From 95f72199c23ba32c98a2f18cd9d9d6f26b376d70 Mon Sep 17 00:00:00 2001
From: "github-actions[bot]"
 <41898282+github-actions[bot]@users.noreply.github.com>
Date: Sun, 30 Jun 2024 23:16:53 +0530
Subject: [PATCH] [material-ui] Support `CssVarsTheme` in `responsiveFontSizes`
 return type (@jxdp) (#42806)

Signed-off-by: jxdp <32483798+jxdp@users.noreply.github.com>
Co-authored-by: jxdp <32483798+jxdp@users.noreply.github.com>
Co-authored-by: ZeeshanTamboli <zeeshan.tamboli@gmail.com>
---
 .../src/styles/responsiveFontSize.spec.ts        | 16 ++++++++++++++++
 .../src/styles/responsiveFontSizes.d.ts          |  7 +++----
 2 files changed, 19 insertions(+), 4 deletions(-)
 create mode 100644 packages/mui-material/src/styles/responsiveFontSize.spec.ts

diff --git a/packages/mui-material/src/styles/responsiveFontSize.spec.ts b/packages/mui-material/src/styles/responsiveFontSize.spec.ts
new file mode 100644
index 00000000000000..d5fd3b16662fa7
--- /dev/null
+++ b/packages/mui-material/src/styles/responsiveFontSize.spec.ts
@@ -0,0 +1,16 @@
+import {
+  responsiveFontSizes,
+  experimental_extendTheme,
+  createTheme,
+  Theme,
+  CssVarsTheme,
+} from '@mui/material/styles';
+import { expectType } from '@mui/types';
+
+const cssVarsTheme = responsiveFontSizes(experimental_extendTheme());
+expectType<Omit<Theme, 'palette' | 'applyStyles'> & CssVarsTheme, typeof cssVarsTheme>(
+  cssVarsTheme,
+);
+
+const theme = responsiveFontSizes(createTheme());
+expectType<Theme, typeof theme>(theme);
diff --git a/packages/mui-material/src/styles/responsiveFontSizes.d.ts b/packages/mui-material/src/styles/responsiveFontSizes.d.ts
index 394419e5a8ef0f..ce66cf94eb1347 100644
--- a/packages/mui-material/src/styles/responsiveFontSizes.d.ts
+++ b/packages/mui-material/src/styles/responsiveFontSizes.d.ts
@@ -1,6 +1,5 @@
 import { Breakpoint } from '@mui/system';
 import { Typography } from './createTypography';
-import { Theme } from './createTheme';
 
 export interface ResponsiveFontSizesOptions {
   breakpoints?: Breakpoint[];
@@ -9,7 +8,7 @@ export interface ResponsiveFontSizesOptions {
   variants?: Array<keyof Typography>;
 }
 
-export default function responsiveFontSizes(
-  theme: Theme,
+export default function responsiveFontSizes<T extends { typography: Typography }>(
+  theme: T,
   options?: ResponsiveFontSizesOptions,
-): Theme;
+): T;