initial support fallback #3559

Job	Run time
macOS / release / homebrew-clang	5m 27s
macOS / debug / homebrew-clang	5m 20s
macOS / release / system-clang	4m 46s
macOS / debug / system-clang	4m 16s
Windows / release / msvc	18m 43s
Windows / release / clang-cl	24m 38s
Windows / release / llvm	17m 36s
Windows / debug / msvc	25m 28s
Windows / debug / clang-cl	22m 57s
Windows / debug / llvm	16m 20s
	2h 25m 31s

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