Use the major version of golang at package time (#21523)

Should hopefully fix #20723

---------

Co-authored-by: Huon Wilson <wilson.huon@gmail.com>

docs/notes/2.24.x.md

@@ -108,6 +108,8 @@ Added a new `cache_scope` field to `adhoc_tool` and `shell_command` targets to a
 
 Fix a bug where Pants raised an internal exception which occurred when compiling a Go package with coverage support when the package also had an external test which imported the base package.
 
+Fix a bug where Pants sent a minor Go version instead of the major one to the Go toolchain during packaging.
+
 Recognize `-fullpath` as a test binary flag.
 
 Add support for the `all:` prefix to patterns used with the `go:embed` directive. The `all:` prefix includes files which start with `_` or `.` which are ordinarilly excluded .

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

@@ -715,7 +715,7 @@ async def build_go_package(
 
     # 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"
+    go_version = go_root.major_version(request.minimum_go_version or "1.16")
     if go_root.is_compatible_version(go_version):
         compile_args.extend(["-lang", f"go{go_version}"])
 

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

@@ -89,7 +89,7 @@ def test_build_pkg(rule_runner: RuleRunner) -> None:
         ).digest,
         s_files=(),
         direct_dependencies=(),
-        minimum_go_version=None,
+        minimum_go_version="1.21.2",
     )
     direct_dep = BuildGoPackageRequest(
         import_path="example.com/foo/dep",

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

@@ -39,6 +39,11 @@ def is_compatible_version(self, version: str) -> bool:
         """Can this Go compiler handle the target version?"""
         return compatible_go_version(compiler_version=self.version, target_version=version)
 
+    def major_version(self, version: str) -> str:
+        _version_components = version.split(".")  # e.g. [1, 17] or [1, 17, 1]
+        major_version = ".".join(_version_components[:2])
+        return major_version
+
     @property
     def full_version(self) -> str:
         return self._raw_metadata["GOVERSION"]