Allow for codegen targets to be used directly by JVM compiler requests (

#14751)

This amends `ClasspathEntryRequest.for_targets` to accept a codegen source request target and output a `ClasspathEntryRequest` that corresponds to a relevant JVM compilation request.

With this approach, it seems that any `GenerateSourcesRequest` with `output` that is compatible with a `ClasspathEntryRequest` will Just Work™. To demonstrate this in action, there's backend registration support for the Java and Scala protobuf generators included in this PR too. 

The main current limitation is when multiple language backends are enabled for a given codegen source type. A solution for this would address #14041, and realistically needs to take multiple JVM languages into account.

src/python/pants/backend/codegen/protobuf/java/register.py

@@ -0,0 +1,33 @@
+# Copyright 2022 Pants project contributors (see CONTRIBUTORS.md).
+# Licensed under the Apache License, Version 2.0 (see LICENSE).
+
+"""Generate Java sources from Protocol Buffers (Protobufs).
+
+See https://www.pantsbuild.org/docs/protobuf.
+"""
+
+from pants.backend.codegen import export_codegen_goal
+from pants.backend.codegen.protobuf import protobuf_dependency_inference
+from pants.backend.codegen.protobuf import tailor as protobuf_tailor
+from pants.backend.codegen.protobuf.java.rules import rules as java_rules
+from pants.backend.codegen.protobuf.target_types import (
+    ProtobufSourcesGeneratorTarget,
+    ProtobufSourceTarget,
+)
+from pants.backend.codegen.protobuf.target_types import rules as protobuf_target_rules
+from pants.core.util_rules import stripped_source_files
+
+
+def rules():
+    return [
+        *java_rules(),
+        *protobuf_dependency_inference.rules(),
+        *protobuf_tailor.rules(),
+        *export_codegen_goal.rules(),
+        *protobuf_target_rules(),
+        *stripped_source_files.rules(),
+    ]
+
+
+def target_types():
+    return [ProtobufSourcesGeneratorTarget, ProtobufSourceTarget]

src/python/pants/backend/codegen/protobuf/java/rules.py

@@ -3,7 +3,11 @@
 
 
 from pants.backend.codegen.protobuf.protoc import Protoc
-from pants.backend.codegen.protobuf.target_types import ProtobufSourceField
+from pants.backend.codegen.protobuf.target_types import (
+    ProtobufSourceField,
+    ProtobufSourcesGeneratorTarget,
+    ProtobufSourceTarget,
+)
 from pants.backend.java.target_types import JavaSourceField
 from pants.backend.python.util_rules import pex
 from pants.core.util_rules.external_tool import DownloadedExternalTool, ExternalToolRequest
@@ -28,6 +32,7 @@
     TransitiveTargetsRequest,
 )
 from pants.engine.unions import UnionRule
+from pants.jvm.target_types import JvmJdkField
 from pants.source.source_root import SourceRoot, SourceRootRequest
 from pants.util.logging import LogLevel
 
@@ -116,9 +121,15 @@ async def generate_java_from_protobuf(
     return GeneratedSources(source_root_restored)
 
 
+class PrefixedJvmJdkField(JvmJdkField):
+    alias = "jvm_jdk"
+
+
 def rules():
     return [
         *collect_rules(),
         *pex.rules(),
         UnionRule(GenerateSourcesRequest, GenerateJavaFromProtobufRequest),
+        ProtobufSourceTarget.register_plugin_field(PrefixedJvmJdkField),
+        ProtobufSourcesGeneratorTarget.register_plugin_field(PrefixedJvmJdkField),
     ]

src/python/pants/backend/codegen/protobuf/scala/register.py

@@ -0,0 +1,33 @@
+# Copyright 2022 Pants project contributors (see CONTRIBUTORS.md).
+# Licensed under the Apache License, Version 2.0 (see LICENSE).
+
+"""Generate Scala sources from Protocol Buffers (Protobufs).
+
+See https://www.pantsbuild.org/docs/protobuf.
+"""
+
+from pants.backend.codegen import export_codegen_goal
+from pants.backend.codegen.protobuf import protobuf_dependency_inference
+from pants.backend.codegen.protobuf import tailor as protobuf_tailor
+from pants.backend.codegen.protobuf.scala.rules import rules as scala_rules
+from pants.backend.codegen.protobuf.target_types import (
+    ProtobufSourcesGeneratorTarget,
+    ProtobufSourceTarget,
+)
+from pants.backend.codegen.protobuf.target_types import rules as protobuf_target_rules
+from pants.core.util_rules import stripped_source_files
+
+
+def rules():
+    return [
+        *scala_rules(),
+        *protobuf_dependency_inference.rules(),
+        *protobuf_tailor.rules(),
+        *export_codegen_goal.rules(),
+        *protobuf_target_rules(),
+        *stripped_source_files.rules(),
+    ]
+
+
+def target_types():
+    return [ProtobufSourcesGeneratorTarget, ProtobufSourceTarget]

