Merge pull request #4562 from criemen/printast-labels

C++: Change PrintAST to provide the predicates that can be used to traverse the AST.

cpp/ql/src/semmle/code/cpp/PrintAST.qll

@@ -124,23 +124,38 @@ class PrintASTNode extends TPrintASTNode {
    * regular parent/child relation traversal.
    */
   final PrintASTNode getChild(int childIndex) {
-    result = getChildInternal(childIndex)
-    or
-    // We first compute the first available child index that is not used by
-    // `getChildInternal`, then we synthesize the child for fully converted
-    // expressions at `nextAvailableIndex` plus the childIndex of the non-converted
-    // expression. This ensures that both disjuncts are disjoint.
-    exists(int nonConvertedIndex, int nextAvailableIndex, Expr expr |
-      nextAvailableIndex = max(int idx | exists(this.getChildInternal(idx))) + 1 and
-      childIndex - nextAvailableIndex = nonConvertedIndex and
-      expr = getChildInternal(nonConvertedIndex).(ASTNode).getAST()
-    |
+    // The exact value of `childIndex` doesn't matter, as long as we preserve the correct order.
+    result =
+      rank[childIndex](PrintASTNode child, int nonConvertedIndex, boolean isConverted |
+        childAndAccessorPredicate(child, _, nonConvertedIndex, isConverted)
+      |
+        // Unconverted children come first, then sort by original child index within each group.
+        child order by isConverted, nonConvertedIndex
+      )
+  }
+
+  /**
+   * Gets the node for the `.getFullyConverted()` version of the child originally at index
+   * `childIndex`, if that node has any conversions.
+   */
+  private PrintASTNode getConvertedChild(int childIndex) {
+    exists(Expr expr |
+      expr = getChildInternal(childIndex).(ASTNode).getAST() and
       expr.getFullyConverted() instanceof Conversion and
       result.(ASTNode).getAST() = expr.getFullyConverted() and
       not expr instanceof Conversion
     )
   }
 
+  /**
+   * Gets the child access predicate for the `.getFullyConverted()` version of the child originally
+   * at index `childIndex`, if that node has any conversions.
+   */
+  private string getConvertedChildAccessorPredicate(int childIndex) {
+    exists(getConvertedChild(childIndex)) and
+    result = getChildAccessorPredicateInternal(childIndex) + ".getFullyConverted()"
+  }
+
   /**
    * Holds if this node should be printed in the output. By default, all nodes
    * within a function are printed, but the query can override
@@ -173,33 +188,46 @@ class PrintASTNode extends TPrintASTNode {
   }
 
   /**
-   * Gets the label for the edge from this node to the specified child. By
-   * default, this is just the index of the child, but subclasses can override
-   * this.
+   * Holds if there is a child node `child` for original child index `nonConvertedIndex` with
+   * predicate name `childPredicate`. If the original child at that index has any conversions, there
+   * will be two result tuples for this predicate: one with the original child and predicate, with
+   * `isConverted = false`, and the other with the `.getFullyConverted()` version of the child and
+   * predicate, with `isConverted = true`. For a child without any conversions, there will be only
+   * one result tuple, with `isConverted = false`.
    */
-  string getChildEdgeLabelInternal(int childIndex) {
-    exists(getChild(childIndex)) and
-    result = childIndex.toString()
+  private predicate childAndAccessorPredicate(
+    PrintASTNode child, string childPredicate, int nonConvertedIndex, boolean isConverted
+  ) {
+    child = getChildInternal(nonConvertedIndex) and
+    childPredicate = getChildAccessorPredicateInternal(nonConvertedIndex) and
+    isConverted = false
+    or
+    child = getConvertedChild(nonConvertedIndex) and
+    childPredicate = getConvertedChildAccessorPredicate(nonConvertedIndex) and
+    isConverted = true
   }
 
