C++: Revert the getName() changes

This reverts the `getName()` parts of 56e88cbac0 and 0a2e28858a.

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

@@ -116,7 +116,7 @@ abstract class Declaration extends Locatable, @declaration {
    * To test whether this declaration has a particular name in the global
    * namespace, use `hasGlobalName`.
    */
-  string getName() { result = underlyingElement(this).(Q::Declaration).getName() }
+  abstract string getName();
 
   /** Holds if this declaration has the given name. */
   predicate hasName(string name) { name = this.getName() }

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

@@ -100,6 +100,11 @@ class EnumConstant extends Declaration, @enumconstant {
     result = this.getDeclaringEnum().getDeclaringType()
   }
 
+  /**
+   * Gets the name of this enumerator.
+   */
+  override string getName() { enumconstants(underlyingElement(this),_,_,_,result,_) }
+
   /**
    * Gets the value that this enumerator is initialized to, as a
    * string. This can be a value explicitly given to the enumerator, or an

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

@@ -35,6 +35,11 @@ class FriendDecl extends Declaration, @frienddecl {
   /** Gets the location of this friend declaration. */
   override Location getLocation() { frienddecls(underlyingElement(this),_,_,result) }
 
+  /** Gets a descriptive string for this friend declaration. */
+  override string getName() {
+    result = this.getDeclaringClass().getName() + "'s friend"
+  }
+
   /**
    * Friend declarations do not have specifiers. It makes no difference
    * whether they are declared in a public, protected or private section of

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

@@ -17,6 +17,8 @@ private import semmle.code.cpp.internal.ResolveClass
  * in more detail in `Declaration.qll`.
  */
 class Function extends Declaration, ControlFlowNode, AccessHolder, @function {
+  override string getName() { functions(underlyingElement(this),result,_) }
+
   /**
    * DEPRECATED: Use `getIdentityString(Declaration)` from `semmle.code.cpp.Print` instead.
    * Gets the full signature of this function, including return type, parameter

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

@@ -148,6 +148,9 @@ deprecated class FinallyBlock extends Block {
 deprecated class Property extends Declaration {
   Property() { none() }
 
+  /** Gets the name of this property. */
+  override string getName() { none() }
+
   /**
    * Gets nothing (provided for compatibility with Declaration).
    *

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

@@ -1,7 +1,6 @@
 import semmle.code.cpp.Location
 import semmle.code.cpp.Declaration
 private import semmle.code.cpp.internal.ResolveClass
-private import semmle.code.cpp.internal.QualifiedName as Q
 
 /**
  * A C/C++ function parameter or catch block parameter.
@@ -14,6 +13,26 @@ private import semmle.code.cpp.internal.QualifiedName as Q
  * have multiple declarations.
  */
 class Parameter extends LocalScopeVariable, @parameter {
+
+  /**
+   * Gets the canonical name, or names, of this parameter.
+   *
+   * The canonical names are the first non-empty category from the
+   * following list:
+   *  1. The name given to the parameter at the function's definition or
+   *     (for catch block parameters) at the catch block.
+   *  2. A name given to the parameter at a function declaration.
+   *  3. The name "p#i" where i is the index of the parameter.
+   */
+  override string getName() {
+    exists (VariableDeclarationEntry vde
+    | vde = getANamedDeclarationEntry() and result = vde.getName()
+    | vde.isDefinition() or not getANamedDeclarationEntry().isDefinition())
+    or
+    (not exists(getANamedDeclarationEntry()) and
+     result = "p#" + this.getIndex().toString())
+  }
+
   /**
    * Gets the name of this parameter, including it's type.
    *
@@ -34,6 +53,27 @@ class Parameter extends LocalScopeVariable, @parameter {
          else result = typeString + nameString))
   }
 
