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MichaelRFairhurstMichaelRFairhurst
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Merge pull request #1044 from github/michaelrfairhurst/implement-deadcode-10-rule-0-2-4
Implement Rule 0.2.4, unused functions with limited visibility.
2 parents f64a352 + d3815ad commit 7241613

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‎change_notes/2026-02-18-unused-member-functions-with-internal-linkage.md‎

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- `A0-1-3` - `UnusedLocalFunction.ql`:
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- Query now reports unused public members of classes in anonymous namespaces, which have internal linkage.
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- Alert message no longer contains the fully qualified name of the function, since the given function is already linked.

‎cpp/autosar/src/rules/A0-1-3/UnusedLocalFunction.ql‎

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import cpp
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import codingstandards.cpp.autosar
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import codingstandards.cpp.DynamicCallGraph
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import codingstandards.cpp.deadcode.UnusedFunctions
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import codingstandards.cpp.rules.unusedlocalfunction.UnusedLocalFunction
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/**
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* Checks if an overloaded function of
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* the function passed in the arguments, is called.
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*/
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predicate overloadedFunctionIsCalled(Function unusedFunction) {
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exists(Function f | f = unusedFunction.getAnOverload() and f = getTarget(_))
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}
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/** Checks if a Function's address was taken. */
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predicate addressBeenTaken(Function unusedFunction) {
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exists(FunctionAccess fa | fa.getTarget() = unusedFunction)
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}
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/** A `Function` nested in an anonymous namespace. */
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class AnonymousNamespaceFunction extends Function {
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AnonymousNamespaceFunction() { getNamespace().getParentNamespace*().isAnonymous() }
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}
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/**
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* A function which is "local" to a particular scope or translation unit.
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*/
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class LocalFunction extends UnusedFunctions::UsableFunction {
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string localFunctionType;
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LocalFunction() {
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this.(MemberFunction).isPrivate() and
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localFunctionType = "Private member"
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or
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// A function in an anonymous namespace (which is deduced to have internal linkage)
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this instanceof AnonymousNamespaceFunction and
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// Not member functions, which don't have internal linkage
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not this instanceof MemberFunction and
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localFunctionType = "Anonymous namespace"
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or
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// Static functions with internal linkage
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this.isStatic() and
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// Member functions never have internal linkage
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not this instanceof MemberFunction and
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// Functions in anonymous namespaces automatically have the "static" specifier added by the
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// extractor. We therefore excluded them from this case, and instead report them in the
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// anonymous namespace, as we don't know whether the "static" specifier was explicitly
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// provided by the user.
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not this instanceof AnonymousNamespaceFunction and
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localFunctionType = "Static"
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}
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/** Gets the type of local function. */
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string getLocalFunctionType() { result = localFunctionType }
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module UnusedLocalFunctionConfig implements UnusedLocalFunctionConfigSig {
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Query getQuery() { result = DeadCodePackage::unusedLocalFunctionQuery() }
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}
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from LocalFunction unusedLocalFunction, string name
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where
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not isExcluded(unusedLocalFunction, DeadCodePackage::unusedLocalFunctionQuery()) and
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// No static or dynamic call target for this function
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not unusedLocalFunction = getTarget(_) and
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// If this is a TemplateFunction or an instantiation of a template, then only report it as unused
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// if all other instantiations of the template are unused
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not exists(
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Function functionFromUninstantiatedTemplate, Function functionFromInstantiatedTemplate
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|
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// `unusedLocalFunction` is a template instantiation from `functionFromUninstantiatedTemplate`
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unusedLocalFunction.isConstructedFrom(functionFromUninstantiatedTemplate)
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or
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// `unusedLocalFunction` is from an uninstantiated template
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unusedLocalFunction = functionFromUninstantiatedTemplate
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|
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// There exists an instantiation which is called
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functionFromInstantiatedTemplate.isConstructedFrom(functionFromUninstantiatedTemplate) and
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functionFromInstantiatedTemplate = getTarget(_)
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) and
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// A function is defined as "used" if any one of the following holds true:
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// - It's an explicitly deleted functions e.g. =delete
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// - It's annotated as "[[maybe_unused]]"
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// - It's part of an overloaded set and any one of the overloaded instance
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// is called.
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// - It's an operand of an expression in an unevaluated context.
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not unusedLocalFunction.isDeleted() and
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not unusedLocalFunction.getAnAttribute().getName() = "maybe_unused" and
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not overloadedFunctionIsCalled(unusedLocalFunction) and
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not addressBeenTaken(unusedLocalFunction) and
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// Get a printable name
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(
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if exists(unusedLocalFunction.getQualifiedName())
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then name = unusedLocalFunction.getQualifiedName()
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else name = unusedLocalFunction.getName()
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)
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select unusedLocalFunction,
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unusedLocalFunction.getLocalFunctionType() + " function " + name +
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" is not statically called, or is in an unused template."
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import UnusedLocalFunction<UnusedLocalFunctionConfig>