   /**
-   * Gets the label for the edge from this node to the specified child,
-   * including labels for edges to nodes that represent conversions.
+   * Gets the QL predicate that can be used to access the child at `childIndex`.
+   * May not always return a QL predicate, see for example `FunctionNode`.
    */
-  final string getChildEdgeLabel(int childIndex) {
-    exists(getChildInternal(childIndex)) and
-    result = getChildEdgeLabelInternal(childIndex)
-    or
-    not exists(getChildInternal(childIndex)) and
-    exists(getChild(childIndex)) and
-    exists(int nonConvertedIndex, int nextAvailableIndex |
-      nextAvailableIndex = max(int idx | exists(this.getChildInternal(idx))) + 1 and
-      childIndex - nextAvailableIndex = nonConvertedIndex
-    |
-      result = getChildEdgeLabelInternal(nonConvertedIndex) + " converted"
-    )
+  final string getChildAccessorPredicate(int childIndex) {
+    // The exact value of `childIndex` doesn't matter, as long as we preserve the correct order.
+    result =
+      rank[childIndex](string childPredicate, int nonConvertedIndex, boolean isConverted |
+        childAndAccessorPredicate(_, childPredicate, nonConvertedIndex, isConverted)
+      |
+        // Unconverted children come first, then sort by original child index within each group.
+        childPredicate order by isConverted, nonConvertedIndex
+      )
   }
 
+  /**
+   * Gets the QL predicate that can be used to access the child at `childIndex`.
+   * INTERNAL DO NOT USE: Does not contain accessors for the synthesized nodes for conversions.
+   */
+  abstract string getChildAccessorPredicateInternal(int childIndex);
+
   /**
    * Gets the `Function` that contains this node.
    */
@@ -261,6 +289,10 @@ class ExprNode extends ASTNode {
     result = expr.getValueCategoryString()
   }
 
+  override string getChildAccessorPredicateInternal(int childIndex) {
+    result = getChildAccessorWithoutConversions(ast, getChildInternal(childIndex).getAST())
+  }
+
   /**
    * Gets the value of this expression, if it is a constant.
    */
@@ -291,8 +323,6 @@ class ConversionNode extends ExprNode {
     result.getAST() = conv.getExpr() and
     conv.getExpr() instanceof Conversion
   }
-
-  override string getChildEdgeLabelInternal(int childIndex) { childIndex = 0 and result = "expr" }
 }
 
 /**
@@ -322,6 +352,8 @@ class DeclarationEntryNode extends BaseASTNode, TDeclarationEntryNode {
 
   override PrintASTNode getChildInternal(int childIndex) { none() }
 
+  override string getChildAccessorPredicateInternal(int childIndex) { none() }
+
   override string getProperty(string key) {
     result = BaseASTNode.super.getProperty(key)
     or
@@ -341,7 +373,10 @@ class VariableDeclarationEntryNode extends DeclarationEntryNode {
     result.getAST() = ast.getVariable().getInitializer()
   }
 
-  override string getChildEdgeLabelInternal(int childIndex) { childIndex = 0 and result = "init" }
+  override string getChildAccessorPredicateInternal(int childIndex) {
+    childIndex = 0 and
+    result = "getVariable().getInitializer()"
+  }
 }
 
 /**
@@ -361,6 +396,10 @@ class StmtNode extends ASTNode {
       )
     )
   }
+
+  override string getChildAccessorPredicateInternal(int childIndex) {
+    result = getChildAccessorWithoutConversions(ast, getChildInternal(childIndex).getAST())
+  }
 }
 
 /**
@@ -389,6 +428,8 @@ class ParameterNode extends ASTNode {
 
   final override PrintASTNode getChildInternal(int childIndex) { none() }
 
+  final override string getChildAccessorPredicateInternal(int childIndex) { none() }
+
   final override string getProperty(string key) {
     result = super.getProperty(key)
     or
@@ -410,9 +451,9 @@ class InitializerNode extends ASTNode {
     result.getAST() = init.getExpr()
   }
 
-  override string getChildEdgeLabelInternal(int childIndex) {
+  override string getChildAccessorPredicateInternal(int childIndex) {
     childIndex = 0 and
-    result = "expr"
+    result = "getExpr()"
   }
 }
 
@@ -432,6 +473,11 @@ class ParametersNode extends PrintASTNode, TParametersNode {
     result.getAST() = func.getParameter(childIndex)
   }
 
+  override string getChildAccessorPredicateInternal(int childIndex) {
+    exists(getChildInternal(childIndex)) and
+    result = "getParameter(" + childIndex.toString() + ")"
+  }
+
   /**
    * Gets the `Function` for which this node represents the parameters.
    */
@@ -454,6 +500,11 @@ class ConstructorInitializersNode extends PrintASTNode, TConstructorInitializers
     result.getAST() = ctor.getInitializer(childIndex)
   }
 
+  final override string getChildAccessorPredicateInternal(int childIndex) {
+    exists(getChildInternal(childIndex)) and
+    result = "getInitializer(" + childIndex.toString() + ")"
+  }
+
   /**
    * Gets the `Constructor` for which this node represents the initializer list.
    */
@@ -476,6 +527,11 @@ class DestructorDestructionsNode extends PrintASTNode, TDestructorDestructionsNo
     result.getAST() = dtor.getDestruction(childIndex)
   }
 
