From 7d9e5a2d674bb2c52cf4da5df1220afe5937a550 Mon Sep 17 00:00:00 2001
From: Andrew Casey <andrew.casey@microsoft.com>
Date: Wed, 4 Mar 2020 18:30:47 -0800
Subject: [PATCH 1/3] packages Name anonymous function type

...to speed up compilation (by simplifying structural type comparison).
Note that, in most cases, the performance benefit of extracting a name
type will be insignificant.
---
 packages/material-ui-styles/src/withStyles/withStyles.d.ts | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/packages/material-ui-styles/src/withStyles/withStyles.d.ts b/packages/material-ui-styles/src/withStyles/withStyles.d.ts
index 3bd02d7900e150..2a20e606102312 100644
--- a/packages/material-ui-styles/src/withStyles/withStyles.d.ts
+++ b/packages/material-ui-styles/src/withStyles/withStyles.d.ts
@@ -9,6 +9,8 @@ export {};
 
 type JSSFontface = CSS.FontFace & { fallbacks?: CSS.FontFace[] };
 
+type PropsFunc<Props, T> = (props: Props) => T;
+
 /**
  * Allows the user to augment the properties available
  */
@@ -29,7 +31,7 @@ export interface CSSProperties extends BaseCSSProperties {
 }
 
 export type BaseCreateCSSProperties<Props extends object = {}> = {
-  [P in keyof BaseCSSProperties]: BaseCSSProperties[P] | ((props: Props) => BaseCSSProperties[P])
+  [P in keyof BaseCSSProperties]: BaseCSSProperties[P] | PropsFunc<Props, BaseCSSProperties[P]>
 };
 
 export interface CreateCSSProperties<Props extends object = {}>
@@ -55,7 +57,7 @@ export type StyleRules<Props extends object = {}, ClassKey extends string = stri
   // JSS property bag where values are based on props
   | CreateCSSProperties<Props>
   // JSS property bag based on props
-  | ((props: Props) => CreateCSSProperties<Props>)
+  | PropsFunc<Props, CreateCSSProperties<Props>>
 >;
 
 /**

From b7559ed3ef86b90780f53ee53a59649cc1f7b677 Mon Sep 17 00:00:00 2001
From: Andrew Casey <andrew.casey@microsoft.com>
Date: Wed, 4 Mar 2020 18:39:25 -0800
Subject: [PATCH 2/3] Add missing type parameter constraint

---
 packages/material-ui-styles/src/withStyles/withStyles.d.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/material-ui-styles/src/withStyles/withStyles.d.ts b/packages/material-ui-styles/src/withStyles/withStyles.d.ts
index 2a20e606102312..9cfe360fe6640c 100644
--- a/packages/material-ui-styles/src/withStyles/withStyles.d.ts
+++ b/packages/material-ui-styles/src/withStyles/withStyles.d.ts
@@ -9,7 +9,7 @@ export {};
 
 type JSSFontface = CSS.FontFace & { fallbacks?: CSS.FontFace[] };
 
-type PropsFunc<Props, T> = (props: Props) => T;
+type PropsFunc<Props extends object, T> = (props: Props) => T;
 
 /**
  * Allows the user to augment the properties available

From 82b88330f9c109ce450bbf97a59864e4ead1141b Mon Sep 17 00:00:00 2001
From: Sebastian Silbermann <silbermann.sebastian@gmail.com>
Date: Thu, 5 Mar 2020 11:39:43 +0100
Subject: [PATCH 3/3] fix snapshot tests

---
 packages/material-ui-styles/test/styles.spec.tsx | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/packages/material-ui-styles/test/styles.spec.tsx b/packages/material-ui-styles/test/styles.spec.tsx
index 03bcc37a288ab6..0219868b3d838b 100644
--- a/packages/material-ui-styles/test/styles.spec.tsx
+++ b/packages/material-ui-styles/test/styles.spec.tsx
@@ -455,14 +455,14 @@ function forwardRefTest() {
   // If there are no props, use the definition that doesn't accept them
   // https://github.com/mui-org/material-ui/issues/16198
 
-  // $ExpectType Record<"root", CSSProperties | CreateCSSProperties<{}> | ((props: {}) => CreateCSSProperties<{}>)>
+  // $ExpectType Record<"root", CSSProperties | CreateCSSProperties<{}> | PropsFunc<{}, CreateCSSProperties<{}>>>
   const styles = createStyles({
     root: {
       width: 1,
     },
   });
 
-  // $ExpectType Record<"root", CSSProperties | CreateCSSProperties<{}> | ((props: {}) => CreateCSSProperties<{}>)>
+  // $ExpectType Record<"root", CSSProperties | CreateCSSProperties<{}> | PropsFunc<{}, CreateCSSProperties<{}>>>
   const styles2 = createStyles({
     root: () => ({
       width: 1,
@@ -473,7 +473,7 @@ function forwardRefTest() {
     foo: boolean;
   }
 
-  // $ExpectType Record<"root", CSSProperties | CreateCSSProperties<testProps> | ((props: testProps) => CreateCSSProperties<testProps>)>
+  // $ExpectType Record<"root", CSSProperties | CreateCSSProperties<testProps> | PropsFunc<testProps, CreateCSSProperties<testProps>>>
   const styles3 = createStyles({
     root: (props: testProps) => ({
       width: 1,