Bug 1729329 - Mark PathExpr::addExpr as infallible. r=farre

Differential Revision: https://phabricator.services.mozilla.com/D124663

dom/xslt/xpath/txExpr.h

@@ -700,9 +700,8 @@ class PathExpr : public Expr {
    * The ownership of the given Expr is passed over the PathExpr,
    * even on failure.
    * @param aExpr the Expr to add to this PathExpr
-   * @return nsresult indicating out of memory
    */
-  nsresult addExpr(Expr* aExpr, PathOperator pathOp);
+  void addExpr(Expr* aExpr, PathOperator pathOp);
 
   /**
    * Removes and deletes the expression at the given index.

dom/xslt/xpath/txExprParser.cpp

@@ -644,11 +644,7 @@ nsresult txExprParser::createPathExpr(txExprLexer& lexer,
 
   // We have a PathExpr containing several steps
   UniquePtr<PathExpr> pathExpr(new PathExpr());
-
-  rv = pathExpr->addExpr(expr.get(), PathExpr::RELATIVE_OP);
-  NS_ENSURE_SUCCESS(rv, rv);
-
-  Unused << expr.release();
+  pathExpr->addExpr(expr.release(), PathExpr::RELATIVE_OP);
 
   // this is ugly
   while (1) {
@@ -669,10 +665,7 @@ nsresult txExprParser::createPathExpr(txExprLexer& lexer,
     rv = createLocationStep(lexer, aContext, getter_Transfers(expr));
     NS_ENSURE_SUCCESS(rv, rv);
 
-    rv = pathExpr->addExpr(expr.get(), pathOp);
-    NS_ENSURE_SUCCESS(rv, rv);
-
-    Unused << expr.release();
+    pathExpr->addExpr(expr.release(), pathOp);
   }
   MOZ_ASSERT_UNREACHABLE("internal xpath parser error");
   return NS_ERROR_UNEXPECTED;

dom/xslt/xpath/txPathExpr.cpp

@@ -21,14 +21,12 @@ using mozilla::WrapUnique;
  * Adds the Expr to this PathExpr
  * @param expr the Expr to add to this PathExpr
  **/
-nsresult PathExpr::addExpr(Expr* aExpr, PathOperator aPathOp) {
+void PathExpr::addExpr(Expr* aExpr, PathOperator aPathOp) {
   NS_ASSERTION(!mItems.IsEmpty() || aPathOp == RELATIVE_OP,
                "First step has to be relative in PathExpr");
   PathExprItem* pxi = mItems.AppendElement();
   pxi->expr = WrapUnique(aExpr);
   pxi->pathOp = aPathOp;
-
-  return NS_OK;
 }
 
 //-----------------------------/