[wip] Merge validate goal with lint goal

# Rust tests and lints will be skipped. Delete if not intended.
[ci skip-rust]

# Building wheels and fs_util will be skipped. Delete if not intended.
[ci skip-build-wheels]

src/python/pants/backend/project_info/source_file_validator.py

@@ -10,13 +10,16 @@
 from typing import Any, cast
 
 from pants.base.exiter import PANTS_FAILED_EXIT_CODE, PANTS_SUCCEEDED_EXIT_CODE
+from pants.core.goals.lint import LintFilesRequest, LintResult, LintResults
 from pants.engine.collection import Collection
 from pants.engine.console import Console
-from pants.engine.fs import Digest, DigestContents, SpecsSnapshot
+from pants.engine.fs import Digest, DigestContents, PathGlobs, SpecsSnapshot
 from pants.engine.goal import Goal, GoalSubsystem
-from pants.engine.rules import Get, collect_rules, goal_rule
+from pants.engine.rules import Get, collect_rules, goal_rule, rule
+from pants.engine.unions import UnionRule
 from pants.option.subsystem import Subsystem
 from pants.util.frozendict import FrozenDict
+from pants.util.logging import LogLevel
 from pants.util.memo import memoized_method
 
 
@@ -330,5 +333,55 @@ async def validate(
     return Validate(exit_code)
 
 
+class ValidateRequest(LintFilesRequest):
+    pass
+
+
+@rule(desc="Validate source files", level=LogLevel.DEBUG)
+async def validate_as_lint(
+    request: ValidateRequest, source_file_validation: SourceFileValidation
+) -> LintResults:
+    multi_matcher = source_file_validation.get_multi_matcher()
+    digest_contents = await Get(DigestContents, PathGlobs(request.file_paths))
+    regex_match_results = RegexMatchResults(
+        multi_matcher.check_source_file(file_content.path, file_content.content)
+        for file_content in sorted(digest_contents, key=lambda fc: fc.path)
+    )
+
+    stdout = ""
+    detail_level = DetailLevel.nonmatching
+    num_matched_all = 0
+    num_nonmatched_some = 0
+    for rmr in regex_match_results:
+        if not rmr.matching and not rmr.nonmatching:
+            continue
+        if detail_level == DetailLevel.names:
+            if rmr.nonmatching:
+                stdout += f"{rmr.path}\n"
+            continue
+
+        if rmr.nonmatching:
+            icon = "X"
+            num_nonmatched_some += 1
+        else:
+            icon = "V"
+            num_matched_all += 1
+        matched_msg = " Matched: {}".format(",".join(rmr.matching)) if rmr.matching else ""
+        nonmatched_msg = (
+            " Didn't match: {}".format(",".join(rmr.nonmatching)) if rmr.nonmatching else ""
+        )
+        if detail_level == DetailLevel.all or (
+            detail_level == DetailLevel.nonmatching and nonmatched_msg
+        ):
+            stdout += f"{icon} {rmr.path}:{matched_msg}{nonmatched_msg}\n"
+
+    if detail_level not in (DetailLevel.none, DetailLevel.names):
+        stdout += f"\n{num_matched_all} files matched all required patterns.\n"
+        stdout += f"{num_nonmatched_some} files failed to match at least one required pattern."
+
+    exit_code = PANTS_FAILED_EXIT_CODE if num_nonmatched_some else PANTS_SUCCEEDED_EXIT_CODE
+    return LintResults((LintResult(exit_code, stdout, ""),), linter_name="validate")
+
+
 def rules():
-    return collect_rules()
+    return (*collect_rules(), UnionRule(LintFilesRequest, ValidateRequest))

src/python/pants/core/goals/lint.py

@@ -12,7 +12,7 @@
 from pants.core.util_rules.distdir import DistDir
 from pants.engine.console import Console
 from pants.engine.engine_aware import EngineAwareReturnType
-from pants.engine.fs import EMPTY_DIGEST, Digest, Workspace
+from pants.engine.fs import EMPTY_DIGEST, Digest, SpecsSnapshot, Workspace
 from pants.engine.goal import Goal, GoalSubsystem
 from pants.engine.process import FallibleProcessResult
 from pants.engine.rules import Get, MultiGet, collect_rules, goal_rule
@@ -133,6 +133,14 @@ class LintRequest(StyleRequest):
     """
 
 
+@union
+@dataclass(frozen=True)
+class LintFilesRequest:
+    """The entry point for linters that do not use targets."""
+
+    file_paths: tuple[str, ...]
+
+
 # If a user wants linter reports to show up in dist/ they must ensure that the reports
 # are written under this directory. E.g.,
 # ./pants --flake8-args="--output-file=reports/report.txt" lint <target>
@@ -178,27 +186,39 @@ async def lint(
     console: Console,
     workspace: Workspace,
     targets: Targets,
+    specs_snapshot: SpecsSnapshot,
     lint_subsystem: LintSubsystem,
     union_membership: UnionMembership,
     dist_dir: DistDir,
 ) -> Lint:
-    request_types = cast("Iterable[type[StyleRequest]]", union_membership[LintRequest])
-    requests = tuple(
+    target_requests = tuple(
         request_type(
             request_type.field_set_type.create(target)
             for target in targets
             if request_type.field_set_type.is_applicable(target)
         )
-        for request_type in request_types
+        for request_type in union_membership[LintRequest]
+    )
+    file_requests = tuple(
+        request_type(specs_snapshot.snapshot.files)
+        for request_type in union_membership[LintFilesRequest]
     )
 
     if lint_subsystem.per_file_caching:
-        all_per_file_results = await MultiGet(
-            Get(LintResults, LintRequest, request.__class__([field_set]))
-            for request in requests
-            for field_set in request.field_sets
-            if request.field_sets
-        )
+        all_requests = [
+            *(
+                Get(LintResults, LintRequest, request.__class__([field_set]))
+                for request in target_requests
+                for field_set in request.field_sets
+                if request.field_sets
+            ),
+            *(
+                Get(LintResults, LintFilesRequest, request.__class__((fp,)))
+                for request in file_requests
+                for fp in request.file_paths
+            ),
+        ]
+        all_per_file_results = await MultiGet(all_requests)
 
         def key_fn(results: LintResults):
             return results.linter_name
@@ -218,9 +238,15 @@ def key_fn(results: LintResults):
             )
         )
     else:
-        all_results = await MultiGet(
-            Get(LintResults, LintRequest, request) for request in requests if request.field_sets
-        )
+        all_requests = [
+            *(
+                Get(LintResults, LintRequest, request)
+                for request in target_requests
+                if request.field_sets
+            ),
+            *(Get(LintResults, LintFilesRequest, request) for request in file_requests),
+        ]
+        all_results = await MultiGet(all_requests)
 
     all_results = tuple(sorted(all_results, key=lambda results: results.linter_name))