gcc/testsuite/g++.dg/cpp1y/digit-sep-line-neg.C

// Test digit separators in #line (bug 82359).  Test invalid usage.
// { dg-do preprocess { target c++14 } }

#line 0''123 // { dg-error "is not a positive integer" }
// { dg-error "adjacent digit separators" "adjacent" { target *-*-* } .-1 }