MacOS clang span issue #592

Job	Run time
Clang C++20 Linux - STL (ubuntu-22.04)	7m 18s
Clang C++14 Linux - STL (ubuntu-22.04)	5m 16s
Clang C++11 Linux - STL (ubuntu-22.04)	5m 29s
Clang C++17 Linux - STL (ubuntu-22.04)	6m 7s
Clang C++20 Linux - No STL (ubuntu-22.04)	6m 39s
Clang C++20 Linux - STL - Force C++03 (ubuntu-22.04)	7m 5s
Clang C++20 Linux - No STL - Force C++03 (ubuntu-22.04)	6m 33s
Clang C++20 OSX - No STL (macos-12)	7m 3s
Clang C++20 OSX - No STL - Force C++03 (macos-12)	6m 46s
Clang C++20 OSX - STL (macos-12)	7m 11s
Clang C++20 OSX - STL - Force C++03 (macos-12)	7m 14s
	1h 12m 41s

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