Rollup merge of #139127 - compiler-errors:prim-ty-hack, r=oli-obk

Fix up partial res of segment in primitive resolution hack

There is a hack in the resolver:

```
// In `a(::assoc_item)*` `a` cannot be a module. If `a` does resolve to a module we
// don't report an error right away, but try to fallback to a primitive type.
```

This fixes up the resolution for primitives which would otherwise resolve to a module, but we weren't also updating the res of the path segment, leading to weird diagnostics.

We explicitly call `self.r.partial_res_map.insert` instead of `record_partial_res` b/c we have recorded a partial res already, and we specifically want to override it.

cc https://github.com/rust-lang/rust/issues/139095#issuecomment-2764371934

compiler/rustc_resolve/src/late.rs

@@ -4606,6 +4606,11 @@ impl<'a, 'ast, 'ra: 'ast, 'tcx> LateResolutionVisitor<'a, 'ast, 'ra, 'tcx> {
                     }
                 };
 
+                // Fix up partial res of segment from `resolve_path` call.
+                if let Some(id) = path[0].id {
+                    self.r.partial_res_map.insert(id, PartialRes::new(Res::PrimTy(prim)));
+                }
+
                 PartialRes::with_unresolved_segments(Res::PrimTy(prim), path.len() - 1)
             }
             PathResult::Module(ModuleOrUniformRoot::Module(module)) => {