fixes #8052

compiler/semtempl.nim

@@ -210,7 +210,7 @@ proc addLocalDecl(c: var TemplCtx, n: var PNode, k: TSymKind) =
       if s != nil and s.owner == c.owner and sfGenSym in s.flags:
         styleCheckUse(n.info, s)
         replaceIdentBySym(c.c, n, newSymNode(s, n.info))
-      else:
+      elif not (n.kind == nkSym and sfGenSym in n.sym.flags):
         let local = newGenSym(k, ident, c)
         addPrelimDecl(c.c, local)
         styleCheckDef(c.c.config, n.info, local)

tests/template/tnested_template.nim

@@ -0,0 +1,23 @@
+# bug #8052
+
+type
+  UintImpl*[N: static[int], T: SomeUnsignedInt] = object
+    raw_data*: array[N, T]
+
+template genLoHi(TypeImpl: untyped): untyped =
+  template loImpl[N: static[int], T: SomeUnsignedInt](dst: TypeImpl[N div 2, T], src: TypeImpl[N, T]) =
+    let halfSize = N div 2
+    for i in 0 ..< halfSize:
+      dst.raw_data[i] = src.raw_data[i]
+
+  proc lo*[N: static[int], T: SomeUnsignedInt](x: TypeImpl[N,T]): TypeImpl[N div 2, T] {.inline.}=
+    loImpl(result, x)
+
+genLoHi(UintImpl)
+
+var a: UintImpl[4, uint32]
+
+a.raw_data = [1'u32, 2'u32, 3'u32, 4'u32]
+assert a.lo.raw_data.len == 2
+assert a.lo.raw_data[0] == 1
+assert a.lo.raw_data[1] == 2