From b813917528115696e23767d05a84e2fd9140f888 Mon Sep 17 00:00:00 2001
From: Florian Apolloner <florian@apolloner.eu>
Date: Wed, 13 Sep 2023 16:07:54 +0200
Subject: [PATCH] Move to src-layout.

The intention of this is better isolation. `trio` is no longer
accidentally on the (python) path and as such requires an explicit
installation for usage, this helps uncover issues in packaging data etc
early on (see
https://packaging.python.org/en/latest/discussions/src-layout-vs-flat-layout/).

This serves as the basis for switching to another build system as well; refs #2790.
---
 .coveragerc                                   |   5 +
 check.sh                                      |  30 +++---
 ci.sh                                         |   2 +-
 docs/source/conf.py                           |   2 +-
 pyproject.toml                                |  91 +++++++++---------
 setup.py                                      |   5 +-
 {trio => src/trio}/__init__.py                |   0
 {trio => src/trio}/_abc.py                    |   0
 {trio => src/trio}/_channel.py                |   0
 {trio => src/trio}/_core/__init__.py          |   0
 {trio => src/trio}/_core/_asyncgens.py        |   0
 {trio => src/trio}/_core/_entry_queue.py      |   0
 {trio => src/trio}/_core/_exceptions.py       |   0
 .../trio}/_core/_generated_instrumentation.py |   0
 .../trio}/_core/_generated_io_epoll.py        |   0
 .../trio}/_core/_generated_io_kqueue.py       |   0
 .../trio}/_core/_generated_io_windows.py      |   0
 {trio => src/trio}/_core/_generated_run.py    |   0
 {trio => src/trio}/_core/_instrumentation.py  |   0
 {trio => src/trio}/_core/_io_common.py        |   0
 {trio => src/trio}/_core/_io_epoll.py         |   0
 {trio => src/trio}/_core/_io_kqueue.py        |   0
 {trio => src/trio}/_core/_io_windows.py       |   0
 {trio => src/trio}/_core/_ki.py               |   0
 {trio => src/trio}/_core/_local.py            |   0
 {trio => src/trio}/_core/_mock_clock.py       |   0
 {trio => src/trio}/_core/_multierror.py       |   0
 {trio => src/trio}/_core/_parking_lot.py      |   0
 {trio => src/trio}/_core/_run.py              |   0
 {trio => src/trio}/_core/_tests/__init__.py   |   0
 .../trio}/_core/_tests/test_asyncgen.py       |   0
 .../trio}/_core/_tests/test_guest_mode.py     |   0
 .../_core/_tests/test_instrumentation.py      |   0
 {trio => src/trio}/_core/_tests/test_io.py    |   0
 {trio => src/trio}/_core/_tests/test_ki.py    |   0
 {trio => src/trio}/_core/_tests/test_local.py |   0
 .../trio}/_core/_tests/test_mock_clock.py     |   0
 .../trio}/_core/_tests/test_multierror.py     |   0
 .../test_multierror_scripts/__init__.py       |   0
 .../_tests/test_multierror_scripts/_common.py |   0
 .../apport_excepthook.py                      |   0
 .../simple_excepthook.py                      |   0
 .../trio}/_core/_tests/test_parking_lot.py    |   0
 {trio => src/trio}/_core/_tests/test_run.py   |   0
 .../trio}/_core/_tests/test_thread_cache.py   |   0
 {trio => src/trio}/_core/_tests/test_tutil.py |   0
 .../_core/_tests/test_unbounded_queue.py      |   0
 .../trio}/_core/_tests/test_windows.py        |   0
 {trio => src/trio}/_core/_tests/tutil.py      |   0
 {trio => src/trio}/_core/_thread_cache.py     |   0
 {trio => src/trio}/_core/_traps.py            |   0
 {trio => src/trio}/_core/_unbounded_queue.py  |   0
 .../trio}/_core/_wakeup_socketpair.py         |   0
 {trio => src/trio}/_core/_windows_cffi.py     |   0
 {trio => src/trio}/_deprecate.py              |   0
 {trio => src/trio}/_dtls.py                   |   0
 {trio => src/trio}/_file_io.py                |   0
 {trio => src/trio}/_highlevel_generic.py      |   0
 .../trio}/_highlevel_open_tcp_listeners.py    |   0
 .../trio}/_highlevel_open_tcp_stream.py       |   0
 .../trio}/_highlevel_open_unix_stream.py      |   0
 .../trio}/_highlevel_serve_listeners.py       |   0
 {trio => src/trio}/_highlevel_socket.py       |   0
 {trio => src/trio}/_highlevel_ssl_helpers.py  |   0
 {trio => src/trio}/_path.py                   |   0
 {trio => src/trio}/_signals.py                |   0
 {trio => src/trio}/_socket.py                 |   0
 {trio => src/trio}/_ssl.py                    |   0
 {trio => src/trio}/_subprocess.py             |   0
 .../trio}/_subprocess_platform/__init__.py    |   0
 .../trio}/_subprocess_platform/kqueue.py      |   0
 .../trio}/_subprocess_platform/waitid.py      |   0
 .../trio}/_subprocess_platform/windows.py     |   0
 {trio => src/trio}/_sync.py                   |   0
 {trio => src/trio}/_tests/__init__.py         |   0
 .../trio}/_tests/astrill-codesigning-cert.cer | Bin
 .../trio}/_tests/check_type_completeness.py   |   0
 .../trio}/_tests/module_with_deprecations.py  |   0
 {trio => src/trio}/_tests/pytest_plugin.py    |   0
 {trio => src/trio}/_tests/test_abc.py         |   0
 {trio => src/trio}/_tests/test_channel.py     |   0
 {trio => src/trio}/_tests/test_contextvars.py |   0
 {trio => src/trio}/_tests/test_deprecate.py   |   0
 {trio => src/trio}/_tests/test_dtls.py        |   0
 {trio => src/trio}/_tests/test_exports.py     |   0
 {trio => src/trio}/_tests/test_fakenet.py     |   0
 {trio => src/trio}/_tests/test_file_io.py     |   0
 .../trio}/_tests/test_highlevel_generic.py    |   0
 .../test_highlevel_open_tcp_listeners.py      |   0
 .../_tests/test_highlevel_open_tcp_stream.py  |   0
 .../_tests/test_highlevel_open_unix_stream.py |   0
 .../_tests/test_highlevel_serve_listeners.py  |   0
 .../trio}/_tests/test_highlevel_socket.py     |   0
 .../_tests/test_highlevel_ssl_helpers.py      |   0
 {trio => src/trio}/_tests/test_path.py        |   0
 .../_tests/test_scheduler_determinism.py      |   0
 {trio => src/trio}/_tests/test_signals.py     |   0
 {trio => src/trio}/_tests/test_socket.py      |   0
 {trio => src/trio}/_tests/test_ssl.py         |   0
 {trio => src/trio}/_tests/test_subprocess.py  |   0
 {trio => src/trio}/_tests/test_sync.py        |   0
 {trio => src/trio}/_tests/test_testing.py     |   0
 {trio => src/trio}/_tests/test_threads.py     |   0
 {trio => src/trio}/_tests/test_timeouts.py    |   0
 {trio => src/trio}/_tests/test_tracing.py     |   0
 {trio => src/trio}/_tests/test_unix_pipes.py  |   0
 {trio => src/trio}/_tests/test_util.py        |   0
 .../trio}/_tests/test_wait_for_object.py      |   0
 .../trio}/_tests/test_windows_pipes.py        |   0
 {trio => src/trio}/_tests/tools/__init__.py   |   0
 .../trio}/_tests/tools/test_gen_exports.py    |   0
 .../trio}/_tests/tools/test_mypy_annotate.py  |   0
 .../trio}/_tests/verify_types_darwin.json     |   0
 .../trio}/_tests/verify_types_linux.json      |   0
 .../trio}/_tests/verify_types_windows.json    |   0
 {trio => src/trio}/_threads.py                |   0
 {trio => src/trio}/_timeouts.py               |   0
 {trio => src/trio}/_tools/__init__.py         |   0
 {trio => src/trio}/_tools/gen_exports.py      |   2 +-
 {trio => src/trio}/_tools/mypy_annotate.py    |   0
 {trio => src/trio}/_unix_pipes.py             |   0
 {trio => src/trio}/_util.py                   |   0
 {trio => src/trio}/_version.py                |   0
 {trio => src/trio}/_wait_for_object.py        |   0
 {trio => src/trio}/_windows_pipes.py          |   0
 {trio => src/trio}/abc.py                     |   0
 {trio => src/trio}/from_thread.py             |   0
 {trio => src/trio}/lowlevel.py                |   0
 {trio => src/trio}/py.typed                   |   0
 {trio => src/trio}/socket.py                  |   0
 {trio => src/trio}/testing/__init__.py        |   0
 {trio => src/trio}/testing/_check_streams.py  |   0
 {trio => src/trio}/testing/_checkpoints.py    |   0
 {trio => src/trio}/testing/_fake_net.py       |   0
 {trio => src/trio}/testing/_memory_streams.py |   0
 {trio => src/trio}/testing/_network.py        |   0
 {trio => src/trio}/testing/_sequencer.py      |   0
 {trio => src/trio}/testing/_trio_test.py      |   0
 {trio => src/trio}/tests.py                   |   0
