Switch bazel default spawn strategy to sandboxed

.bazelrc

@@ -27,26 +27,20 @@ build --config=short_logs
 # PyTorch/XLA uses exceptions to communicate with Python.
 build --copt=-fexceptions
 
-# Force GCC because clang/bazel has issues.
-build --action_env=CC=gcc
-build --action_env=CXX=g++
-build --spawn_strategy=standalone
-
-###########################################################################
-
-build:clang --action_env=CC=/usr/bin/clang-17
-build:clang --action_env=CXX=/usr/bin/clang++-17
-
-# clang requires the sandbox mode. Without this, `bazel build` generates an
-# error like:
+# Why we use the sandbox mode:
+#
+# 1. it's a good practice that enforces explicit dependency declarations
+#    (see https://bazel.build/docs/user-manual#spawn-strategy).
+# 2. clang requires the sandbox mode. Without this, `bazel build` generates an
+#    error like:
 #
-# ERROR: .../external/llvm-project/llvm/BUILD.bazel:2006:11: Compiling
-# llvm/lib/CodeGenTypes/LowLevelType.cpp failed: undeclared inclusion(s) in
-# rule '@llvm-project//llvm:CodeGenTypes':
-# this rule is missing dependency declarations for the following files
-# included by 'llvm/lib/CodeGenTypes/LowLevelType.cpp':
-#   'bazel-out/k8-opt/bin/external/llvm-project/llvm/config.cppmap'
-#   'bazel-out/k8-opt/bin/external/llvm-project/llvm/Demangle.cppmap'
+#    ERROR: .../external/llvm-project/llvm/BUILD.bazel:2006:11: Compiling
+#    llvm/lib/CodeGenTypes/LowLevelType.cpp failed: undeclared inclusion(s) in
+#    rule '@llvm-project//llvm:CodeGenTypes':
+#    this rule is missing dependency declarations for the following files
+#    included by 'llvm/lib/CodeGenTypes/LowLevelType.cpp':
+#      'bazel-out/k8-opt/bin/external/llvm-project/llvm/config.cppmap'
+#      'bazel-out/k8-opt/bin/external/llvm-project/llvm/Demangle.cppmap'
 #
 # The sandbox mode requires all source files to be readable by others, as
 # inside the docker we build PyTorch/XLA as root, not the original user who
@@ -57,7 +51,16 @@ build:clang --action_env=CXX=/usr/bin/clang++-17
 #    execute permission to directories, and to files only if they already have
 #    execute permission for the owner (or group or others). This is generally
 #    safer than o+rx.
-build:clang --spawn_strategy=sandboxed
+build --spawn_strategy=sandboxed
+
+# Use GCC for C/C++ compilation.
+build --action_env=CC=gcc
+build --action_env=CXX=g++
+
+###########################################################################
+
+build:clang --action_env=CC=/usr/bin/clang-17
+build:clang --action_env=CXX=/usr/bin/clang++-17
 
 ###########################################################################
 

torch_xla/csrc/helpers.cpp

@@ -6,7 +6,6 @@
 #include <iterator>
 #include <limits>
 
-#include "absl/status/status.h"
 #include "absl/strings/str_join.h"
 #include "torch_xla/csrc/convert_ops.h"
 #include "torch_xla/csrc/dtype.h"
@@ -1043,11 +1042,9 @@ absl::StatusOr<xla::XlaComputation> XlaHelpers::WrapXlaComputation(
   xla::XlaOp orig_result = xla::Call(&builder, computation, inner_params);
 
   // Rebuild aliasing.
-  if (buffer_donor_indices.size() > 0) {
-    for (size_t i : buffer_donor_indices) {
-      builder.AddBufferDonor(/*param_number=*/0,
-                             /*param_index=*/xla::ShapeIndex({i}));
-    }
+  for (const int64_t i : buffer_donor_indices) {
+    builder.AddBufferDonor(/*param_number=*/0,
+                           /*param_index=*/xla::ShapeIndex({i}));
   }
 
   return builder.Build(orig_result);