fix[ux]: improve error message on failed imports (#4409)

Previously, when an import failed, the error message only displayed
the paths that were attempted, but did not point to the specific import
statement which caused the exception.

To address this, we wrap the main node-handling loop in
`ImportAnalyzer` with `tag_exception`, which propagates information
with the specific line and file to the error message.

tests/functional/syntax/test_import.py

@@ -28,8 +28,9 @@ def foo():
     )
 
     file_input = input_bundle.load_file("top.vy")
-    with pytest.raises(ModuleNotFound):
+    with pytest.raises(ModuleNotFound) as e:
         compiler.compile_from_file_input(file_input, input_bundle=input_bundle)
+    assert "lib0.vy:" in str(e.value)
 
 
 def test_implicitly_relative_import_crashes_2(make_input_bundle):
@@ -44,8 +45,9 @@ def foo():
     )
 
     file_input = input_bundle.load_file("top.vy")
-    with pytest.raises(ModuleNotFound):
+    with pytest.raises(ModuleNotFound) as e:
         compiler.compile_from_file_input(file_input, input_bundle=input_bundle)
+    assert "lib0.vy:" in str(e.value)
 
 
 def test_relative_import_searches_only_current_path(make_input_bundle):
@@ -70,8 +72,9 @@ def foo():
     input_bundle = make_input_bundle({"top.vy": top, "a.vy": a, "subdir/b.vy": b})
     file_input = input_bundle.load_file("top.vy")
 
-    with pytest.raises(ModuleNotFound):
+    with pytest.raises(ModuleNotFound) as e:
         compiler.compile_from_file_input(file_input, input_bundle=input_bundle)
+    assert "b.vy:" in str(e.value)
 
 
 def test_absolute_import_within_relative_import(make_input_bundle):

tests/functional/syntax/test_interfaces.py

@@ -411,26 +411,31 @@ def foobar():
     assert compiler.compile_code(code, input_bundle=input_bundle) is not None
 
 
-def test_builtins_not_found():
+def test_builtins_not_found(make_input_bundle):
     code = """
 from vyper.interfaces import foobar
     """
+    input_bundle = make_input_bundle({"code.vy": code})
+    file_input = input_bundle.load_file("code.vy")
     with pytest.raises(ModuleNotFound) as e:
-        compiler.compile_code(code)
-
+        compiler.compile_from_file_input(file_input, input_bundle=input_bundle)
     assert e.value._message == "vyper.interfaces.foobar"
     assert e.value._hint == "try renaming `vyper.interfaces` to `ethereum.ercs`"
+    assert "code.vy:" in str(e.value)
 
 
 @pytest.mark.parametrize("erc", ("ERC20", "ERC721", "ERC4626"))
-def test_builtins_not_found2(erc):
+def test_builtins_not_found2(erc, make_input_bundle):
     code = f"""
 from ethereum.ercs import {erc}
     """
+    input_bundle = make_input_bundle({"code.vy": code})
+    file_input = input_bundle.load_file("code.vy")
     with pytest.raises(ModuleNotFound) as e:
-        compiler.compile_code(code)
+        compiler.compile_from_file_input(file_input, input_bundle=input_bundle)
     assert e.value._message == f"ethereum.ercs.{erc}"
     assert e.value._hint == f"try renaming `{erc}` to `I{erc}`"
+    assert "code.vy:" in str(e.value)
 
 
 def test_interface_body_check(make_input_bundle):

vyper/semantics/analysis/imports.py

@@ -19,6 +19,7 @@
     ImportCycle,
     ModuleNotFound,
     StructureException,
+    tag_exceptions,
 )
 from vyper.semantics.analysis.base import ImportInfo
 from vyper.utils import safe_relpath, sha256sum
@@ -106,10 +107,11 @@ def _resolve_imports_r(self, module_ast: vy_ast.Module):
             return
         with self.graph.enter_path(module_ast):
             for node in module_ast.body:
-                if isinstance(node, vy_ast.Import):
-                    self._handle_Import(node)
-                elif isinstance(node, vy_ast.ImportFrom):
-                    self._handle_ImportFrom(node)
+                with tag_exceptions(node):
+                    if isinstance(node, vy_ast.Import):
+                        self._handle_Import(node)
+                    elif isinstance(node, vy_ast.ImportFrom):
+                        self._handle_ImportFrom(node)
         self.seen.add(id(module_ast))
 
     def _handle_Import(self, node: vy_ast.Import):