C++: Take QualifiedName.qll from Ian's branch

This imports `QualifiedName.qll` from
2f74a456290b9e0850b7308582e07f5d68de3a36 and makes minimal changes so it
compiles.

Original author: Ian Lynagh <ian@semmle.com>

cpp/ql/src/semmle/code/cpp/internal/QualifiedName.qll

@@ -0,0 +1,203 @@
+private import semmle.code.cpp.internal.ResolveClass as ResolveClass
+
+class Namespace extends @namespace {
+  string toString() { result = "QualifiedName Namespace" }
+
+  string getName() { namespaces(this, result) }
+
+  string getQualifiedName() {
+    if namespacembrs(_, this)
+    then exists(Namespace ns |
+                namespacembrs(ns, this) and
+                result = ns.getQualifiedName() + "::" + this.getName())
+    else result = this.getName()
+  }
+
+  Declaration getADeclaration() {
+    if this.getName() = ""
+    then result.isTopLevel() and not namespacembrs(_, result)
+    else namespacembrs(this, result)
+  }
+}
+
+abstract class Declaration extends @declaration {
+  string toString() { result = "QualifiedName Declaration" }
+
+  /** Gets the name of this declaration. */
+  abstract string getName();
+
+  // Note: This is not as full featured as the getNamespace in the AST,
+  // but it covers the cases we need here.
+  Namespace getNamespace() {
+    // Top level declaration in a namespace ...
+    result.getADeclaration() = this
+    // ... or nested in another structure.
+    or
+    exists (Declaration m
+    | m = this and result = m.getDeclaringType().getNamespace())
+  }
+
+  string getQualifiedName() {
+    // MemberFunction, MemberVariable, MemberType
+    exists (Declaration m
+    | m = this and
+      result = m.getDeclaringType().getQualifiedName() + "::" + m.getName())
+    or
+    exists (EnumConstant c
+    | c = this and
+      result = c.getDeclaringEnum().getQualifiedName() + "::" + c.getName())
+    or
+    exists (GlobalOrNamespaceVariable v, string s1, string s2
+    | v = this and
+      s2 = v.getNamespace().getQualifiedName() and
+      s1 = v.getName()
+    | (s2 != "" and result = s2 + "::" + s1) or (s2 = "" and result = s1))
+    or
+    exists (Function f, string s1, string s2
+    | f = this and f.isTopLevel() and
+      s2 = f.getNamespace().getQualifiedName() and
+      s1 = f.getName()
+    | (s2 != "" and result = s2 + "::" + s1) or (s2 = "" and result = s1))
+    or
+    exists (UserType t, string s1, string s2
+    | t = this and t.isTopLevel() and
+      s2 = t.getNamespace().getQualifiedName() and
+      s1 = t.getName()
+    | (s2 != "" and result = s2 + "::" + s1) or (s2 = "" and result = s1))
+  }
+
+  predicate isTopLevel() {
+    not (this.isMember() or
+         this instanceof FriendDecl or
+         this instanceof EnumConstant or
+         this instanceof Parameter or
+         this instanceof ProxyClass or
+         this instanceof LocalVariable or
+         this instanceof TemplateParameter or
+         this.(UserType).isLocal())
+  }
+
+  /** Holds if this declaration is a member of a class/struct/union. */
+  predicate isMember() { this.hasDeclaringType() }
+
+  /** Holds if this declaration is a member of a class/struct/union. */
+  predicate hasDeclaringType() {
+    exists(this.getDeclaringType())
+  }
+
+  /**
+   * Gets the class where this member is declared, if it is a member.
+   * For templates, both the template itself and all instantiations of
+   * the template are considered to have the same declaring class.
+   */
+  Class getDeclaringType() {
+    this = result.getAMember()
+  }
+}
+
+class Variable extends Declaration, @variable {
+  override string getName() { none() }
+}
+
+class TemplateVariable extends Variable {
+  TemplateVariable() { is_variable_template(this) }
+
+  Variable getAnInstantiation() { variable_instantiation(result, this) }
+}
+
+class LocalScopeVariable extends Variable, @localscopevariable {}
+
+class LocalVariable extends LocalScopeVariable, @localvariable {
+  override string getName() { localvariables(this, _, result) }
+}
+
+class Parameter extends LocalScopeVariable, @parameter {
+  override string getName() {
+    exists(int i | params(this, _, i, _) and result = "p#" + i.toString())
+  }
+}
+
+class GlobalOrNamespaceVariable extends Variable, @globalvariable {
+  override string getName() { globalvariables(this, _, result) }
+}
+
+class MemberVariable extends Variable, @membervariable {
+  MemberVariable() {
+    this.isMember()
+  }
+
+  override string getName() { membervariables(this, _, result) }
+}
+
+class EnumConstant extends Declaration, @enumconstant {
+  override string getName() { enumconstants(this, _, _, _, result,_) }
+
+  UserType getDeclaringEnum() { enumconstants(this, result, _, _, _, _) }
+}
+
+class Function extends Declaration, @function {
+  override string getName() { functions(this, result, _) }
+}
+
+class TemplateFunction extends Function {
+  TemplateFunction() {
+    is_function_template(this) and function_template_argument(this, _, _)
+  }
+
+  Function getAnInstantiation() {
+    function_instantiation(result, this)
+    and not exists(@fun_decl fd |
+              fun_decls(fd, this, _, _, _) and fun_specialized(fd))
+  }
+}
+
+class UserType extends Declaration, @usertype {
+  override string getName() { usertypes(this, result, _) }
+
+  predicate isLocal() {
+    enclosingfunction(this, _)
+  }
+}
+
+class ProxyClass extends UserType {
+  ProxyClass() { usertypes(this, _, 9) }
+}
+
+class TemplateParameter extends UserType {
+  TemplateParameter() { usertypes(this, _, 7) or usertypes(this, _, 8) }
+}
+
+class Class extends UserType {
+  Class() { ResolveClass::isClass(this) }
+
+  Declaration getAMember() {
+    exists(Declaration d | member(this, _ ,d) |
+      result = d or
+      result = d.(TemplateClass).getAnInstantiation() or
+      result = d.(TemplateFunction).getAnInstantiation() or
+      result = d.(TemplateVariable).getAnInstantiation())
+  }
+}
+
+class TemplateClass extends Class {
+  TemplateClass() { usertypes(this, _, 6) }
+
+  Class getAnInstantiation() {
+    class_instantiation(result, this) and
+    class_template_argument(result, _, _)
+  }
+}
+
+deprecated class Property extends Declaration {
+  Property() { none() }
+
+  override string getName() { none() }
+}
+
+class FriendDecl extends Declaration, @frienddecl {
+  override string getName() {
+    result = this.getDeclaringClass().getName() + "'s friend"
+  }
+
+  Class getDeclaringClass() { frienddecls(this, result, _, _) }
+}