fix: allow symlink collision error to be downgraded

Cargo.toml

@@ -6,7 +6,6 @@ members = [
     "py/tools/unpack_bin",
 ]
 
-
 [workspace.package]
 version = "0.1.0"
 categories = ["development-tools"]
@@ -17,5 +16,8 @@ edition = "2021"
 readme = "README.md"
 rust-version = "1.74.1"
 
+[workspace.dependencies]
+miette = { version = "7.2", features = ["fancy"] }
+
 [profile.release]
 strip = true

examples/pytest/BUILD.bazel

@@ -13,10 +13,11 @@ py_test(
     ],
     imports = ["../.."],
     main = ":__test__.py",
+    package_collisions = "warning",
     deps = [
         ":__test__",
-        "@pypi_pytest//:pkg",
         "@pypi_ftfy//:pkg",
         "@pypi_neptune//:pkg",
+        "@pypi_pytest//:pkg",
     ],
 )

py/defs.bzl

@@ -30,12 +30,15 @@ def _py_binary_or_test(name, rule, srcs, main, deps = [], resolutions = {}, **kw
         **propagate_common_rule_attributes(kwargs)
     )
 
+    package_collisions = kwargs.pop("package_collisions", None)
+
     rule(
         name = name,
         srcs = srcs,
         main = main_target,
         deps = deps,
         resolutions = resolutions,
+        package_collisions = package_collisions,
         **kwargs
     )
 
@@ -44,6 +47,7 @@ def _py_binary_or_test(name, rule, srcs, main, deps = [], resolutions = {}, **kw
         deps = deps,
         imports = kwargs.get("imports"),
         resolutions = resolutions,
+        package_collisions = package_collisions,
         tags = ["manual"],
         testonly = kwargs.get("testonly", False),
     )

py/private/py_binary.bzl

@@ -70,6 +70,7 @@ def _py_binary_rule_impl(ctx):
             "{{BASH_RLOCATION_FN}}": BASH_RLOCATION_FUNCTION,
             "{{INTERPRETER_FLAGS}}": " ".join(py_toolchain.flags),
             "{{VENV_TOOL}}": to_rlocation_path(ctx, venv_toolchain.bin),
+            "{{ARG_COLLISION_STRATEGY}}": ctx.attr.package_collisions,
             "{{ARG_PYTHON}}": to_rlocation_path(ctx, py_toolchain.python) if py_toolchain.runfiles_interpreter else py_toolchain.python.path,
             "{{ARG_VENV_NAME}}": ".{}.venv".format(ctx.attr.name),
             "{{ARG_VENV_PYTHON_VERSION}}": "{}.{}.{}".format(
@@ -172,7 +173,18 @@ python = use_extension("@rules_python//python/extensions:python.bzl", "python")
 python.toolchain(python_version = "3.8.12", is_default = False)
 python.toolchain(python_version = "3.9", is_default = True)
 ```
-"""
+""",
+    ),
+    "package_collisions": attr.string(
+        doc = """The action that should be taken when a symlink collision is encountered when creating the venv.
+A collision can occour when multiple packages providing the same file are installed into the venv. The possible values are:
+
+* "error": When conflicting symlinks are found, an error is reported and venv creation halts.
+* "warning": When conflicting symlinks are found, an warning is reported, however venv creation continues.
+* "ignore": When conflicting symlinks are found, no message is reported and venv creation continues.
+        """,
+        default = "error",
+        values = ["error", "warning", "ignore"],
     ),
     "_run_tmpl": attr.label(
         allow_single_file = True,
@@ -211,7 +223,7 @@ py_base = struct(
         PY_TOOLCHAIN,
         VENV_TOOLCHAIN,
     ],
-    cfg = _python_version_transition
+    cfg = _python_version_transition,
 )
 
 py_binary = rule(
@@ -220,7 +232,7 @@ py_binary = rule(
     attrs = py_base.attrs,
     toolchains = py_base.toolchains,
     executable = True,
-    cfg = py_base.cfg
+    cfg = py_base.cfg,
 )
 
 py_test = rule(
@@ -229,5 +241,5 @@ py_test = rule(
     attrs = py_base.attrs,
     toolchains = py_base.toolchains,
     test = True,
-    cfg = py_base.cfg
+    cfg = py_base.cfg,
 )

py/private/py_venv.bzl

@@ -45,6 +45,7 @@ def _py_venv_rule_imp(ctx):
             "{{INTERPRETER_FLAGS}}": " ".join(py_toolchain.flags),
             "{{VENV_TOOL}}": to_rlocation_path(ctx, venv_toolchain.bin),
             "{{ARG_PYTHON}}": to_rlocation_path(ctx, py_toolchain.python) if py_toolchain.runfiles_interpreter else py_toolchain.python.path,
+            "{{ARG_COLLISION_STRATEGY}}": ctx.attr.package_collisions,
             "{{ARG_VENV_LOCATION}}": paths.join(ctx.attr.location, ctx.attr.venv_name),
             "{{ARG_VENV_PYTHON_VERSION}}": "{}.{}.{}".format(
                 py_toolchain.interpreter_version_info.major,
@@ -108,6 +109,17 @@ _py_venv = rule(
         "resolutions": attr.label_keyed_string_dict(
             doc = "FIXME",
         ),
+        "package_collisions": attr.string(
+            doc = """The action that should be taken when a symlink collision is encountered when creating the venv.
+A collision can occour when multiple packages providing the same file are installed into the venv. The possible values are:
+
+* "error": When conflicting symlinks are found, an error is reported and venv creation halts.
+* "warning": When conflicting symlinks are found, an warning is reported, however venv creation continues.
+* "ignore": When conflicting symlinks are found, no message is reported and venv creation continues.
+            """,
+            default = "error",
+            values = ["error", "warning", "ignore"],
+        ),
         "_venv_tmpl": attr.label(
             allow_single_file = True,
             default = "//py/private:venv.tmpl.sh",

py/private/run.tmpl.sh

@@ -39,7 +39,8 @@ export VIRTUAL_ENV
     --location "${VIRTUAL_ENV}" \
     --python "$(python_location)" \
     --python-version "{{ARG_VENV_PYTHON_VERSION}}" \
-    --pth-file "$(rlocation {{ARG_PTH_FILE}})"
+    --pth-file "$(rlocation {{ARG_PTH_FILE}})" \
+    --collision-strategy "{{ARG_COLLISION_STRATEGY}}"
 
 PATH="${VIRTUAL_ENV}/bin:${PATH}"
 export PATH

py/private/venv.tmpl.sh

@@ -29,4 +29,5 @@ VIRTUAL_ENV="$(alocation "${VENV_ROOT}/{{ARG_VENV_LOCATION}}")"
     --python "$(alocation $(rlocation {{ARG_PYTHON}}))" \
     --python-version "{{ARG_VENV_PYTHON_VERSION}}" \
     --pth-file "$(rlocation {{ARG_PTH_FILE}})" \
-    --pth-entry-prefix "${RUNFILES_DIR}"
+    --pth-entry-prefix "${RUNFILES_DIR}" \
+    --collision-strategy "{{ARG_COLLISION_STRATEGY}}"

py/tests/virtual/django/BUILD.bazel

@@ -29,6 +29,7 @@ py_library(
 py_binary(
     name = "manage",
     srcs = ["proj/manage.py"],
+    package_collisions = "warning",
     # Resolve django to the "standard" one from our requirements.txt
     resolutions = django_resolutions,
     deps = [

py/tests/virtual/django/requirements.in

@@ -1 +1,2 @@
-django==4.2.7
+django==4.2.7
+PyQt6==6.6.1