MisraType: Avoid misuse of getSize()

Author: lcartey

cpp/misra/src/codingstandards/cpp/misra/BuiltInTypeRules.qll

@@ -93,8 +93,11 @@ newtype Signedness =
  * - Typedefs to built in types
  * - References to built in types
  * - Enum types with an explicit underlying type that is a built-in type.
+ *
+ * Note: this does not extend `Type` directly, to prevent accidental use of `getSize()`, which
+ * returns the "wrong" size for e.g. reference types.
  */
-classMisraBuiltInTypeextendsType{
+classMisraBuiltInTypeextendsElement{
 // The built in type underlying this MISRA built in type
 BuiltInTypebuiltInType;
 
@@ -108,6 +111,8 @@ class MisraBuiltInType extends Type{
 TypeCategorygetTypeCategory(){result=getBuiltInTypeCategory(builtInType)}
 
 predicateisSameType(MisraBuiltInTypeother){this.getBuiltInType()=other.getBuiltInType()}
+
+stringgetName(){result=this.(Type).getName()}
 }
 
 classCharacterTypeextendsMisraBuiltInType{
@@ -298,13 +303,13 @@ CanonicalIntegerNumericType getBitFieldType(BitField bf){
 bitfieldActualType=bf.getType()and
 // Integral type with the same signedness as the bit field, and big enough to hold the bit field value
 result.getSignedness()=bitfieldActualType.getSignedness()and
-result.getSize()*8>=bf.getNumBits()and
+result.getBuiltInSize()*8>=bf.getNumBits()and
 // No smaller integral type can hold the bit field value
 notexists(CanonicalIntegerNumericTypeother|
-other.getSize()*8>=bf.getNumBits()and
+other.getBuiltInSize()*8>=bf.getNumBits()and
 other.getSignedness()=result.getSignedness()
 |
-other.getSize()<result.getBuiltInSize()
+other.getBuiltInSize()<result.getBuiltInSize()
 )
 )
 }

cpp/misra/src/rules/RULE-7-0-4/InappropriateBitwiseOrShiftOperands.ql

@@ -45,7 +45,7 @@ predicate isSignedConstantLeftShiftException(LShiftExpr shift){
 leftVal=left.getValue().toBigInt()and
 rightVal=right.getValue().toInt()and
 leftVal>=0.toBigInt()and
-maxBit=leftType.getSize()*8-1and
+maxBit=leftType.getBuiltInSize()*8-1and
 // Check that no set bit is shifted into or beyond the sign bit
 leftVal*2.toBigInt().pow(rightVal)<2.toBigInt().pow(maxBit)
 )