Make local functions static where applicable

src/Microsoft.ML.Core/Utilities/ThreadUtils.cs

@@ -66,7 +66,7 @@ private static Task Queue(Delegate threadStart, object state)
                 // Return the task.
                 return tcs.Task;
 
-                void CreateThread()
+                static void CreateThread()
                 {
                     // Create a new background thread to run the work.
                     var t = new Thread(() =>
@@ -96,7 +96,7 @@ void CreateThread()
                     t.Start();
                 }
 
-                void Enqueue((Delegate, object, TaskCompletionSource<bool>) item)
+                static void Enqueue((Delegate, object, TaskCompletionSource<bool>) item)
                 {
                     // Enqueue the work. If there are currently fewer threads waiting
                     // for work than there are work items in the queue, create another
@@ -120,7 +120,7 @@ void Enqueue((Delegate, object, TaskCompletionSource<bool>) item)
                     CreateThread();
                 }
 
-                bool TryDequeue(out (Delegate action, object state, TaskCompletionSource<bool> tcs) item)
+                static bool TryDequeue(out (Delegate action, object state, TaskCompletionSource<bool> tcs) item)
                 {
                     // Dequeues the next item if one is available. Before checking,
                     // the available thread count is increased, so that enqueuers can

src/Microsoft.ML.Data/DataLoadSave/LegacyCompositeDataLoader.cs

@@ -130,7 +130,7 @@ private static ILegacyDataLoader CreateCore(IHost host, ILegacyDataLoader srcLoa
             if (Utils.Size(transformArgs) == 0)
                 return srcLoader;
 
-            string GetTagData(IComponentFactory<IDataView, IDataTransform> factory)
+            static string GetTagData(IComponentFactory<IDataView, IDataTransform> factory)
             {
                 // When coming from the command line, preserve the string arguments.
                 // For other factories, we aren't able to get the string.

test/Microsoft.ML.Functional.Tests/DataTransformation.cs

@@ -39,7 +39,7 @@ void ExtensibilityAddAColumnAsAFunctionOfMultipleColumns()
             data = mlContext.Data.TakeRows(data, numSamples);
 
             // Create a stand-alone function to produce a random number.
-            float angiospermCosine(float petalWidth, float petalLength, float sepalWidth, float sepalLength)
+            static float angiospermCosine(float petalWidth, float petalLength, float sepalWidth, float sepalLength)
             {
                 var petalMagnitude = Math.Sqrt(petalWidth * petalWidth + petalLength * petalLength);
                 var sepalMagnitude = Math.Sqrt(sepalWidth * sepalWidth + sepalLength * sepalLength);

test/Microsoft.ML.Functional.Tests/ModelFiles.cs

@@ -190,7 +190,7 @@ public void LoadModelAndExtractPredictor()
                 loadedTransformerModel1 = mlContext.Model.LoadWithDataLoader(fs, out var l);
             }
 
-            void AssertIsGam(ITransformer trans)
+            static void AssertIsGam(ITransformer trans)
             {
                 Assert.IsType<GamBinaryModelParameters>(
                     Assert.IsAssignableFrom<CalibratedModelParametersBase>(

test/Microsoft.ML.Tests/Transformers/ConcatTests.cs

@@ -56,7 +56,7 @@ void TestConcat()
             }, new MultiFileSource(dataPath));
             var data = loader.Load(source);
 
-            DataViewType GetType(DataViewSchema schema, string name)
+            static DataViewType GetType(DataViewSchema schema, string name)
             {
                 Assert.True(schema.TryGetColumnIndex(name, out int cIdx), $"Could not find '{name}'");
                 return schema[cIdx].Type;
@@ -113,7 +113,7 @@ public void ConcatWithAliases()
             }, new MultiFileSource(dataPath));
             var data = loader.Load(source);
 
-            DataViewType GetType(DataViewSchema schema, string name)
+            static DataViewType GetType(DataViewSchema schema, string name)
             {
                 Assert.True(schema.TryGetColumnIndex(name, out int cIdx), $"Could not find '{name}'");
                 return schema[cIdx].Type;