From 78d4aa3d0108fad32ca200eb4f12cd09be48635f Mon Sep 17 00:00:00 2001
From: metagn <metagngn@gmail.com>
Date: Wed, 30 Aug 2023 08:23:14 +0300
Subject: [PATCH] handle typedesc params in VM (#22581)

* handle typedesc params in VM

fixes #15760

* add test

* fix getType(typedesc) test

(cherry picked from commit 2e4e2f8f5076b39e5976ba20f231f468b1b5052c)
---
 compiler/vmgen.nim     |  8 +++++++-
 tests/vm/ttypedesc.nim | 18 ++++++++++++++++++
 tests/vm/tvmmisc.nim   |  5 +++--
 3 files changed, 28 insertions(+), 3 deletions(-)
 create mode 100644 tests/vm/ttypedesc.nim

diff --git a/compiler/vmgen.nim b/compiler/vmgen.nim
index 0ce90a4158..6d556fa9d4 100644
--- a/compiler/vmgen.nim
+++ b/compiler/vmgen.nim
@@ -1534,6 +1534,7 @@ proc checkCanEval(c: PCtx; n: PNode) =
     # little hack ahead for bug #12612: assume gensym'ed variables
     # are in the right scope:
     if sfGenSym in s.flags and c.prc.sym == nil: discard
+    elif s.kind == skParam and s.typ.kind == tyTypeDesc: discard
     else: cannotEval(c, n)
   elif s.kind in {skProc, skFunc, skConverter, skMethod,
                   skIterator} and sfForward in s.flags:
@@ -2088,8 +2089,13 @@ proc gen(c: PCtx; n: PNode; dest: var TDest; flags: TGenFlags = {}) =
     let s = n.sym
     checkCanEval(c, n)
     case s.kind
-    of skVar, skForVar, skTemp, skLet, skParam, skResult:
+    of skVar, skForVar, skTemp, skLet, skResult:
       genRdVar(c, n, dest, flags)
+    of skParam:
+      if s.typ.kind == tyTypeDesc:
+        genTypeLit(c, s.typ, dest)
+      else:
+        genRdVar(c, n, dest, flags)
     of skProc, skFunc, skConverter, skMacro, skTemplate, skMethod, skIterator:
       # 'skTemplate' is only allowed for 'getAst' support:
       if s.kind == skIterator and s.typ.callConv == TCallingConvention.ccClosure:
diff --git a/tests/vm/ttypedesc.nim b/tests/vm/ttypedesc.nim
new file mode 100644
index 0000000000..a112584c54
--- /dev/null
+++ b/tests/vm/ttypedesc.nim
@@ -0,0 +1,18 @@
+block: # issue #15760
+  type
+    Banana = object
+    SpecialBanana = object
+    
+  proc getName(_: type Banana): string = "Banana"
+  proc getName(_: type SpecialBanana): string = "SpecialBanana"
+
+  proc x[T](): string = 
+    const n = getName(T) # this one works
+    result = n
+    
+  proc y(T: type): string =
+    const n = getName(T) # this one failed to compile
+    result = n
+
+  doAssert x[SpecialBanana]() == "SpecialBanana"
+  doAssert y(SpecialBanana) == "SpecialBanana"
diff --git a/tests/vm/tvmmisc.nim b/tests/vm/tvmmisc.nim
index d1c9ace405..e5fb5755ea 100644
--- a/tests/vm/tvmmisc.nim
+++ b/tests/vm/tvmmisc.nim
@@ -1,10 +1,11 @@
-# bug #4462
 import macros
 import os
 
+# bug #4462
 block:
   proc foo(t: typedesc) {.compileTime.} =
-    assert sameType(getType(t), getType(int))
+    assert sameType(getType(t), getType(typedesc[int]))
+    assert sameType(getType(t), getType(type int))
 
   static:
     foo(int)