fix[lang]: disallow absolute relative imports

tests/functional/syntax/test_import.py

@@ -0,0 +1,88 @@
+import pytest
+
+from vyper import compiler
+from vyper.exceptions import ModuleNotFound
+
+
+def test_implicitly_relative_import_crashes(make_input_bundle):
+    top = """
+import subdir0.lib0 as lib0
+
+@external
+def foo():
+    lib0.foo()
+    """
+
+    lib0 = """
+import subdir1.lib1 as lib1
+
+def foo():
+    lib1.foo()
+    """
+
+    lib1 = """
+
+def foo():
+    pass
+    """
+
+    input_bundle = make_input_bundle(
+        {"top.vy": top, "subdir0/lib0.vy": lib0, "subdir0/subdir1/lib1.vy": lib1}
+    )
+
+    with pytest.raises(ModuleNotFound):
+        compiler.compile_code(top, input_bundle=input_bundle)
+
+    lib0 = """
+from subdir1 import lib1 as lib1
+
+def foo():
+    lib1.foo()
+    """
+
+    input_bundle = make_input_bundle(
+        {"top.vy": top, "subdir0/lib0.vy": lib0, "subdir0/subdir1/lib1.vy": lib1}
+    )
+
+    with pytest.raises(ModuleNotFound):
+        compiler.compile_code(top, input_bundle=input_bundle)
+
+
+def test_absolute_path_passes(make_input_bundle):
+    top = """
+import subdir0.lib0 as lib0
+
+@external
+def foo():
+    lib0.foo()
+    """
+
+    lib0 = """
+import subdir0.subdir1.lib1 as lib1
+
+def foo():
+    lib1.foo()
+    """
+
+    lib1 = """
+
+def foo():
+    pass
+    """
+
+    input_bundle = make_input_bundle(
+        {"top.vy": top, "subdir0/lib0.vy": lib0, "subdir0/subdir1/lib1.vy": lib1}
+    )
+    compiler.compile_code(top, input_bundle=input_bundle)
+
+    lib0 = """
+from .subdir1 import lib1 as lib1
+
+def foo():
+    lib1.foo()
+    """
+
+    input_bundle = make_input_bundle(
+        {"top.vy": top, "subdir0/lib0.vy": lib0, "subdir0/subdir1/lib1.vy": lib1}
+    )
+    compiler.compile_code(top, input_bundle=input_bundle)

tests/unit/cli/vyper_json/test_compile_json.py

@@ -293,5 +293,5 @@ def get(filename, contractname):
 def test_relative_import_paths(input_json):
     input_json["sources"]["contracts/potato/baz/baz.vy"] = {"content": "from ... import foo"}
     input_json["sources"]["contracts/potato/baz/potato.vy"] = {"content": "from . import baz"}
-    input_json["sources"]["contracts/potato/footato.vy"] = {"content": "from baz import baz"}
+    input_json["sources"]["contracts/potato/footato.vy"] = {"content": "from .baz import baz"}
     compile_from_input_dict(input_json)

vyper/semantics/analysis/module.py

@@ -1,3 +1,4 @@
+import contextlib
 import os
 from pathlib import Path, PurePath
 from typing import Any, Optional
@@ -792,7 +793,9 @@ def _load_import(self, node: vy_ast.VyperNode, level: int, module_str: str, alia
         # the directory this (currently being analyzed) module is in
         self_search_path = Path(self.ast.resolved_path).parent
 
-        with self.input_bundle.poke_search_path(self_search_path):
+        with self.input_bundle.search_path(
+            self_search_path
+        ) if level != 0 else contextlib.nullcontext():
             return self._load_import_helper(node, level, module_str, alias)
 
     def _load_import_helper(