[gcc r9-9444] c: Avoid clobbering TREE_TYPE (error_mark_node) [PR99990]

[Jakub Jelinek <jakub@gcc.gnu.org>]

https://gcc.gnu.org/g:9861f00a08a5f5fecd2c1c4135d3d540b0ed9cc7

commit r9-9444-g9861f00a08a5f5fecd2c1c4135d3d540b0ed9cc7
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Sat Apr 10 17:01:54 2021 +0200

    c: Avoid clobbering TREE_TYPE (error_mark_node) [PR99990]
    
    The following testcase ICEs during error recovery, because finish_decl
    overwrites TREE_TYPE (error_mark_node), which better should stay always
    to be error_mark_node.
    
    2021-04-10  Jakub Jelinek  <jakub@redhat.com>
    
            PR c/99990
            * c-decl.c (finish_decl): Don't overwrite TREE_TYPE of
            error_mark_node.
    
            * gcc.dg/pr99990.c: New test.
    
    (cherry picked from commit 91e076f3a66c1c9f6aa51e9d53d07803606e3bf1)

Diff:
---
 gcc/c/c-decl.c                 |  2 +-
 gcc/testsuite/gcc.dg/pr99990.c | 12 ++++++++++++
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/gcc/c/c-decl.c b/gcc/c/c-decl.c
index 80071112130..e1e765e29e9 100644
--- a/gcc/c/c-decl.c
+++ b/gcc/c/c-decl.c
@@ -5180,7 +5180,7 @@ finish_decl (tree decl, location_t init_loc, tree init,
 	  gcc_unreachable ();
 	}
 
-      if (DECL_INITIAL (decl))
+      if (DECL_INITIAL (decl) && DECL_INITIAL (decl) != error_mark_node)
 	TREE_TYPE (DECL_INITIAL (decl)) = type;
 
       relayout_decl (decl);
diff --git a/gcc/testsuite/gcc.dg/pr99990.c b/gcc/testsuite/gcc.dg/pr99990.c
new file mode 100644
index 00000000000..6878b00ce0d
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr99990.c
@@ -0,0 +1,12 @@
+/* PR c/99990 */
+/* { dg-do compile } */
+/* { dg-options "" } */
+
+#include <stdarg.h>
+
+void
+foo ()
+{
+  va_arg (0, long);	/* { dg-error "first argument to 'va_arg' not of type 'va_list'" } */
+  void *b[] = 0;	/* { dg-error "invalid initializer" } */
+}