From 57f98a095e55faec178f454a1bc3fd5193c854e7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Morten=20S=C3=B8rvig?= <morten.sorvig@qt.io>
Date: Fri, 7 Mar 2025 10:27:04 +0100
Subject: [PATCH] wasm: implement move for QWasmEventHandler
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Implement move by copying the emscripten::val member
variables, and clearing the moved-from ones. This ensures
that the moved-from val is in a known state ("undefined").

Also move the non-default constructor declaration up to
the top of the class.

Change-Id: If9574cc91a53d4029d49b29b89819d98319acaa3
Reviewed-by: Even Oscar Andersen <even.oscar.andersen@qt.io>
Reviewed-by: Morten Johan Sørvig <morten.sorvig@qt.io>
---
 .../wasm/qwasmsuspendresumecontrol.cpp        | 25 +++++++++++++++++++
 .../wasm/qwasmsuspendresumecontrol_p.h        |  7 +++---
 2 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/src/corelib/platform/wasm/qwasmsuspendresumecontrol.cpp b/src/corelib/platform/wasm/qwasmsuspendresumecontrol.cpp
index bf1d30bf23c..7b71e73816b 100644
--- a/src/corelib/platform/wasm/qwasmsuspendresumecontrol.cpp
+++ b/src/corelib/platform/wasm/qwasmsuspendresumecontrol.cpp
@@ -180,12 +180,37 @@ QWasmEventHandler::QWasmEventHandler(emscripten::val element, const std::string
 
 QWasmEventHandler::~QWasmEventHandler()
 {
+    // Do nothing if this instance is default-constructed, or was moved from.
+    if (m_element.isUndefined())
+        return;
+
     QWasmSuspendResumeControl *suspendResume = QWasmSuspendResumeControl::get();
     Q_ASSERT(suspendResume);
     m_element.call<void>("removeEventListener", m_name, suspendResume->jsEventHandlerAt(m_eventHandlerIndex));
     suspendResume->removeEventHandler(m_eventHandlerIndex);
 }
 
+QWasmEventHandler::QWasmEventHandler(QWasmEventHandler&& other) noexcept
+:m_element(std::move(other.m_element))
+,m_name(std::move(other.m_name))
+,m_eventHandlerIndex(other.m_eventHandlerIndex)
+{
+    other.m_element = emscripten::val();
+    other.m_name = emscripten::val();
+    other.m_eventHandlerIndex = 0;
+}
+
+QWasmEventHandler& QWasmEventHandler::operator=(QWasmEventHandler&& other) noexcept
+{
+    m_element = std::move(other.m_element);
+    other.m_element = emscripten::val();
+    m_name = std::move(other.m_name);
+    other.m_name = emscripten::val();
+    m_eventHandlerIndex = other.m_eventHandlerIndex;
+    other.m_eventHandlerIndex = 0;
+    return *this;
+}
+
 //
 // The QWasmTimer class creates a native single-shot timer. The event handler is provided in the
 // constructor and can be reused: each call setTimeout() sets a new timeout, though with the
diff --git a/src/corelib/platform/wasm/qwasmsuspendresumecontrol_p.h b/src/corelib/platform/wasm/qwasmsuspendresumecontrol_p.h
index c500c40791a..8b660a91719 100644
--- a/src/corelib/platform/wasm/qwasmsuspendresumecontrol_p.h
+++ b/src/corelib/platform/wasm/qwasmsuspendresumecontrol_p.h
@@ -51,12 +51,13 @@ class Q_CORE_EXPORT QWasmEventHandler
 {
 public:
     QWasmEventHandler() = default;
+    QWasmEventHandler(emscripten::val element, const std::string &name,
+                      std::function<void(emscripten::val)> fn);
     ~QWasmEventHandler();
     QWasmEventHandler(QWasmEventHandler const&) = delete;
     QWasmEventHandler& operator=(QWasmEventHandler const&) = delete;
-    QWasmEventHandler(emscripten::val element, const std::string &name,
-                      std::function<void(emscripten::val)> fn);
-
+    QWasmEventHandler(QWasmEventHandler&& other) noexcept;
+    QWasmEventHandler& operator=(QWasmEventHandler&& other) noexcept;
 private:
     emscripten::val m_element;
     emscripten::val m_name;