C++: Add support for requires clauses and constraints on template parameters

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

@@ -715,6 +715,27 @@ class FunctionDeclarationEntry extends DeclarationEntry, @fun_decl {
    * specification.
    */
   predicate isNoExcept() { fun_decl_empty_noexcept(underlyingElement(this)) }
+
+  /**
+   * Gets a requires clause if this declaration is a template with such a clause.
+   */
+  Expr getARequiresClause() { fun_requires(underlyingElement(this), _, unresolveElement(result)) }
+
+  /**
+   * Gets the requires clause that appears after the template argument list if this
+   * declaration is a template with such a clause.
+   */
+  Expr getTemplateRequiresClause() {
+    fun_requires(underlyingElement(this), 1, unresolveElement(result))
+  }
+
+  /**
+   * Gets the requires clause that appears after the declarator if this declaration
+   * is a template with such a clause.
+   */
+  Expr getFunctionRequiresClause() {
+    fun_requires(underlyingElement(this), 2, unresolveElement(result))
+  }
 }
 
 /**

cpp/ql/lib/semmle/code/cpp/TemplateParameter.qll

@@ -59,6 +59,13 @@ class TypeTemplateParameter extends UserType, TemplateParameterImpl {
   override string getAPrimaryQlClass() { result = "TypeTemplateParameter" }
 
   override predicate involvesTemplateParameter() { any() }
+
+  /**
+   * Get the type constraint of this type template parameter.
+   */
+  Expr getTypeConstraint() {
+    type_template_type_constraint(underlyingElement(this), unresolveElement(result))
+  }
 }
 
 /**

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

@@ -129,4 +129,9 @@ class TypeDeclarationEntry extends DeclarationEntry, @type_decl {
    * class or typedef.
    */
   predicate isTopLevel() { type_decl_top(underlyingElement(this)) }
+
+  /**
+   * Gets the requires clause if this declaration is a template with such a clause.
+   */
+  Expr getRequiresClause() { type_requires(underlyingElement(this), unresolveElement(result)) }
 }

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

@@ -278,6 +278,11 @@ class VariableDeclarationEntry extends DeclarationEntry, @var_decl {
 
   /** Holds if this declaration is a template specialization. */
   predicate isSpecialization() { var_specialized(underlyingElement(this)) }
+
+  /**
+   * Gets the requires clause if this declaration is a template with such a clause.
+   */
+  Expr getRequiresClause() { var_requires(underlyingElement(this), unresolveElement(result)) }
 }
 
 /**