C language with Xcode 12.1 - could not build module 'Darwin'

I'm studying c language with xcode.
I only typed #include <stdio.h> and an error appeared.
Could not build module 'Darwin'
I can't find anywhere to solve this problem.
I already reinstalled xcode but same error appears.
please help me with this trouble.

These are versions of os and app.
macOS catalina 10.15.7
and
xcode 12.1
Catalina 10.15.7, Xcode 12.1

How are you creating your C source file?

In an iOS project, if I go to the "File" menu, File > New > File...
Then Source > C File
And check "Also create a header file"...

Xcode creates the .h and .c files.

The .h already includes "#include <stdio.h>", so there is no need to type it, and it builds okay.

Can you add some more details to your question?
What kind of project have you created?
I created command line tools with c

https://developer.apple.com/forums/thread/120076

I have the same issue with this one.
C language with Xcode 12.1 - could not build module 'Darwin'
 
 
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