[clang] [clang] Fix an out-of-bound crash when checking template partial specializations. (PR #86794)

[Shafik Yaghmour via cfe-commits]

================
@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -std=c++20 -verify %s
+// RUN: %clang_cc1 -std=c++20 -ferror-limit 0 -verify %s
----------------
shafik wrote:

Why the `ferror-limit 0`?

https://github.com/llvm/llvm-project/pull/86794