Recently I upgraded to Xcode 11.0 and re-synced to top-of-tree WebKit. With a clean WebKitBuild directory I'm seeing the following build error:

$ ./Tools/Scripts/build-webkit --release > build-log.txt

...

In file included from /Users/kbr/src/WebKit/WebKitBuild/Release/DerivedSources/WebKitLegacy/unified-sources/UnifiedSource20-mm.mm:4:
/Users/kbr/src/WebKit/Source/WebKitLegacy/mac/WebView/WebHTMLView.mm:222:5: error: use of undeclared identifier '_subviews'; did you mean 'subviews'?
    _subviews = subviews;
    ^~~~~~~~~
    subviews
/Users/kbr/src/WebKit/Source/WebKitLegacy/mac/WebView/WebHTMLView.mm:220:63: note: 'subviews' declared here
- (void)_setSubviewsIvar:(NSMutableArray<__kindof NSView *> *)subviews {
                                                              ^
/Users/kbr/src/WebKit/Source/WebKitLegacy/mac/WebView/WebHTMLView.mm:222:15: error: explicitly assigning value of variable of type 'NSMutableArray<__kindof NSView *> *' to itself [-Werror,-Wself-assign]
    _subviews = subviews;
    ~~~~~~~~~ ^ ~~~~~~~~
/Users/kbr/src/WebKit/Source/WebKitLegacy/mac/WebView/WebHTMLView.mm:228:30: error: use of undeclared identifier '_subviews'
    return (NSMutableArray *)_subviews;
                             ^
3 errors generated.

Has anyone else run into this?

Thanks,

-Ken