[gcc r9-10200] Revert "libcpp: Fix up ##__VA_OPT__ handling [PR89971]"

[Richard Biener <rguenth@gcc.gnu.org>]

https://gcc.gnu.org/g:859eddcc06e859078502271ae331d4848fb98219

commit r9-10200-g859eddcc06e859078502271ae331d4848fb98219
Author: Richard Biener <rguenther@suse.de>
Date:   Fri May 27 08:49:26 2022 +0200

    Revert "libcpp: Fix up ##__VA_OPT__ handling [PR89971]"
    
    This reverts commit 86b98701bf927ea438354723932e623557c04e42.

Diff:
---
 gcc/testsuite/c-c++-common/cpp/va-opt-9.c | 20 --------------------
 libcpp/macro.c                            |  5 -----
 2 files changed, 25 deletions(-)

diff --git a/gcc/testsuite/c-c++-common/cpp/va-opt-9.c b/gcc/testsuite/c-c++-common/cpp/va-opt-9.c
deleted file mode 100644
index 3f1d42b352f..00000000000
--- a/gcc/testsuite/c-c++-common/cpp/va-opt-9.c
+++ /dev/null
@@ -1,20 +0,0 @@
-/* PR preprocessor/89971 */
-/* { dg-do compile } */
-/* { dg-options "-std=gnu99" { target c } } */
-/* { dg-options "-std=c++2a" { target c++ } } */
-
-int a, c;
-#define m1(...) a /##__VA_OPT__(b) c
-#define m2(...) a /##__VA_OPT__() c
-#define m3(...) a##__VA_OPT__()##b = 1
-#define m4(...) a##__VA_OPT__(b c d)##e = 2
-
-int
-foo (void)
-{
-  int d = m1();
-  int e = m2(1);
-  int m3(1 2 3);
-  int m4();
-  return d + e + ab + ae;
-}
diff --git a/libcpp/macro.c b/libcpp/macro.c
index 5f50438cf4f..97f3ca09181 100644
--- a/libcpp/macro.c
+++ b/libcpp/macro.c
@@ -1889,11 +1889,6 @@ replace_args (cpp_reader *pfile, cpp_hashnode *node, cpp_macro *macro,
 		  paste_flag = tokens_buff_last_token_ptr (buff);
 		}
 
-	      if (start && paste_flag == start && (*start)->flags & PASTE_LEFT)
-		/* If __VA_OPT__ expands to nothing (either because __VA_ARGS__
-		   is empty or because it is __VA_OPT__() ), drop PASTE_LEFT
-		   flag from previous token.  */
-		copy_paste_flag (pfile, start, &pfile->avoid_paste);
 	      if (src->flags & PASTE_LEFT)
 		{
 		  /* With a non-empty __VA_OPT__ on the LHS of ##, the last