C++/C#: Fix some duplicate IRType problems, and add a sanity test

cpp/ql/src/semmle/code/cpp/ir/implementation/IRType.qll

@@ -248,4 +248,14 @@ module IRTypeSanity {
     strictcount(type.getCanonicalLanguageType()) > 1 and
     message = "Type has multiple canonical `LanguageType`s: " + concat(type.getCanonicalLanguageType().toString(), ", ")
   }
+
+  query predicate missingIRType(Language::LanguageType type, string message) {
+    not exists(type.getIRType()) and
+    message = "`LanguageType` does not have a corresponding `IRType`."
+  }
+
+  query predicate multipleIRTypes(Language::LanguageType type, string message) {
+    strictcount(type.getIRType()) > 1 and
+    message = "`LanguageType` " + type.getAQlClass() + " has multiple `IRType`s: " + concat(type.getIRType().toString(), ", ")
+  }
 }

cpp/ql/src/semmle/code/cpp/ir/internal/CppType.qll

@@ -263,7 +263,7 @@ private class CppUnknownOpaqueType extends CppType, TUnknownOpaqueType {
   }
 
   override final IROpaqueType getIRType() {
-    result.getByteSize() = byteSize
+    result.getByteSize() = byteSize and result.getTag() instanceof UnknownType
   }
 
   override predicate hasType(Type type, boolean isGLValue) {

cpp/ql/test/library-tests/ir/ir/aliased_ssa_sanity.expected

@@ -15,3 +15,5 @@ backEdgeCountMismatch
 useNotDominatedByDefinition
 missingCanonicalLanguageType
 multipleCanonicalLanguageTypes
+missingIRType
+multipleIRTypes

cpp/ql/test/library-tests/ir/ir/raw_sanity.expected

@@ -15,3 +15,5 @@ backEdgeCountMismatch
 useNotDominatedByDefinition
 missingCanonicalLanguageType
 multipleCanonicalLanguageTypes
+missingIRType
+multipleIRTypes

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

@@ -15,3 +15,5 @@ backEdgeCountMismatch
 useNotDominatedByDefinition
 missingCanonicalLanguageType
 multipleCanonicalLanguageTypes
+missingIRType
+multipleIRTypes

cpp/ql/test/library-tests/ir/ssa/aliased_ssa_sanity.expected

@@ -15,3 +15,5 @@ backEdgeCountMismatch
 useNotDominatedByDefinition
 missingCanonicalLanguageType
 multipleCanonicalLanguageTypes
+missingIRType
+multipleIRTypes

cpp/ql/test/library-tests/ir/ssa/unaliased_ssa_sanity.expected

@@ -15,3 +15,5 @@ backEdgeCountMismatch
 useNotDominatedByDefinition
 missingCanonicalLanguageType
 multipleCanonicalLanguageTypes
+missingIRType
+multipleIRTypes

cpp/ql/test/library-tests/syntax-zoo/aliased_ssa_sanity.expected

@@ -546,3 +546,5 @@ backEdgeCountMismatch
 useNotDominatedByDefinition
 missingCanonicalLanguageType
 multipleCanonicalLanguageTypes
+missingIRType
+multipleIRTypes

cpp/ql/test/library-tests/syntax-zoo/raw_sanity.expected

@@ -694,3 +694,5 @@ useNotDominatedByDefinition
 | vla.c:14:74:14:79 | Operand | Operand 'Operand' is not dominated by its definition in function '$@'. | vla.c:11:6:11:16 | IR: vla_typedef | void vla_typedef() |
 missingCanonicalLanguageType
 multipleCanonicalLanguageTypes
+missingIRType
+multipleIRTypes

cpp/ql/test/library-tests/syntax-zoo/unaliased_ssa_sanity.expected

@@ -555,3 +555,5 @@ backEdgeCountMismatch
 useNotDominatedByDefinition
 missingCanonicalLanguageType
 multipleCanonicalLanguageTypes
+missingIRType
+multipleIRTypes