Tests: Cover macOS host architecture selection on Apple Silicon hosts

Add test cases verifying that `CMAKE_APPLE_SILICON_PROCESSOR` set as
either a cache or environment variable causes that to be selected as the
host architecture.  Also verify that sources compile using whatever is
selected as the host architecture, even when the explicit setting is not
used.

Issue: #21554

1 files changed, 14 insertions, 0 deletions

diff --git a/Tests/RunCMake/AppleSilicon/default.c b/Tests/RunCMake/AppleSilicon/default.c
new file mode 100644
index 0000000..7b0535b
--- /dev/null
+++ b/Tests/RunCMake/AppleSilicon/default.c
@@ -0,0 +1,14 @@
+#if defined(HOST_ARM64)
+#  if !defined(__aarch64__)
+#    error "Not compiling as host arm64"
+#  endif
+#elif defined(HOST_X86_64)
+#  if !defined(__x86_64__)
+#    error "Not compiling as host x86_64"
+#  endif
+#else
+#  error "One of HOST_ARM64 or HOST_X86_64 must be defined."
+#endif
+void default_arch(void)
+{
+}