test/Preprocessor/macro_paste_c_block_comment.c

// RUN: %clang_cc1 %s -Eonly -verify

// expected-error@9 {{EOF}}
#define COMM / ## *
COMM // expected-error {{pasting formed '/*', an invalid preprocessing token}}

// Demonstrate that an invalid preprocessing token
// doesn't swallow the rest of the file...
#error EOF