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Bazel can overwrite __init__.py with empty file in source tree #2947
Description
Description of the bug:
If I mess up my BUILD structure, and forget to include srcs = ["__init__.py"], it seems it can happen that Bazel overwrites the existing __init__.py with an empty file.
Reproduce:
Setup the directory:
cd $(mktemp -d)
cat > MODULE.bazel <<-EOF
module(name = "test_module")
bazel_dep(name = "rules_python", version = "1.4.1")
EOF
mkdir some_package
cat > some_package/BUILD.bazel <<-EOF
load("@rules_python//python:defs.bzl", "py_library", "py_test")
py_library(
name = "_some_library",
srcs = ["_some_library.py"],
)
py_library(
name = "some_package",
srcs = ["__init__.py"],
deps = [":_some_library"],
)
py_test(
name = "correct_test",
srcs = ["test.py"],
main = "test.py",
deps = [":some_package"],
)
py_test(
name = "bad_dep_test",
srcs = ["test.py"],
main = "test.py",
deps = [":_some_library"],
)
EOF
cat > some_package/__init__.py <<-EOF
import some_package._some_library
method=_some_library.method
EOF
cat > some_package/_some_library.py <<-EOF
def method():
pass
EOF
cat > some_package/test.py <<-EOF
import some_package
some_package.method()
EOF
Double check the with tree. This gives:
.
├── MODULE.bazel
└── some_package
├── BUILD.bazel
├── __init__.py
├── _some_library.py
└── test.py
Run the good test -- it will pass.
bazel test //some_package:correct_test
Then run the bad test. It fails and overwrites __init__.py.
bazel test //some_package:bad_dep_test
The run the good test. It now fails.
bazel test //some_package:correct_test
Note: Setting common --incompatible_default_to_explicit_init_py in .bazelrc fixes this.
See also #2945.
Activity
aignas commentedon May 31, 2025
Right now this looks like a duplicate of #2945, could you please explain how this is different, I don't fully understand the word "overwrite" here. Does it replace data inside the source tree?
tholenst commentedon May 31, 2025
Yes, it deletes data inside the source tree.
tholenst commentedon May 31, 2025
This bug is about bazel deleting my code. #2945 is about a cleanup.
SandyChapman commentedon Nov 28, 2025
If you add
common --incompatible_default_to_explicit_init_pyto your .bazelrc, it disables this behaviour. You'll now be responsible for creating your own init files though!https://bazel.build/reference/command-line-reference#flag--incompatible_default_to_explicit_init_py
Vinh-CHUC commentedon Jan 26, 2026
I'm witnessing this even when my
__init__.pyis declared in mysrcs=super odd. Usingbazel8.4.2Anyone else also witnessed that? About to try that flat in
.bazelrcto see if the problem goes away. In my case it seems to happen only onbazel testfailures