[SYCL][E2E] Use lit env in subprocess calls (#17200)

Fixes #16982

subprocess calls for checking if certain features were available used
the external shell environment instead of the internal one used for
running lit tests, leading to failures in those checks for certain PRs.
This changes those subprocess calls to use the internal lit environment
instead.

Author: ayylol

sycl/test-e2e/lit.cfg.py

@@ -173,6 +173,19 @@
             lit_config.note("\tUnset " + var)
             llvm_config.with_environment(var, "")
 
+
+# Temporarily modify environment to be the same that we use when running tests
+class test_env:
+    def __enter__(self):
+        self.old_environ = dict(os.environ)
+        os.environ.clear()
+        os.environ.update(config.environment)
+
+    def __exit__(self, exc_type, exc_value, exc_traceback):
+        os.environ.clear()
+        os.environ.update(self.old_environ)
+
+
 config.substitutions.append(("%sycl_libs_dir", config.sycl_libs_dir))
 if platform.system() == "Windows":
     config.substitutions.append(
@@ -263,10 +276,11 @@ def open_check_file(file_name):
 
 # check if compiler supports CL command line options
 cl_options = False
-sp = subprocess.getstatusoutput(config.dpcpp_compiler + " /help")
-if sp[0] == 0:
-    cl_options = True
-    config.available_features.add("cl_options")
+with test_env():
+    sp = subprocess.getstatusoutput(config.dpcpp_compiler + " /help")
+    if sp[0] == 0:
+        cl_options = True
+        config.available_features.add("cl_options")
 
 # check if the compiler was built in NDEBUG configuration
 has_ndebug = False
@@ -321,14 +335,15 @@ def open_check_file(file_name):
 
 config.substitutions.append(("%level_zero_options", level_zero_options))
 
-sp = subprocess.getstatusoutput(
-    config.dpcpp_compiler + " -fsycl  " + check_l0_file + level_zero_options
-)
-if sp[0] == 0:
-    config.available_features.add("level_zero_dev_kit")
-    config.substitutions.append(("%level_zero_options", level_zero_options))
-else:
-    config.substitutions.append(("%level_zero_options", ""))
+with test_env():
+    sp = subprocess.getstatusoutput(
+        config.dpcpp_compiler + " -fsycl  " + check_l0_file + level_zero_options
+    )
+    if sp[0] == 0:
+        config.available_features.add("level_zero_dev_kit")
+        config.substitutions.append(("%level_zero_options", level_zero_options))
+    else:
+        config.substitutions.append(("%level_zero_options", ""))
 
 if lit_config.params.get("test-preview-mode", False):
     config.available_features.add("preview-mode")
@@ -349,13 +364,14 @@ def open_check_file(file_name):
             file=fp,
         )
 
-    sp = subprocess.getstatusoutput(
-        config.dpcpp_compiler
-        + " -fsycl -fpreview-breaking-changes "
-        + check_preview_breaking_changes_file
-    )
-    if sp[0] == 0:
-        config.available_features.add("preview-breaking-changes-supported")
+    with test_env():
+        sp = subprocess.getstatusoutput(
+            config.dpcpp_compiler
+            + " -fsycl -fpreview-breaking-changes "
+            + check_preview_breaking_changes_file
+        )
+        if sp[0] == 0:
+            config.available_features.add("preview-breaking-changes-supported")
 
 # Check if clang is built with ZSTD and compression support.
 fPIC_opt = "-fPIC" if platform.system() != "Windows" else ""
@@ -418,14 +434,15 @@ def open_check_file(file_name):
 
 config.substitutions.append(("%cuda_options", cuda_options))
 
-sp = subprocess.getstatusoutput(
-    config.dpcpp_compiler + " -fsycl  " + check_cuda_file + cuda_options
-)
-if sp[0] == 0:
-    config.available_features.add("cuda_dev_kit")
-    config.substitutions.append(("%cuda_options", cuda_options))
-else:
-    config.substitutions.append(("%cuda_options", ""))
+with test_env():
+    sp = subprocess.getstatusoutput(
+        config.dpcpp_compiler + " -fsycl  " + check_cuda_file + cuda_options
+    )
+    if sp[0] == 0:
+        config.available_features.add("cuda_dev_kit")
+        config.substitutions.append(("%cuda_options", cuda_options))
+    else:
+        config.substitutions.append(("%cuda_options", ""))
 
 # Check for OpenCL ICD
 if config.opencl_libs_dir: