Emit warnings when requiring or importing with an already used alias (#1050)

Partially addresses #1045

Author: chrisrink10

.gitignore

@@ -51,6 +51,7 @@ docs/_build/
 
 # Environments
 .env
+.graalvenv
 .venv
 env/
 venv/

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased]
 ### Added
  * Added a compiler metadata flag for suppressing warnings when Var indirection is unavoidable (#1052)
+ * Added the `--emit-generated-python` CLI argument to control whether generated Python code strings are stored by the runtime for each compiled namespace (#1045)
+
+### Changed
+ * The compiler will issue a warning when adding any alias that might conflict with any other alias (#1045)
 
 ### Fixed
  * Basilisp now respects the value of Python's `sys.dont_write_bytecode` flag when generating bytecode (#1054)

docs/runtime.rst

@@ -111,6 +111,31 @@ This is roughly analogous to the Java classpath in Clojure.
 These values may be set manually, but are more often configured by some project management tool such as Poetry or defined in your Python virtualenv.
 These values may also be set via :ref:`cli` arguments.
 
+.. _namespace_imports:
+
+Namespace Imports
+^^^^^^^^^^^^^^^^^
+
+Basilisp compiles Lisp code into Python code in Python modules exactly the same way the Python compiler does.
+The Python code compiled by the Basilisp compiler expects certain features to be available at runtime beyond the standard Python builtins.
+To support this, the Python modules compiled by Basilisp automatically import a number of modules both from the Basilisp runtime, the Python standard library, and Basilisp's Python dependencies.
+In Basilisp modules (particularly :lpy:ns:`basilisp.core`) you may find references to such modules without any corresponding :lpy:form:`import`.
+
+The modules imported by default are given below:
+
+- ``attr`` (from the `attrs <https://www.attrs.org/en/stable/>`_ project)
+- :external:py:mod:`builtins` (Basilisp users should prefer the ``python`` namespace for calling :ref:`python_builtins`)
+- :external:py:mod:`functools`
+- :external:py:mod:`io`
+- :external:py:mod:`importlib`
+- :external:py:mod:`operator`
+- :external:py:mod:`sys`
+- The majority of the modules in ``basilisp.lang.*``
+
+.. warning::
+
+   Using any of these names (particularly the Python standard library module names) as an alias for a required namespace or imported Python module will trigger a warning.
+
 .. _vars:
 
 Vars

pyproject.toml

@@ -85,6 +85,7 @@ exclude = '''
     \.git
   | \.hg
   | \.cache
+  | \.graalvenv
   | \.mypy_cache
   | \.pytest_cache
   | \.tox
@@ -133,6 +134,7 @@ skip = [
   ".env",
   ".hg",
   ".git",
+  ".graalvenv",
   ".mypy_cache",
   ".pytest_cache",
   ".tox",

src/basilisp/cli.py

@@ -307,6 +307,20 @@ def _add_debug_arg_group(parser: argparse.ArgumentParser) -> None:
             "(env: BASILISP_LOGGING_LEVEL; default: WARNING)"
         ),
     )
+    group.add_argument(
+        "--emit-generated-python",
+        action=_set_envvar_action(
+            "BASILISP_EMIT_GENERATED_PYTHON", parent=argparse._StoreAction
+        ),
+        nargs="?",
+        const=True,
+        type=_to_bool,
+        help=(
+            "if true, store generated Python code in `*generated-python*` dynamic "
+            "Vars within each namespace (env: BASILISP_EMIT_GENERATED_PYTHON; "
+            "default: true)"
+        ),
+    )
 
 
 def _add_import_arg_group(parser: argparse.ArgumentParser) -> None:

src/basilisp/core.lpy

@@ -6,8 +6,6 @@
          datetime
          decimal
          fractions
-         functools
-         importlib
          importlib.util
          math
          multiprocessing
@@ -20,10 +18,6 @@
          [time :as py-time]
          uuid)
 
