Implement Conversions rule package
#919
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Detects implicit and explicit conversions from type bool to other types, preventing potential confusion between bitwise and logical operators and ensuring clear type usage. [a]
- Simplify query implementation - Format test code
Detects implicit conversions to bool type from fundamental types, unscoped enumerations, and pointers that may lead to unintended behavior in conditional expressions.
Detects inappropriate assignments between numeric types that violate type compatibility requirements, including implicit conversions that may cause information loss or unexpected behavior changes. [a]
- Add additional test cases - Allow name qualifiers - Prohibit explicit casts (inc. parameters)
Reference types can be numeric types according to the rule. In addition to making NumericTypes reference types, we also add a helper predicate which gets the size of the real type (rather than the size of the reference).
Migrate conversion generic code to a shared library.
- Add extra testing - Support signed bitfields
- Exclude booleans and chars from our determination of numeric types. - Deduplicate integer types deduced for bitfields - identifying a canonical set of integer types.
The `getValue()` provided in the database applies the conversions, which can be unhelpful when trying to write rules the refer to conversions.
- Use IntegerConstantExpr to determine both the expressions which are constant, and the BigInt value of those constants (before final conversion). - Implement a BigInt type upper/lower bound to determine whether a constant assignment is valid.
- Support assignment to pointer to members - Support pointer-to-member function calls
Overload independence should consider what parameters are default.
Consider the conversion as the source, not the pre-conversion value.
- Use BinaryOperations library to merge reporting of assign and binary operations. - Report the actual type of the operand. - Report the operand which is in contravention, instead of the operation. - Split reporting of cases where a constant is not valid from cases where the it is not unsigned for better reporting.
Improve handling for constructors with default arguments.
- Create new shared library for canonical integer types - Implement `isMinimal` case to handle instances where multiple canonical types have the same size (for example `long` and `long long` on some platforms). - Create a new CanonicalIntegerNumericType for representing the concept of MISRA numeric canonical types. Set isMinimal() in the charpred to automatically filter out multiple canonical types for the same size and signedness.
- Only `Cast`s participate in integer promotions and arithmetic conversions. - Rename conversion classes to clarify what they cover. - Update documentation to improve clarity on coverage.
Simplify the handling of bitfields.
MichaelRFairhurst
requested changes
Aug 21, 2025
For bool to class conversions.
Make it clearer that a static_assert is not unevaluated.
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Description
This PR adds support for an updated
Conversionspackage.As a number of the early rules in the original conversions package - particularly Rule 7.0.6 - turned out to be more complex than expected, I've created a
Conversions2package and shuffled around the queries in the following way:Conversionspackage.ConversionsfromPreconditions- as the rule concepts related more closely to the otherConversionsqueries than to preconditions.Conversions2.Implementation notes:
BigInttype, to help support analysis of larger integer constants. In CodeQL CLI 2.19.4, this feature is considered "experimental". Therefore, I would recommend we merge the PR to upgrade the CodeQL dependency to 2.20.7 (Upgradegithub/codeqldependency to 2.20.7 #913) before we merge this PR.BuiltInTypeRulesCodeQL library, which implements the behaviour described in the section4.7.0 The built-in type rulesof MISRA C++ 2023. These are similar in purpose to the essential type rules from MISRA C, but different enough that we needed to provide a clean implementation.Change request type
.ql,.qll,.qlsor unit tests)Rules with added or modified queries
RULE-7-0-1RULE-7-0-2RULE-7-0-3RULE-7-0-4RULE-7-0-5RULE-7-0-6RULE-7-11-3Release change checklist
A change note (development_handbook.md#change-notes) is required for any pull request which modifies:
If you are only adding new rule queries, a change note is not required.
Author: Is a change note required?
🚨🚨🚨
Reviewer: Confirm that format of shared queries (not the .qll file, the
.ql file that imports it) is valid by running them within VS Code.
Reviewer: Confirm that either a change note is not required or the change note is required and has been added.
Query development review checklist
For PRs that add new queries or modify existing queries, the following checklist should be completed by both the author and reviewer:
Author
As a rule of thumb, predicates specific to the query should take no more than 1 minute, and for simple queries be under 10 seconds. If this is not the case, this should be highlighted and agreed in the code review process.
Reviewer
As a rule of thumb, predicates specific to the query should take no more than 1 minute, and for simple queries be under 10 seconds. If this is not the case, this should be highlighted and agreed in the code review process.