[clang] Fix for OpenMP offloading compilation error with GNU++20 option when using complex header (PR #115306)

[Shilei Tian via cfe-commits]

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@@ -64,8 +64,13 @@ template <class _Tp> __DEVICE__ _Tp norm(const std::complex<_Tp> &__c) {
 }
 
 // conj
-
-template <class _Tp> std::complex<_Tp> conj(const std::complex<_Tp> &__c) {
+#ifdef _GLIBCXX20_CONSTEXPR
+#define CXX20_CONSTEXPR_DEVICE __DEVICE__
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shiltian wrote:

I wonder why this is not `constexpr` in C++20 but `__DEVICE__` instead?

https://github.com/llvm/llvm-project/pull/115306