C#: Move the declaration of synthetic fields to where they are needed.

Author: michaelnebel

csharp/ql/lib/semmle/code/csharp/dataflow/LibraryTypeDataFlow.qll

@@ -473,32 +473,6 @@ class IEnumerableFlow extends LibraryTypeDataFlow, RefType {
   }
 }
 
-abstract private class SyntheticTaskField extends SyntheticField {
-  bindingset[this]
-  SyntheticTaskField() { any() }
-
-  override Type getType() { result instanceof SystemThreadingTasksTaskTClass }
-}
-
-private class SyntheticTaskAwaiterUnderlyingTaskField extends SyntheticTaskField {
-  SyntheticTaskAwaiterUnderlyingTaskField() { this = "m_task_task_awaiter" }
-}
-
-private class SyntheticConfiguredTaskAwaitableUnderlyingTaskField extends SyntheticTaskField {
-  SyntheticConfiguredTaskAwaitableUnderlyingTaskField() {
-    this = "m_task_configured_task_awaitable"
-  }
-}
-
-private class SyntheticConfiguredTaskAwaiterField extends SyntheticField {
-  SyntheticConfiguredTaskAwaiterField() { this = "m_configuredTaskAwaiter" }
-
-  override Type getType() {
-    result instanceof
-      SystemRuntimeCompilerServicesConfiguredTaskAwaitableTConfiguredTaskAwaiterStruct
-  }
-}
-
 private predicate recordConstructorFlow(Constructor c, int i, Property p) {
   c = any(Record r).getAMember() and
   exists(string name |

csharp/ql/lib/semmle/code/csharp/frameworks/system/runtime/CompilerServices.qll

@@ -2,6 +2,7 @@
 
 import csharp
 private import semmle.code.csharp.frameworks.system.Runtime
+private import semmle.code.csharp.dataflow.internal.DataFlowPrivate
 private import semmle.code.csharp.dataflow.ExternalFlow
 
 /** The `System.Runtime.CompilerServices` namespace. */
@@ -53,6 +54,15 @@ class SystemRuntimeCompilerServicesConfiguredTaskAwaitableTStruct extends System
   }
 }
 
+private class SyntheticConfiguredTaskAwaiterField extends SyntheticField {
+  SyntheticConfiguredTaskAwaiterField() { this = "m_configuredTaskAwaiter" }
+
+  override Type getType() {
+    result instanceof
+      SystemRuntimeCompilerServicesConfiguredTaskAwaitableTConfiguredTaskAwaiterStruct
+  }
+}
+
 /** Data flow for `System.Runtime.CompilerServices.ConfiguredTaskAwaitable<>`. */
 private class SystemRuntimeCompilerServicesConfiguredTaskAwaitableTFlowModelCsv extends SummaryModelCsv {
   override predicate row(string row) {

csharp/ql/lib/semmle/code/csharp/frameworks/system/threading/Tasks.qll

@@ -2,6 +2,7 @@
 
 import csharp
 private import semmle.code.csharp.frameworks.system.Threading
+private import semmle.code.csharp.dataflow.internal.DataFlowPrivate
 private import semmle.code.csharp.dataflow.ExternalFlow
 
 /** The `System.Threading.Tasks` namespace. */
@@ -91,6 +92,23 @@ class SystemThreadingTasksTaskTClass extends SystemThreadingTasksUnboundGenericC
   Method getConfigureAwaitMethod() { result = this.getAMethod("ConfigureAwait") }
 }
 
+abstract private class SyntheticTaskField extends SyntheticField {
+  bindingset[this]
+  SyntheticTaskField() { any() }
+
+  override Type getType() { result instanceof SystemThreadingTasksTaskTClass }
+}
+
+private class SyntheticTaskAwaiterUnderlyingTaskField extends SyntheticTaskField {
+  SyntheticTaskAwaiterUnderlyingTaskField() { this = "m_task_task_awaiter" }
+}
+
+private class SyntheticConfiguredTaskAwaitableUnderlyingTaskField extends SyntheticTaskField {
+  SyntheticConfiguredTaskAwaitableUnderlyingTaskField() {
+    this = "m_task_configured_task_awaitable"
+  }
+}
+
 /** Data flow for `System.Threading.Tasks.Task<>`. */
 private class SystemThreadingTasksTaskTFlowModelCsv extends SummaryModelCsv {
   override predicate row(string row) {