[TaskAnalyzer] Align diagnostic severities and ignore open generic ITaskItem<T>

src/TaskAnalyzer.Tests/PreferTypedParameterAnalyzerTests.cs

@@ -39,7 +39,7 @@ public override bool Execute()
         diags.Length.ShouldBe(1);
         diags[0].GetMessage().ShouldContain("InputPath");
         diags[0].GetMessage().ShouldContain("AbsolutePath");
-        diags[0].Severity.ShouldBe(Microsoft.CodeAnalysis.DiagnosticSeverity.Warning);
+        diags[0].Severity.ShouldBe(Microsoft.CodeAnalysis.DiagnosticSeverity.Info);
     }
 
     [Fact]
@@ -66,7 +66,7 @@ public override bool Execute()
         diags.ShouldNotContain(d => d.Id == DiagnosticIds.PreferTypedPathParameter);
         diags[0].GetMessage().ShouldContain("InputPath");
         diags[0].GetMessage().ShouldContain("AbsolutePath");
-        diags[0].Severity.ShouldBe(Microsoft.CodeAnalysis.DiagnosticSeverity.Warning);
+        diags[0].Severity.ShouldBe(Microsoft.CodeAnalysis.DiagnosticSeverity.Info);
     }
 
     [Fact]
@@ -373,7 +373,7 @@ public override bool Execute()
         diags.Length.ShouldBe(1);
         diags[0].GetMessage().ShouldContain("int");
         diags[0].GetMessage().ShouldContain("Item");
-        diags[0].Severity.ShouldBe(Microsoft.CodeAnalysis.DiagnosticSeverity.Warning);
+        diags[0].Severity.ShouldBe(Microsoft.CodeAnalysis.DiagnosticSeverity.Info);
     }
 
     [Fact]

src/TaskAnalyzer.Tests/UnsupportedTaskItemTypeAnalyzerTests.cs

@@ -1,6 +1,7 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.CodeAnalysis;
 using Shouldly;
@@ -45,7 +46,7 @@ public class MyTask : Microsoft.Build.Utilities.Task
     [InlineData("double")]
     [InlineData("decimal")]
     [InlineData("System.DateTime")]
-    public async Task ConvertChangeTypeType_ProducesError(string typeName)
+    public async Task ConvertChangeTypeType_ProducesWarning(string typeName)
     {
         var diags = await GetUnsupportedTaskItemTypeDiagnosticsAsync($$"""
             using Microsoft.Build.Framework;
@@ -59,7 +60,7 @@ public class MyTask : Microsoft.Build.Utilities.Task
         diags.ShouldNotContain(d => d.Id == DiagnosticIds.UnsupportedTaskItemType);
         Diagnostic diagnostic = diags.ShouldHaveSingleItem();
         diagnostic.Id.ShouldBe(DiagnosticIds.CultureSensitiveTaskItemType);
-        diagnostic.Severity.ShouldBe(Microsoft.CodeAnalysis.DiagnosticSeverity.Error);
+        diagnostic.Severity.ShouldBe(Microsoft.CodeAnalysis.DiagnosticSeverity.Warning);
         diagnostic.GetMessage().ShouldContain("Convert.ChangeType");
         diagnostic.GetMessage().ShouldContain("CultureInfo.InvariantCulture");
     }
@@ -116,7 +117,7 @@ public class MyTask : Microsoft.Build.Utilities.Task
     // ═══════════════════════════════════════════════════════════════════════
 
     [Fact]
-    public async Task ConvertChangeTypeArray_ProducesError()
+    public async Task ConvertChangeTypeArray_ProducesWarning()
     {
         var diags = await GetUnsupportedTaskItemTypeDiagnosticsAsync("""
             using Microsoft.Build.Framework;
@@ -129,7 +130,7 @@ public class MyTask : Microsoft.Build.Utilities.Task
 
