Merge pull request #1121 from github/michaelrfairhurst/classes-3-take-2-rule-15-0-1

Narrowly focused implementation of RULE 15-0-1

Author: jeongsoolee09

cpp/common/src/codingstandards/cpp/exclusions/cpp/Classes3.qll

@@ -0,0 +1,44 @@
+//** THIS FILE IS AUTOGENERATED, DO NOT MODIFY DIRECTLY.  **/
+import cpp
+import RuleMetadata
+import codingstandards.cpp.exclusions.RuleMetadata
+
+newtype Classes3Query =
+  TImproperlyProvidedSpecialMemberFunctionsQuery() or
+  TImproperlyProvidedSpecialMemberFunctionsAuditQuery()
+
+predicate isClasses3QueryMetadata(Query query, string queryId, string ruleId, string category) {
+  query =
+    // `Query` instance for the `improperlyProvidedSpecialMemberFunctions` query
+    Classes3Package::improperlyProvidedSpecialMemberFunctionsQuery() and
+  queryId =
+    // `@id` for the `improperlyProvidedSpecialMemberFunctions` query
+    "cpp/misra/improperly-provided-special-member-functions" and
+  ruleId = "RULE-15-0-1" and
+  category = "required"
+  or
+  query =
+    // `Query` instance for the `improperlyProvidedSpecialMemberFunctionsAudit` query
+    Classes3Package::improperlyProvidedSpecialMemberFunctionsAuditQuery() and
+  queryId =
+    // `@id` for the `improperlyProvidedSpecialMemberFunctionsAudit` query
+    "cpp/misra/improperly-provided-special-member-functions-audit" and
+  ruleId = "RULE-15-0-1" and
+  category = "required"
+}
+
+module Classes3Package {
+  Query improperlyProvidedSpecialMemberFunctionsQuery() {
+    //autogenerate `Query` type
+    result =
+      // `Query` type for `improperlyProvidedSpecialMemberFunctions` query
+      TQueryCPP(TClasses3PackageQuery(TImproperlyProvidedSpecialMemberFunctionsQuery()))
+  }
+
+  Query improperlyProvidedSpecialMemberFunctionsAuditQuery() {
+    //autogenerate `Query` type
+    result =
+      // `Query` type for `improperlyProvidedSpecialMemberFunctionsAudit` query
+      TQueryCPP(TClasses3PackageQuery(TImproperlyProvidedSpecialMemberFunctionsAuditQuery()))
+  }
+}

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

@@ -18,6 +18,7 @@ import BannedSyntax
 import BannedTypes
 import Classes
 import Classes2
+import Classes3
 import Classes4
 import Comments
 import Concurrency
@@ -129,6 +130,7 @@ newtype TCPPQuery =
   TBannedTypesPackageQuery(BannedTypesQuery q) or
   TClassesPackageQuery(ClassesQuery q) or
   TClasses2PackageQuery(Classes2Query q) or
+  TClasses3PackageQuery(Classes3Query q) or
   TClasses4PackageQuery(Classes4Query q) or
   TCommentsPackageQuery(CommentsQuery q) or
   TConcurrencyPackageQuery(ConcurrencyQuery q) or
@@ -240,6 +242,7 @@ predicate isQueryMetadata(Query query, string queryId, string ruleId, string cat
   isBannedTypesQueryMetadata(query, queryId, ruleId, category) or
   isClassesQueryMetadata(query, queryId, ruleId, category) or
   isClasses2QueryMetadata(query, queryId, ruleId, category) or
+  isClasses3QueryMetadata(query, queryId, ruleId, category) or
   isClasses4QueryMetadata(query, queryId, ruleId, category) or
   isCommentsQueryMetadata(query, queryId, ruleId, category) or
   isConcurrencyQueryMetadata(query, queryId, ruleId, category) or

