From cfb5119fc08aedef0180e94b2e07555f35598cba Mon Sep 17 00:00:00 2001
From: Peter Van der Beken <peterv@propagandism.org>
Date: Tue, 13 Feb 2024 09:02:20 +0000
Subject: [PATCH] Bug 1878045 - Progress element's max property should ignore
 non-positive values on setting. r=dom-core,edgar

Tests will be in WPT (https://github.com/web-platform-tests/wpt/pull/44355)

Differential Revision: https://phabricator.services.mozilla.com/D200619
---
 dom/html/HTMLProgressElement.h  |  5 ++++-
 dom/html/nsGenericHTMLElement.h | 17 +++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/dom/html/HTMLProgressElement.h b/dom/html/HTMLProgressElement.h
index 04c3c2a77f69..e0de5362821a 100644
--- a/dom/html/HTMLProgressElement.h
+++ b/dom/html/HTMLProgressElement.h
@@ -37,7 +37,10 @@ class HTMLProgressElement final : public nsGenericHTMLElement {
   }
   double Max() const;
   void SetMax(double aValue, ErrorResult& aRv) {
-    SetDoubleAttr(nsGkAtoms::max, aValue, aRv);
+    // https://html.spec.whatwg.org/multipage/form-elements.html#dom-progress-max
+    // The max IDL attribute must reflect the content attribute of the same
+    // name, limited to only positive numbers.
+    SetDoubleAttr<Reflection::OnlyPositive>(nsGkAtoms::max, aValue, aRv);
   }
   double Position() const;
 
diff --git a/dom/html/nsGenericHTMLElement.h b/dom/html/nsGenericHTMLElement.h
index b3790314208c..f6e7d2415db3 100644
--- a/dom/html/nsGenericHTMLElement.h
+++ b/dom/html/nsGenericHTMLElement.h
@@ -858,14 +858,31 @@ class nsGenericHTMLElement : public nsGenericHTMLElementBase {
   uint32_t GetDimensionAttrAsUnsignedInt(nsAtom* aAttr,
                                          uint32_t aDefault) const;
 
+  enum class Reflection {
+    Unlimited,
+    OnlyPositive,
+  };
+
   /**
    * Sets value of attribute to specified double. Only works for attributes
    * in null namespace.
    *
+   * Implements
+   * https://html.spec.whatwg.org/multipage/common-dom-interfaces.html#reflecting-content-attributes-in-idl-attributes:idl-double
+   *
    * @param aAttr    name of attribute.
    * @param aValue   Double value of attribute.
    */
+  template <Reflection Limited = Reflection::Unlimited>
   void SetDoubleAttr(nsAtom* aAttr, double aValue, mozilla::ErrorResult& aRv) {
+    // 1. If the reflected IDL attribute is limited to only positive numbers and
+    //    the given value is not greater than 0, then return.
+    if (Limited == Reflection::OnlyPositive && aValue <= 0) {
+      return;
+    }
+
+    // 2. Run this's set the content attribute with the given value, converted
+    //    to the best representation of the number as a floating-point number.
     nsAutoString value;
     value.AppendFloat(aValue);