+  final override string getChildAccessorPredicateInternal(int childIndex) {
+    exists(getChildInternal(childIndex)) and
+    result = "getDestruction(" + childIndex.toString() + ")"
+  }
+
   /**
    * Gets the `Destructor` for which this node represents the destruction list.
    */
@@ -506,14 +562,14 @@ class FunctionNode extends ASTNode {
     result.(DestructorDestructionsNode).getDestructor() = func
   }
 
-  override string getChildEdgeLabelInternal(int childIndex) {
-    childIndex = 0 and result = "params"
+  override string getChildAccessorPredicateInternal(int childIndex) {
+    childIndex = 0 and result = "<params>"
     or
-    childIndex = 1 and result = "initializations"
+    childIndex = 1 and result = "<initializations>"
     or
-    childIndex = 2 and result = "body"
+    childIndex = 2 and result = "getEntryPoint()"
     or
-    childIndex = 3 and result = "destructions"
+    childIndex = 3 and result = "<destructions>"
   }
 
   private int getOrder() {
@@ -538,36 +594,237 @@ class FunctionNode extends ASTNode {
   final Function getFunction() { result = func }
 }
 
-/**
- * A node representing an `ClassAggregateLiteral`.
- */
-class ClassAggregateLiteralNode extends ExprNode {
-  ClassAggregateLiteral list;
-
-  ClassAggregateLiteralNode() { list = ast }
-
-  override string getChildEdgeLabelInternal(int childIndex) {
-    exists(Field field |
-      list.getFieldExpr(field) = list.getChild(childIndex) and
-      result = "." + field.getName()
+private string getChildAccessorWithoutConversions(Locatable parent, Element child) {
+  shouldPrintFunction(getEnclosingFunction(parent)) and
+  (
+    exists(Stmt s | s = parent |
+      namedStmtChildPredicates(s, child, result)
+      or
+      not namedStmtChildPredicates(s, child, _) and
+      exists(int n | s.getChild(n) = child and result = "getChild(" + n + ")")
     )
-  }
+    or
+    exists(Expr expr | expr = parent |
+      namedExprChildPredicates(expr, child, result)
+      or
+      not namedExprChildPredicates(expr, child, _) and
+      exists(int n | expr.getChild(n) = child and result = "getChild(" + n + ")")
+    )
+  )
 }
 
