[clang] [clang][python] Don't add check-clang-python to check-all if cross-compiling (PR #111657)

[Alex Bradbury via cfe-commits]

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@@ -47,6 +47,14 @@ if(${LLVM_NATIVE_ARCH} MATCHES "^(AArch64|Hexagon|Sparc|SystemZ)$")
   set(RUN_PYTHON_TESTS FALSE)
 endif()
 
+# Tests will fail if cross-compiling for a different target, as tests will try
+# to use the host Python3_EXECUTABLE and make FFI calls to functions in target
+# libraries.
+if(CMAKE_CROSS_COMPILING)
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asb wrote:

I think fundamentally it can't really work. We could add a search for a python interpreter built for the target in the sysroot, and add logic to use it if we know we can execute it with qemu-user...but I'm not sure it's worth that kind of complexity and I personally prefer to minimise dependency on the sysroot as much as possible other than providing some needed libraries and headers. A FIXME could suggest adding some logic for specifying a guest python3_executable, but I'm not sure that's a path we'd want to commit to. So I'm a bit torn.

https://github.com/llvm/llvm-project/pull/111657