 {trio => src/trio}/to_thread.py               |   0
 140 files changed, 72 insertions(+), 65 deletions(-)
 rename {trio => src/trio}/__init__.py (100%)
 rename {trio => src/trio}/_abc.py (100%)
 rename {trio => src/trio}/_channel.py (100%)
 rename {trio => src/trio}/_core/__init__.py (100%)
 rename {trio => src/trio}/_core/_asyncgens.py (100%)
 rename {trio => src/trio}/_core/_entry_queue.py (100%)
 rename {trio => src/trio}/_core/_exceptions.py (100%)
 rename {trio => src/trio}/_core/_generated_instrumentation.py (100%)
 rename {trio => src/trio}/_core/_generated_io_epoll.py (100%)
 rename {trio => src/trio}/_core/_generated_io_kqueue.py (100%)
 rename {trio => src/trio}/_core/_generated_io_windows.py (100%)
 rename {trio => src/trio}/_core/_generated_run.py (100%)
 rename {trio => src/trio}/_core/_instrumentation.py (100%)
 rename {trio => src/trio}/_core/_io_common.py (100%)
 rename {trio => src/trio}/_core/_io_epoll.py (100%)
 rename {trio => src/trio}/_core/_io_kqueue.py (100%)
 rename {trio => src/trio}/_core/_io_windows.py (100%)
 rename {trio => src/trio}/_core/_ki.py (100%)
 rename {trio => src/trio}/_core/_local.py (100%)
 rename {trio => src/trio}/_core/_mock_clock.py (100%)
 rename {trio => src/trio}/_core/_multierror.py (100%)
 rename {trio => src/trio}/_core/_parking_lot.py (100%)
 rename {trio => src/trio}/_core/_run.py (100%)
 rename {trio => src/trio}/_core/_tests/__init__.py (100%)
 rename {trio => src/trio}/_core/_tests/test_asyncgen.py (100%)
 rename {trio => src/trio}/_core/_tests/test_guest_mode.py (100%)
 rename {trio => src/trio}/_core/_tests/test_instrumentation.py (100%)
 rename {trio => src/trio}/_core/_tests/test_io.py (100%)
 rename {trio => src/trio}/_core/_tests/test_ki.py (100%)
 rename {trio => src/trio}/_core/_tests/test_local.py (100%)
 rename {trio => src/trio}/_core/_tests/test_mock_clock.py (100%)
 rename {trio => src/trio}/_core/_tests/test_multierror.py (100%)
 rename {trio => src/trio}/_core/_tests/test_multierror_scripts/__init__.py (100%)
 rename {trio => src/trio}/_core/_tests/test_multierror_scripts/_common.py (100%)
 rename {trio => src/trio}/_core/_tests/test_multierror_scripts/apport_excepthook.py (100%)
 rename {trio => src/trio}/_core/_tests/test_multierror_scripts/simple_excepthook.py (100%)
 rename {trio => src/trio}/_core/_tests/test_parking_lot.py (100%)
 rename {trio => src/trio}/_core/_tests/test_run.py (100%)
 rename {trio => src/trio}/_core/_tests/test_thread_cache.py (100%)
 rename {trio => src/trio}/_core/_tests/test_tutil.py (100%)
 rename {trio => src/trio}/_core/_tests/test_unbounded_queue.py (100%)
 rename {trio => src/trio}/_core/_tests/test_windows.py (100%)
 rename {trio => src/trio}/_core/_tests/tutil.py (100%)
 rename {trio => src/trio}/_core/_thread_cache.py (100%)
 rename {trio => src/trio}/_core/_traps.py (100%)
 rename {trio => src/trio}/_core/_unbounded_queue.py (100%)
 rename {trio => src/trio}/_core/_wakeup_socketpair.py (100%)
 rename {trio => src/trio}/_core/_windows_cffi.py (100%)
 rename {trio => src/trio}/_deprecate.py (100%)
 rename {trio => src/trio}/_dtls.py (100%)
 rename {trio => src/trio}/_file_io.py (100%)
 rename {trio => src/trio}/_highlevel_generic.py (100%)
 rename {trio => src/trio}/_highlevel_open_tcp_listeners.py (100%)
 rename {trio => src/trio}/_highlevel_open_tcp_stream.py (100%)
 rename {trio => src/trio}/_highlevel_open_unix_stream.py (100%)
 rename {trio => src/trio}/_highlevel_serve_listeners.py (100%)
 rename {trio => src/trio}/_highlevel_socket.py (100%)
 rename {trio => src/trio}/_highlevel_ssl_helpers.py (100%)
 rename {trio => src/trio}/_path.py (100%)
 rename {trio => src/trio}/_signals.py (100%)
 rename {trio => src/trio}/_socket.py (100%)
 rename {trio => src/trio}/_ssl.py (100%)
 rename {trio => src/trio}/_subprocess.py (100%)
 rename {trio => src/trio}/_subprocess_platform/__init__.py (100%)
 rename {trio => src/trio}/_subprocess_platform/kqueue.py (100%)
 rename {trio => src/trio}/_subprocess_platform/waitid.py (100%)
 rename {trio => src/trio}/_subprocess_platform/windows.py (100%)
 rename {trio => src/trio}/_sync.py (100%)
 rename {trio => src/trio}/_tests/__init__.py (100%)
 rename {trio => src/trio}/_tests/astrill-codesigning-cert.cer (100%)
 rename {trio => src/trio}/_tests/check_type_completeness.py (100%)
 rename {trio => src/trio}/_tests/module_with_deprecations.py (100%)
 rename {trio => src/trio}/_tests/pytest_plugin.py (100%)
 rename {trio => src/trio}/_tests/test_abc.py (100%)
 rename {trio => src/trio}/_tests/test_channel.py (100%)
 rename {trio => src/trio}/_tests/test_contextvars.py (100%)
 rename {trio => src/trio}/_tests/test_deprecate.py (100%)
 rename {trio => src/trio}/_tests/test_dtls.py (100%)
 rename {trio => src/trio}/_tests/test_exports.py (100%)
 rename {trio => src/trio}/_tests/test_fakenet.py (100%)
 rename {trio => src/trio}/_tests/test_file_io.py (100%)
 rename {trio => src/trio}/_tests/test_highlevel_generic.py (100%)
 rename {trio => src/trio}/_tests/test_highlevel_open_tcp_listeners.py (100%)
 rename {trio => src/trio}/_tests/test_highlevel_open_tcp_stream.py (100%)
 rename {trio => src/trio}/_tests/test_highlevel_open_unix_stream.py (100%)
 rename {trio => src/trio}/_tests/test_highlevel_serve_listeners.py (100%)
 rename {trio => src/trio}/_tests/test_highlevel_socket.py (100%)
 rename {trio => src/trio}/_tests/test_highlevel_ssl_helpers.py (100%)
 rename {trio => src/trio}/_tests/test_path.py (100%)
 rename {trio => src/trio}/_tests/test_scheduler_determinism.py (100%)
 rename {trio => src/trio}/_tests/test_signals.py (100%)
 rename {trio => src/trio}/_tests/test_socket.py (100%)
 rename {trio => src/trio}/_tests/test_ssl.py (100%)
 rename {trio => src/trio}/_tests/test_subprocess.py (100%)
 rename {trio => src/trio}/_tests/test_sync.py (100%)
 rename {trio => src/trio}/_tests/test_testing.py (100%)
 rename {trio => src/trio}/_tests/test_threads.py (100%)
 rename {trio => src/trio}/_tests/test_timeouts.py (100%)
 rename {trio => src/trio}/_tests/test_tracing.py (100%)
 rename {trio => src/trio}/_tests/test_unix_pipes.py (100%)
 rename {trio => src/trio}/_tests/test_util.py (100%)
 rename {trio => src/trio}/_tests/test_wait_for_object.py (100%)
 rename {trio => src/trio}/_tests/test_windows_pipes.py (100%)
 rename {trio => src/trio}/_tests/tools/__init__.py (100%)
 rename {trio => src/trio}/_tests/tools/test_gen_exports.py (100%)
 rename {trio => src/trio}/_tests/tools/test_mypy_annotate.py (100%)
 rename {trio => src/trio}/_tests/verify_types_darwin.json (100%)
 rename {trio => src/trio}/_tests/verify_types_linux.json (100%)
 rename {trio => src/trio}/_tests/verify_types_windows.json (100%)
 rename {trio => src/trio}/_threads.py (100%)
 rename {trio => src/trio}/_timeouts.py (100%)
 rename {trio => src/trio}/_tools/__init__.py (100%)
 rename {trio => src/trio}/_tools/gen_exports.py (99%)
 rename {trio => src/trio}/_tools/mypy_annotate.py (100%)
 rename {trio => src/trio}/_unix_pipes.py (100%)
 rename {trio => src/trio}/_util.py (100%)
 rename {trio => src/trio}/_version.py (100%)
 rename {trio => src/trio}/_wait_for_object.py (100%)
 rename {trio => src/trio}/_windows_pipes.py (100%)
 rename {trio => src/trio}/abc.py (100%)
 rename {trio => src/trio}/from_thread.py (100%)
 rename {trio => src/trio}/lowlevel.py (100%)
 rename {trio => src/trio}/py.typed (100%)
 rename {trio => src/trio}/socket.py (100%)
 rename {trio => src/trio}/testing/__init__.py (100%)
 rename {trio => src/trio}/testing/_check_streams.py (100%)
 rename {trio => src/trio}/testing/_checkpoints.py (100%)
 rename {trio => src/trio}/testing/_fake_net.py (100%)
 rename {trio => src/trio}/testing/_memory_streams.py (100%)
 rename {trio => src/trio}/testing/_network.py (100%)
 rename {trio => src/trio}/testing/_sequencer.py (100%)
 rename {trio => src/trio}/testing/_trio_test.py (100%)
 rename {trio => src/trio}/tests.py (100%)
 rename {trio => src/trio}/to_thread.py (100%)

