From 0d6dcff9b6a57a61457dd29ffad23f1c881c5afb Mon Sep 17 00:00:00 2001
From: Fabian Meumertzheim <fabian@meumertzhe.im>
Date: Mon, 22 May 2023 01:09:10 +0200
Subject: [PATCH] WIP

---
 internal/bzlmod/go_deps.bzl | 39 ++++++++++++++++++++++++++-----------
 1 file changed, 28 insertions(+), 11 deletions(-)

diff --git a/internal/bzlmod/go_deps.bzl b/internal/bzlmod/go_deps.bzl
index 90cb6d05d..49800c72e 100644
--- a/internal/bzlmod/go_deps.bzl
+++ b/internal/bzlmod/go_deps.bzl
@@ -18,6 +18,8 @@ load(
 
 visibility("//")
 
+_HIGHEST_VERSION_SENTINEL = semver.to_comparable("999999.999999.999999")
+
 _FORBIDDEN_OVERRIDE_TAG = """\
 Using the "go_deps.{tag_class}" tag in a non-root Bazel module is forbidden, \
 but module "{module_name}" requests it.
@@ -251,12 +253,20 @@ def _go_deps_impl(module_ctx):
             if module.is_root:
                 replace_map.update(go_mod_replace_map)
             else:
-                # Register this Bazel module as providing the specified Go module.
-                # This ensures that there is only ever one repository representing each Go module.
-                bazel_deps[module_path] = struct(
-                    canonical_name = "@" + from_file_tag.go_mod.workspace_name,
-                    module_name = module.name,
-                )
+                # Register this Bazel module as providing the specified Go module. It participates
+                # in version resolution using its registry version, which is assumed to be an
+                # actual semver. An empty version string signals an override, which is assumed to
+                # be newer than any other version.
+                # TODO: Decide whether and how to handle non-semver versions.
+                raw_version = _canonicalize_raw_version(module.version)
+                version = semver.to_comparable(raw_version) if raw_version else _HIGHEST_VERSION_SENTINEL
+                if module_path not in bazel_deps or version > bazel_deps[module_path].version:
+                    bazel_deps[module_path] = struct(
+                        module_name = module.name,
+                        repo_name = "@" + from_file_tag.go_mod.workspace_name,
+                        version = version,
+                        raw_version = raw_version,
+                    )
 
             # Load all sums from transitively resolved `go.sum` files that have modules.
             if len(module_tags_from_go_mod) > 0:
@@ -342,7 +352,16 @@ def _go_deps_impl(module_ctx):
                     # not ever report an implicit version upgrade.
                     root_versions.pop(path)
                 else:
-                    root_versions[path] = new_version
+                    root_versions[path] = replace.version
+
+    for path, bazel_dep in bazel_deps.items():
+        if path in gazelle_overrides or path in module_overrides or path in replace_map:
+            continue
+        if path not in module_resolutions or bazel_dep.version >= module_resolutions[path].version:
+            # The Bazel module may not be declared as a Go dependency, so don't fail if it doesn't
+            # appear in these maps.
+            module_resolutions.pop(path, None)
+            root_versions.pop(path, None)
 
     for path, root_version in root_versions.items():
         if semver.to_comparable(root_version) < module_resolutions[path].version:
@@ -377,13 +396,12 @@ def _go_deps_impl(module_ctx):
         importpaths = {
             module.repo_name: path
             for path, module in module_resolutions.items()
-            if path not in bazel_deps
         } | {
-            info.canonical_name: path
+            info.repo_name: path
             for path, info in bazel_deps.items()
         },
         module_names = {
-            info.canonical_name: info.module_name
+            info.repo_name: info.module_name
             for path, info in bazel_deps.items()
         },
         build_naming_conventions = drop_nones({
@@ -392,7 +410,6 @@ def _go_deps_impl(module_ctx):
                 "go_naming_convention",
             )
             for path, module in module_resolutions.items()
-            if path not in bazel_deps
         }),
     )