverity severity)
         {
             switch (severity)
@@ -520,10 +533,8 @@ internal static int GetDefaultWarningLevel(DiagnosticSeverity severity)
                     return 0;
 
                 case DiagnosticSeverity.Warning:
-                    return 1;
-
                 default:
-                    return HighestValidWarningLevel;
+                    return 1;
             }
         }
 

src/Compilers/VisualBasic/Test/Semantic/Diagnostics/GetDiagnosticsTests.vb

@@ -112,12 +112,12 @@ End Class
             Dim hidden = warning.WithSeverity(DiagnosticSeverity.Hidden)
             Assert.Equal(DiagnosticSeverity.Hidden, hidden.Severity)
             Assert.Equal(DiagnosticSeverity.Warning, hidden.DefaultSeverity)
-            Assert.Equal(4, hidden.WarningLevel)
+            Assert.Equal(1, hidden.WarningLevel)
 
             Dim info = warning.WithSeverity(DiagnosticSeverity.Info)
             Assert.Equal(DiagnosticSeverity.Info, info.Severity)
             Assert.Equal(DiagnosticSeverity.Warning, info.DefaultSeverity)
-            Assert.Equal(4, info.WarningLevel)
+            Assert.Equal(1, info.WarningLevel)
         End Sub
 
         <Fact, WorkItem(7446, "https://github.com/dotnet/roslyn/issues/7446")>

src/EditorFeatures/CSharpTest/Diagnostics/SimplifyTypeNames/SimplifyTypeNamesTests.cs

@@ -3995,6 +3995,37 @@ void Main()
                 options: PreferIntrinsicTypeInMemberAccess);
         }
 
+        [Theory]
+        [InlineData(0)]
+        [InlineData(1)]
+        [InlineData(2)]
+        [InlineData(3)]
+        [InlineData(4)]
+        [Trait(Traits.Feature, Traits.Features.CodeActionsSimplifyTypeNames)]
+        [WorkItem(20377, "https://github.com/dotnet/roslyn/issues/20377")]
+        public async Task TestWarningLevel(int warningLevel)
+        {
+            await TestInRegularAndScriptAsync(
+@"using System;
+
+namespace Root
+{
+    class A
+    {
+        [|System.Exception|] c;
+    }
+}",
+@"using System;
+
+namespace Root
+{
+    class A
+    {
+        Exception c;
+    }
+}", compilationOptions: new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary, warningLevel: warningLevel));
+        }
+
         private async Task TestWithPredefinedTypeOptionsAsync(string code, string expected, int index = 0)
         {
             await TestInRegularAndScriptAsync(code, expected, index: index, options: PreferIntrinsicTypeEverywhere);
@@ -4004,6 +4035,10 @@ private async Task TestWithPredefinedTypeOptionsAsync(string code, string expect
             SingleOption(CodeStyleOptions.PreferIntrinsicPredefinedTypeKeywordInDeclaration, true, NotificationOption.Error),
             SingleOption(CodeStyleOptions.PreferIntrinsicPredefinedTypeKeywordInMemberAccess, this.onWithError, GetLanguage()));
 
+        private IDictionary<OptionKey, object> PreferIntrinsicTypeEverywhereAsWarning => OptionsSet(
+            SingleOption(CodeStyleOptions.PreferIntrinsicPredefinedTypeKeywordInDeclaration, true, NotificationOption.Warning),
+            SingleOption(CodeStyleOptions.PreferIntrinsicPredefinedTypeKeywordInMemberAccess, this.onWithWarning, GetLanguage()));
+
         private IDictionary<OptionKey, object> PreferIntrinsicTypeInDeclaration => OptionsSet(
             SingleOption(CodeStyleOptions.PreferIntrinsicPredefinedTypeKeywordInDeclaration, true, NotificationOption.Error),
             SingleOption(CodeStyleOptions.PreferIntrinsicPredefinedTypeKeywordInMemberAccess, this.offWithNone, GetLanguage()));

src/EditorFeatures/CSharpTest/RemoveUnnecessaryImports/RemoveUnnecessaryImportsTests.cs

@@ -1353,5 +1353,34 @@ static void Main(string[] args)
     }
 }");
         }
+
+        [Theory]
+        [InlineData(0)]
+        [InlineData(1)]
+        [InlineData(2)]
+        [InlineData(3)]
+        [InlineData(4)]
+        [Trait(Traits.Feature, Traits.Features.CodeActionsRemoveUnnecessaryImports)]
+        [WorkItem(20377, "https://github.com/dotnet/roslyn/issues/20377")]
+        public async Task TestWarningLevel(int warningLevel)
+        {
+            await TestInRegularAndScriptAsync(
+@"[|using System;
+using System.Collections.Generic;
+using System.Linq;
+
+class Program
+{
+    static void Main(string[] args)
+    {
+    }
+}|]",
+@"class Program
+{
+    static void Main(string[] args)
+    {
+    }
+}", compilationOptions: new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary, warningLevel: warningLevel));
+        }
     }
 }