diff --git a/.coveragerc b/.coveragerc
index de12642263..a44aae1376 100644
--- a/.coveragerc
+++ b/.coveragerc
@@ -14,6 +14,11 @@ omit=
 # this doesn't corrupt the coverage files
 parallel=True
 
+[paths]
+source =
+  src/trio
+  **/site-packages/trio
+
 [report]
 precision = 1
 skip_covered = True
diff --git a/check.sh b/check.sh
index 95049080f3..e385e4602e 100755
--- a/check.sh
+++ b/check.sh
@@ -11,7 +11,7 @@ fi
 
 # Test if the generated code is still up to date
 echo "::group::Generate Exports"
-python ./trio/_tools/gen_exports.py --test \
+python src/trio/_tools/gen_exports.py --test \
     || EXIT_STATUS=$?
 echo "::endgroup::"
 
@@ -21,10 +21,10 @@ echo "::endgroup::"
 # autoflake --recursive --in-place .
 # pyupgrade --py3-plus $(find . -name "*.py")
 echo "::group::Black"
-if ! black --check setup.py trio; then
+if ! black --check setup.py src/trio; then
     echo "* Black found issues" >> $GITHUB_STEP_SUMMARY
     EXIT_STATUS=1
-    black --diff setup.py trio
+    black --diff setup.py src/trio
     echo "::endgroup::"
     echo "::error:: Black found issues"
 else
@@ -32,10 +32,10 @@ else
 fi
 
 echo "::group::ISort"
-if ! isort --check setup.py trio; then
+if ! isort --check setup.py src/trio; then
     echo "* isort found issues." >> $GITHUB_STEP_SUMMARY
     EXIT_STATUS=1
-    isort --diff setup.py trio
+    isort --diff setup.py src/trio
     echo "::endgroup::"
     echo "::error:: isort found issues"
 else
@@ -44,7 +44,7 @@ fi
 
 # Run flake8, configured in pyproject.toml
 echo "::group::Flake8"
-flake8 trio/ || EXIT_STATUS=$?
+flake8 src/trio/ || EXIT_STATUS=$?
 echo "::endgroup::"
 
 # Run mypy on all supported platforms
@@ -55,16 +55,16 @@ echo "::group::Mypy"
 rm -f mypy_annotate.dat
 # Pipefail makes these pipelines fail if mypy does, even if mypy_annotate.py succeeds.
 set -o pipefail
-mypy trio --show-error-end --platform linux | python ./trio/_tools/mypy_annotate.py --dumpfile mypy_annotate.dat --platform Linux \
+mypy src/trio --show-error-end --platform linux | python ./src/trio/_tools/mypy_annotate.py --dumpfile mypy_annotate.dat --platform Linux \
     || { echo "* Mypy (Linux) found type errors." >> $GITHUB_STEP_SUMMARY; MYPY=1; }
 # Darwin tests FreeBSD too
-mypy trio --show-error-end --platform darwin | python ./trio/_tools/mypy_annotate.py --dumpfile mypy_annotate.dat --platform Mac \
+mypy src/trio --show-error-end --platform darwin | python ./src/trio/_tools/mypy_annotate.py --dumpfile mypy_annotate.dat --platform Mac \
     || { echo "* Mypy (Mac) found type errors." >> $GITHUB_STEP_SUMMARY; MYPY=1; }
-mypy trio --show-error-end --platform win32 | python ./trio/_tools/mypy_annotate.py --dumpfile mypy_annotate.dat --platform Windows \
+mypy src/trio --show-error-end --platform win32 | python ./src/trio/_tools/mypy_annotate.py --dumpfile mypy_annotate.dat --platform Windows \
     || { echo "* Mypy (Windows) found type errors." >> $GITHUB_STEP_SUMMARY; MYPY=1; }
 set +o pipefail
 # Re-display errors using Github's syntax, read out of mypy_annotate.dat
-python ./trio/_tools/mypy_annotate.py --dumpfile mypy_annotate.dat
+python ./src/trio/_tools/mypy_annotate.py --dumpfile mypy_annotate.dat
 # Then discard.
 rm -f mypy_annotate.dat
 echo "::endgroup::"
@@ -94,11 +94,11 @@ fi
 
 codespell || EXIT_STATUS=$?
 