‎cpp/autosar/test/rules/A0-1-3/UnusedLocalFunction.expected‎

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‎cpp/autosar/test/rules/A0-1-3/UnusedLocalFunction.qlref‎

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‎cpp/autosar/test/rules/A0-1-3/UnusedLocalFunction.testref‎

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cpp/common/test/rules/unusedlocalfunction/UnusedLocalFunction.ql

‎cpp/common/src/codingstandards/cpp/exclusions/cpp/DeadCode10.qll‎

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//** THIS FILE IS AUTOGENERATED, DO NOT MODIFY DIRECTLY. **/
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import cpp
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import RuleMetadata
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import codingstandards.cpp.exclusions.RuleMetadata
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newtype DeadCode10Query = TUnusedLimitedVisibilityFunctionQuery()
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predicate isDeadCode10QueryMetadata(Query query, string queryId, string ruleId, string category) {
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query =
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// `Query` instance for the `unusedLimitedVisibilityFunction` query
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DeadCode10Package::unusedLimitedVisibilityFunctionQuery() and
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queryId =
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// `@id` for the `unusedLimitedVisibilityFunction` query
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"cpp/misra/unused-limited-visibility-function" and
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ruleId = "RULE-0-2-4" and
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category = "advisory"
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}
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module DeadCode10Package {
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Query unusedLimitedVisibilityFunctionQuery() {
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//autogenerate `Query` type
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result =
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// `Query` type for `unusedLimitedVisibilityFunction` query
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TQueryCPP(TDeadCode10PackageQuery(TUnusedLimitedVisibilityFunctionQuery()))
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}
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}

‎cpp/common/src/codingstandards/cpp/exclusions/cpp/RuleMetadata.qll‎

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import Conversions
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import Conversions2
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import DeadCode
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import DeadCode10
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import DeadCode11
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import DeadCode3
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import DeadCode4
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TConversionsPackageQuery(ConversionsQuery q) or
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TConversions2PackageQuery(Conversions2Query q) or
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TDeadCodePackageQuery(DeadCodeQuery q) or
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TDeadCode10PackageQuery(DeadCode10Query q) or
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TDeadCode11PackageQuery(DeadCode11Query q) or
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TDeadCode3PackageQuery(DeadCode3Query q) or
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TDeadCode4PackageQuery(DeadCode4Query q) or
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isConversionsQueryMetadata(query, queryId, ruleId, category) or
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isConversions2QueryMetadata(query, queryId, ruleId, category) or
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isDeadCodeQueryMetadata(query, queryId, ruleId, category) or
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isDeadCode10QueryMetadata(query, queryId, ruleId, category) or
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isDeadCode11QueryMetadata(query, queryId, ruleId, category) or
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isDeadCode3QueryMetadata(query, queryId, ruleId, category) or
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isDeadCode4QueryMetadata(query, queryId, ruleId, category) or

‎cpp/common/src/codingstandards/cpp/rules/unusedlocalfunction/UnusedLocalFunction.qll‎

