[clang][test] Modified python program to return error code when failing

to get file size

This patch removes the print statement that executes in the case of
exceptions, opting to let the system return its own error code when
failing to get the file size of a certain file. There are also some NFC
changes: adding description for compare-file-size.py and changing the
%{python} syntax to use the exisitng lit substitution %python.

Author: connieyzhu

clang/test/Modules/compare-file-size.py

@@ -1,22 +1,14 @@
+# This program takes in two file path arguments and returns true if the
+# file size of the first file is smaller than the file size of the second file
+
 import argparse
 import os
 
-def get_file_size(file_path):
-    try:
-        return os.path.getsize(file_path)
-    except:
-        print(f"Unable to get file size of {file_path}")
-        return None
-
-def main():
-    parser = argparse.ArgumentParser()
-
-    parser.add_argument("file1", type=str)
-    parser.add_argument("file2", type=str)
+parser = argparse.ArgumentParser()
 
-    args = parser.parse_args()
+parser.add_argument("file1", type=str)
+parser.add_argument("file2", type=str)
 
-    return get_file_size(args.file1) < get_file_size(args.file2)
+args = parser.parse_args()
 
-if __name__ == "__main__":
-    main()
+return os.path.getsize(args.file1) < os.path.getsize(args.file2)

clang/test/Modules/reduced-bmi-size.cppm

@@ -10,6 +10,6 @@
 // RUN: %clang_cc1 -std=c++20 -emit-module-interface %s -o %t/a.pcm
 // RUN: %clang_cc1 -std=c++20 -emit-reduced-module-interface %s -o %t/a.reduced.pcm
 //
-// RUN: %{python} %S/compare-file-size.py %t/a.pcm %t/a.reduced.pcm
+// RUN: %python %S/compare-file-size.py %t/a.pcm %t/a.reduced.pcm
 
 export module a;

clang/test/lit.cfg.py

@@ -74,8 +74,6 @@
 
 config.substitutions.append(("%PATH%", config.environment["PATH"]))
 
-config.substitutions.append(("%{python}", '"%s"' % (sys.executable)))
-
 
 # For each occurrence of a clang tool name, replace it with the full path to
 # the build directory holding that tool.  We explicitly specify the directories