[clang] [clang][c++20] Fix code coverage mapping crash with generalized NTTPs (PR #85837)

[Eli Friedman via cfe-commits]

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@@ -1,4 +1,4 @@
-// RUN: %clang_cc1 -mllvm -emptyline-comment-coverage=false -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping -emit-llvm-only -main-file-name templates.cpp %s | FileCheck %s
+// RUN: %clang_cc1 -std=c++20 -mllvm -emptyline-comment-coverage=false -fprofile-instrument=clang -fcoverage-mapping -dump-coverage-mapping -emit-llvm-only -main-file-name templates.cpp %s | FileCheck %s
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efriedma-quic wrote:

If you don't have any reason to expect the shared cases might differently in earlier standard versions, this is fine.

https://github.com/llvm/llvm-project/pull/85837