+  private VariableDeclarationEntry getANamedDeclarationEntry() {
+    result = getAnEffectiveDeclarationEntry() and result.getName() != ""
+  }
+
+  /**
+   * Gets a declaration entry corresponding to this declaration.
+   *
+   * This predicate is the same as getADeclarationEntry(), except that for
+   * parameters of instantiated function templates, gives the declaration
+   * entry of the prototype instantiation of the parameter (as
+   * non-prototype instantiations don't have declaration entries of their
+   * own).
+   */
+  private VariableDeclarationEntry getAnEffectiveDeclarationEntry() {
+    if getFunction().isConstructedFrom(_)
+      then exists (Function prototypeInstantiation
+           | prototypeInstantiation.getParameter(getIndex()) = result.getVariable() and
+             getFunction().isConstructedFrom(prototypeInstantiation))
+      else result = getADeclarationEntry()
+  }
+
   /**
    * Gets the name of this parameter in the given block (which should be
    * the body of a function with which the parameter is associated).
@@ -55,9 +95,7 @@ class Parameter extends LocalScopeVariable, @parameter {
    * In other words, this predicate holds precisely when the result of
    * `getName()` is not "p#i" (where `i` is the index of the parameter).
    */
-  predicate isNamed() {
+  predicate isNamed() { exists(getANamedDeclarationEntry()) }
-    exists(underlyingElement(this).(Q::Parameter).getANamedDeclarationEntry())
-  }
 
   /**
    * Gets the function to which this parameter belongs, if it is a function
@@ -97,13 +135,8 @@ class Parameter extends LocalScopeVariable, @parameter {
    *    of the declaration locations.
    */
   override Location getLocation() {
-    exists(VariableDeclarationEntry vde |
+    exists(VariableDeclarationEntry vde | vde = getAnEffectiveDeclarationEntry() and result = vde.getLocation() |
-      vde = underlyingElement(this).(Q::Parameter).getAnEffectiveDeclarationEntry() and
+      vde.isDefinition() or not getAnEffectiveDeclarationEntry().isDefinition()
-      result = vde.getLocation()
-    |
-      vde.isDefinition()
-      or
-      not underlyingElement(this).(Q::Parameter).getAnEffectiveDeclarationEntry().isDefinition()
     )
   }
 }

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

@@ -9,9 +9,10 @@ private import semmle.code.cpp.internal.ResolveClass
  * `Enum`, and `TypedefType`.
  */
 class UserType extends Type, Declaration, NameQualifyingElement, AccessHolder, @usertype {
-  override string getName() {
+  /**
-    result = Declaration.super.getName()
+   * Gets the name of this type.
-  }
+   */
+  override string getName() { usertypes(underlyingElement(this),result,_) }
 
   /**
    * Gets the simple name of this type, without any template parameters.  For example

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

@@ -41,6 +41,9 @@ class Variable extends Declaration, @variable {
   /** Holds if this variable is `volatile`. */
   predicate isVolatile() { this.getType().isVolatile() }
 
+  /** Gets the name of this variable. */
+  override string getName() { none() }
+
   /** Gets the type of this variable. */
   Type getType() { none() }
 
@@ -294,6 +297,8 @@ deprecated class StackVariable extends Variable {
  * A local variable can be declared by a `DeclStmt` or a `ConditionDeclExpr`.
  */
 class LocalVariable extends LocalScopeVariable, @localvariable {
+  override string getName() { localvariables(underlyingElement(this),_,result) }
+
   override Type getType() { localvariables(underlyingElement(this),unresolveElement(result),_) }
 
   override Function getFunction() {
@@ -306,6 +311,8 @@ class LocalVariable extends LocalScopeVariable, @localvariable {
  * A C/C++ variable which has global scope or namespace scope.
  */
 class GlobalOrNamespaceVariable extends Variable, @globalvariable {
+  override string getName() { globalvariables(underlyingElement(this),_,result) }
+
   override Type getType() { globalvariables(underlyingElement(this),unresolveElement(result),_) }
 
   override Element getEnclosingElement() { none() }
@@ -353,6 +360,8 @@ class MemberVariable extends Variable, @membervariable {
   /** Holds if this member is public. */
   predicate isPublic() { this.hasSpecifier("public") }
 
+  override string getName() { membervariables(underlyingElement(this),_,result) }
+
   override Type getType() {
     if (strictcount(this.getAType()) = 1) then (
        result = this.getAType()