         Diagnostic diagnostic = diags.ShouldHaveSingleItem();
         diagnostic.Id.ShouldBe(DiagnosticIds.CultureSensitiveTaskItemType);
-        diagnostic.Severity.ShouldBe(Microsoft.CodeAnalysis.DiagnosticSeverity.Error);
+        diagnostic.Severity.ShouldBe(Microsoft.CodeAnalysis.DiagnosticSeverity.Warning);
     }
 
     [Fact]
@@ -149,7 +150,7 @@ public class MyTask : Microsoft.Build.Utilities.Task
     }
 
     [Fact]
-    public async Task ConvertChangeTypeOutputProperty_ProducesError()
+    public async Task ConvertChangeTypeOutputProperty_ProducesWarning()
     {
         var diags = await GetUnsupportedTaskItemTypeDiagnosticsAsync("""
             using Microsoft.Build.Framework;
@@ -163,7 +164,7 @@ public class MyTask : Microsoft.Build.Utilities.Task
 
         Diagnostic diagnostic = diags.ShouldHaveSingleItem();
         diagnostic.Id.ShouldBe(DiagnosticIds.CultureSensitiveTaskItemType);
-        diagnostic.Severity.ShouldBe(Microsoft.CodeAnalysis.DiagnosticSeverity.Error);
+        diagnostic.Severity.ShouldBe(Microsoft.CodeAnalysis.DiagnosticSeverity.Warning);
     }
 
     [Fact]
@@ -201,6 +202,7 @@ public class MyTask : Microsoft.Build.Utilities.Task
             """);
 
         diags.ShouldContain(d => d.Id == DiagnosticIds.UnsupportedTaskItemType);
+        diags.ShouldHaveSingleItem().Severity.ShouldBe(Microsoft.CodeAnalysis.DiagnosticSeverity.Warning);
         diags[0].GetMessage().ShouldContain("Item");
         diags[0].GetMessage().ShouldContain("Guid");
         diags[0].GetMessage().ShouldContain("string, bool, AbsolutePath, FileInfo, DirectoryInfo");
@@ -225,6 +227,41 @@ public class MyTask : Microsoft.Build.Utilities.Task
         diags[0].GetMessage().ShouldContain("TimeSpan");
     }
 
+    [Fact]
+    public async Task TypedTaskItemDiagnostics_AreIndependentOfMtOptIn()
+    {
+        var diags = await GetUnsupportedTaskItemTypeDiagnosticsAsync("""
+            using System;
+            using Microsoft.Build.Framework;
+            public class MyTask : Microsoft.Build.Utilities.Task
+            {
+                public ITaskItem<Guid> Invalid { get; set; } = null!;
+                public ITaskItem<int> CultureSensitive { get; set; } = null!;
+                public override bool Execute() => true;
+            }
+            """);
+
+        diags.Where(d => d.Id == DiagnosticIds.UnsupportedTaskItemType).ShouldHaveSingleItem()
+            .Severity.ShouldBe(Microsoft.CodeAnalysis.DiagnosticSeverity.Warning);
+        diags.Where(d => d.Id == DiagnosticIds.CultureSensitiveTaskItemType).ShouldHaveSingleItem()
+            .Severity.ShouldBe(Microsoft.CodeAnalysis.DiagnosticSeverity.Warning);
+    }
+
+    [Fact]
+    public async Task GenericTaskItemTypeParameter_NoDiagnostic()
+    {
+        var diags = await GetUnsupportedTaskItemTypeDiagnosticsAsync("""
+            using Microsoft.Build.Framework;
+            public class GenericTask<T> : Microsoft.Build.Utilities.Task
+            {
+                public ITaskItem<T> Item { get; set; } = null!;
+                public override bool Execute() => true;
+            }
+            """);
+
+        diags.ShouldBeEmpty();
+    }
+
     [Fact]
     public async Task Enum_ProducesDiagnostic()
     {