-python trio/_tests/check_type_completeness.py --overwrite-file || EXIT_STATUS=$?
-if git status --porcelain trio/_tests/verify_types*.json | grep -q "M"; then
+python src/trio/_tests/check_type_completeness.py --overwrite-file || EXIT_STATUS=$?
+if git status --porcelain src/trio/_tests/verify_types*.json | grep -q "M"; then
     echo "* Type completeness changed, please update!" >> $GITHUB_STEP_SUMMARY
     echo "::error::Type completeness changed, please update!"
-    git --no-pager diff --color trio/_tests/verify_types*.json
+    git --no-pager diff --color src/trio/_tests/verify_types*.json
     EXIT_STATUS=1
 fi
 
@@ -112,8 +112,8 @@ Problems were found by static analysis (listed above).
 To fix formatting and see remaining errors, run
 
     pip install -r test-requirements.txt
-    black setup.py trio
-    isort setup.py trio
+    black setup.py src/trio
+    isort setup.py src/trio
     ./check.sh
 
 in your local checkout.
diff --git a/ci.sh b/ci.sh
index e469c0243a..ad162a62cb 100755
--- a/ci.sh
+++ b/ci.sh
@@ -87,7 +87,7 @@ else
         # when installing, and then running 'certmgr.msc' and exporting the
         # certificate. See:
         #    http://www.migee.com/2010/09/24/solution-for-unattendedsilent-installs-and-would-you-like-to-install-this-device-software/
-        certutil -addstore "TrustedPublisher" trio/_tests/astrill-codesigning-cert.cer
+        certutil -addstore "TrustedPublisher" src/trio/_tests/astrill-codesigning-cert.cer
         # Double-slashes are how you tell windows-bash that you want a single
         # slash, and don't treat this as a unix-style filename that needs to
         # be replaced by a windows-style filename.
diff --git a/docs/source/conf.py b/docs/source/conf.py
index 66aa8dea05..82ec6a23a7 100755
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -22,7 +22,7 @@
 # For our local_customization module
 sys.path.insert(0, os.path.abspath("."))
 # For trio itself
-sys.path.insert(0, os.path.abspath("../.."))
+sys.path.insert(0, os.path.abspath("../../src"))
 
 # https://docs.readthedocs.io/en/stable/builds.html#build-environment
 if "READTHEDOCS" in os.environ:
diff --git a/pyproject.toml b/pyproject.toml
index 79beab840d..253b2b2dd8 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -13,13 +13,13 @@ ignore-words-list = 'astroid,crasher,asend'
 [tool.flake8]
 extend-ignore = ['D', 'E', 'W', 'F403', 'F405', 'F821', 'F822']
 per-file-ignores = [
-  'trio/__init__.py: F401',
-  'trio/_core/__init__.py: F401',
-  'trio/_core/_tests/test_multierror_scripts/*: F401',
-  'trio/abc.py: F401',
-  'trio/lowlevel.py: F401',
-  'trio/socket.py: F401',
-  'trio/testing/__init__.py: F401'
+  'src/trio/__init__.py: F401',
+  'src/trio/_core/__init__.py: F401',
+  'src/trio/_core/_tests/test_multierror_scripts/*: F401',
+  'src/trio/abc.py: F401',
+  'src/trio/lowlevel.py: F401',
+  'src/trio/socket.py: F401',
+  'src/trio/testing/__init__.py: F401'
 ]
 
 [tool.isort]
@@ -61,48 +61,48 @@ disallow_untyped_calls = false
 [[tool.mypy.overrides]]
 module = [
 # 2761
-"trio/_core/_generated_io_windows",
-"trio/_core/_io_windows",
+"src/trio/_core/_generated_io_windows",
+"src/trio/_core/_io_windows",
 
 # internal
-"trio/_windows_pipes",
+"src/trio/_windows_pipes",
 
 # tests
-"trio/testing/_fake_net",
-"trio/_core/_tests/test_guest_mode",
-"trio/_core/_tests/test_instrumentation",
-"trio/_core/_tests/test_ki",
-"trio/_core/_tests/test_local",
-"trio/_core/_tests/test_mock_clock",
-"trio/_core/_tests/test_multierror",
-"trio/_core/_tests/test_multierror_scripts/ipython_custom_exc",
-"trio/_core/_tests/test_multierror_scripts/simple_excepthook",
-"trio/_core/_tests/test_parking_lot",
-"trio/_core/_tests/test_thread_cache",
-"trio/_core/_tests/test_unbounded_queue",
-"trio/_tests/test_exports",
-"trio/_tests/test_file_io",
-"trio/_tests/test_highlevel_generic",
-"trio/_tests/test_highlevel_open_tcp_listeners",
-"trio/_tests/test_highlevel_open_tcp_stream",
-"trio/_tests/test_highlevel_open_unix_stream",
-"trio/_tests/test_highlevel_serve_listeners",
-"trio/_tests/test_highlevel_socket",
-"trio/_tests/test_highlevel_ssl_helpers",
-"trio/_tests/test_path",
-"trio/_tests/test_scheduler_determinism",
-"trio/_tests/test_socket",
-"trio/_tests/test_ssl",
-"trio/_tests/test_subprocess",
-"trio/_tests/test_sync",
-"trio/_tests/test_testing",
-"trio/_tests/test_threads",
-"trio/_tests/test_timeouts",
-"trio/_tests/test_tracing",
-"trio/_tests/test_util",
-"trio/_tests/test_wait_for_object",
-"trio/_tests/test_windows_pipes",
-"trio/_tests/tools/test_gen_exports",
+"src/trio/testing/_fake_net",
+"src/trio/_core/_tests/test_guest_mode",
+"src/trio/_core/_tests/test_instrumentation",
+"src/trio/_core/_tests/test_ki",
+"src/trio/_core/_tests/test_local",
+"src/trio/_core/_tests/test_mock_clock",
+"src/trio/_core/_tests/test_multierror",
+"src/trio/_core/_tests/test_multierror_scripts/ipython_custom_exc",
+"src/trio/_core/_tests/test_multierror_scripts/simple_excepthook",
+"src/trio/_core/_tests/test_parking_lot",
+"src/trio/_core/_tests/test_thread_cache",
+"src/trio/_core/_tests/test_unbounded_queue",
+"src/trio/_tests/test_exports",
+"src/trio/_tests/test_file_io",
+"src/trio/_tests/test_highlevel_generic",
+"src/trio/_tests/test_highlevel_open_tcp_listeners",
+"src/trio/_tests/test_highlevel_open_tcp_stream",
+"src/trio/_tests/test_highlevel_open_unix_stream",
+"src/trio/_tests/test_highlevel_serve_listeners",
+"src/trio/_tests/test_highlevel_socket",
+"src/trio/_tests/test_highlevel_ssl_helpers",
+"src/trio/_tests/test_path",
+"src/trio/_tests/test_scheduler_determinism",
+"src/trio/_tests/test_socket",
+"src/trio/_tests/test_ssl",
+"src/trio/_tests/test_subprocess",
+"src/trio/_tests/test_sync",
+"src/trio/_tests/test_testing",
+"src/trio/_tests/test_threads",
+"src/trio/_tests/test_timeouts",
+"src/trio/_tests/test_tracing",
+"src/trio/_tests/test_util",
+"src/trio/_tests/test_wait_for_object",
+"src/trio/_tests/test_windows_pipes",
+"src/trio/_tests/tools/test_gen_exports",
 ]
 check_untyped_defs = false
 disallow_any_decorated = false
@@ -142,6 +142,7 @@ issue_format = "`#{issue} <https://github.com/python-trio/trio/issues/{issue}>`_
 # - At release time after bumping version number, run: towncrier
 # (or towncrier --draft)
 package = "trio"
+package_dir = "src"
 underlines = ["-", "~", "^"]
 
