I know it's half serious but it's simply not true, in the same way as grepping for "Stallman" in the leaked Windows source code (nobody actually mentioned RMS there, these were false positives). In this case, some headers contain multiple occurrences of GNU in a single header. Then there are several #ifdefs like "__GNU_LIBRARY__" or "__GNUC__" or e-mail addresses of people in the gnu.org domain.

In practice, it doesn't matter at all as the preprocessor replaces all license headers with a single space even before the compiler has the chance to look at it.

The preprocessor removes the comments? I thought that was the compiler?

Nope. See https://gcc.gnu.org/onlinedocs/gcc-2.95.3/cpp_1.html#SEC2

The preprocessor doesn't remove comments and at least in clang, comments are parsed into the AST.

Well, according to C99, it should. Section "5.1.1.2 Translation phases" says (in phase 3): "Each comment is replaced by one space character."

Edit: just checked and clang behaves just like gcc with -E. Maybe you didn't mean comments but preprocessor directives?

Clang, like GCC, has -C and -CC flags to preserve comments during preprocessing. However, these are really flags for the underlying preprocessor. Your parent might be thinking of some application of the Clang frontend that does not run preprocessing. For example, clang-format will probably not want to preprocess the code nor strip out comments.

You are correct, my bad.