src/TaskAnalyzer/AnalyzerReleases.Unshipped.md

@@ -7,11 +7,11 @@ MSBuildTask0002 | MSBuild.TaskAuthoring | Warning | APIs that should use TaskEnv
 MSBuildTask0003 | MSBuild.TaskAuthoring | Warning | File APIs that need absolute paths
 MSBuildTask0004 | MSBuild.TaskAuthoring | Warning | APIs that may cause issues in multithreaded task execution
 MSBuildTask0005 | MSBuild.TaskAuthoring | Warning | Transitive unsafe API usage detected in task call chain
-MSBuildTask0006 | MSBuild.TaskAuthoring | Warning | Prefer typed path parameter (AbsolutePath/FileInfo/DirectoryInfo) over string (code fix available)
-MSBuildTask0007 | MSBuild.TaskAuthoring | Warning | Prefer ITaskItem<T> over manual ItemSpec parsing (code fix available)
-MSBuildTask0008 | MSBuild.TaskAuthoring | Warning | Initialize a relative default path in Execute() so TaskEnvironment can root it when the property is retyped (code fix available)
+MSBuildTask0006 | MSBuild.TaskAuthoring | Info | Prefer typed path parameter (AbsolutePath/FileInfo/DirectoryInfo) over string (code fix available)
+MSBuildTask0007 | MSBuild.TaskAuthoring | Info | Prefer ITaskItem<T> over manual ItemSpec parsing (code fix available)
+MSBuildTask0008 | MSBuild.TaskAuthoring | Info | Initialize a relative default path in Execute() so TaskEnvironment can root it when the property is retyped (code fix available)
 MSBuildTask0009 | MSBuild.TaskAuthoring | Warning | ITaskItem<T> used with a type argument T that MSBuild cannot bind as a task parameter
-MSBuildTask0010 | MSBuild.TaskAuthoring | Error | ITaskItem<T> used with a type argument T that MSBuild parses through Convert.ChangeType
+MSBuildTask0010 | MSBuild.TaskAuthoring | Warning | ITaskItem<T> used with a type argument T that MSBuild parses through Convert.ChangeType
 MSBuildTask0011 | MSBuild.TaskAuthoring | Info | Prefer constructor injection for TaskEnvironment
 MSBuildTask0012 | MSBuild.TaskAuthoring | Warning | TaskEnvironment property is never assigned by MSBuild because the task does not implement IMultiThreadableTask
 MSBuildTask0013 | MSBuild.TaskAuthoring | Info | Task declares IMultiThreadableTask but is not marked with [MSBuildMultiThreadableTask] (disabled by default)

src/TaskAnalyzer/DiagnosticDescriptors.cs

@@ -63,7 +63,7 @@ internal static class DiagnosticDescriptors
             title: "Prefer typed path parameter over manual path construction",
             messageFormat: "Consider changing task property '{0}' from '{1}' to '{2}' instead of converting inside the task body",
             category: "MSBuild.TaskAuthoring",
-            defaultSeverity: DiagnosticSeverity.Warning,
+            defaultSeverity: DiagnosticSeverity.Info,
             isEnabledByDefault: true,
             description: "MSBuild can bind AbsolutePath, FileInfo, and DirectoryInfo task parameters automatically for tasks that opt into multithreaded support. Using these types avoids manual path construction in the task body.");
 
@@ -72,7 +72,7 @@ internal static class DiagnosticDescriptors
             title: "Prefer ITaskItem<T> over manual ItemSpec parsing",
             messageFormat: "Consider changing task property '{0}' from '{1}' to 'ITaskItem<{2}>{3}' instead of parsing ItemSpec manually",
             category: "MSBuild.TaskAuthoring",
-            defaultSeverity: DiagnosticSeverity.Warning,
+            defaultSeverity: DiagnosticSeverity.Info,
             isEnabledByDefault: true,
             description: "MSBuild can bind ITaskItem<T> task parameters that provide a strongly-typed Value property parsed from ItemSpec for tasks that opt into multithreaded support. Using ITaskItem<T> avoids manual parsing in the task body.");
 
