C++/C#: Add sanity test for invalid overlap from getDefinitionOverlap()

The result of `getDefinitionOverlap()` should never be `MayPartiallyOverlap`, because if that were the case, we should have inserted as `Chi` instruction and hooked the definition up to that instead.

There are quite a few existing failures.

csharp/ql/src/semmle/code/csharp/ir/implementation/raw/IRSanity.qll

@@ -5,6 +5,7 @@ import IRTypeSanity // module is in IRType.qll
 module InstructionSanity {
   private import internal.InstructionImports as Imports
   private import Imports::OperandTag
+  private import Imports::Overlap
   private import internal.IRInternal
 
   /**
@@ -272,4 +273,18 @@ module InstructionSanity {
     func = switchInstr.getEnclosingIRFunction() and
     funcText = Language::getIdentityString(func.getFunction())
   }
+
+  query predicate invalidOverlap(
+    MemoryOperand useOperand, string message, IRFunction func, string funcText
+  ) {
+    exists(Overlap overlap |
+      overlap = useOperand.getDefinitionOverlap() and
+      overlap instanceof MayPartiallyOverlap and
+      message =
+        "MemoryOperand '" + useOperand.toString() + "' has a `getDefinitionOverlap()` of '" +
+          overlap.toString() + "'." and
+      func = useOperand.getEnclosingIRFunction() and
+      funcText = Language::getIdentityString(func.getFunction())
+    )
+  }
 }

csharp/ql/src/semmle/code/csharp/ir/implementation/raw/Operand.qll

@@ -384,6 +384,8 @@ class PositionalArgumentOperand extends ArgumentOperand {
 
 class SideEffectOperand extends TypedOperand {
   override SideEffectOperandTag tag;
+
+  override string toString() { result = "SideEffect" }
 }
 
 /**

csharp/ql/src/semmle/code/csharp/ir/implementation/raw/internal/InstructionImports.qll

@@ -3,3 +3,4 @@ import semmle.code.csharp.ir.implementation.IRType as IRType
 import semmle.code.csharp.ir.implementation.MemoryAccessKind as MemoryAccessKind
 import semmle.code.csharp.ir.implementation.Opcode as Opcode
 import semmle.code.csharp.ir.implementation.internal.OperandTag as OperandTag
+import semmle.code.csharp.ir.internal.Overlap as Overlap

csharp/ql/src/semmle/code/csharp/ir/implementation/unaliased_ssa/IRSanity.qll

@@ -5,6 +5,7 @@ import IRTypeSanity // module is in IRType.qll
 module InstructionSanity {
   private import internal.InstructionImports as Imports
   private import Imports::OperandTag
+  private import Imports::Overlap
   private import internal.IRInternal
 
   /**
@@ -272,4 +273,18 @@ module InstructionSanity {
     func = switchInstr.getEnclosingIRFunction() and
     funcText = Language::getIdentityString(func.getFunction())
   }
+
+  query predicate invalidOverlap(
+    MemoryOperand useOperand, string message, IRFunction func, string funcText
+  ) {
+    exists(Overlap overlap |
+      overlap = useOperand.getDefinitionOverlap() and
+      overlap instanceof MayPartiallyOverlap and
+      message =
+        "MemoryOperand '" + useOperand.toString() + "' has a `getDefinitionOverlap()` of '" +
+          overlap.toString() + "'." and
+      func = useOperand.getEnclosingIRFunction() and
+      funcText = Language::getIdentityString(func.getFunction())
+    )
+  }
 }

csharp/ql/src/semmle/code/csharp/ir/implementation/unaliased_ssa/Operand.qll

@@ -384,6 +384,8 @@ class PositionalArgumentOperand extends ArgumentOperand {
 
 class SideEffectOperand extends TypedOperand {
   override SideEffectOperandTag tag;
+
+  override string toString() { result = "SideEffect" }
 }
 
 /**

csharp/ql/src/semmle/code/csharp/ir/implementation/unaliased_ssa/internal/InstructionImports.qll

@@ -3,3 +3,4 @@ import semmle.code.csharp.ir.implementation.IRType as IRType
 import semmle.code.csharp.ir.implementation.MemoryAccessKind as MemoryAccessKind
 import semmle.code.csharp.ir.implementation.Opcode as Opcode
 import semmle.code.csharp.ir.implementation.internal.OperandTag as OperandTag
+import semmle.code.csharp.ir.internal.Overlap as Overlap

csharp/ql/test/library-tests/ir/ir/raw_ir_sanity.expected

@@ -16,6 +16,7 @@ lostReachability
 backEdgeCountMismatch
 useNotDominatedByDefinition
 switchInstructionWithoutDefaultEdge
+invalidOverlap
 missingCanonicalLanguageType
 multipleCanonicalLanguageTypes
 missingIRType

csharp/ql/test/library-tests/ir/ir/unaliased_ssa_sanity.expected

@@ -16,6 +16,7 @@ lostReachability
 backEdgeCountMismatch
 useNotDominatedByDefinition
 switchInstructionWithoutDefaultEdge
+invalidOverlap
 missingCanonicalLanguageType
 multipleCanonicalLanguageTypes
 missingIRType