 [[tool.towncrier.type]]
diff --git a/setup.py b/setup.py
index dbce61c0fd..f6cb207375 100644
--- a/setup.py
+++ b/setup.py
@@ -1,6 +1,6 @@
 from setuptools import find_packages, setup
 
-exec(open("trio/_version.py", encoding="utf-8").read())
+exec(open("src/trio/_version.py", encoding="utf-8").read())
 
 LONG_DESC = """\
 .. image:: https://raw.githubusercontent.com/python-trio/trio/9b0bec646a31e0d0f67b8b6ecc6939726faf3e17/logo/logo-with-background.svg
@@ -80,7 +80,8 @@
     author_email="njs@pobox.com",
     url="https://github.com/python-trio/trio",
     license="MIT OR Apache-2.0",
-    packages=find_packages(),
+    packages=find_packages(where="src"),
+    package_dir={"": "src"},
     install_requires=[
         # attrs 19.2.0 adds `eq` option to decorators
         # attrs 20.1.0 adds @frozen
diff --git a/trio/__init__.py b/src/trio/__init__.py
similarity index 100%
rename from trio/__init__.py
rename to src/trio/__init__.py
diff --git a/trio/_abc.py b/src/trio/_abc.py
similarity index 100%
rename from trio/_abc.py
rename to src/trio/_abc.py
diff --git a/trio/_channel.py b/src/trio/_channel.py
similarity index 100%
rename from trio/_channel.py
rename to src/trio/_channel.py
diff --git a/trio/_core/__init__.py b/src/trio/_core/__init__.py
similarity index 100%
rename from trio/_core/__init__.py
rename to src/trio/_core/__init__.py
diff --git a/trio/_core/_asyncgens.py b/src/trio/_core/_asyncgens.py
similarity index 100%
rename from trio/_core/_asyncgens.py
rename to src/trio/_core/_asyncgens.py
diff --git a/trio/_core/_entry_queue.py b/src/trio/_core/_entry_queue.py
similarity index 100%
rename from trio/_core/_entry_queue.py
rename to src/trio/_core/_entry_queue.py
diff --git a/trio/_core/_exceptions.py b/src/trio/_core/_exceptions.py
similarity index 100%
rename from trio/_core/_exceptions.py
rename to src/trio/_core/_exceptions.py
diff --git a/trio/_core/_generated_instrumentation.py b/src/trio/_core/_generated_instrumentation.py
similarity index 100%
rename from trio/_core/_generated_instrumentation.py
rename to src/trio/_core/_generated_instrumentation.py
diff --git a/trio/_core/_generated_io_epoll.py b/src/trio/_core/_generated_io_epoll.py
similarity index 100%
rename from trio/_core/_generated_io_epoll.py
rename to src/trio/_core/_generated_io_epoll.py
diff --git a/trio/_core/_generated_io_kqueue.py b/src/trio/_core/_generated_io_kqueue.py
similarity index 100%
rename from trio/_core/_generated_io_kqueue.py
rename to src/trio/_core/_generated_io_kqueue.py
diff --git a/trio/_core/_generated_io_windows.py b/src/trio/_core/_generated_io_windows.py
similarity index 100%
rename from trio/_core/_generated_io_windows.py
rename to src/trio/_core/_generated_io_windows.py
diff --git a/trio/_core/_generated_run.py b/src/trio/_core/_generated_run.py
similarity index 100%
rename from trio/_core/_generated_run.py
rename to src/trio/_core/_generated_run.py
diff --git a/trio/_core/_instrumentation.py b/src/trio/_core/_instrumentation.py
similarity index 100%
rename from trio/_core/_instrumentation.py
rename to src/trio/_core/_instrumentation.py
diff --git a/trio/_core/_io_common.py b/src/trio/_core/_io_common.py
similarity index 100%
rename from trio/_core/_io_common.py
rename to src/trio/_core/_io_common.py
diff --git a/trio/_core/_io_epoll.py b/src/trio/_core/_io_epoll.py
similarity index 100%
rename from trio/_core/_io_epoll.py
rename to src/trio/_core/_io_epoll.py
diff --git a/trio/_core/_io_kqueue.py b/src/trio/_core/_io_kqueue.py
similarity index 100%
rename from trio/_core/_io_kqueue.py
rename to src/trio/_core/_io_kqueue.py
diff --git a/trio/_core/_io_windows.py b/src/trio/_core/_io_windows.py
similarity index 100%
rename from trio/_core/_io_windows.py
rename to src/trio/_core/_io_windows.py
diff --git a/trio/_core/_ki.py b/src/trio/_core/_ki.py
similarity index 100%
rename from trio/_core/_ki.py
rename to src/trio/_core/_ki.py
diff --git a/trio/_core/_local.py b/src/trio/_core/_local.py
similarity index 100%
rename from trio/_core/_local.py
rename to src/trio/_core/_local.py
diff --git a/trio/_core/_mock_clock.py b/src/trio/_core/_mock_clock.py
similarity index 100%
rename from trio/_core/_mock_clock.py
rename to src/trio/_core/_mock_clock.py
diff --git a/trio/_core/_multierror.py b/src/trio/_core/_multierror.py
similarity index 100%
rename from trio/_core/_multierror.py
rename to src/trio/_core/_multierror.py
diff --git a/trio/_core/_parking_lot.py b/src/trio/_core/_parking_lot.py
similarity index 100%
rename from trio/_core/_parking_lot.py
rename to src/trio/_core/_parking_lot.py
diff --git a/trio/_core/_run.py b/src/trio/_core/_run.py
similarity index 100%
rename from trio/_core/_run.py
rename to src/trio/_core/_run.py
diff --git a/trio/_core/_tests/__init__.py b/src/trio/_core/_tests/__init__.py
similarity index 100%
rename from trio/_core/_tests/__init__.py
rename to src/trio/_core/_tests/__init__.py
diff --git a/trio/_core/_tests/test_asyncgen.py b/src/trio/_core/_tests/test_asyncgen.py
similarity index 100%
rename from trio/_core/_tests/test_asyncgen.py
rename to src/trio/_core/_tests/test_asyncgen.py
diff --git a/trio/_core/_tests/test_guest_mode.py b/src/trio/_core/_tests/test_guest_mode.py
similarity index 100%
rename from trio/_core/_tests/test_guest_mode.py
rename to src/trio/_core/_tests/test_guest_mode.py
diff --git a/trio/_core/_tests/test_instrumentation.py b/src/trio/_core/_tests/test_instrumentation.py
similarity index 100%
rename from trio/_core/_tests/test_instrumentation.py
rename to src/trio/_core/_tests/test_instrumentation.py
diff --git a/trio/_core/_tests/test_io.py b/src/trio/_core/_tests/test_io.py
similarity index 100%
rename from trio/_core/_tests/test_io.py
rename to src/trio/_core/_tests/test_io.py
diff --git a/trio/_core/_tests/test_ki.py b/src/trio/_core/_tests/test_ki.py
similarity index 100%
rename from trio/_core/_tests/test_ki.py
rename to src/trio/_core/_tests/test_ki.py
diff --git a/trio/_core/_tests/test_local.py b/src/trio/_core/_tests/test_local.py
similarity index 100%
rename from trio/_core/_tests/test_local.py
rename to src/trio/_core/_tests/test_local.py
diff --git a/trio/_core/_tests/test_mock_clock.py b/src/trio/_core/_tests/test_mock_clock.py
similarity index 100%
rename from trio/_core/_tests/test_mock_clock.py
rename to src/trio/_core/_tests/test_mock_clock.py
diff --git a/trio/_core/_tests/test_multierror.py b/src/trio/_core/_tests/test_multierror.py
similarity index 100%
rename from trio/_core/_tests/test_multierror.py
