explore using ctx.actions.declare_symlink

Author: philsc

python/bin/BUILD.bazel

@@ -10,6 +10,10 @@ _interpreter_binary(
     name = "python",
     binary = ":python_src",
     visibility = ["//visibility:public"],
+    target_compatible_with = select({
+        "@platforms//os:windows": ["@platforms//:incompatible"],
+        "//conditions:default": [],
+    }),
 )
 
 # The user can modify this flag to source different interpreters for the

python/private/interpreter.bzl

@@ -18,6 +18,7 @@ load("@bazel_skylib//lib:paths.bzl", "paths")
 load("//python:py_runtime_info.bzl", "PyRuntimeInfo")
 load(":sentinel.bzl", "SentinelInfo")
 load(":toolchain_types.bzl", "TARGET_TOOLCHAIN_TYPE")
+load(":py_executable.bzl", "relative_path", "runfiles_root_path")
 
 def _interpreter_binary_impl(ctx):
     if SentinelInfo in ctx.attr.binary:
@@ -30,6 +31,13 @@ def _interpreter_binary_impl(ctx):
     # because of things like pyenv: they use $0 to determine what to
     # re-exec. If it's not a recognized name, then they fail.
     if runtime.interpreter:
+        # Option 1:
+        # Works locally, but not remotely.
+        #executable = ctx.actions.declare_file(runtime.interpreter.basename)
+        #ctx.actions.symlink(output = executable, target_file = runtime.interpreter)
+
+        # Option 2:
+        # Works locally, and remotely, but not on Windows.
         executable = ctx.actions.declare_file(runtime.interpreter.basename)
         ctx.actions.expand_template(
             template = ctx.file._template,
@@ -39,6 +47,14 @@ def _interpreter_binary_impl(ctx):
             },
             is_executable = True,
         )
+
+        # Option 3:
+        # Works locally and remotely, but only in runfiles, doesn't work via "bazel run".
+        #executable = ctx.actions.declare_symlink(runtime.interpreter.basename)
+        #ctx.actions.symlink(output = executable, target_path = relative_path(
+        #    from_ = paths.dirname(runfiles_root_path(ctx, executable.short_path)),
+        #    to = runfiles_root_path(ctx, runtime.interpreter.short_path),
+        #))
     else:
         executable = ctx.actions.declare_symlink(paths.basename(runtime.interpreter_path))
         ctx.actions.symlink(output = executable, target_path = runtime.interpreter_path)

python/private/py_executable.bzl

@@ -447,7 +447,7 @@ def _create_executable(
     )
 
 def _create_zip_main(ctx, *, stage2_bootstrap, runtime_details, venv):
-    python_binary = _runfiles_root_path(ctx, venv.interpreter.short_path)
+    python_binary = runfiles_root_path(ctx, venv.interpreter.short_path)
     python_binary_actual = venv.interpreter_actual_path
 
     # The location of this file doesn't really matter. It's added to
@@ -522,7 +522,7 @@ def _create_venv(ctx, output_prefix, imports, runtime_details):
 
     if not venvs_use_declare_symlink_enabled:
         if runtime.interpreter:
-            interpreter_actual_path = _runfiles_root_path(ctx, runtime.interpreter.short_path)
+            interpreter_actual_path = runfiles_root_path(ctx, runtime.interpreter.short_path)
         else:
             interpreter_actual_path = runtime.interpreter_path
 
@@ -543,11 +543,11 @@ def _create_venv(ctx, output_prefix, imports, runtime_details):
         # may choose to write what symlink() points to instead.
         interpreter = ctx.actions.declare_symlink("{}/bin/{}".format(venv, py_exe_basename))
 
-        interpreter_actual_path = _runfiles_root_path(ctx, runtime.interpreter.short_path)
+        interpreter_actual_path = runfiles_root_path(ctx, runtime.interpreter.short_path)
         rel_path = relative_path(
             # dirname is necessary because a relative symlink is relative to
             # the directory the symlink resides within.
-            from_ = paths.dirname(_runfiles_root_path(ctx, interpreter.short_path)),
+            from_ = paths.dirname(runfiles_root_path(ctx, interpreter.short_path)),
             to = interpreter_actual_path,
         )
 
@@ -646,7 +646,7 @@ def _create_stage2_bootstrap(
     )
     return output
 
-def _runfiles_root_path(ctx, short_path):
+def runfiles_root_path(ctx, short_path):
     """Compute a runfiles-root relative path from `File.short_path`
 
     Args:
@@ -676,7 +676,7 @@ def _create_stage1_bootstrap(
     runtime = runtime_details.effective_runtime
 
     if venv:
-        python_binary_path = _runfiles_root_path(ctx, venv.interpreter.short_path)
+        python_binary_path = runfiles_root_path(ctx, venv.interpreter.short_path)
     else:
         python_binary_path = runtime_details.executable_interpreter_path