From a953e3383e3c4c769ab7094a0cce36dea679af74 Mon Sep 17 00:00:00 2001
From: Olivier Tassinari <olivier.tassinari@gmail.com>
Date: Thu, 22 Aug 2024 02:40:14 +0200
Subject: [PATCH 1/3] [button] Fix loading button regression

---
 .../migration/upgrade-to-v6/upgrade-to-v6.md       |  4 ----
 .../mui-lab/src/LoadingButton/LoadingButton.js     | 14 +++-----------
 2 files changed, 3 insertions(+), 15 deletions(-)

diff --git a/docs/data/material/migration/upgrade-to-v6/upgrade-to-v6.md b/docs/data/material/migration/upgrade-to-v6/upgrade-to-v6.md
index a6efdaa62f5cd1..532a70fcc9ed0c 100644
--- a/docs/data/material/migration/upgrade-to-v6/upgrade-to-v6.md
+++ b/docs/data/material/migration/upgrade-to-v6/upgrade-to-v6.md
@@ -365,10 +365,6 @@ As the `ListItem` no longer supports these props, the class names related to the
 +listItemButtonClasses.selected
 ```
 
-### Loading Button
-
-In v6, the `children` prop passed to the Loading Button component is now wrapped in a `<span>` tag to avoid [issues](https://github.com/mui/material-ui/issues/27853) when using tools to translate websites.
-
 ### Rating
 
 Previously, due to a bug, the `aria-label` attribute was "null Stars" when no value was set in the Rating component.
diff --git a/packages/mui-lab/src/LoadingButton/LoadingButton.js b/packages/mui-lab/src/LoadingButton/LoadingButton.js
index 13d5a9aec21df1..f81b0951d9e880 100644
--- a/packages/mui-lab/src/LoadingButton/LoadingButton.js
+++ b/packages/mui-lab/src/LoadingButton/LoadingButton.js
@@ -241,17 +241,9 @@ const LoadingButton = React.forwardRef(function LoadingButton(inProps, ref) {
       classes={classes}
       ownerState={ownerState}
     >
-      {ownerState.loadingPosition === 'end' ? (
-        <span>{children}</span>
-      ) : (
-        loadingButtonLoadingIndicator
-      )}
-
-      {ownerState.loadingPosition === 'end' ? (
-        loadingButtonLoadingIndicator
-      ) : (
-        <span>{children}</span>
-      )}
+      {ownerState.loadingPosition === 'end' ? null : loadingButtonLoadingIndicator}
+      {children}
+      {ownerState.loadingPosition === 'end' ? loadingButtonLoadingIndicator : null}
     </LoadingButtonRoot>
   );
 });

From a9b73cc1dd69f6ae89d769683d43220e9f259100 Mon Sep 17 00:00:00 2001
From: Olivier Tassinari <olivier.tassinari@gmail.com>
Date: Fri, 23 Aug 2024 18:11:05 +0200
Subject: [PATCH 2/3] wip

---
 packages/mui-lab/src/LoadingButton/LoadingButton.js | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/packages/mui-lab/src/LoadingButton/LoadingButton.js b/packages/mui-lab/src/LoadingButton/LoadingButton.js
index f81b0951d9e880..cbc2ef2b1206a8 100644
--- a/packages/mui-lab/src/LoadingButton/LoadingButton.js
+++ b/packages/mui-lab/src/LoadingButton/LoadingButton.js
@@ -242,7 +242,9 @@ const LoadingButton = React.forwardRef(function LoadingButton(inProps, ref) {
       ownerState={ownerState}
     >
       {ownerState.loadingPosition === 'end' ? null : loadingButtonLoadingIndicator}
-      {children}
+      <React.Fragment>
+        {children}
+      </React.Fragment>
       {ownerState.loadingPosition === 'end' ? loadingButtonLoadingIndicator : null}
     </LoadingButtonRoot>
   );

From 8089a45755048a52b4e16c5628ce6314a3ba50ac Mon Sep 17 00:00:00 2001
From: Olivier Tassinari <olivier.tassinari@gmail.com>
Date: Sun, 25 Aug 2024 19:49:02 +0200
Subject: [PATCH 3/3] try this

---
 packages/mui-lab/src/LoadingButton/LoadingButton.js     | 6 ++----
 packages/mui-utils/src/composeClasses/composeClasses.ts | 4 ++--
 2 files changed, 4 insertions(+), 6 deletions(-)

diff --git a/packages/mui-lab/src/LoadingButton/LoadingButton.js b/packages/mui-lab/src/LoadingButton/LoadingButton.js
index cbc2ef2b1206a8..c3b17dacf5d9c7 100644
--- a/packages/mui-lab/src/LoadingButton/LoadingButton.js
+++ b/packages/mui-lab/src/LoadingButton/LoadingButton.js
@@ -229,7 +229,7 @@ const LoadingButton = React.forwardRef(function LoadingButton(inProps, ref) {
     <LoadingButtonLoadingIndicator className={classes.loadingIndicator} ownerState={ownerState}>
       {loadingIndicator}
     </LoadingButtonLoadingIndicator>
-  ) : null;
+  ) : <span />;
 
   return (
     <LoadingButtonRoot
@@ -242,9 +242,7 @@ const LoadingButton = React.forwardRef(function LoadingButton(inProps, ref) {
       ownerState={ownerState}
     >
       {ownerState.loadingPosition === 'end' ? null : loadingButtonLoadingIndicator}
-      <React.Fragment>
-        {children}
-      </React.Fragment>
+      {children}
       {ownerState.loadingPosition === 'end' ? loadingButtonLoadingIndicator : null}
     </LoadingButtonRoot>
   );
diff --git a/packages/mui-utils/src/composeClasses/composeClasses.ts b/packages/mui-utils/src/composeClasses/composeClasses.ts
index 2b8e91af5fb540..88fe25b1c3cc07 100644
--- a/packages/mui-utils/src/composeClasses/composeClasses.ts
+++ b/packages/mui-utils/src/composeClasses/composeClasses.ts
@@ -17,10 +17,10 @@ export default function composeClasses<ClassKey extends string>(
     for (let i = 0; i < slot.length; i += 1) {
       const value = slot[i];
       if (value) {
-        buffer += getUtilityClass(value) + ' ';
+        buffer += (buffer === '' ? '' : ' ') + getUtilityClass(value);
 
         if (classes && classes[value]) {
-          buffer += classes[value] + ' ';
+          buffer += ' ' + classes[value];
         }
       }
     }