src/python/pants/backend/java/bsp/rules.py

@@ -36,7 +36,11 @@
 )
 from pants.engine.unions import UnionMembership, UnionRule
 from pants.jvm.bsp.spec import JvmBuildTarget
-from pants.jvm.compile import ClasspathEntryRequest, FallibleClasspathEntry
+from pants.jvm.compile import (
+    ClasspathEntryRequest,
+    ClasspathEntryRequestFactory,
+    FallibleClasspathEntry,
+)
 from pants.jvm.resolve.key import CoursierResolveKey
 
 LANGUAGE_ID = "java"
@@ -178,8 +182,7 @@ class JavaBSPCompileFieldSet(BSPCompileFieldSet):
 
 @rule
 async def bsp_java_compile_request(
-    request: JavaBSPCompileFieldSet,
-    union_membership: UnionMembership,
+    request: JavaBSPCompileFieldSet, classpath_entry_request: ClasspathEntryRequestFactory
 ) -> BSPCompileResult:
     coarsened_targets = await Get(CoarsenedTargets, Addresses([request.source.address]))
     assert len(coarsened_targets) == 1
@@ -189,9 +192,7 @@ async def bsp_java_compile_request(
     result = await Get(
         FallibleClasspathEntry,
         ClasspathEntryRequest,
-        ClasspathEntryRequest.for_targets(
-            union_membership, component=coarsened_target, resolve=resolve
-        ),
+        classpath_entry_request.for_targets(component=coarsened_target, resolve=resolve),
     )
     _logger.info(f"java compile result = {result}")
     output_digest = EMPTY_DIGEST

src/python/pants/backend/java/goals/check.py

@@ -11,8 +11,12 @@
 from pants.engine.addresses import Addresses
 from pants.engine.rules import Get, MultiGet, collect_rules, rule
 from pants.engine.target import CoarsenedTargets
-from pants.engine.unions import UnionMembership, UnionRule
-from pants.jvm.compile import ClasspathEntryRequest, FallibleClasspathEntry
+from pants.engine.unions import UnionRule
+from pants.jvm.compile import (
+    ClasspathEntryRequest,
+    ClasspathEntryRequestFactory,
+    FallibleClasspathEntry,
+)
 from pants.jvm.resolve.key import CoursierResolveKey
 from pants.util.logging import LogLevel
 
@@ -27,7 +31,7 @@ class JavacCheckRequest(CheckRequest):
 @rule(desc="Check javac compilation", level=LogLevel.DEBUG)
 async def javac_check(
     request: JavacCheckRequest,
-    union_membership: UnionMembership,
+    classpath_entry_request: ClasspathEntryRequestFactory,
 ) -> CheckResults:
     coarsened_targets = await Get(
         CoarsenedTargets, Addresses(field_set.address for field_set in request.field_sets)
@@ -43,7 +47,7 @@ async def javac_check(
         Get(
             FallibleClasspathEntry,
             ClasspathEntryRequest,
-            ClasspathEntryRequest.for_targets(union_membership, component=target, resolve=resolve),
+            classpath_entry_request.for_targets(component=target, resolve=resolve),
         )
         for target, resolve in zip(coarsened_targets, resolves)
     )