rename to src/trio/_core/_tests/test_multierror.py
diff --git a/trio/_core/_tests/test_multierror_scripts/__init__.py b/src/trio/_core/_tests/test_multierror_scripts/__init__.py
similarity index 100%
rename from trio/_core/_tests/test_multierror_scripts/__init__.py
rename to src/trio/_core/_tests/test_multierror_scripts/__init__.py
diff --git a/trio/_core/_tests/test_multierror_scripts/_common.py b/src/trio/_core/_tests/test_multierror_scripts/_common.py
similarity index 100%
rename from trio/_core/_tests/test_multierror_scripts/_common.py
rename to src/trio/_core/_tests/test_multierror_scripts/_common.py
diff --git a/trio/_core/_tests/test_multierror_scripts/apport_excepthook.py b/src/trio/_core/_tests/test_multierror_scripts/apport_excepthook.py
similarity index 100%
rename from trio/_core/_tests/test_multierror_scripts/apport_excepthook.py
rename to src/trio/_core/_tests/test_multierror_scripts/apport_excepthook.py
diff --git a/trio/_core/_tests/test_multierror_scripts/simple_excepthook.py b/src/trio/_core/_tests/test_multierror_scripts/simple_excepthook.py
similarity index 100%
rename from trio/_core/_tests/test_multierror_scripts/simple_excepthook.py
rename to src/trio/_core/_tests/test_multierror_scripts/simple_excepthook.py
diff --git a/trio/_core/_tests/test_parking_lot.py b/src/trio/_core/_tests/test_parking_lot.py
similarity index 100%
rename from trio/_core/_tests/test_parking_lot.py
rename to src/trio/_core/_tests/test_parking_lot.py
diff --git a/trio/_core/_tests/test_run.py b/src/trio/_core/_tests/test_run.py
similarity index 100%
rename from trio/_core/_tests/test_run.py
rename to src/trio/_core/_tests/test_run.py
diff --git a/trio/_core/_tests/test_thread_cache.py b/src/trio/_core/_tests/test_thread_cache.py
similarity index 100%
rename from trio/_core/_tests/test_thread_cache.py
rename to src/trio/_core/_tests/test_thread_cache.py
diff --git a/trio/_core/_tests/test_tutil.py b/src/trio/_core/_tests/test_tutil.py
similarity index 100%
rename from trio/_core/_tests/test_tutil.py
rename to src/trio/_core/_tests/test_tutil.py
diff --git a/trio/_core/_tests/test_unbounded_queue.py b/src/trio/_core/_tests/test_unbounded_queue.py
similarity index 100%
rename from trio/_core/_tests/test_unbounded_queue.py
rename to src/trio/_core/_tests/test_unbounded_queue.py
diff --git a/trio/_core/_tests/test_windows.py b/src/trio/_core/_tests/test_windows.py
similarity index 100%
rename from trio/_core/_tests/test_windows.py
rename to src/trio/_core/_tests/test_windows.py
diff --git a/trio/_core/_tests/tutil.py b/src/trio/_core/_tests/tutil.py
similarity index 100%
rename from trio/_core/_tests/tutil.py
rename to src/trio/_core/_tests/tutil.py
diff --git a/trio/_core/_thread_cache.py b/src/trio/_core/_thread_cache.py
similarity index 100%
rename from trio/_core/_thread_cache.py
rename to src/trio/_core/_thread_cache.py
diff --git a/trio/_core/_traps.py b/src/trio/_core/_traps.py
similarity index 100%
rename from trio/_core/_traps.py
rename to src/trio/_core/_traps.py
diff --git a/trio/_core/_unbounded_queue.py b/src/trio/_core/_unbounded_queue.py
similarity index 100%
rename from trio/_core/_unbounded_queue.py
rename to src/trio/_core/_unbounded_queue.py
diff --git a/trio/_core/_wakeup_socketpair.py b/src/trio/_core/_wakeup_socketpair.py
similarity index 100%
rename from trio/_core/_wakeup_socketpair.py
rename to src/trio/_core/_wakeup_socketpair.py
diff --git a/trio/_core/_windows_cffi.py b/src/trio/_core/_windows_cffi.py
similarity index 100%
rename from trio/_core/_windows_cffi.py
rename to src/trio/_core/_windows_cffi.py
diff --git a/trio/_deprecate.py b/src/trio/_deprecate.py
similarity index 100%
rename from trio/_deprecate.py
rename to src/trio/_deprecate.py
diff --git a/trio/_dtls.py b/src/trio/_dtls.py
similarity index 100%
rename from trio/_dtls.py
rename to src/trio/_dtls.py
diff --git a/trio/_file_io.py b/src/trio/_file_io.py
similarity index 100%
rename from trio/_file_io.py
rename to src/trio/_file_io.py
diff --git a/trio/_highlevel_generic.py b/src/trio/_highlevel_generic.py
similarity index 100%
rename from trio/_highlevel_generic.py
rename to src/trio/_highlevel_generic.py
diff --git a/trio/_highlevel_open_tcp_listeners.py b/src/trio/_highlevel_open_tcp_listeners.py
similarity index 100%
rename from trio/_highlevel_open_tcp_listeners.py
rename to src/trio/_highlevel_open_tcp_listeners.py
diff --git a/trio/_highlevel_open_tcp_stream.py b/src/trio/_highlevel_open_tcp_stream.py
similarity index 100%
rename from trio/_highlevel_open_tcp_stream.py
rename to src/trio/_highlevel_open_tcp_stream.py
diff --git a/trio/_highlevel_open_unix_stream.py b/src/trio/_highlevel_open_unix_stream.py
similarity index 100%
rename from trio/_highlevel_open_unix_stream.py
rename to src/trio/_highlevel_open_unix_stream.py
diff --git a/trio/_highlevel_serve_listeners.py b/src/trio/_highlevel_serve_listeners.py
similarity index 100%
rename from trio/_highlevel_serve_listeners.py
rename to src/trio/_highlevel_serve_listeners.py
diff --git a/trio/_highlevel_socket.py b/src/trio/_highlevel_socket.py
similarity index 100%
rename from trio/_highlevel_socket.py
rename to src/trio/_highlevel_socket.py
diff --git a/trio/_highlevel_ssl_helpers.py b/src/trio/_highlevel_ssl_helpers.py
similarity index 100%
rename from trio/_highlevel_ssl_helpers.py
rename to src/trio/_highlevel_ssl_helpers.py
diff --git a/trio/_path.py b/src/trio/_path.py
similarity index 100%
rename from trio/_path.py
rename to src/trio/_path.py
diff --git a/trio/_signals.py b/src/trio/_signals.py
similarity index 100%
rename from trio/_signals.py
rename to src/trio/_signals.py
diff --git a/trio/_socket.py b/src/trio/_socket.py
similarity index 100%
rename from trio/_socket.py
rename to src/trio/_socket.py
diff --git a/trio/_ssl.py b/src/trio/_ssl.py
similarity index 100%
rename from trio/_ssl.py
rename to src/trio/_ssl.py
diff --git a/trio/_subprocess.py b/src/trio/_subprocess.py
similarity index 100%
rename from trio/_subprocess.py
rename to src/trio/_subprocess.py
diff --git a/trio/_subprocess_platform/__init__.py b/src/trio/_subprocess_platform/__init__.py
similarity index 100%
rename from trio/_subprocess_platform/__init__.py
rename to src/trio/_subprocess_platform/__init__.py
diff --git a/trio/_subprocess_platform/kqueue.py b/src/trio/_subprocess_platform/kqueue.py
similarity index 100%
rename from trio/_subprocess_platform/kqueue.py
rename to src/trio/_subprocess_platform/kqueue.py
diff --git a/trio/_subprocess_platform/waitid.py b/src/trio/_subprocess_platform/waitid.py
