[gcc r11-8404] libcpp: Fix up -fdirectives-only preprocessing of includes not ending with newline [PR100392]

[gcc r11-8404] libcpp: Fix up -fdirectives-only preprocessing of includes not ending with newline [PR100392]

[Jakub Jelinek]

https://gcc.gnu.org/g:b6ecd493886891f8150905a2fd3b7d54e88fc7be

commit r11-8404-gb6ecd493886891f8150905a2fd3b7d54e88fc7be
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed May 12 15:14:35 2021 +0200

    libcpp: Fix up -fdirectives-only preprocessing of includes not ending with newline [PR100392]
    
    If a header doesn't end with a new-line, with -fdirectives-only we right now
    preprocess it as
    int i = 1;# 2 "pr100392.c" 2
    i.e. the line directive isn't on the next line, which means we fail to parse
    it when compiling.
    
    GCC 10 and earlier libcpp/directives-only.c had for this:
      if (!pfile->state.skipping && cur != base)
        {
          /* If the file was not newline terminated, add rlimit, which is
             guaranteed to point to a newline, to the end of our range.  */
          if (cur[-1] != '\n')
            {
              cur++;
              CPP_INCREMENT_LINE (pfile, 0);
              lines++;
            }
    
          cb->print_lines (lines, base, cur - base);
        }
    and we have the assertion
          /* Files always end in a newline or carriage return.  We rely on this for
             character peeking safety.  */
          gcc_assert (buffer->rlimit[0] == '\n' || buffer->rlimit[0] == '\r');
    So, this patch just does readd the more less same thing, so that we emit
    a newline after the inline even when it wasn't there before.
    
    2021-05-12  Jakub Jelinek  <jakub@redhat.com>
    
            PR preprocessor/100392
            * lex.c (cpp_directive_only_process): If buffer doesn't end with '\n',
            add buffer->rlimit[0] character to the printed range and
            CPP_INCREMENT_LINE and increment line_count.
    
            * gcc.dg/cpp/pr100392.c: New test.
            * gcc.dg/cpp/pr100392.h: New file.
    
    (cherry picked from commit c6b664e2c4c127025e076d8b584abe0976694629)

Diff:
---
 gcc/testsuite/gcc.dg/cpp/pr100392.c |  5 +++++
 gcc/testsuite/gcc.dg/cpp/pr100392.h |  4 ++++
 libcpp/lex.c                        | 13 ++++++++++++-
 3 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/gcc/testsuite/gcc.dg/cpp/pr100392.c b/gcc/testsuite/gcc.dg/cpp/pr100392.c
new file mode 100644
index 00000000000..670ad2b742c
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/pr100392.c
@@ -0,0 +1,5 @@
+/* PR preprocessor/100392 */
+/* { dg-do compile } */
+/* { dg-options "-save-temps -fdirectives-only" } */
+
+#include "pr100392.h"
diff --git a/gcc/testsuite/gcc.dg/cpp/pr100392.h b/gcc/testsuite/gcc.dg/cpp/pr100392.h
new file mode 100644
index 00000000000..340bc92cd56
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/cpp/pr100392.h
@@ -0,0 +1,4 @@
+/* PR preprocessor/100392 */
+
+/* No newline after ; below.  */
+int i = 1;
\ No newline at end of file
diff --git a/libcpp/lex.c b/libcpp/lex.c
index 27388754ea1..6c0ca8d2e2d 100644
--- a/libcpp/lex.c
+++ b/libcpp/lex.c
@@ -4757,7 +4757,18 @@ cpp_directive_only_process (cpp_reader *pfile,
 	}
 
       if (buffer->rlimit > base && !pfile->state.skipping)
-	cb (pfile, CPP_DO_print, data, line_count, base, buffer->rlimit - base);
+	{
+	  const unsigned char *limit = buffer->rlimit;
+	  /* If the file was not newline terminated, add rlimit, which is
+	     guaranteed to point to a newline, to the end of our range.  */
+	  if (limit[-1] != '\n')
+	    {
+	      limit++;
+	      CPP_INCREMENT_LINE (pfile, 0);
+	      line_count++;
+	    }
+	  cb (pfile, CPP_DO_print, data, line_count, base, limit - base);
+	}
 
       _cpp_pop_buffer (pfile);
     }