src/python/pants/backend/scala/bsp/rules.py

@@ -29,7 +29,6 @@
 from pants.bsp.util_rules.lifecycle import BSPLanguageSupport
 from pants.bsp.util_rules.targets import BSPBuildTargets, BSPBuildTargetsRequest
 from pants.build_graph.address import Address, AddressInput
-from pants.core.util_rules.system_binaries import BashBinary, UnzipBinary
 from pants.engine.addresses import Addresses
 from pants.engine.fs import EMPTY_DIGEST, AddPrefix, CreateDigest, Digest, DigestEntries
 from pants.engine.internals.selectors import Get, MultiGet
@@ -42,7 +41,11 @@
     WrappedTarget,
 )
 from pants.engine.unions import UnionMembership, UnionRule
-from pants.jvm.compile import ClasspathEntryRequest, FallibleClasspathEntry
+from pants.jvm.compile import (
+    ClasspathEntryRequest,
+    ClasspathEntryRequestFactory,
+    FallibleClasspathEntry,
+)
 from pants.jvm.resolve.key import CoursierResolveKey
 from pants.jvm.subsystems import JvmSubsystem
 from pants.jvm.target_types import JvmResolveField
@@ -199,9 +202,7 @@ class ScalaBSPCompileFieldSet(BSPCompileFieldSet):
 @rule
 async def bsp_scala_compile_request(
     request: ScalaBSPCompileFieldSet,
-    union_membership: UnionMembership,
-    unzip: UnzipBinary,
-    bash: BashBinary,
+    classpath_entry_request: ClasspathEntryRequestFactory,
 ) -> BSPCompileResult:
     coarsened_targets = await Get(CoarsenedTargets, Addresses([request.source.address]))
     assert len(coarsened_targets) == 1
@@ -211,9 +212,7 @@ async def bsp_scala_compile_request(
     result = await Get(
         FallibleClasspathEntry,
         ClasspathEntryRequest,
-        ClasspathEntryRequest.for_targets(
-            union_membership, component=coarsened_target, resolve=resolve
-        ),
+        classpath_entry_request.for_targets(component=coarsened_target, resolve=resolve),
     )
     _logger.info(f"scala compile result = {result}")
     output_digest = EMPTY_DIGEST

src/python/pants/backend/scala/goals/check.py

@@ -11,8 +11,12 @@
 from pants.engine.addresses import Addresses
 from pants.engine.rules import Get, MultiGet, collect_rules, rule
 from pants.engine.target import CoarsenedTargets
-from pants.engine.unions import UnionMembership, UnionRule
-from pants.jvm.compile import ClasspathEntryRequest, FallibleClasspathEntry
+from pants.engine.unions import UnionRule
+from pants.jvm.compile import (
+    ClasspathEntryRequest,
+    ClasspathEntryRequestFactory,
+    FallibleClasspathEntry,
+)
 from pants.jvm.resolve.key import CoursierResolveKey
 from pants.util.logging import LogLevel
 
@@ -27,7 +31,7 @@ class ScalacCheckRequest(CheckRequest):
 @rule(desc="Check compilation for Scala", level=LogLevel.DEBUG)
 async def scalac_check(
     request: ScalacCheckRequest,
-    union_membership: UnionMembership,
+    classpath_entry_request: ClasspathEntryRequestFactory,
 ) -> CheckResults:
     coarsened_targets = await Get(
         CoarsenedTargets, Addresses(field_set.address for field_set in request.field_sets)
@@ -43,7 +47,7 @@ async def scalac_check(
         Get(
             FallibleClasspathEntry,
             ClasspathEntryRequest,
-            ClasspathEntryRequest.for_targets(union_membership, component=target, resolve=resolve),
+            classpath_entry_request.for_targets(component=target, resolve=resolve),
         )
         for target, resolve in zip(coarsened_targets, resolves)
     )

src/python/pants/jvm/classpath.py

@@ -10,8 +10,7 @@
 from pants.engine.fs import Digest
 from pants.engine.rules import Get, MultiGet, collect_rules, rule
 from pants.engine.target import CoarsenedTargets
-from pants.engine.unions import UnionMembership
-from pants.jvm.compile import ClasspathEntry, ClasspathEntryRequest
+from pants.jvm.compile import ClasspathEntry, ClasspathEntryRequest, ClasspathEntryRequestFactory
 from pants.jvm.resolve.key import CoursierResolveKey
 
 logger = logging.getLogger(__name__)
@@ -69,7 +68,7 @@ def root_immutable_inputs_args(self, *, prefix: str = "") -> Iterator[str]:
 @rule
 async def classpath(
     coarsened_targets: CoarsenedTargets,
-    union_membership: UnionMembership,
+    classpath_entry_request: ClasspathEntryRequestFactory,
 ) -> Classpath:
     # Compute a single shared resolve for all of the roots, which will validate that they
     # are compatible with one another.
@@ -80,9 +79,7 @@ async def classpath(
         Get(
             ClasspathEntry,
             ClasspathEntryRequest,
-            ClasspathEntryRequest.for_targets(
-                union_membership, component=t, resolve=resolve, root=True
-            ),
+            classpath_entry_request.for_targets(component=t, resolve=resolve, root=True),
         )
         for t in coarsened_targets
     )