-(import* attr)
-
-(import* basilisp.lang.multifn)
-
 (def ^{:doc      "Create a list from the arguments."
        :arglists '([& args])}
   list

src/basilisp/io.lpy

@@ -5,7 +5,6 @@
   streams from a wide variety of different input types as well as utility functions for
   interacting with the filesystem."
   (:import
-   io
    os.path
    pathlib
    shutil

src/basilisp/lang/compiler/__init__.py

@@ -139,7 +139,7 @@ def _emit_ast_string(
     # TODO: eventually, this default should become "false" but during this
     #       period of heavy development, having it set to "true" by default
     #       is tremendously useful
-    if os.getenv("BASILISP_EMIT_GENERATED_PYTHON", "true") != "true":
+    if os.getenv("BASILISP_EMIT_GENERATED_PYTHON", "true").lower() != "true":
         return
 
     if runtime.print_generated_python():

src/basilisp/lang/compiler/analyzer.py

@@ -9,6 +9,7 @@
 import re
 import sys
 import uuid
+from collections import defaultdict
 from datetime import datetime
 from decimal import Decimal
 from fractions import Fraction
@@ -35,6 +36,7 @@
 )
 
 import attr
+from typing_extensions import Literal
 
 from basilisp.lang import keyword as kw
 from basilisp.lang import list as llist
@@ -611,7 +613,7 @@ def syntax_position(self) -> NodeSyntacticPosition:
     def get_node_env(self, pos: Optional[NodeSyntacticPosition] = None) -> NodeEnv:
         """Return the current Node environment.
 
-        If a synax position is given, it will be included in the environment.
+        If a syntax position is given, it will be included in the environment.
         Otherwise, the position will be set to None."""
         return NodeEnv(
             ns=self.current_ns, file=self.filename, pos=pos, func_ctx=self.func_ctx
@@ -2505,6 +2507,55 @@ def _if_ast(form: ISeq, ctx: AnalyzerContext) -> If:
     )
 
 
+T_alias_node = TypeVar("T_alias_node", ImportAlias, RequireAlias)
+
+
+def _do_warn_on_import_or_require_name_clash(
+    ctx: AnalyzerContext,
+    alias_nodes: List[T_alias_node],
+    action: Literal["import", "require"],
+) -> None:
+    assert alias_nodes, "Must have at least one alias"
+
+    # Fetch these locally to avoid triggering more locks than we need to
+    current_ns = ctx.current_ns
+    aliases, import_aliases, imports = (
+        current_ns.aliases,
+        current_ns.import_aliases,
+        current_ns.imports,
+    )
+
+    # Identify duplicates in the import list first
+    name_to_nodes = defaultdict(list)
+    for node in alias_nodes:
+        name_to_nodes[(node.alias or node.name)].append(node)
+
+    for name, nodes in name_to_nodes.items():
+        if len(nodes) < 2:
+            continue
+
+        logger.warning(f"duplicate name or alias '{name}' in {action}")
+
+    # Now check against names in the namespace
+    for name, nodes in name_to_nodes.items():
+        name_sym = sym.symbol(name)
+        node, *_ = nodes
+
+        if name_sym in aliases:
+            logger.warning(
+                f"name '{name}' may shadow an existing alias in '{current_ns}'"
+            )
+        if name_sym in import_aliases:
+            logger.warning(
+                f"name '{name}' may be shadowed by an existing import alias in "
+                f"'{current_ns}'"
+            )
+        if name_sym in imports:
+            logger.warning(
+                f"name '{name}' may be shadowed by an existing import in '{current_ns}'"
+            )
+
+
 def _import_ast(form: ISeq, ctx: AnalyzerContext) -> Import:
     assert form.first == SpecialForm.IMPORT
 
@@ -2567,6 +2618,12 @@ def _import_ast(form: ISeq, ctx: AnalyzerContext) -> Import:
             )
         )
 
+    if not aliases:
+        raise ctx.AnalyzerException(
+            "import forms must name at least one module", form=form
+        )
+
+    _do_warn_on_import_or_require_name_clash(ctx, aliases, "import")
     return Import(
         form=form,
         aliases=aliases,
@@ -3103,6 +3160,12 @@ def _require_ast(form: ISeq, ctx: AnalyzerContext) -> Require:
             )
         )
 
+    if not aliases:
+        raise ctx.AnalyzerException(
+            "require forms must name at least one namespace", form=form
+        )
+
+    _do_warn_on_import_or_require_name_clash(ctx, aliases, "require")
     return Require(
         form=form,
         aliases=aliases,

src/basilisp/lang/compiler/constants.py

@@ -1,5 +1,6 @@
 from basilisp.lang import keyword as kw
 from basilisp.lang import symbol as sym
+from basilisp.lang.util import genname
 
 
 class SpecialForm:
@@ -32,6 +33,8 @@ class SpecialForm:
 
 DEFAULT_COMPILER_FILE_PATH = "NO_SOURCE_PATH"
 
+OPERATOR_ALIAS = genname("operator")
+
 SYM_ABSTRACT_META_KEY = kw.keyword("abstract")
 SYM_ABSTRACT_MEMBERS_META_KEY = kw.keyword("abstract-members")
 SYM_ASYNC_META_KEY = kw.keyword("async")