cpp/misra/src/rules/RULE-15-0-1/AnalyzableClass.qll

@@ -0,0 +1,289 @@
+/**
+ * Provides predicates and classes to perform a precursor analysis of which classes the rule can
+ * potentially analyze, or should be excluded and instead selected by the audit query.
+ *
+ * For example, the class `AnalyzableClass` resolves all of the special member functions that we
+ * must have in order to determine rule compliance.
+ *
+ * Part of what this module does is perform a very approximate analysis of which classes will
+ * produce a value of true in `std::is_(copy|move)_(constructible|assignable)_v`.
+ *
+ * Fully predicting these standard type traits requires performing a very thorough overload
+ * resolution analysis, including value category propagation and reference binding and user defined
+ * conversion operators and standard conversions and promotions and ranking viable candidates and
+ * properly handling ambiguous overloads.
+ */
+
+import cpp
+
+/**
+ * For `std::is_(copy|move)_(constructible|assignable)_v` to return true for a given class, the
+ * member must exist, it must not be deleted, and it must be publicly accessible.
+ *
+ * This is a very coarse approximation of true behavior of the standard type traits.
+ */
+private predicate isUsable(MemberFunction f) {
+  not f.isDeleted() and
+  f.isPublic()
+}
+
+/**
+ * Holds if the member function `f` has been "customized" by the user, e.g., they explicitly wrote
+ * the implementation of the function.
+ */
+private predicate isMemberCustomized(MemberFunction f) {
+  exists(f.getDefinition()) and
+  not f.isDefaulted() and
+  not f.isDeleted() and
+  not f.isCompilerGenerated()
+}
+
+/**
+ * Holds if the user declared the member function `f`, as opposed to it being implicitly declared
+ * by the compiler.
+ *
+ * Note that `T(T&&) = default` and `T(T&&) = delete` are both user declared. This is not to be
+ * confused with "user defined."
+ */
+private predicate isUserDeclared(MemberFunction f) { not f.isCompilerGenerated() }
+
+/**
+ * Holds if the class `c` contains a user declared copy constructor, copy assignment operator,
+ * or destructor.
+ *
+ * Encapsulates common behavior related to implicit move operation suppression defined in
+ * [class.copy.ctor]/8 and [class.copy.assign]/4.
+ */
+predicate hasUserDeclaredCopyOrDestruct(Class c) {
+  isUserDeclared(c.getAConstructor().(CopyConstructor))
+  or
+  isUserDeclared(c.getAMemberFunction().(CopyAssignmentOperator))
+  or
+  isUserDeclared(c.getDestructor())
+}
+
+/**
+ * Holds if the implicit move constructor of the class `c` will not be declared, as specified in
+ * [class.copy.ctor]/8.
+ */
+private predicate implicitMoveConstructorSuppressed(Class c) {
+  // Sanity check: if the move constructor exists, it must not have been suppressed.
+  not exists(c.getAConstructor().(MoveConstructor)) and
+  (
+    // Per the spec, the move constructor is suppressed if:
+    // There is a user declared copy constructor, copy assignment operator, or destructor,
+    hasUserDeclaredCopyOrDestruct(c)
+    or
+    // or, the move assignment operator is user declared.
+    isUserDeclared(c.getAMemberFunction().(MoveAssignmentOperator))
+  )
+}
+
+/**
+ * Holds if the implicit move assignment operator of the class `c` will not be declared, as specified
+ * in [class.copy.assign]/4.
+ */
+private predicate implicitMoveAssignmentSuppressed(Class c) {
+  // Sanity check: if the move assignment operator exists, it must not have been suppressed.
+  not exists(c.getAMemberFunction().(MoveAssignmentOperator)) and
+  (
+    // Per the spec, the move assignment operator is suppressed if:
+    // There is a user declared copy constructor, copy assignment operator, or destructor,
+    hasUserDeclaredCopyOrDestruct(c)
+    or
+    // or, the move constructor is user declared.
+    isUserDeclared(c.getAMemberFunction().(MoveConstructor))
+  )
+}
+
+/**
+ * Returns the move constructor of the class `c` if it exists, or the copy constructor if it does
+ * not exist and the implicit definition was suppressed by the compiler.
