[PATCH][match-and-simplify] Caret diagnostics

[Richard Biener]

The following implements very simple caret diagnostics.  A
slow implementation is possible as we're only emitting
fatal errors (and thus at most one).

Committed.

Richard.

2014-09-23  Richard Biener  <rguent...@suse.de>

        * genmatch.c (error_cb): Implement simple caret diagnostics.

Index: gcc/genmatch.c
===================================================================
--- gcc/genmatch.c      (revision 215512)
+++ gcc/genmatch.c      (working copy)
@@ -48,6 +48,29 @@ error_cb (cpp_reader *, int, int, source
   fprintf (stderr, "%s:%d:%d error: ", loc.file, loc.line, loc.column);
   vfprintf (stderr, msg, *ap);
   fprintf (stderr, "\n");
+  FILE *f = fopen (loc.file, "r");
+  if (f)
+    {
+      char buf[128];
+      while (loc.line > 0)
+       {
+         if (!fgets (buf, 128, f))
+           goto notfound;
+         if (buf[strlen (buf) - 1] != '\n')
+           {
+             if (loc.line > 1)
+               loc.line++;
+           }
+         loc.line--;
+       }
+      fprintf (stderr, "%s", buf);
+      for (int i = 0; i < loc.column - 1; ++i)
+       fputc (' ', stderr);
+      fputc ('^', stderr);
+      fputc ('\n', stderr);
+notfound:
+      fclose (f);
+    }
   exit (1);
 }