@@ -81,7 +81,7 @@ internal static class DiagnosticDescriptors
             title: "Initialize relative default path in Execute()",
             messageFormat: "Task property '{0}' has a relative default path; initialize it in Execute() so it can be rooted through TaskEnvironment when the property is changed to '{1}'",
             category: "MSBuild.TaskAuthoring",
-            defaultSeverity: DiagnosticSeverity.Warning,
+            defaultSeverity: DiagnosticSeverity.Info,
             isEnabledByDefault: true,
             description: "A relative default path cannot be rooted in a property initializer because the MSBuild engine only assigns TaskEnvironment after the task is constructed. Move the default into Execute(), where TaskEnvironment.GetAbsolutePath can resolve it, guarding the assignment so a value bound from the project is not overwritten.");
 
@@ -99,7 +99,7 @@ internal static class DiagnosticDescriptors
             title: "ITaskItem<T> type argument relies on culture-sensitive conversion",
             messageFormat: "Task property '{0}' uses ITaskItem<{1}>, which MSBuild parses through Convert.ChangeType using CultureInfo.InvariantCulture. Use ITaskItem<string> and parse explicitly with a chosen culture.",
             category: "MSBuild.TaskAuthoring",
-            defaultSeverity: DiagnosticSeverity.Error,
+            defaultSeverity: DiagnosticSeverity.Warning,
             isEnabledByDefault: true,
             description: "ITaskItem<T> type arguments parsed through Convert.ChangeType use CultureInfo.InvariantCulture. Bind the item as a string and parse it explicitly with the intended culture.");
 

src/TaskAnalyzer/README.md

@@ -19,11 +19,11 @@ This analyzer catches unsafe API usage at compile time and offers code fixes to
 | **MSBuildTask0003** | Warning | All `ITask` implementations | File system API requires absolute path |
 | **MSBuildTask0004** | Warning | All `ITask` implementations | API may cause issues in multithreaded tasks |
 | **MSBuildTask0005** | Warning | All `ITask` implementations | Transitive unsafe API usage in task call chain |
-| **MSBuildTask0006** | Warning | Tasks with `[MSBuildMultiThreadableTask]` applied directly | Prefer typed path parameter over string |
-| **MSBuildTask0007** | Warning | Tasks with `[MSBuildMultiThreadableTask]` applied directly | Prefer `ITaskItem<T>` over manual ItemSpec parsing |
-| **MSBuildTask0008** | Warning | Tasks with `[MSBuildMultiThreadableTask]` applied directly | Initialize a relative-default path property in `Execute()` |
+| **MSBuildTask0006** | Info | Tasks with `[MSBuildMultiThreadableTask]` applied directly | Prefer typed path parameter over string |
+| **MSBuildTask0007** | Info | Tasks with `[MSBuildMultiThreadableTask]` applied directly | Prefer `ITaskItem<T>` over manual ItemSpec parsing |
+| **MSBuildTask0008** | Info | Tasks with `[MSBuildMultiThreadableTask]` applied directly | Initialize a relative-default path property in `Execute()` |
 | **MSBuildTask0009** | Warning | All `ITask` implementations | `ITaskItem<T>` used with unsupported type argument |
-| **MSBuildTask0010** | Error | All `ITask` implementations | `ITaskItem<T>` relies on culture-sensitive conversion |
+| **MSBuildTask0010** | Warning | All `ITask` implementations | `ITaskItem<T>` relies on culture-sensitive conversion |
 | **MSBuildTask0011** | Info | Concrete `IMultiThreadableTask` implementations | Prefer constructor injection for `TaskEnvironment` |
 | **MSBuildTask0012** | Warning | Concrete tasks with `[MSBuildMultiThreadableTask]` applied directly | MSBuild never assigns the `TaskEnvironment` property |
 | **MSBuildTask0013** | Info (off by default) | Concrete tasks declaring `IMultiThreadableTask` in their own base list | Missing `[MSBuildMultiThreadableTask]`, so the task still runs out-of-proc |
@@ -245,7 +245,7 @@ public class MyTask : Task
 {
     public ITaskItem<System.Guid> Id { get; set; }       // warning
     public ITaskItem<System.TimeSpan>[] Durations { get; set; }  // warning
-    public ITaskItem<int> Count { get; set; }             // MSBuildTask0010 error
+    public ITaskItem<int> Count { get; set; }             // MSBuildTask0010 warning
 }
 ```
 
@@ -255,13 +255,13 @@ No code fix is offered for MSBuildTask0009 — the resolution depends on the int
 
 ### MSBuildTask0010 — Culture-Sensitive `ITaskItem<T>` Conversion
 
-MSBuild binds `ITaskItem<T>` for `char`, numeric primitives, `decimal`, and `DateTime` through `Convert.ChangeType` using `CultureInfo.InvariantCulture`. Because this implicit conversion may not match the task's intended culture, the analyzer reports an **Error** whenever one of these types is used.
+MSBuild binds `ITaskItem<T>` for `char`, numeric primitives, `decimal`, and `DateTime` through `Convert.ChangeType` using `CultureInfo.InvariantCulture`. Because this implicit conversion may not match the task's intended culture, the analyzer reports a **Warning** whenever one of these types is used.
 
