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MISRA C++ 2023: Create StandardConversions library
Migrate conversion generic code to a shared library.
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-123
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‎cpp/misra/src/codingstandards/cpp/misra/StandardConversions.qll

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import cpp
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import codingstandards.cpp.misra
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/**
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* The signedness of a numeric type.
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*/
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newtype Signedness =
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Signed() or
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Unsigned()
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/**
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* The type category of a numeric type - either integral or floating-point.
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*/
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newtype TypeCategory =
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Integral() or
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FloatingPoint()
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/**
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* A numeric type is a type that represents a number, either an integral or a floating-point.
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*
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* In addition to the basic integral and floating-point types, it includes:
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* - Enum types with an explicit underlying type that is a numeric type.
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* - Typedef'd types that are numeric types.
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* - Numeric types with specifiers (e.g., `const`, `volatile`, `restrict`).
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*/
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class NumericType extends Type {
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Type realType;
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NumericType() {
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realType = this.getUnspecifiedType().(ReferenceType).getBaseType().(NumericType).getRealType() or
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realType = this.getUnspecifiedType().(IntegralType) or
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realType = this.getUnspecifiedType().(FloatingPointType) or
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realType = this.getUnspecifiedType().(Enum).getExplicitUnderlyingType().getUnspecifiedType()
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}
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Signedness getSignedness() {
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if realType.(IntegralType).isUnsigned() then result = Unsigned() else result = Signed()
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}
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/** Gets the size of the actual numeric type */
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int getRealSize() { result = realType.getSize() }
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TypeCategory getTypeCategory() {
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realType instanceof IntegralType and result = Integral()
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or
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realType instanceof FloatingPointType and result = FloatingPoint()
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}
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float getUpperBound() { result = typeUpperBound(realType) }
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float getLowerBound() { result = typeLowerBound(realType) }
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Type getRealType() { result = realType }
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}
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predicate isAssignment(Expr source, NumericType targetType, string context) {
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// Assignment operator (but not compound assignment)
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exists(AssignExpr assign |
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assign.getRValue() = source and
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context = "assignment"
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|
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// TODO generalize to variable init (do we need this for bitfields?) and extract
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if isAssignedToBitfield(source, _)
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then
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exists(BitField bf |
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isAssignedToBitfield(source, bf) and
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// TODO integral after numeric?
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targetType.(IntegralType).(NumericType).getSignedness() =
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bf.getType().(NumericType).getSignedness() and
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// smallest integral type that can hold the bit field value
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targetType.getRealSize() * 8 >= bf.getNumBits() and
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not exists(IntegralType other |
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other.getSize() * 8 >= bf.getNumBits() and
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other.(NumericType).getSignedness() = targetType.getSignedness() and
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other.getSize() < targetType.getRealSize()
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)
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)
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else targetType = assign.getLValue().getType()
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)
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or
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// Variable initialization
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exists(Variable v, Initializer init |
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init.getExpr() = source and
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v.getInitializer() = init and
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targetType = v.getType() and
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context = "initialization"
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)
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or
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// Passing a function parameter by value
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exists(Call call, int i |
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call.getArgument(i) = source and
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not targetType.stripTopLevelSpecifiers() instanceof ReferenceType and
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context = "function argument"
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|
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targetType = call.getTarget().getParameter(i).getType()
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or
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// Handle varargs - use the fully converted type of the argument
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call.getTarget().getNumberOfParameters() <= i and
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targetType = source.getFullyConverted().getType()
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)
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or
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// Return statement
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exists(ReturnStmt ret, Function f |
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ret.getExpr() = source and
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ret.getEnclosingFunction() = f and
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targetType = f.getType() and
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not targetType.stripTopLevelSpecifiers() instanceof ReferenceType and
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context = "return"
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)
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or
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// Switch case
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exists(SwitchCase case, SwitchStmt switch |
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case.getExpr() = source and
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case.getSwitchStmt() = switch and
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targetType = switch.getExpr().getFullyConverted().getType() and
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context = "switch case"
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)
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}
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predicate isAssignedToBitfield(Expr source, BitField bf) {
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exists(Assignment assign |
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assign.getRValue() = source and
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assign.getLValue() = bf.getAnAccess()
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)
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}