+ *
+ * For example:
+ * ```cpp
+ * class OnlyCopyCtor {
+ * public:
+ *   OnlyCopyCtor(const OnlyCopyCtor &) = default;
+ * };
+ *
+ * static_assert(std::is_copy_constructible_v<OnlyCopyCtor>); // Succeeds
+ * static_assert(std::is_move_constructible_v<OnlyCopyCtor>); // Also succeeds
+ * ```
+ *
+ * Note that without the declared copy constructor, the compiler may define an implicit move
+ * constructor.
+ *
+ * Additionally note that if the move constructor was declared as `= delete;`, then the second
+ * assertion in the above example would fail.
+ */
+private Constructor getMoveConstructor(Class c) {
+  if implicitMoveConstructorSuppressed(c)
+  then result = c.getAConstructor().(CopyConstructor)
+  else result = c.getAConstructor().(MoveConstructor)
+}
+
+/**
+ * Returns the move assignment operator of the class `c` if it exists, or the copy assignment
+ * operator if it does not exist and the implicit definition was suppressed by the compiler.
+ *
+ * For example:
+ * ```cpp
+ * class OnlyCopyAssign {
+ * public:
+ *   OnlyCopyAssign& operator=(const OnlyCopyAssign &) = default;
+ * };
+ *
+ * static_assert(std::is_copy_assignable_v<OnlyCopyAssign>); // Succeeds
+ * static_assert(std::is_move_assignable_v<OnlyCopyAssign>); // Also succeeds
+ * ```
+ *
+ * Note that without the declared copy assignment operator, the compiler may define an implicit move
+ * assignment operator.
+ *
+ * Additionally note that if the move assignment operator was declared as `= delete;`, then the second
+ * assertion in the above example would fail.
+ */
+private Operator getMoveAssign(Class c) {
+  if implicitMoveAssignmentSuppressed(c)
+  then result = c.getAMemberFunction().(CopyAssignmentOperator)
+  else result = c.getAMemberFunction().(MoveAssignmentOperator)
+}
+
+/**
+ * The types of special member functions that the `AnalyzableClass` tracks and analyzes.
+ */
+newtype TSpecialMember =
+  TMoveConstructor() or
+  TMoveAssignmentOperator() or
+  TCopyConstructor() or
+  TCopyAssignmentOperator() or
+  TDestructor()
+
+/**
+ * A class for which we can see all special member functions, including implicitly declared ones,
+ * and therefore we can attempt to analyze it in the current rule.
+ *
+ * If one of the special member functions cannot be found, we cannot know if it is missing because
+ * it should not have been generated, or if EDG did not emit a definition for it. For instance, EDG
+ * may not generate these functions if they are trivial, or if they are delete, or not ODR used. We,
+ * the authors of this project, do not know the exact conditions we have to consider in this case.
+ *
+ * Determining for ourselves whether a certain constructor would be implicitly declared, and with
+ * what signature, and whether it is deleted, requires implementing a significant portion of the C++
+ * language rules regarding special member function generation, including a significant portion of
+ * C++ overload resolution rules which are non-trivial.
+ *
+ * Therefore we must find a definition for each special member in the database to proceed. The only
+ * exception we allow is certain missing `MoveConstructor` or `MoveAssignmentOperator` members; if
+ * the class defines copy operations or the destructor, we expect these to be missing, and typically
+ * this means the corresponding copy operation acts in place of the equivalent move.
+ *
+ * The last difficulty in analysis that this class attempts to handle is the values of the type
+ * traits `std::is_(copy|move)_(constructible|assignable)`. These type traits are defined as true if
+ * certain C++ expressions, such as `T(declval<T>())` or `declval<T>() = declval<T>()`, are
+ * well-formed. We cannot correctly determine this in all cases without implementing a significant
+ * portion of the C++ language rules for reference binding and overload resolution.
+ *
+ * To handle these type traits, we take a very rough approximation. If the corresponding special
+ * member function is public and not deleted, then we assume the type trait will evaluate to true.
