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EssentialTypes: Implement Rule 10.5
Adds a query that identifies explicit casts to an inappropriate essential type, according to the conditions set by MISRA C 2012.
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‎c/misra/src/rules/RULE-10-5/InappropriateEssentialTypeCast.ql

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/**
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* @id c/misra/inappropriate-essential-type-cast
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* @name RULE-10-5: The value of an expression should not be cast to an inappropriate essential type
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* @description
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* @kind problem
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* @precision very-high
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* @problem.severity error
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* @tags external/misra/id/rule-10-5
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* external/misra/obligation/advisory
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*/
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import cpp
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import codingstandards.c.misra
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import codingstandards.c.misra.EssentialTypes
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import codingstandards.c.misra.MisraExpressions
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predicate isIncompatibleEssentialTypeCast(EssentialTypeCategory fromCat, EssentialTypeCategory toCat) {
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fromCat = EssentiallyBooleanType() and
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toCat =
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[
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EssentiallyCharacterType(), EssentiallyEnumType(), EssentiallySignedType(),
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EssentiallyUnsignedType(), EssentiallyFloatingType().(TEssentialTypeCategory)
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]
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or
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fromCat = EssentiallyCharacterType() and
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toCat =
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[
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EssentiallyBooleanType(), EssentiallyEnumType(),
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EssentiallyFloatingType().(TEssentialTypeCategory)
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]
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or
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fromCat = EssentiallyEnumType() and
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toCat = [EssentiallyBooleanType(), EssentiallyEnumType().(TEssentialTypeCategory)] // NOTE only if different enum types
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or
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fromCat = EssentiallySignedType() and
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toCat = [EssentiallyBooleanType(), EssentiallyEnumType().(TEssentialTypeCategory)]
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or
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fromCat = EssentiallyUnsignedType() and
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toCat = [EssentiallyBooleanType(), EssentiallyEnumType().(TEssentialTypeCategory)]
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or
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fromCat = EssentiallyFloatingType() and
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toCat =
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[
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EssentiallyBooleanType(), EssentiallyCharacterType(),
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EssentiallyEnumType().(TEssentialTypeCategory)
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]
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}
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from
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Cast c, Type essentialFromType, Type essentialToType, EssentialTypeCategory fromCategory,
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EssentialTypeCategory toCategory, string message
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where
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not isExcluded(c, EssentialTypesPackage::inappropriateEssentialTypeCastQuery()) and
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not c.isImplicit() and
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essentialFromType = getEssentialTypeBeforeConversions(c.getExpr()) and
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essentialToType = c.getType() and
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fromCategory = getEssentialTypeCategory(essentialFromType) and
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toCategory = getEssentialTypeCategory(essentialToType) and
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isIncompatibleEssentialTypeCast(fromCategory, toCategory) and
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(
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if fromCategory = EssentiallyEnumType() and toCategory = EssentiallyEnumType()
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then
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// If from/to enum types, then only report if the essential types are different
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not essentialToType = essentialFromType and
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message = "Incompatible cast from " + essentialFromType + " to " + essentialToType + "."
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else message = "Incompatible cast from " + fromCategory + " to " + toCategory + "."
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) and
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not (
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// Exception - casting from `0` or `1` to a boolean type is permitted
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(fromCategory = EssentiallySignedType() or fromCategory = EssentiallyUnsignedType()) and
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toCategory = EssentiallyBooleanType() and
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c.getExpr().getValue().toInt() = [0, 1]
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)
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select c, message

