[internal] go: refactor link step into separate rule

src/python/pants/backend/experimental/go/register.py

@@ -13,6 +13,7 @@
     go_mod,
     go_pkg,
     import_analysis,
+    link,
     sdk,
 )
 
@@ -31,6 +32,7 @@ def rules():
         *import_analysis.rules(),
         *go_mod.rules(),
         *go_pkg.rules(),
+        *link.rules(),
         *sdk.rules(),
         *tailor.rules(),
         *target_type_rules.rules(),

src/python/pants/backend/go/goals/package_binary.py

@@ -11,7 +11,7 @@
     is_third_party_package_target,
 )
 from pants.backend.go.util_rules.import_analysis import GatheredImports, GatherImportsRequest
-from pants.backend.go.util_rules.sdk import GoSdkProcess
+from pants.backend.go.util_rules.link import LinkedGoBinary, LinkGoBinaryRequest
 from pants.build_graph.address import Address, AddressInput
 from pants.core.goals.package import (
     BuiltPackage,
@@ -21,7 +21,6 @@
 )
 from pants.engine.fs import AddPrefix, Digest, MergeDigests
 from pants.engine.internals.selectors import Get, MultiGet
-from pants.engine.process import ProcessResult
 from pants.engine.rules import collect_rules, rule
 from pants.engine.target import TransitiveTargets, TransitiveTargetsRequest, WrappedTarget
 from pants.engine.unions import UnionRule
@@ -79,27 +78,20 @@ async def package_go_binary(
     )
 
     output_filename = PurePath(field_set.output_path.value_or_default(file_ending=None))
-    result = await Get(
-        ProcessResult,
-        GoSdkProcess(
+
+    binary = await Get(
+        LinkedGoBinary,
+        LinkGoBinaryRequest(
             input_digest=input_digest,
-            command=(
-                "tool",
-                "link",
-                "-importcfg",
-                "./importcfg",
-                "-o",
-                f"./{output_filename.name}",
-                "-buildmode=exe",  # seen in `go build -x` output
-                "./__pkg__.a",
-            ),
+            archives=("./__pkg__.a",),
+            import_config_path="./importcfg",
+            output_filename=f"./{output_filename.name}",
             description="Link Go binary.",
-            output_files=(f"./{output_filename.name}",),
         ),
     )
 
     renamed_output_digest = await Get(
-        Digest, AddPrefix(result.output_digest, str(output_filename.parent))
+        Digest, AddPrefix(binary.output_digest, str(output_filename.parent))
     )
 
     artifact = BuiltPackageArtifact(relpath=str(output_filename))

src/python/pants/backend/go/goals/package_binary_integration_test.py

@@ -18,6 +18,7 @@
     go_mod,
     go_pkg,
     import_analysis,
+    link,
     sdk,
 )
 from pants.build_graph.address import Address
@@ -40,6 +41,7 @@ def rule_runner() -> RuleRunner:
             *build_go_pkg.rules(),
             *go_pkg.rules(),
             *go_mod.rules(),
+            *link.rules(),
             *target_type_rules.rules(),
             *external_module.rules(),
             *sdk.rules(),

src/python/pants/backend/go/util_rules/link.py

@@ -0,0 +1,59 @@
+# Copyright 2021 Pants project contributors (see CONTRIBUTORS.md).
+# Licensed under the Apache License, Version 2.0 (see LICENSE).
+from __future__ import annotations
+
+from dataclasses import dataclass
+
+from pants.backend.go.util_rules.sdk import GoSdkProcess
+from pants.engine.fs import Digest
+from pants.engine.process import ProcessResult
+from pants.engine.rules import Get, collect_rules, rule
+
+
+@dataclass(frozen=True)
+class LinkGoBinaryRequest:
+    """Link a Go binary from package archives and an import configuration."""
+
+    input_digest: Digest
+    archives: tuple[str, ...]
+    import_config_path: str
+    output_filename: str
+    description: str
+
+
+@dataclass(frozen=True)
+class LinkedGoBinary:
+    """A linked Go binary stored in a `Digest`."""
+
+    output_digest: Digest
+    output_filename: str
+
+
+@rule
+async def link_go_binary(request: LinkGoBinaryRequest) -> LinkedGoBinary:
+    result = await Get(
+        ProcessResult,
+        GoSdkProcess(
+            input_digest=request.input_digest,
+            command=(
+                "tool",
+                "link",
+                "-importcfg",
+                request.import_config_path,
+                "-o",
+                request.output_filename,
+                "-buildmode=exe",  # seen in `go build -x` output
+                *request.archives,
+            ),
+            description="Link Go binary.",
+            output_files=(request.output_filename,),
+        ),
+    )
+
+    return LinkedGoBinary(
+        output_digest=result.output_digest, output_filename=request.output_filename
+    )
+
+
+def rules():
+    return collect_rules()