-/**
- * A node representing an `ArrayAggregateLiteral`.
- */
-class ArrayAggregateLiteralNode extends ExprNode {
-  ArrayAggregateLiteral list;
-
-  ArrayAggregateLiteralNode() { list = ast }
-
-  override string getChildEdgeLabelInternal(int childIndex) {
-    exists(int elementIndex |
-      list.getElementExpr(elementIndex) = list.getChild(childIndex) and
-      result = "[" + elementIndex.toString() + "]"
+private predicate namedStmtChildPredicates(Locatable s, Element e, string pred) {
+  shouldPrintFunction(getEnclosingFunction(s)) and
+  (
+    exists(int n | s.(BlockStmt).getStmt(n) = e and pred = "getStmt(" + n + ")")
+    or
+    s.(ComputedGotoStmt).getExpr() = e and pred = "getExpr()"
+    or
+    s.(ConstexprIfStmt).getCondition() = e and pred = "getCondition()"
+    or
+    s.(ConstexprIfStmt).getThen() = e and pred = "getThen()"
+    or
+    s.(ConstexprIfStmt).getElse() = e and pred = "getElse()"
+    or
+    s.(IfStmt).getCondition() = e and pred = "getCondition()"
+    or
+    s.(IfStmt).getThen() = e and pred = "getThen()"
+    or
+    s.(IfStmt).getElse() = e and pred = "getElse()"
+    or
+    s.(SwitchStmt).getExpr() = e and pred = "getExpr()"
+    or
+    s.(SwitchStmt).getStmt() = e and pred = "getStmt()"
+    or
+    s.(DoStmt).getCondition() = e and pred = "getCondition()"
+    or
+    s.(DoStmt).getStmt() = e and pred = "getStmt()"
+    or
+    s.(ForStmt).getInitialization() = e and pred = "getInitialization()"
+    or
+    s.(ForStmt).getCondition() = e and pred = "getCondition()"
+    or
+    s.(ForStmt).getUpdate() = e and pred = "getUpdate()"
+    or
+    s.(ForStmt).getStmt() = e and pred = "getStmt()"
+    or
+    s.(RangeBasedForStmt).getChild(0) = e and pred = "getChild(0)"
+    or
+    s.(RangeBasedForStmt).getBeginEndDeclaration() = e and pred = "getBeginEndDeclaration()"
+    or
+    s.(RangeBasedForStmt).getCondition() = e and pred = "getCondition()"
+    or
+    s.(RangeBasedForStmt).getUpdate() = e and pred = "getUpdate()"
+    or
+    s.(RangeBasedForStmt).getChild(4) = e and pred = "getChild(4)"
+    or
+    s.(RangeBasedForStmt).getStmt() = e and pred = "getStmt()"
+    or
+    s.(WhileStmt).getCondition() = e and pred = "getCondition()"
+    or
+    s.(WhileStmt).getStmt() = e and pred = "getStmt()"
+    or
+    exists(int n |
+      s.(DeclStmt).getDeclarationEntry(n) = e and pred = "getDeclarationEntry(" + n.toString() + ")"
     )
-  }
+    or
+    // EmptyStmt does not have children
+    s.(ExprStmt).getExpr() = e and pred = "getExpr()"
+    or
+    s.(Handler).getBlock() = e and pred = "getBlock()"
+    or
+    s.(JumpStmt).getTarget() = e and pred = "getTarget()"
+    or
+    s.(MicrosoftTryStmt).getStmt() = e and pred = "getStmt()"
+    or
+    s.(MicrosoftTryExceptStmt).getCondition() = e and pred = "getCondition()"
+    or
+    s.(MicrosoftTryExceptStmt).getExcept() = e and pred = "getExcept()"
+    or
+    s.(MicrosoftTryFinallyStmt).getFinally() = e and pred = "getFinally()"
+    or
+    s.(ReturnStmt).getExpr() = e and pred = "getExpr()"
+    or
+    s.(SwitchCase).getExpr() = e and pred = "getExpr()"
+    or
+    s.(SwitchCase).getEndExpr() = e and pred = "getEndExpr()"
+    or
+    s.(TryStmt).getStmt() = e and pred = "getStmt()"
+    or
+    s.(VlaDimensionStmt).getDimensionExpr() = e and pred = "getDimensionExpr()"
+  )
+}
+
+private predicate namedExprChildPredicates(Expr expr, Element ele, string pred) {
+  shouldPrintFunction(expr.getEnclosingFunction()) and
+  (
+    expr.(Access).getTarget() = ele and pred = "getTarget()"
+    or
+    expr.(VariableAccess).getQualifier() = ele and pred = "getQualifier()"
+    or
+    exists(Field f |
+      expr.(ClassAggregateLiteral).getFieldExpr(f) = ele and
+      pred = "getFieldExpr(" + f.toString() + ")"
+    )
+    or
+    exists(int n |
+      expr.(ArrayOrVectorAggregateLiteral).getElementExpr(n) = ele and
+      pred = "getElementExpr(" + n.toString() + ")"
+    )
+    or
+    expr.(AlignofExprOperator).getExprOperand() = ele and pred = "getExprOperand()"
+    or
+    expr.(ArrayExpr).getArrayBase() = ele and pred = "getArrayBase()"
+    or
+    expr.(ArrayExpr).getArrayOffset() = ele and pred = "getArrayOffset()"
+    or
+    expr.(AssumeExpr).getOperand() = ele and pred = "getOperand()"
+    or
+    expr.(BuiltInComplexOperation).getRealOperand() = ele and pred = "getRealOperand()"
+    or
+    expr.(BuiltInComplexOperation).getImaginaryOperand() = ele and pred = "getImaginaryOperand()"
+    or
+    expr.(BuiltInVarArg).getVAList() = ele and pred = "getVAList()"
+    or
