Don't WARN when a spec matches no relevant targets.

src/python/pants/base/specs.py

@@ -333,6 +333,7 @@ def __bool__(self) -> bool:
 class Specs:
     address_specs: AddressSpecs
     filesystem_specs: FilesystemSpecs
+    from_change_detection: bool = False
 
     @property
     def provided(self) -> bool:

src/python/pants/engine/internals/graph.py

@@ -1320,7 +1320,18 @@ async def find_valid_field_sets_for_target_roots(
         )
         if request.no_applicable_targets_behavior == NoApplicableTargetsBehavior.error:
             raise no_applicable_exception
-        if request.no_applicable_targets_behavior == NoApplicableTargetsBehavior.warn:
+        # We squelch the warning if the specs came from change detection or only from address globs,
+        # since in that case we interpret the user's intent as "if there are relevant matching
+        # targets, act on them". But we still want to warn if the specs were literal, or empty.
+        empty_ok = specs.from_change_detection or (
+            specs.address_specs.globs
+            and not specs.address_specs.literals
+            and not specs.filesystem_specs
+        )
+        if (
+            request.no_applicable_targets_behavior == NoApplicableTargetsBehavior.warn
+            and not empty_ok
+        ):
             logger.warning(str(no_applicable_exception))
 
     result = TargetRootsToFieldSets(targets_to_applicable_field_sets)

src/python/pants/init/specs_calculator.py

@@ -75,7 +75,11 @@ def calculate_specs(
                 parameters=address_input.parameters,
             )
         )
-    return Specs(AddressSpecs(address_specs, filter_by_global_options=True), FilesystemSpecs([]))
+    return Specs(
+        AddressSpecs(address_specs, filter_by_global_options=True),
+        FilesystemSpecs([]),
+        from_change_detection=True,
+    )
 
 
 def rules():