‎cpp/misra/src/rules/RULE-7-0-6/NumericAssignmentTypeMismatch.ql

Lines changed: 1 addition & 123 deletions
Original file line numberDiff line numberDiff line change
@@ -15,129 +15,7 @@
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import cpp
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import codingstandards.cpp.misra
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import semmle.code.cpp.rangeanalysis.SimpleRangeAnalysis
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/**
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* The signedness of a numeric type.
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*/
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newtype Signedness =
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Signed() or
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Unsigned()
26-
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/**
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* The type category of a numeric type - either integral or floating-point.
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*/
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newtype TypeCategory =
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Integral() or
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FloatingPoint()
33-
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/**
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* A numeric type is a type that represents a number, either an integral or a floating-point.
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*
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* In addition to the basic integral and floating-point types, it includes:
38-
* - Enum types with an explicit underlying type that is a numeric type.
39-
* - Typedef'd types that are numeric types.
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* - Numeric types with specifiers (e.g., `const`, `volatile`, `restrict`).
41-
*/
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class NumericType extends Type {
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Type realType;
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NumericType() {
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realType = this.getUnspecifiedType().(ReferenceType).getBaseType().(NumericType).getRealType() or
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realType = this.getUnspecifiedType().(IntegralType) or
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realType = this.getUnspecifiedType().(FloatingPointType) or
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realType = this.getUnspecifiedType().(Enum).getExplicitUnderlyingType().getUnspecifiedType()
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}
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Signedness getSignedness() {
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if realType.(IntegralType).isUnsigned() then result = Unsigned() else result = Signed()
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}
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int getRealSize() { result = realType.getSize() }
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TypeCategory getTypeCategory() {
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realType instanceof IntegralType and result = Integral()
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or
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realType instanceof FloatingPointType and result = FloatingPoint()
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}
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float getUpperBound() { result = typeUpperBound(realType) }
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float getLowerBound() { result = typeLowerBound(realType) }
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Type getRealType() { result = realType }
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}
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predicate isAssignment(Expr source, NumericType targetType, string context) {
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// Assignment operator (but not compound assignment)
73-
exists(AssignExpr assign |
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assign.getRValue() = source and
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context = "assignment"
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|
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// TODO generalize to variable init (do we need this for bitfields?) and extract
78-
if isAssignedToBitfield(source, _)
79-
then
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exists(BitField bf |
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isAssignedToBitfield(source, bf) and
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// TODO integral after numeric?
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targetType.(IntegralType).(NumericType).getSignedness() =
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bf.getType().(NumericType).getSignedness() and
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// smallest integral type that can hold the bit field value
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targetType.getRealSize() * 8 >= bf.getNumBits() and
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not exists(IntegralType other |
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other.getSize() * 8 >= bf.getNumBits() and
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other.(NumericType).getSignedness() = targetType.getSignedness() and
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other.getSize() < targetType.getRealSize()
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)
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)
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else targetType = assign.getLValue().getType()
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)
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or
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// Variable initialization
97-
exists(Variable v, Initializer init |
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init.getExpr() = source and
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v.getInitializer() = init and
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targetType = v.getType() and
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context = "initialization"
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)
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or
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// Passing a function parameter by value
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exists(Call call, int i |
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call.getArgument(i) = source and
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not targetType.stripTopLevelSpecifiers() instanceof ReferenceType and
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context = "function argument"
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|
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targetType = call.getTarget().getParameter(i).getType()
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or
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// Handle varargs - use the fully converted type of the argument
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call.getTarget().getNumberOfParameters() <= i and
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targetType = source.getFullyConverted().getType()
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)
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or
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// Return statement
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exists(ReturnStmt ret, Function f |
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ret.getExpr() = source and
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ret.getEnclosingFunction() = f and
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targetType = f.getType() and
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not targetType.stripTopLevelSpecifiers() instanceof ReferenceType and
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context = "return"
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)
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or
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// Switch case
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exists(SwitchCase case, SwitchStmt switch |
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case.getExpr() = source and
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case.getSwitchStmt() = switch and
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targetType = switch.getExpr().getFullyConverted().getType() and
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context = "switch case"
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)
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}
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predicate isAssignedToBitfield(Expr source, BitField bf) {
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exists(Assignment assign |
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assign.getRValue() = source and
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assign.getLValue() = bf.getAnAccess()
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)
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}
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import codingstandards.cpp.misra.StandardConversions
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predicate isValidConstantAssignment(Expr source, NumericType targetType) {
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isAssignment(source, targetType, _) and

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