 ```csharp
 public class MyTask : Task
 {
-    public ITaskItem<int> Count { get; set; }       // error
-    public ITaskItem<DateTime>[] Dates { get; set; } // error
+    public ITaskItem<int> Count { get; set; }       // warning
+    public ITaskItem<DateTime>[] Dates { get; set; } // warning
 }
 ```
 
@@ -414,12 +414,8 @@ The `[MSBuildMultiThreadableTaskAnalyzed]` attribute allows opting helper classe
 ### Severity Levels
 
 - **MSBuildTask0001** is always **Error** — these APIs are never safe in any MSBuild task.
-- **MSBuildTask0010** is always **Error** — task item conversions must not rely on `Convert.ChangeType`.
-- **MSBuildTask0002–MSBuildTask0009** report as **Warning**, with MSBuildTask0006–MSBuildTask0008 limited to tasks directly marked with `[MSBuildMultiThreadableTask]`.
-- **MSBuildTask0011** reports as **Info** — it is a modernization suggestion rather than a correctness issue.
-- **MSBuildTask0012** reports as **Warning** — the `TaskEnvironment` property is silently inert, which is a correctness issue.
-- **MSBuildTask0013** is **disabled by default** — running out-of-proc is a performance characteristic, and the shape it reports is a valid intermediate migration state.
-- **MSBuildTask0014** reports as **Warning** — the attribute is inert, and the task the author meant to mark is usually still running out-of-proc.
+- **MSBuildTask0002–MSBuildTask0005, MSBuildTask0009, and MSBuildTask0010** report as **Warning**.
+- **MSBuildTask0006–MSBuildTask0008 and MSBuildTask0011** report as **Info** — these are modernization suggestions, not correctness issues.
 
 ## Code Fixes
 

src/TaskAnalyzer/UnsupportedTaskItemTypeAnalyzer.cs

@@ -95,6 +95,13 @@ property.ContainingType is not null &&
 
                     ITypeSymbol typeArg = namedPropertyType.TypeArguments[0];
 
+                    // A generic task can be constructed with a supported type. Its open type
+                    // parameter does not provide enough information for a binding diagnostic.
+                    if (typeArg.TypeKind == TypeKind.TypeParameter)
+                    {
+                        continue;
+                    }
+
                     if (SupportedTaskItemTypes.IsConvertChangeTypeTaskItemType(typeArg.SpecialType))
                     {
                         symbolContext.ReportDiagnostic(Diagnostic.Create(