Debugging...

src/python/pants/backend/python/goals/run_pex_binary_integration_test.py

@@ -369,4 +369,4 @@ def main():
     ]
     result = run_pants(args, use_pantsd=False)
 
-    assert "No such file or directory" not in result.stderr
+    assert "No such file or directory" not in result.stderr, result.stderr

src/python/pants/backend/python/util_rules/python_sources.py

@@ -5,6 +5,7 @@
 
 from dataclasses import dataclass
 from typing import Iterable
+import sys
 
 from pants.backend.python.target_types import PythonSourceField
 from pants.backend.python.util_rules import ancestor_files
@@ -134,6 +135,7 @@ async def prepare_python_sources(
         )
         for tgt in codegen_targets
     )
+    sys.stderr.write(f"{codegen_sources=}\n")
     source_root_requests = [
         *(SourceRootRequest.for_target(tgt) for tgt in python_and_resources_targets),
         *(
@@ -142,11 +144,14 @@ async def prepare_python_sources(
             for f in sources.snapshot.files
         ),
     ]
+    sys.stderr.write(f"{source_root_requests=}\n")
 
     source_root_objs = await MultiGet(
         Get(SourceRoot, SourceRootRequest, req) for req in source_root_requests
     )
     source_root_paths = {source_root_obj.path for source_root_obj in source_root_objs}
+    sys.stderr.write(f"{sources.unrooted_files=}\n")
+    sys.stderr.write(f"{init_injected=}\n")
     return PythonSourceFiles(
         SourceFiles(init_injected, sources.unrooted_files), tuple(sorted(source_root_paths))
     )

src/python/pants/core/register.py

@@ -5,6 +5,7 @@
 
 These are always activated and cannot be disabled.
 """
+
 from pants.backend.codegen import export_codegen_goal
 from pants.build_graph.build_file_aliases import BuildFileAliases
 from pants.core.goals import (
@@ -63,7 +64,11 @@
 from pants.vcs import git
 from pants.version import PANTS_SEMVER
 
-wrap_as_resources = wrap_source_rule_and_target(ResourceSourceField, "resources")
+wrap_as_resources = wrap_source_rule_and_target(
+    ResourceSourceField,
+    "resources",
+    uses_source_roots=True,
+)
 
 
 def rules():

src/python/pants/core/util_rules/source_files.py

@@ -1,6 +1,7 @@
 # Copyright 2020 Pants project contributors (see CONTRIBUTORS.md).
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
+import sys
 from dataclasses import dataclass
 from pathlib import PurePath
 from typing import Collection, Iterable, Set, Tuple, Type, Union
@@ -60,6 +61,8 @@ async def determine_source_files(request: SourceFilesRequest) -> SourceFiles:
     )
 
     for hydrated_sources, sources_field in zip(all_hydrated_sources, request.sources_fields):
+        sys.stderr.write(f"{type(sources_field)=}\n")
+        sys.stderr.write(f"{sources_field.uses_source_roots=}\n")
         if not sources_field.uses_source_roots:
             unrooted_files.update(hydrated_sources.snapshot.files)
 

src/python/pants/core/util_rules/wrap_source.py

@@ -45,6 +45,12 @@ class ActivateWrapSourceTargetFieldBase(MultipleSourcesField):
     uses_source_roots = False
     expected_num_files = 0
 
+class ActivateWrapSourceTargetFieldBase(MultipleSourcesField):
+    # We solely register so that codegen can match a fieldset.
+    # One unique subclass must be defined per target type.
+    alias = "_sources"
+    uses_source_roots = False
+    expected_num_files = 0
 
 class WrapSourceInputsField(SpecialCasedDependencies):
     alias = "inputs"
@@ -99,7 +105,9 @@ async def _wrap_source(wrapper: GenerateSourcesRequest) -> GeneratedSources:
 
 
 def wrap_source_rule_and_target(
-    source_field_type: type[SourcesField], target_name_suffix: str
+    source_field_type: type[SourcesField],
+    target_name_suffix: str,
+    uses_source_roots: bool = False,
 ) -> WrapSource:
     if source_field_type.expected_file_extensions:
         outputs_help = (