similarity index 100%
rename from trio/_subprocess_platform/waitid.py
rename to src/trio/_subprocess_platform/waitid.py
diff --git a/trio/_subprocess_platform/windows.py b/src/trio/_subprocess_platform/windows.py
similarity index 100%
rename from trio/_subprocess_platform/windows.py
rename to src/trio/_subprocess_platform/windows.py
diff --git a/trio/_sync.py b/src/trio/_sync.py
similarity index 100%
rename from trio/_sync.py
rename to src/trio/_sync.py
diff --git a/trio/_tests/__init__.py b/src/trio/_tests/__init__.py
similarity index 100%
rename from trio/_tests/__init__.py
rename to src/trio/_tests/__init__.py
diff --git a/trio/_tests/astrill-codesigning-cert.cer b/src/trio/_tests/astrill-codesigning-cert.cer
similarity index 100%
rename from trio/_tests/astrill-codesigning-cert.cer
rename to src/trio/_tests/astrill-codesigning-cert.cer
diff --git a/trio/_tests/check_type_completeness.py b/src/trio/_tests/check_type_completeness.py
similarity index 100%
rename from trio/_tests/check_type_completeness.py
rename to src/trio/_tests/check_type_completeness.py
diff --git a/trio/_tests/module_with_deprecations.py b/src/trio/_tests/module_with_deprecations.py
similarity index 100%
rename from trio/_tests/module_with_deprecations.py
rename to src/trio/_tests/module_with_deprecations.py
diff --git a/trio/_tests/pytest_plugin.py b/src/trio/_tests/pytest_plugin.py
similarity index 100%
rename from trio/_tests/pytest_plugin.py
rename to src/trio/_tests/pytest_plugin.py
diff --git a/trio/_tests/test_abc.py b/src/trio/_tests/test_abc.py
similarity index 100%
rename from trio/_tests/test_abc.py
rename to src/trio/_tests/test_abc.py
diff --git a/trio/_tests/test_channel.py b/src/trio/_tests/test_channel.py
similarity index 100%
rename from trio/_tests/test_channel.py
rename to src/trio/_tests/test_channel.py
diff --git a/trio/_tests/test_contextvars.py b/src/trio/_tests/test_contextvars.py
similarity index 100%
rename from trio/_tests/test_contextvars.py
rename to src/trio/_tests/test_contextvars.py
diff --git a/trio/_tests/test_deprecate.py b/src/trio/_tests/test_deprecate.py
similarity index 100%
rename from trio/_tests/test_deprecate.py
rename to src/trio/_tests/test_deprecate.py
diff --git a/trio/_tests/test_dtls.py b/src/trio/_tests/test_dtls.py
similarity index 100%
rename from trio/_tests/test_dtls.py
rename to src/trio/_tests/test_dtls.py
diff --git a/trio/_tests/test_exports.py b/src/trio/_tests/test_exports.py
similarity index 100%
rename from trio/_tests/test_exports.py
rename to src/trio/_tests/test_exports.py
diff --git a/trio/_tests/test_fakenet.py b/src/trio/_tests/test_fakenet.py
similarity index 100%
rename from trio/_tests/test_fakenet.py
rename to src/trio/_tests/test_fakenet.py
diff --git a/trio/_tests/test_file_io.py b/src/trio/_tests/test_file_io.py
similarity index 100%
rename from trio/_tests/test_file_io.py
rename to src/trio/_tests/test_file_io.py
diff --git a/trio/_tests/test_highlevel_generic.py b/src/trio/_tests/test_highlevel_generic.py
similarity index 100%
rename from trio/_tests/test_highlevel_generic.py
rename to src/trio/_tests/test_highlevel_generic.py
diff --git a/trio/_tests/test_highlevel_open_tcp_listeners.py b/src/trio/_tests/test_highlevel_open_tcp_listeners.py
similarity index 100%
rename from trio/_tests/test_highlevel_open_tcp_listeners.py
rename to src/trio/_tests/test_highlevel_open_tcp_listeners.py
diff --git a/trio/_tests/test_highlevel_open_tcp_stream.py b/src/trio/_tests/test_highlevel_open_tcp_stream.py
similarity index 100%
rename from trio/_tests/test_highlevel_open_tcp_stream.py
rename to src/trio/_tests/test_highlevel_open_tcp_stream.py
diff --git a/trio/_tests/test_highlevel_open_unix_stream.py b/src/trio/_tests/test_highlevel_open_unix_stream.py
similarity index 100%
rename from trio/_tests/test_highlevel_open_unix_stream.py
rename to src/trio/_tests/test_highlevel_open_unix_stream.py
diff --git a/trio/_tests/test_highlevel_serve_listeners.py b/src/trio/_tests/test_highlevel_serve_listeners.py
similarity index 100%
rename from trio/_tests/test_highlevel_serve_listeners.py
rename to src/trio/_tests/test_highlevel_serve_listeners.py
diff --git a/trio/_tests/test_highlevel_socket.py b/src/trio/_tests/test_highlevel_socket.py
similarity index 100%
rename from trio/_tests/test_highlevel_socket.py
rename to src/trio/_tests/test_highlevel_socket.py
diff --git a/trio/_tests/test_highlevel_ssl_helpers.py b/src/trio/_tests/test_highlevel_ssl_helpers.py
similarity index 100%
rename from trio/_tests/test_highlevel_ssl_helpers.py
rename to src/trio/_tests/test_highlevel_ssl_helpers.py
diff --git a/trio/_tests/test_path.py b/src/trio/_tests/test_path.py
similarity index 100%
rename from trio/_tests/test_path.py
rename to src/trio/_tests/test_path.py
diff --git a/trio/_tests/test_scheduler_determinism.py b/src/trio/_tests/test_scheduler_determinism.py
similarity index 100%
rename from trio/_tests/test_scheduler_determinism.py
rename to src/trio/_tests/test_scheduler_determinism.py
diff --git a/trio/_tests/test_signals.py b/src/trio/_tests/test_signals.py
similarity index 100%
rename from trio/_tests/test_signals.py
rename to src/trio/_tests/test_signals.py
diff --git a/trio/_tests/test_socket.py b/src/trio/_tests/test_socket.py
similarity index 100%
rename from trio/_tests/test_socket.py
rename to src/trio/_tests/test_socket.py
diff --git a/trio/_tests/test_ssl.py b/src/trio/_tests/test_ssl.py
similarity index 100%
rename from trio/_tests/test_ssl.py
rename to src/trio/_tests/test_ssl.py
diff --git a/trio/_tests/test_subprocess.py b/src/trio/_tests/test_subprocess.py
similarity index 100%
rename from trio/_tests/test_subprocess.py
rename to src/trio/_tests/test_subprocess.py
diff --git a/trio/_tests/test_sync.py b/src/trio/_tests/test_sync.py
similarity index 100%
rename from trio/_tests/test_sync.py
rename to src/trio/_tests/test_sync.py
diff --git a/trio/_tests/test_testing.py b/src/trio/_tests/test_testing.py
similarity index 100%
rename from trio/_tests/test_testing.py
rename to src/trio/_tests/test_testing.py
diff --git a/trio/_tests/test_threads.py b/src/trio/_tests/test_threads.py
similarity index 100%
rename from trio/_tests/test_threads.py
rename to src/trio/_tests/test_threads.py
diff --git a/trio/_tests/test_timeouts.py b/src/trio/_tests/test_timeouts.py
similarity index 100%
rename from trio/_tests/test_timeouts.py
rename to src/trio/_tests/test_timeouts.py
diff --git a/trio/_tests/test_tracing.py b/src/trio/_tests/test_tracing.py
