Add tooling to detect Python2 syntax errors

shell.nix

@@ -14,6 +14,7 @@ pkgs.mkShell {
 
   buildInputs = [
     tools.env
+    tools.py2-astparse
     tools.flamegraph
     tools.release
     pkgs.nixpkgs-fmt

tools/default.nix

@@ -77,4 +77,20 @@ in
     projectDir = ./.;
   };
 
+  py2-astparse = pkgs.writeScriptBin "py2-astparse" ''
+    #!${pkgs.python2.interpreter}
+    # Used as a smoke test for Python2 compatibility in Python files
+    import sys
+    import ast
+
+    if __name__ == "__main__":
+        with open(sys.argv[1]) as f:
+            try:
+                ast.parse(f.read())
+            except Exception as e:
+                sys.stderr.write("Error parsing '{}':\n".format(sys.argv[1]))
+                sys.stderr.flush()
+                raise
+  '';
+
 }