buildGoModule: warn for passthru.overrideModAttrs lost after overriding

doc/release-notes/rl-2511.section.md

@@ -21,7 +21,11 @@
 - The `offrss` package was removed due to lack of upstream maintenance since 2012. It's recommended for users to migrate to another RSS reader
 
 - `base16-builder` node package has been removed due to lack of upstream maintenance.
+
+- `buildGoModule` now warns if `<pkg>.passthru.overrideModAttrs` is lost during the overriding of its result packages.
+
 - `gentium` package now provides `Gentium-*.ttf` files, and not `GentiumPlus-*.ttf` files like before. The font identifiers `Gentium Plus*` are available in the `gentium-plus` package, and if you want to use the more recently updated package `gentium` [by sil](https://software.sil.org/gentium/), you should update your configuration files to use the `Gentium` font identifier.
+
 - `space-orbit` package has been removed due to lack of upstream maintenance. Debian upstream stopped tracking it in 2011.
 
 - Derivations setting both `separateDebugInfo` and one of `allowedReferences`, `allowedRequistes`, `disallowedReferences` or `disallowedRequisites` must now set `__structuredAttrs` to `true`. The effect of reference whitelisting or blacklisting will be disabled on the `debug` output created by `separateDebugInfo`.

pkgs/build-support/go/module.nix

@@ -202,7 +202,15 @@ lib.extendMkDerivation {
             outputHashAlgo = if finalAttrs.vendorHash == "" then "sha256" else null;
             # in case an overlay clears passthru by accident, don't fail evaluation
           }).overrideAttrs
-            (finalAttrs.passthru.overrideModAttrs or overrideModAttrs);
+            (
+              let
+                pos = builtins.unsafeGetAttrPos "passthru" finalAttrs;
+                posString =
+                  if pos == null then "unknown" else "${pos.file}:${toString pos.line}:${toString pos.column}";
+              in
+              finalAttrs.passthru.overrideModAttrs
+                or (lib.warn "buildGoModule: ${finalAttrs.name or finalAttrs.pname}: passthru.overrideModAttrs missing after overrideAttrs. Last overridden at ${posString}." overrideModAttrs)
+            );
 
       nativeBuildInputs = [ go ] ++ nativeBuildInputs;