+ * We also handle the case where a user declared copy operation suppresses the implicit move
+ * operations, which typically means overload resolution selects the copy operation. (This is not
+ * the case when the move operations are declared as deleted). We handle this by treating the copy
+ * operation as effectively acting in place of the move operation for the purposes of evaluating
+ * the type traits.
+ */
+class AnalyzableClass extends Class {
+  CopyConstructor copyCtor;
+  // The move constructor may be suppressed, and the copy constructor may be used during moves.
+  Constructor moveCtor;
+  CopyAssignmentOperator copyAssign;
+  // The move assignment operator may be suppressed, and the copy assignment operator may be used during moves.
+  Operator moveAssign;
+  Destructor dtor;
+
+  AnalyzableClass() {
+    copyCtor = this.getAConstructor() and
+    moveCtor = getMoveConstructor(this) and
+    copyAssign = this.getAMemberFunction() and
+    moveAssign = getMoveAssign(this) and
+    dtor = this.getDestructor()
+  }
+
+  /**
+   * Holds `std::is_move_constructible_v<T>` is likely true for this class.
+   *
+   * Specifically this holds if there's a non-deleted public move constructor available for this
+   * class, or if there is a non-deleted public copy constructor that acts as the move constructor.
+   */
+  predicate moveConstructible() { isUsable(moveCtor) }
+
+  /**
+   * Holds `std::is_copy_constructible_v<T>` is likely true for this class.
+   *
+   * Specifically this holds if there's a non-deleted public copy constructor available for this
+   * class.
+   */
+  predicate copyConstructible() { isUsable(copyCtor) }
+
+  /**
+   * Holds `std::is_move_assignable_v<T>` is likely true for this class.
+   *
+   * Specifically this holds if there's a non-deleted public move assignment operator available for
+   * this class, or if there is a non-deleted public copy assignment operator that acts as the move
+   * assignment operator.
+   */
+  predicate moveAssignable() { isUsable(moveAssign) }
+
+  /**
+   * Holds `std::is_copy_assignable_v<T>` is likely true for this class.
+   *
+   * Specifically this holds if there's a non-deleted public copy assignment operator available for
+   * this class.
+   */
+  predicate copyAssignable() { isUsable(copyAssign) }
+
+  /**
+   * Holds if the given special member function `s` is customized for this class.
+   *
+   * For most cases, this checks that the given special member function `s` has a user-provided
+   * body (other than `= default;` or `= delete;`).
+   *
+   * If the class has copy operations that act in place of the move operations, that means the
+   * corresponding move operation was not declared, so we say this predicate does not hold for the
+   * given move operation `s`.
+   */
+  predicate isCustomized(TSpecialMember s) {
+    s instanceof TMoveConstructor and
+    isMemberCustomized(moveCtor) and
+    declaresMoveConstructor()
+    or
+    s instanceof TMoveAssignmentOperator and
+    isMemberCustomized(moveAssign) and
+    declaresMoveAssignmentOperator()
+    or
+    s instanceof TCopyConstructor and isMemberCustomized(copyCtor)
+    or
+    s instanceof TCopyAssignmentOperator and isMemberCustomized(copyAssign)
+    or
+    s instanceof TDestructor and isMemberCustomized(dtor)
+  }
+
+  /**
+   * Holds if this class declares a move constructor.
+   *
+   * This will be true if move constructor resolution found a non-implicit constructor that is not
+   * the copy constructor masquerading as a move constructor.
+   */
+  predicate declaresMoveConstructor() { not moveCtor = copyCtor and isUserDeclared(moveCtor) }
+
+  /**
+   * Holds if this class declares a move assignment operator.
+   *
+   * This will be true if move assignment resolution found a non-implicit operator that is not
+   * the copy assignment operator masquerading as a move assignment operator.
+   */
+  predicate declaresMoveAssignmentOperator() {
+    not moveAssign = copyAssign and isUserDeclared(moveAssign)
+  }
+}