fix #15916 (#15917) [backport]

* fix #15916

* add testcase for #15916

* add comments

(cherry picked from commit 402df0b061)

compiler/docgen.nim

@@ -591,8 +591,10 @@ proc getRoutineBody(n: PNode): PNode =
   (0 or more) doc comments and runnableExamples.
   ]##
   result = n[bodyPos]
-  if result.kind == nkAsgn and n.len > bodyPos+1 and n[bodyPos+1].kind == nkSym:
-    doAssert result[0].kind == nkSym
+
+  # This won't be transformed: result.id = 10. Namely result[0].kind != nkSym.
+  if result.kind == nkAsgn and result[0].kind == nkSym and
+                               n.len > bodyPos+1 and n[bodyPos+1].kind == nkSym:
     doAssert result.len == 2
     result = result[1]
 

tests/nimdoc/t15916.nim

@@ -0,0 +1,16 @@
+discard """
+cmd: "nim doc --hints:off $file"
+action: "compile"
+joinable: false
+"""
+
+type
+  Test* = object
+    id: int
+
+proc initTest*(id: int): Test =
+  result.id = id
+
+proc hello*() =
+  runnableExamples:
+    discard