‎c/misra/test/rules/RULE-10-5/InappropriateEssentialTypeCast.expected

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| test.c:9:3:9:9 | (char)... | Incompatible cast from essentially Boolean type to essentially Character type. |
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| test.c:10:3:10:13 | (E1)... | Incompatible cast from essentially Boolean type to essentially Enum Type. |
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| test.c:11:3:11:15 | (signed int)... | Incompatible cast from essentially Boolean type to essentially Signed type. |
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| test.c:12:3:12:17 | (unsigned int)... | Incompatible cast from essentially Boolean type to essentially Unsigned type. |
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| test.c:13:3:13:10 | (float)... | Incompatible cast from essentially Boolean type to essentially Floating type. |
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| test.c:16:3:16:11 | (bool)... | Incompatible cast from essentially Character type to essentially Boolean type. |
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| test.c:18:3:18:13 | (E1)... | Incompatible cast from essentially Character type to essentially Enum Type. |
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| test.c:21:3:21:10 | (float)... | Incompatible cast from essentially Character type to essentially Floating type. |
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| test.c:24:3:24:11 | (bool)... | Incompatible cast from essentially Enum Type to essentially Boolean type. |
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| test.c:26:3:26:13 | (E1)... | Incompatible cast from E2 to E1. |
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| test.c:33:3:33:11 | (bool)... | Incompatible cast from essentially Signed type to essentially Boolean type. |
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| test.c:35:3:35:13 | (E1)... | Incompatible cast from essentially Signed type to essentially Enum Type. |
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| test.c:41:3:41:11 | (bool)... | Incompatible cast from essentially Unsigned type to essentially Boolean type. |
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| test.c:43:3:43:13 | (E1)... | Incompatible cast from essentially Unsigned type to essentially Enum Type. |
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| test.c:49:3:49:11 | (bool)... | Incompatible cast from essentially Floating type to essentially Boolean type. |
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| test.c:50:3:50:9 | (char)... | Incompatible cast from essentially Floating type to essentially Character type. |
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| test.c:51:3:51:13 | (E1)... | Incompatible cast from essentially Floating type to essentially Enum Type. |
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| test.c:68:3:68:10 | (bool)... | Incompatible cast from essentially Signed type to essentially Boolean type. |
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| test.c:72:3:72:16 | (MyBool)... | Incompatible cast from essentially Signed type to essentially Boolean type. |
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| test.c:76:3:76:12 | (boolean)... | Incompatible cast from essentially Signed type to essentially Boolean type. |

‎c/misra/test/rules/RULE-10-5/InappropriateEssentialTypeCast.qlref

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rules/RULE-10-5/InappropriateEssentialTypeCast.ql

‎c/misra/test/rules/RULE-10-5/test.c

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#include <stdbool.h>
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void testIncompatibleCasts() {
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enum E1 { A, B };
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_Bool b = true;
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(_Bool) b; // COMPLIANT
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(char)b; // NON_COMPLIANT
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(enum E1) b; // NON_COMPLIANT
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(signed int)b; // NON_COMPLIANT
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(unsigned int)b; // NON_COMPLIANT
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(float)b; // NON_COMPLIANT
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char c = 100;
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(_Bool) c; // NON_COMPLIANT
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(char)c; // COMPLIANT
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(enum E1) c; // NON_COMPLIANT
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(signed int)c; // COMPLIANT
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(unsigned int)c; // COMPLIANT
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(float)c; // NON_COMPLIANT
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enum E2 { C, D } e = C;
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(_Bool) e; // NON_COMPLIANT
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(char)e; // COMPLIANT
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(enum E1) e; // NON_COMPLIANT
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(enum E2) e; // COMPLIANT
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(signed int)e; // COMPLIANT
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(unsigned int)e; // COMPLIANT
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(float)e; // COMPLIANT
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signed int i = 100;
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(_Bool) i; // NON_COMPLIANT
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(char)i; // COMPLIANT
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(enum E1) i; // NON_COMPLIANT
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(signed int)i; // COMPLIANT
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(unsigned int)i; // COMPLIANT
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(float)i; // COMPLIANT
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unsigned int u = 100;
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(_Bool) u; // NON_COMPLIANT
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(char)u; // COMPLIANT
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(enum E1) u; // NON_COMPLIANT
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(signed int)u; // COMPLIANT
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(unsigned int)u; // COMPLIANT
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(float)u; // COMPLIANT
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float f = 100.0;
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(_Bool) f; // NON_COMPLIANT
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(char)f; // NON_COMPLIANT
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(enum E1) f; // NON_COMPLIANT
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(signed int)f; // COMPLIANT
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(unsigned int)f; // COMPLIANT
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(float)f; // COMPLIANT
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}
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void testImplicit() {
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// Implicit conversions are not checked by this rule.
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char c = true; // Not covered by rule
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_Bool b = 100; // Not covered by rule
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unsigned int u = 100;
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_Bool b2 = u; // Not covered by rule
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}
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void testIntegerConstantBool() {
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(_Bool)0; // COMPLIANT
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(_Bool)1; // COMPLIANT
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(_Bool)2; // NON_COMPLIANT
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enum MyBool { f, t };
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(enum MyBool)0; // COMPLIANT
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(enum MyBool)1; // COMPLIANT
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(enum MyBool)2; // NON_COMPLIANT
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typedef int boolean;
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(boolean)0; // COMPLIANT
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(boolean)1; // COMPLIANT
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(boolean)2; // NON_COMPLIANT
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}

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