similarity index 100%
rename from trio/_tests/test_tracing.py
rename to src/trio/_tests/test_tracing.py
diff --git a/trio/_tests/test_unix_pipes.py b/src/trio/_tests/test_unix_pipes.py
similarity index 100%
rename from trio/_tests/test_unix_pipes.py
rename to src/trio/_tests/test_unix_pipes.py
diff --git a/trio/_tests/test_util.py b/src/trio/_tests/test_util.py
similarity index 100%
rename from trio/_tests/test_util.py
rename to src/trio/_tests/test_util.py
diff --git a/trio/_tests/test_wait_for_object.py b/src/trio/_tests/test_wait_for_object.py
similarity index 100%
rename from trio/_tests/test_wait_for_object.py
rename to src/trio/_tests/test_wait_for_object.py
diff --git a/trio/_tests/test_windows_pipes.py b/src/trio/_tests/test_windows_pipes.py
similarity index 100%
rename from trio/_tests/test_windows_pipes.py
rename to src/trio/_tests/test_windows_pipes.py
diff --git a/trio/_tests/tools/__init__.py b/src/trio/_tests/tools/__init__.py
similarity index 100%
rename from trio/_tests/tools/__init__.py
rename to src/trio/_tests/tools/__init__.py
diff --git a/trio/_tests/tools/test_gen_exports.py b/src/trio/_tests/tools/test_gen_exports.py
similarity index 100%
rename from trio/_tests/tools/test_gen_exports.py
rename to src/trio/_tests/tools/test_gen_exports.py
diff --git a/trio/_tests/tools/test_mypy_annotate.py b/src/trio/_tests/tools/test_mypy_annotate.py
similarity index 100%
rename from trio/_tests/tools/test_mypy_annotate.py
rename to src/trio/_tests/tools/test_mypy_annotate.py
diff --git a/trio/_tests/verify_types_darwin.json b/src/trio/_tests/verify_types_darwin.json
similarity index 100%
rename from trio/_tests/verify_types_darwin.json
rename to src/trio/_tests/verify_types_darwin.json
diff --git a/trio/_tests/verify_types_linux.json b/src/trio/_tests/verify_types_linux.json
similarity index 100%
rename from trio/_tests/verify_types_linux.json
rename to src/trio/_tests/verify_types_linux.json
diff --git a/trio/_tests/verify_types_windows.json b/src/trio/_tests/verify_types_windows.json
similarity index 100%
rename from trio/_tests/verify_types_windows.json
rename to src/trio/_tests/verify_types_windows.json
diff --git a/trio/_threads.py b/src/trio/_threads.py
similarity index 100%
rename from trio/_threads.py
rename to src/trio/_threads.py
diff --git a/trio/_timeouts.py b/src/trio/_timeouts.py
similarity index 100%
rename from trio/_timeouts.py
rename to src/trio/_timeouts.py
diff --git a/trio/_tools/__init__.py b/src/trio/_tools/__init__.py
similarity index 100%
rename from trio/_tools/__init__.py
rename to src/trio/_tools/__init__.py
diff --git a/trio/_tools/gen_exports.py b/src/trio/_tools/gen_exports.py
similarity index 99%
rename from trio/_tools/gen_exports.py
rename to src/trio/_tools/gen_exports.py
index 6549d473ab..d40f8d5c78 100755
--- a/trio/_tools/gen_exports.py
+++ b/src/trio/_tools/gen_exports.py
@@ -252,7 +252,7 @@ def main() -> None:  # pragma: no cover
     source_root = Path.cwd()
     # Double-check we found the right directory
     assert (source_root / "LICENSE").exists()
-    core = source_root / "trio/_core"
+    core = source_root / "src/trio/_core"
     to_wrap = [
         File(core / "_run.py", "runner", imports=IMPORTS_RUN),
         File(
diff --git a/trio/_tools/mypy_annotate.py b/src/trio/_tools/mypy_annotate.py
similarity index 100%
rename from trio/_tools/mypy_annotate.py
rename to src/trio/_tools/mypy_annotate.py
diff --git a/trio/_unix_pipes.py b/src/trio/_unix_pipes.py
similarity index 100%
rename from trio/_unix_pipes.py
rename to src/trio/_unix_pipes.py
diff --git a/trio/_util.py b/src/trio/_util.py
similarity index 100%
rename from trio/_util.py
rename to src/trio/_util.py
diff --git a/trio/_version.py b/src/trio/_version.py
similarity index 100%
rename from trio/_version.py
rename to src/trio/_version.py
diff --git a/trio/_wait_for_object.py b/src/trio/_wait_for_object.py
similarity index 100%
rename from trio/_wait_for_object.py
rename to src/trio/_wait_for_object.py
diff --git a/trio/_windows_pipes.py b/src/trio/_windows_pipes.py
similarity index 100%
rename from trio/_windows_pipes.py
rename to src/trio/_windows_pipes.py
diff --git a/trio/abc.py b/src/trio/abc.py
similarity index 100%
rename from trio/abc.py
rename to src/trio/abc.py
diff --git a/trio/from_thread.py b/src/trio/from_thread.py
similarity index 100%
rename from trio/from_thread.py
rename to src/trio/from_thread.py
diff --git a/trio/lowlevel.py b/src/trio/lowlevel.py
similarity index 100%
rename from trio/lowlevel.py
rename to src/trio/lowlevel.py
diff --git a/trio/py.typed b/src/trio/py.typed
similarity index 100%
rename from trio/py.typed
rename to src/trio/py.typed
diff --git a/trio/socket.py b/src/trio/socket.py
similarity index 100%
rename from trio/socket.py
rename to src/trio/socket.py
diff --git a/trio/testing/__init__.py b/src/trio/testing/__init__.py
similarity index 100%
rename from trio/testing/__init__.py
rename to src/trio/testing/__init__.py
diff --git a/trio/testing/_check_streams.py b/src/trio/testing/_check_streams.py
similarity index 100%
rename from trio/testing/_check_streams.py
rename to src/trio/testing/_check_streams.py
diff --git a/trio/testing/_checkpoints.py b/src/trio/testing/_checkpoints.py
similarity index 100%
rename from trio/testing/_checkpoints.py
rename to src/trio/testing/_checkpoints.py
diff --git a/trio/testing/_fake_net.py b/src/trio/testing/_fake_net.py
similarity index 100%
rename from trio/testing/_fake_net.py
rename to src/trio/testing/_fake_net.py
diff --git a/trio/testing/_memory_streams.py b/src/trio/testing/_memory_streams.py
similarity index 100%
rename from trio/testing/_memory_streams.py
rename to src/trio/testing/_memory_streams.py
diff --git a/trio/testing/_network.py b/src/trio/testing/_network.py
similarity index 100%
rename from trio/testing/_network.py
rename to src/trio/testing/_network.py
diff --git a/trio/testing/_sequencer.py b/src/trio/testing/_sequencer.py
similarity index 100%
rename from trio/testing/_sequencer.py
rename to src/trio/testing/_sequencer.py
diff --git a/trio/testing/_trio_test.py b/src/trio/testing/_trio_test.py
similarity index 100%
rename from trio/testing/_trio_test.py
rename to src/trio/testing/_trio_test.py
diff --git a/trio/tests.py b/src/trio/tests.py
similarity index 100%
rename from trio/tests.py
rename to src/trio/tests.py
diff --git a/trio/to_thread.py b/src/trio/to_thread.py
similarity index 100%
rename from trio/to_thread.py
rename to src/trio/to_thread.py