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/**
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* Provides a configurable module UnusedLocalFunction with a `problems` predicate
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* for the following issue:
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* Unused functions may indicate a coding error or require maintenance; functions that
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* are unused with certain visibility have no effect on the program and should be
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* removed.
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*/
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import cpp
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import codingstandards.cpp.Customizations
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import codingstandards.cpp.Exclusions
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import codingstandards.cpp.DynamicCallGraph
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import codingstandards.cpp.deadcode.UnusedFunctions
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/**
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* Checks if an overloaded function of
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* the function passed in the arguments, is called.
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*/
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predicate overloadedFunctionIsCalled(Function unusedFunction) {
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exists(Function f | f = unusedFunction.getAnOverload() and f = getTarget(_))
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}
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/** Checks if a Function's address was taken. */
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predicate addressBeenTaken(Function unusedFunction) {
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exists(FunctionAccess fa | fa.getTarget() = unusedFunction)
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}
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/** A `Function` nested in an anonymous namespace. */
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class AnonymousNamespaceFunction extends Function {
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AnonymousNamespaceFunction() { getNamespace().getParentNamespace*().isAnonymous() }
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}
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/**
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* A function which is "local" to a particular scope or translation unit.
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*/
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class LocalFunction extends UnusedFunctions::UsableFunction {
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string localFunctionType;
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LocalFunction() {
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this.(MemberFunction).isPrivate() and
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localFunctionType = "Private member"
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or
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// A function in an anonymous namespace (which is deduced to have internal linkage)
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this instanceof AnonymousNamespaceFunction and
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not this instanceof MemberFunction and
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localFunctionType = "Anonymous namespace"
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or
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// Class members in anonymous namespaces also have internal linkage.
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this instanceof AnonymousNamespaceFunction and
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this instanceof MemberFunction and
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localFunctionType = "Anonymous namespace class member"
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or
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// Static functions with internal linkage
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this.isStatic() and
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// Member functions never have internal linkage
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not this instanceof MemberFunction and
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// Functions in anonymous namespaces automatically have the "static" specifier added by the
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// extractor. We therefore excluded them from this case, and instead report them in the
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// anonymous namespace, as we don't know whether the "static" specifier was explicitly
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// provided by the user.
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not this instanceof AnonymousNamespaceFunction and
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localFunctionType = "Static"
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}
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/** Gets the type of local function. */
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string getLocalFunctionType() { result = localFunctionType }
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}
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signature module UnusedLocalFunctionConfigSig {
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Query getQuery();
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}
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module UnusedLocalFunction<UnusedLocalFunctionConfigSig Config> {
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query predicate problems(LocalFunction unusedLocalFunction, string message) {
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not isExcluded(unusedLocalFunction, Config::getQuery()) and
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// No static or dynamic call target for this function
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not unusedLocalFunction = getTarget(_) and
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// If this is a TemplateFunction or an instantiation of a template, then only report it as unused
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// if all other instantiations of the template are unused
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not exists(
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Function functionFromUninstantiatedTemplate, Function functionFromInstantiatedTemplate
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|
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// `unusedLocalFunction` is a template instantiation from `functionFromUninstantiatedTemplate`
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unusedLocalFunction.isConstructedFrom(functionFromUninstantiatedTemplate)
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or
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// `unusedLocalFunction` is from an uninstantiated template
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unusedLocalFunction = functionFromUninstantiatedTemplate
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|
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// There exists an instantiation which is called
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functionFromInstantiatedTemplate.isConstructedFrom(functionFromUninstantiatedTemplate) and
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functionFromInstantiatedTemplate = getTarget(_)
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) and
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// A function is defined as "used" if any one of the following holds true:
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// - It's an explicitly deleted functions e.g. =delete
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// - It's annotated as "[[maybe_unused]]"
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// - It's part of an overloaded set and any one of the overloaded instance
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// is called.
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// - It's an operand of an expression in an unevaluated context.
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not unusedLocalFunction.isDeleted() and
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not unusedLocalFunction.getAnAttribute().getName() = "maybe_unused" and
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not overloadedFunctionIsCalled(unusedLocalFunction) and
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not addressBeenTaken(unusedLocalFunction) and
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message =
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unusedLocalFunction.getLocalFunctionType() + " function " + unusedLocalFunction.getName() +
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" is not statically called, or is in an unused template."
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}
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}

‎cpp/common/test/rules/unusedlocalfunction/UnusedLocalFunction.expected‎

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| test.cpp:3:13:3:14 | f1 | Static function f1 is not statically called, or is in an unused template. |
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| test.cpp:21:29:21:33 | getAT | Static function getAT is not statically called, or is in an unused template. |
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| test.cpp:45:8:45:9 | g2 | Private member function g2 is not statically called, or is in an unused template. |
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| test.cpp:60:5:60:9 | getAT | Private member function getAT is not statically called, or is in an unused template. |
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| test.cpp:81:6:81:7 | h2 | Anonymous namespace function h2 is not statically called, or is in an unused template. |
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| test.cpp:85:6:85:7 | h3 | Anonymous namespace function h3 is not statically called, or is in an unused template. |
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| test.cpp:144:8:144:8 | f | Anonymous namespace class member function f is not statically called, or is in an unused template. |
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| test.cpp:150:8:150:8 | f | Anonymous namespace class member function f is not statically called, or is in an unused template. |

‎cpp/common/test/rules/unusedlocalfunction/UnusedLocalFunction.ql‎

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// GENERATED FILE - DO NOT MODIFY
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import codingstandards.cpp.rules.unusedlocalfunction.UnusedLocalFunction
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module TestFileConfig implements UnusedLocalFunctionConfigSig {
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Query getQuery() { result instanceof TestQuery }
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}
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import UnusedLocalFunction<TestFileConfig>

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