[gcc r17-3300] c: fix checking ICE on pointer to a VLA of a tagged type [PR126284]

https://gcc.gnu.org/g:736361789c1309e3aff154210c07653f06a769d9

commit r17-3300-g736361789c1309e3aff154210c07653f06a769d9
Author: Martin Uecker <[email protected]>
Date:   Sat Jul 18 23:07:31 2026 +0200

    c: fix checking ICE on pointer to a VLA of a tagged type [PR126284]
    
    Remove the check for complete types in top_array_vla_p because
    it is not correct and we may end up encountering an array with
    incomplete element type in c_verify_type.  This can happen by
    replacing structures or unions with their incomplete version when
    constructing the canonical type.
    
            PR c/126284
    
    gcc/c/ChangeLog:
            * c-typeck.cc (top_array_vla_p): Remove check.
    
    gcc/testsuite/ChangeLog:
            * gcc.dg/pr126284.c: New test.

Diff:
---
 gcc/c/c-typeck.cc               | 2 --
 gcc/testsuite/gcc.dg/pr126284.c | 6 ++++++
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index 5199a352ecc9..ed234f075ca8 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -4120,8 +4120,6 @@ top_array_vla_p (const_tree type)
 {
   if (TREE_CODE (type) != ARRAY_TYPE)
     return false;
-  if (!COMPLETE_TYPE_P (type))
-    return false;
 
   tree d = TYPE_DOMAIN (type);
 
diff --git a/gcc/testsuite/gcc.dg/pr126284.c b/gcc/testsuite/gcc.dg/pr126284.c
new file mode 100644
index 000000000000..b2a785392470
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr126284.c
@@ -0,0 +1,6 @@
+/* { dg-do compile } */
+/* { dg-options "-std=gnu23" } */
+
+struct S { int x; };
+void f (int n) { struct { struct S (*p)[n]; } s; }
+