libcpp: modules and -include again

I enabled include translation to header units in r15-1104-ga29f481bbcaf2b,
but it seems that patch wasn't sufficient, as any diagnostics in the main
source file would show up as coming from the header instead.

Fixed by setting buffer->file for leaving the file transition that my
previous patch made us enter.  And don't push a buffer of newlines, in this
case that messes up line numbers instead of aligning them.

libcpp/ChangeLog:

	* files.cc (_cpp_stack_file): Handle -include of header unit more
	specially.

gcc/testsuite/ChangeLog:

	* g++.dg/modules/dashinclude-1_b.C: Add an #error.
	* g++.dg/modules/dashinclude-1_a.H: Remove dg-module-do run.

1 files changed, 8 insertions, 2 deletions

diff --git a/libcpp/files.cc b/libcpp/files.cc
index 1cbce49..a60fe1f 100644
--- a/libcpp/files.cc
+++ b/libcpp/files.cc
@@ -977,8 +977,11 @@ _cpp_stack_file (cpp_reader *pfile, _cpp_file *file, include_type type,
 	 that.  (We also need an extra newline, so this looks like a regular
 	 file, which we do that to to make sure we don't fall off the end in the
 	 middle of a line.  */
-      static uchar newlines[] = "\n\n\n";
-      cpp_push_buffer (pfile, newlines, 2, true);
+      if (type != IT_CMDLINE)
+	{
+	  static uchar newlines[] = "\n\n\n";
+	  cpp_push_buffer (pfile, newlines, 2, true);
+	}
 
       size_t len = strlen (buf);
       buf[len] = '\n'; /* See above  */
@@ -986,6 +989,9 @@ _cpp_stack_file (cpp_reader *pfile, _cpp_file *file, include_type type,
 	= cpp_push_buffer (pfile, reinterpret_cast<unsigned char *> (buf),
 			   len, true);
       buffer->to_free = buffer->buf;
+      if (type == IT_CMDLINE)
+	/* Tell _cpp_pop_buffer to change files.  */
+	buffer->file = file;
 
       file->header_unit = +1;
       _cpp_mark_file_once_only (pfile, file);