asan: replace used python in mlir lit.cfg with shim script

Author: philippjh

mlir/test/lit.cfg.py

@@ -177,7 +177,19 @@ def add_runtime(name):
 # Python configuration with sanitizer requires some magic preloading. This will only work on clang/linux.
 # TODO: detect Darwin/Windows situation (or mark these tests as unsupported on these platforms).
 if "asan" in config.available_features and "Linux" in config.host_os:
-    python_executable = f"LD_PRELOAD=$({config.host_cxx} -print-file-name=libclang_rt.asan-{config.host_arch}.so) {config.python_executable}"
+    # Write shim script that preloads the necessary shared object for ASAN tests. Fallback to such script for two reasons:
+    #
+    # (1) Provide full support for LLVM's test utils like `not`, which are prepended to the original statement containing the `LD_PRELOAD` env definition.
+    #     Having environment definitions in the middle of a command line is syntactically illegal.
+    # (2) Mitigate issues with LIT's internal shell that puts single quotes around the environment definition,
+    #     which leads to malformed command lines:
+    #     `LD_PRELOAD=$(/usr/bin/clang++-17' '-print-file-name=libclang_rt.asan-x86_64.so)' python (...)`
+    with open("python-asan-shim", "w") as file:
+        file.write(
+            f"#!/usr/bin/env bash\nLD_PRELOAD=$({config.host_cxx} -print-file-name=libclang_rt.asan-{config.host_arch}.so) {python_executable} $@\n"
+        )
+    os.chmod(os.path.abspath("python-asan-shim"), 0o700)
+    python_executable = os.path.abspath("python-asan-shim")
 # On Windows the path to python could contains spaces in which case it needs to be provided in quotes.
 # This is the equivalent of how %python is setup in llvm/utils/lit/lit/llvm/config.py.
 elif "Windows" in config.host_os: