2006-08-16  Jakub Jelinek  <jakub@redhat.com>

	PR preprocessor/28709
	* macro.c (paste_tokens): Do error reporting here, use BUF with the
	spelled LHS token as opposed to spelling it again.
	(paste_all_tokens): Don't report errors here, just break on failure.

	* gcc.dg/cpp/paste14.c: New test.

--- libcpp/macro.c.jj	2006-06-09 23:07:54.000000000 +0200
+++ libcpp/macro.c	2006-08-16 17:30:17.000000000 +0200
@@ -430,15 +430,14 @@ stringify_arg (cpp_reader *pfile, macro_
 static bool
 paste_tokens (cpp_reader *pfile, const cpp_token **plhs, const cpp_token *rhs)
 {
-  unsigned char *buf, *end;
+  unsigned char *buf, *end, *lhsend;
   const cpp_token *lhs;
   unsigned int len;
-  bool valid;
 
   lhs = *plhs;
   len = cpp_token_len (lhs) + cpp_token_len (rhs) + 1;
   buf = (unsigned char *) alloca (len);
-  end = cpp_spell_token (pfile, lhs, buf, false);
+  end = lhsend = cpp_spell_token (pfile, lhs, buf, false);
 
   /* Avoid comment headers, since they are still processed in stage 3.
      It is simpler to insert a space here, rather than modifying the
@@ -455,10 +454,22 @@ paste_tokens (cpp_reader *pfile, const c
   /* Set pfile->cur_token as required by _cpp_lex_direct.  */
   pfile->cur_token = _cpp_temp_token (pfile);
   *plhs = _cpp_lex_direct (pfile);
-  valid = pfile->buffer->cur == pfile->buffer->rlimit;
-  _cpp_pop_buffer (pfile);
+  if (pfile->buffer->cur != pfile->buffer->rlimit)
+    {
+      _cpp_pop_buffer (pfile);
+      _cpp_backup_tokens (pfile, 1);
+      *lhsend = '\0';
 
-  return valid;
+      /* Mandatory error for all apart from assembler.  */
+      if (CPP_OPTION (pfile, lang) != CLK_ASM)
+	cpp_error (pfile, CPP_DL_ERROR,
+	 "pasting \"%s\" and \"%s\" does not give a valid preprocessing token",
+		   buf, cpp_token_as_text (pfile, rhs));
+      return false;
+    }
+
+  _cpp_pop_buffer (pfile);
+  return true;
 }
 
 /* Handles an arbitrarily long sequence of ## operators, with initial
@@ -490,17 +501,7 @@ paste_all_tokens (cpp_reader *pfile, con
 	abort ();
 
       if (!paste_tokens (pfile, &lhs, rhs))
-	{
-	  _cpp_backup_tokens (pfile, 1);
-
-	  /* Mandatory error for all apart from assembler.  */
-	  if (CPP_OPTION (pfile, lang) != CLK_ASM)
-	    cpp_error (pfile, CPP_DL_ERROR,
-	 "pasting \"%s\" and \"%s\" does not give a valid preprocessing token",
-		       cpp_token_as_text (pfile, lhs),
-		       cpp_token_as_text (pfile, rhs));
-	  break;
-	}
+	break;
     }
   while (rhs->flags & PASTE_LEFT);
 
--- gcc/testsuite/gcc.dg/cpp/paste14.c.jj	2006-08-16 16:51:45.000000000 +0200
+++ gcc/testsuite/gcc.dg/cpp/paste14.c	2006-08-16 16:53:30.000000000 +0200
@@ -0,0 +1,7 @@
+/* PR preprocessor/28709 */
+/* { dg-do preprocess } */
+
+#define foo - ## >>
+foo		/* { dg-error "pasting \"-\" and \">>\"" } */
+#define bar = ## ==
+bar		/* { dg-error "pasting \"=\" and \"==\"" } */