[gcc r10-10636] c++: Ensure OpenMP reduction with reference type references complete type [PR101516]

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

https://gcc.gnu.org/g:17a947ee50f8b8e01022a31bc69729f2dc563dd8

commit r10-10636-g17a947ee50f8b8e01022a31bc69729f2dc563dd8
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Wed Jul 21 09:38:59 2021 +0200

    c++: Ensure OpenMP reduction with reference type references complete type [PR101516]
    
    The following testcase ICEs because we haven't verified if reduction decl
    has reference type that TREE_TYPE of the reference is a complete type,
    require_complete_type on the decl doesn't ensure that.
    
    2021-07-21  Jakub Jelinek  <jakub@redhat.com>
    
            PR c++/101516
            * semantics.c (finish_omp_reduction_clause): Also call
            complete_type_or_else and return true if it fails.
    
            * g++.dg/gomp/pr101516.C: New test.
    
    (cherry picked from commit aea199f96cf116ba4c81426207acde371556610c)

Diff:
---
 gcc/cp/semantics.c                   | 3 ++-
 gcc/testsuite/g++.dg/gomp/pr101516.C | 8 ++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/gcc/cp/semantics.c b/gcc/cp/semantics.c
index 0d2ba529a29..4c6f70804c1 100644
--- a/gcc/cp/semantics.c
+++ b/gcc/cp/semantics.c
@@ -5806,7 +5806,8 @@ finish_omp_reduction_clause (tree c, bool *need_default_ctor, bool *need_dtor)
       if (!processing_template_decl)
 	{
 	  t = require_complete_type (t);
-	  if (t == error_mark_node)
+	  if (t == error_mark_node
+	      || !complete_type_or_else (oatype, NULL_TREE))
 	    return true;
 	  tree size = size_binop (EXACT_DIV_EXPR, TYPE_SIZE_UNIT (oatype),
 				  TYPE_SIZE_UNIT (type));
diff --git a/gcc/testsuite/g++.dg/gomp/pr101516.C b/gcc/testsuite/g++.dg/gomp/pr101516.C
new file mode 100644
index 00000000000..48f60de6bb0
--- /dev/null
+++ b/gcc/testsuite/g++.dg/gomp/pr101516.C
@@ -0,0 +1,8 @@
+// PR c++/101516
+
+void
+foo (int (&v) [])
+{
+  #pragma omp parallel reduction (+:v)	// { dg-error "invalid use of array with unspecified bounds" }
+  ;
+}