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unified: Add local name binding and tests
As documented in the test, 'guard if' statements are still not properly supported.
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‎unified/ql/lib/codeql/unified/internal/Variables.qll‎

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/**
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* Provides classes for reasoning about lexically scoped variables and references to these.
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*/
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private import unified
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private import unified as U
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private import codeql.namebinding.LocalNameBinding
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private module LocalNameBindingInput implements LocalNameBindingInputSig<Location> {
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class AstNode = U::AstNode;
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private class LogicalAndRoot extends LogicalAndExpr {
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LogicalAndRoot() { not this = any(LogicalAndExpr e).getAnOperand() }
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private Expr getDescendent(string path) {
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path = "" and result = this
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or
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exists(LogicalAndExpr mid, string midPath | mid = this.getDescendent(midPath) |
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result = mid.getLeft() and path = midPath + "A"
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or
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result = mid.getRight() and path = midPath + "B"
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)
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}
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Expr getNthLeaf(int n) {
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result =
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rank[n](Expr e, string path |
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e = this.getDescendent(path) and not e instanceof LogicalAndExpr
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|
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e order by path
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)
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}
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Expr getLastLeaf() { result = max(int n | | this.getNthLeaf(n) order by n) }
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}
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private AstNode getChild1(AstNode n, int index) {
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result = n.(Block).getStmt(index)
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or
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result = n.(LogicalAndRoot).getNthLeaf(index)
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or
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exists(PatternGuardExpr guard | n = guard |
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index = 0 and result = guard.getPattern()
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or
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index = 1 and result = guard.getValue()
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)
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or
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exists(IfExpr expr | n = expr |
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index = 0 and result = expr.getCondition()
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or
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index = 1 and result = expr.getThen()
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or
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index = 2 and result = expr.getElse()
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)
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or
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exists(VariableDeclaration decl | n = decl |
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index = 0 and result = decl.getPattern()
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or
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index = 1 and result = decl.getType()
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or
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index = 2 and result = decl.getValue()
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)
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}
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AstNode getChild(AstNode n, int index) {
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result = getChild1(n, index)
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or
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not exists(getChild1(n, _)) and
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not n instanceof LogicalAndExpr and // also ignore intermediate nodes within a 'logical and' tree
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index = 0 and
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result = n.getAFieldOrChild()
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}
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abstract class Conditional extends AstNode {
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/** Gets the condition of this conditional. */
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abstract AstNode getCondition();
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/** Gets the then-branch of this conditional. */
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abstract AstNode getThen();
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/** Gets the else-branch of this conditional. */
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abstract AstNode getElse();
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}
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private class IfExprConditional extends Conditional instanceof IfExpr {
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override AstNode getCondition() { result = IfExpr.super.getCondition() }
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override AstNode getThen() { result = IfExpr.super.getThen() }
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override AstNode getElse() { result = IfExpr.super.getElse() }
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}
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abstract class SiblingShadowingDecl extends AstNode {
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/** Gets the left-hand side of this declaration. */
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abstract AstNode getLhs();
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/**
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* Gets the right-hand side of this declaration.
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*
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* Any local declared in the left-hand side of this declaration is _not_ in scope
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* in the right-hand side.
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*/
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abstract AstNode getRhs();
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/**
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* Gets the else-branch of this declaration, if any.
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*
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* Any local declared in the left-hand side of this declaration is _not_ in scope
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* in the else-branch.
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*/
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abstract AstNode getElse();
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}
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private class LocalVariableDeclarationSiblingShadowingDecl extends SiblingShadowingDecl instanceof LocalVariableDeclaration
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{
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override AstNode getLhs() { result = LocalVariableDeclaration.super.getPattern() }
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override AstNode getRhs() { result = LocalVariableDeclaration.super.getValue() }
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override AstNode getElse() { none() }
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}
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private class PatternGuardExprSiblingShadowingDecl extends SiblingShadowingDecl instanceof PatternGuardExpr
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{
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override AstNode getLhs() { result = PatternGuardExpr.super.getPattern() }
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override AstNode getRhs() { result = PatternGuardExpr.super.getValue() }
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override AstNode getElse() { none() }
