@vstinner I tested this manually (I created a file called <stdin> with some text in it and saw that it no longer displays this text). I'm not sure how to write a unit test though.

I think this is worth having even without a specific unit test as it's mimicking linecache's tested behavior anyway. Since the work is done already, we could just merge it and close the issue if CI's green.

🤖 New build scheduled with the buildbot fleet by @ambv for commit 945149c 🤖

If you want to schedule another build, you need to add the ":hammer: test-with-buildbots" label again.

Usually, reading the first character of a string is unsafe if the string length is not checked, but PyUnicode_READ_CHAR(filename, 0) is safe for an empty string because CPython strings always with a null character, even for the empty string ;-)