From 14e1f82f426e6eaf027292ab3fa4472cf0374262 Mon Sep 17 00:00:00 2001
From: Andreas Rumpf <rumpf_a@web.de>
Date: Tue, 11 Feb 2020 23:48:41 +0100
Subject: [PATCH] fixes #13378 [backport] (#13392)

(cherry picked from commit c446c0f57af03e0be3a5b39be48d14676e7deebe)
---
 compiler/sigmatch.nim        |  2 ++
 tests/generics/tgeneric0.nim | 16 ++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/compiler/sigmatch.nim b/compiler/sigmatch.nim
index 5fa7c995a472..a15df695c2ed 100644
--- a/compiler/sigmatch.nim
+++ b/compiler/sigmatch.nim
@@ -1945,6 +1945,8 @@ proc localConvMatch(c: PContext, m: var TCandidate, f, a: PType,
 
   if result != nil:
     if result.typ == nil: return nil
+    # bug #13378, ensure we produce a real generic instantiation:
+    result = c.semExpr(c, call)
     # resulting type must be consistent with the other arguments:
     var r = typeRel(m, f.sons[0], result.typ)
     if r < isGeneric: return nil
diff --git a/tests/generics/tgeneric0.nim b/tests/generics/tgeneric0.nim
index ca012734b9ef..ae4820f5719e 100644
--- a/tests/generics/tgeneric0.nim
+++ b/tests/generics/tgeneric0.nim
@@ -4,6 +4,7 @@ discard """
 0
 float32
 float32
+(name: "Resource 1", readers: ..., writers: ...)
 '''
 """
 
@@ -124,3 +125,18 @@ block tgeneric5:
     echo T
 
   bar(0.0'f32)
+
+# bug #13378
+
+type
+  Resource = ref object of RootObj
+    name: string
+    readers, writers: seq[RenderTask]
+
+  RenderTask = ref object
+    name: string
+
+var res = Resource(name: "Resource 1")
+
+(proc (r: typeof(res)) =
+   echo r[])(res)