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}
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private class GuardIfStmtSiblingShadowingDecl extends SiblingShadowingDecl instanceof GuardIfStmt {
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override AstNode getLhs() { result = GuardIfStmt.super.getCondition() }
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override AstNode getRhs() { none() }
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override AstNode getElse() { result = GuardIfStmt.super.getElse() }
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}
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private predicate bindingContext(AstNode pattern, AstNode scope) {
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exists(LocalVariableDeclaration decl |
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scope = decl and // LocalVariableDeclaration is a ShadowingSiblingDecl, it must use itself as the scope
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pattern = decl.getPattern()
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)
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or
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exists(LocalFunctionDeclaration func |
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scope = func.getDeclaringBlock() and
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pattern = func.getName()
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)
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or
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exists(Parameter param |
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scope = param.getParent() and // TODO: add SourceCallable and use .getParameter() instead
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pattern = param.getPattern()
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)
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or
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exists(CatchClause catch |
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scope = catch and // ensure both 'body' and 'guard' clause are in scope
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pattern = catch.getPattern()
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)
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or
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exists(SwitchCase case |
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scope = case and // ensure both 'body' and 'guard' clause are in scope (TODO: merge CatchClause and SwitchCase?)
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pattern = case.getPattern()
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)
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or
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exists(ForEachStmt stmt |
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scope = stmt and // ensure both 'body' and 'guard' are in scope
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pattern = stmt.getPattern()
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)
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or
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exists(TuplePattern pat |
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bindingContext(pat, scope) and
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pattern = pat.getElement(_).getPattern()
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)
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or
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exists(ConstructorPattern pat |
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bindingContext(pat, scope) and
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pattern = pat.getElement(_).getPattern()
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)
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or
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exists(OrPattern pat |
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bindingContext(pat, scope) and
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pattern = pat.getPattern(_)
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)
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or
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exists(PatternGuardExpr expr |
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pattern = expr.getPattern() and
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scope = expr
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)
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}
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predicate declInScope(AstNode definingNode, string name, AstNode scope) {
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bindingContext(definingNode, scope) and
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(
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definingNode.(NamePattern).getIdentifier().getValue() = name
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or
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definingNode.(Identifier).getValue() = name
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)
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}
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predicate implicitDeclInScope(string name, AstNode scope) {
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none()
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// TODO: self
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}
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predicate accessCand(AstNode n, string name) {
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n.(NameExpr).getIdentifier().getValue() = name
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or
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n.(NamePattern).getIdentifier().getValue() = name
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or
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n = any(LocalFunctionDeclaration f).getName() and
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n.(Identifier).getValue() = name
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}
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predicate lookupStartsAt(AstNode n, AstNode scope) { none() }
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}
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module LocalNameBindingOutput = LocalNameBinding<Location, LocalNameBindingInput>;
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module Public {
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/**
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* A local variable.
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*/
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class Variable extends LocalNameBindingOutput::Local {
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VariableAccess getAnAccess() { result.getVariable() = this }
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}
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/**
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* An AST node that is a reference to a local variable.
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*/
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class VariableAccess extends AstNode instanceof LocalNameBindingOutput::LocalAccess {
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Variable getVariable() { result = super.getLocal() }
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Identifier getIdentifier() {
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result = this.(NameExpr).getIdentifier()
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or
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result = this.(NamePattern).getIdentifier()
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or
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result = this
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}
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string getName() { result = this.getIdentifier().getValue() }
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}
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}

‎unified/ql/lib/qlpack.yml‎

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@@ -7,5 +7,6 @@ library: true
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upgrades: upgrades
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dependencies:
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codeql/util: ${workspace}
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codeql/namebinding: ${workspace}
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warnOnImplicitThis: true
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compileForOverlayEval: true

‎unified/ql/lib/unified.qll‎

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@@ -6,3 +6,4 @@ import codeql.Locations
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import codeql.files.FileSystem
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import codeql.unified.Ast::Unified
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import codeql.unified.internal.AstExtra::Public
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import codeql.unified.internal.Variables::Public

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