+    expr.(BuiltInVarArgCopy).getDestinationVAList() = ele and pred = "getDestinationVAList()"
+    or
+    expr.(BuiltInVarArgCopy).getSourceVAList() = ele and pred = "getSourceVAList()"
+    or
+    expr.(BuiltInVarArgsEnd).getVAList() = ele and pred = "getVAList()"
+    or
+    expr.(BuiltInVarArgsStart).getVAList() = ele and pred = "getVAList()"
+    or
+    expr.(BuiltInVarArgsStart).getLastNamedParameter() = ele and pred = "getLastNamedParameter()"
+    or
+    expr.(Call).getQualifier() = ele and pred = "getQualifier()"
+    or
+    exists(int n | expr.(Call).getArgument(n) = ele and pred = "getArgument(" + n.toString() + ")")
+    or
+    expr.(ExprCall).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(OverloadedArrayExpr).getArrayBase() = ele and pred = "getArrayBase()"
+    or
+    expr.(OverloadedArrayExpr).getArrayOffset() = ele and pred = "getArrayOffset()"
+    or
+    expr.(OverloadedPointerDereferenceExpr).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(CommaExpr).getLeftOperand() = ele and pred = "getLeftOperand()"
+    or
+    expr.(CommaExpr).getRightOperand() = ele and pred = "getRightOperand()"
+    or
+    expr.(ConditionDeclExpr).getVariableAccess() = ele and pred = "getVariableAccess()"
+    or
+    expr.(ConstructorFieldInit).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(Conversion).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(DeleteArrayExpr).getAllocatorCall() = ele and pred = "getAllocatorCall()"
+    or
+    expr.(DeleteArrayExpr).getDestructorCall() = ele and pred = "getDestructorCall()"
+    or
+    expr.(DeleteArrayExpr).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(DeleteExpr).getAllocatorCall() = ele and pred = "getAllocatorCall()"
+    or
+    expr.(DeleteExpr).getDestructorCall() = ele and pred = "getDestructorCall()"
+    or
+    expr.(DeleteExpr).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(DestructorFieldDestruction).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(FoldExpr).getInitExpr() = ele and pred = "getInitExpr()"
+    or
+    expr.(FoldExpr).getPackExpr() = ele and pred = "getPackExpr()"
+    or
+    expr.(LambdaExpression).getInitializer() = ele and pred = "getInitializer()"
+    or
+    expr.(NewOrNewArrayExpr).getAllocatorCall() = ele and pred = "getAllocatorCall()"
+    or
+    expr.(NewOrNewArrayExpr).getAlignmentArgument() = ele and pred = "getAlignmentArgument()"
+    or
+    expr.(NewArrayExpr).getInitializer() = ele and pred = "getInitializer()"
+    or
+    expr.(NewArrayExpr).getExtent() = ele and pred = "getExtent()"
+    or
+    expr.(NewExpr).getInitializer() = ele and pred = "getInitializer()"
+    or
+    expr.(NoExceptExpr).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(Assignment).getLValue() = ele and pred = "getLValue()"
+    or
+    expr.(Assignment).getRValue() = ele and pred = "getRValue()"
+    or
+    not expr instanceof RelationalOperation and
+    expr.(BinaryOperation).getLeftOperand() = ele and
+    pred = "getLeftOperand()"
+    or
+    not expr instanceof RelationalOperation and
+    expr.(BinaryOperation).getRightOperand() = ele and
+    pred = "getRightOperand()"
+    or
+    expr.(RelationalOperation).getGreaterOperand() = ele and pred = "getGreaterOperand()"
+    or
+    expr.(RelationalOperation).getLesserOperand() = ele and pred = "getLesserOperand()"
+    or
+    expr.(ConditionalExpr).getCondition() = ele and pred = "getCondition()"
+    or
+    // If ConditionalExpr is in two-operand form, getThen() = getCondition() holds
+    not expr.(ConditionalExpr).isTwoOperand() and
+    expr.(ConditionalExpr).getThen() = ele and
+    pred = "getThen()"
+    or
+    expr.(ConditionalExpr).getElse() = ele and pred = "getElse()"
+    or
+    expr.(UnaryOperation).getOperand() = ele and pred = "getOperand()"
+    or
+    expr.(SizeofExprOperator).getExprOperand() = ele and pred = "getExprOperand()"
+    or
+    expr.(StmtExpr).getStmt() = ele and pred = "getStmt()"
+    or
+    expr.(ThrowExpr).getExpr() = ele and pred = "getExpr()"
+    or
+    expr.(TypeidOperator).getExpr() = ele and pred = "getExpr()"
+  )
 }
 
 /** Holds if `node` belongs to the output tree, and its property `key` has the given `value`. */
@@ -586,7 +843,7 @@ query predicate edges(PrintASTNode source, PrintASTNode target, string key, stri
     target.shouldPrint() and
     target = source.getChild(childIndex) and
     (
-      key = "semmle.label" and value = source.getChildEdgeLabel(childIndex)
+      key = "semmle.label" and value = source.getChildAccessorPredicate(childIndex)
       or
       key = "semmle.order" and value = childIndex.toString()
     )