Fix handling of Go version for third-party packages (pantsbuild#14457)

We weren't following the spec properly. Closes pantsbuild#14446.

[ci skip-rust]
[ci skip-build-wheels]

src/python/pants/backend/go/subsystems/golang.py

@@ -97,6 +97,24 @@ class GoRoot:
     """Path to the Go installation (the `GOROOT`)."""
 
     path: str
+    version: str
+
+    def is_compatible_version(self, version: str) -> bool:
+        """Can this Go compiler handle the target version?
+
+        Inspired by
+        https://github.com/golang/go/blob/30501bbef9fcfc9d53e611aaec4d20bb3cdb8ada/src/cmd/go/internal/work/exec.go#L429-L445.
+
+        Input expected in the form `1.17`.
+        """
+        if version == "1.0":
+            return True
+
+        def parse(v: str) -> tuple[int, int]:
+            major, minor = v.split(".", maxsplit=1)
+            return int(major), int(minor)
+
+        return parse(version) <= parse(self.version)
 
 
 @rule(desc="Find Go binary", level=LogLevel.DEBUG)
@@ -163,7 +181,7 @@ async def setup_goroot(golang_subsystem: GolangSubsystem) -> GoRoot:
                 ),
             )
             goroot = env_result.stdout.decode("utf-8").strip()
-            return GoRoot(goroot)
+            return GoRoot(goroot, version)
 
         logger.debug(
             f"Go binary at {binary_path.path} has version {version}, but this "

src/python/pants/backend/go/subsystems/golang_test.py

@@ -114,3 +114,13 @@ def test_no_valid_versions(rule_runner: RuleRunner) -> None:
     exc = e.value.wrapped_exceptions[0]
     assert isinstance(exc, BinaryNotFoundError)
     assert "Cannot find a `go` binary with the expected version" in str(exc)
+
+
+def test_valid_go_version() -> None:
+    go_root = GoRoot("", "1.15")
+    for v in range(16):
+        assert go_root.is_compatible_version(f"1.{v}") is True
+    for v in range(17, 40):
+        assert go_root.is_compatible_version(f"1.{v}") is False
+    for v in range(2, 4):
+        assert go_root.is_compatible_version(f"{v}.0") is False

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

@@ -6,6 +6,7 @@
 import os.path
 from dataclasses import dataclass
 
+from pants.backend.go.subsystems.golang import GoRoot
 from pants.backend.go.util_rules.assembly import (
     AssemblyPostCompilation,
     AssemblyPostCompilationRequest,
@@ -198,7 +199,9 @@ class RenderedEmbedConfig:
 # NB: We must have a description for the streaming of this rule to work properly
 # (triggered by `FallibleBuiltGoPackage` subclassing `EngineAwareReturnType`).
 @rule(desc="Compile with Go", level=LogLevel.DEBUG)
-async def build_go_package(request: BuildGoPackageRequest) -> FallibleBuiltGoPackage:
+async def build_go_package(
+    request: BuildGoPackageRequest, go_root: GoRoot
+) -> FallibleBuiltGoPackage:
     maybe_built_deps = await MultiGet(
         Get(FallibleBuiltGoPackage, BuildGoPackageRequest, build_request)
         for build_request in request.direct_dependencies
@@ -255,11 +258,14 @@ async def build_go_package(request: BuildGoPackageRequest) -> FallibleBuiltGoPac
         request.import_path,
         "-importcfg",
         import_config.CONFIG_PATH,
-        # See https://github.com/golang/go/blob/f229e7031a6efb2f23241b5da000c3b3203081d6/src/cmd/go/internal/work/gc.go#L79-L100
-        # for why Go sets the default to 1.16.
-        f"-lang=go{request.minimum_go_version or '1.16'}",
     ]
 
+    # See https://github.com/golang/go/blob/f229e7031a6efb2f23241b5da000c3b3203081d6/src/cmd/go/internal/work/gc.go#L79-L100
+    # for where this logic comes from.
+    go_version = request.minimum_go_version or "1.16"
+    if go_root.is_compatible_version(go_version):
+        compile_args.append(f"-lang=go{go_version}")
+
     if symabis_path:
         compile_args.extend(["-symabis", symabis_path])