C++: Consistently use getUnspecifiedType in structured binding IR translation

cpp/ql/lib/semmle/code/cpp/ir/implementation/raw/internal/TranslatedExpr.qll

@@ -895,15 +895,15 @@ class TranslatedStructuredBindingVariableAccess extends TranslatedNonConstantExp
   override predicate hasInstruction(Opcode opcode, InstructionTag tag, CppType resultType) {
     tag = StructuredBindingAccessTag() and
     opcode instanceof Opcode::VariableAddress and
-    resultType = getTypeForGLValue(this.getReferenceType())
+    resultType = getTypeForGLValue(this.getLValueReferenceType())
     or
     tag = LoadTag() and
     opcode instanceof Opcode::Load and
-    resultType = getTypeForPRValue(this.getReferenceType())
+    resultType = getTypeForPRValue(this.getLValueReferenceType())
   }
 
-  private Type getReferenceType() {
-    result.(LValueReferenceType).getBaseType() = expr.getUnderlyingType()
+  private LValueReferenceType getLValueReferenceType() {
+    result.getBaseType() = expr.getUnspecifiedType()
   }
 
   override Instruction getInstructionRegisterOperand(InstructionTag tag, OperandTag operandTag) {

cpp/ql/lib/semmle/code/cpp/ir/internal/IRUtilities.qll

@@ -17,7 +17,7 @@ private Type getDecayedType(Type type) {
  */
 predicate isNonReferenceStructuredBinding(Variable v) {
   v.isStructuredBinding() and
-  not v.getUnderlyingType() instanceof ReferenceType
+  not v.getUnspecifiedType() instanceof ReferenceType
 }
 
 /**
@@ -41,7 +41,7 @@ Type getVariableType(Variable v) {
         not exists(v.getInitializer()) and result = v.getType()
       else
         if isNonReferenceStructuredBinding(v)
-        then exists(LValueReferenceType r | r.getBaseType() = v.getUnderlyingType() | result = r)
+        then exists(LValueReferenceType r | r.getBaseType() = v.getUnspecifiedType() | result = r)
         else result = v.getType()
   )
 }