[Bug preprocessor/101298] New: Inclusion of a file without trailing newline breaks -fdirectives-only

[boris at kolpackov dot net]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101298

            Bug ID: 101298
           Summary: Inclusion of a file without trailing newline breaks
                    -fdirectives-only
           Product: gcc
           Version: 11.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: preprocessor
          Assignee: unassigned at gcc dot gnu.org
          Reporter: boris at kolpackov dot net
  Target Milestone: ---

cat <<EOF >test.cxx
#include "test.hxx"
#include <iostream>
int main () {}
EOF

echo -n "// no newline" >test.hxx

g++ -E -fdirectives-only -o test.ii test.cxx
In file included from test.cxx:1:
test.hxx:1:1: error: unterminated comment

echo -n "void f () {}" >test.hxx

g++ -E -fdirectives-only -o test.ii test.cxx

grep "void f () {}" test.ii
void f () {}# 2 "test.cxx" 2

g++ -c -fdirectives-only test.ii
In file included from test.cxx:1:
test.hxx:1:13: error: stray ‘#’ in program

This used to work fine prior to GCC 11. I believe this issue is similar but not
the same as bug #100646.