fixes #9381; Fix double evaluation of types in generic objects (#23072)

fixes https://github.com/nim-lang/Nim/issues/9381

(cherry picked from commit 1b7b0d69db)

compiler/semtypinst.nim

@@ -88,7 +88,7 @@ type
     recursionLimit: int
 
 proc replaceTypeVarsTAux(cl: var TReplTypeVars, t: PType): PType
-proc replaceTypeVarsS(cl: var TReplTypeVars, s: PSym): PSym
+proc replaceTypeVarsS(cl: var TReplTypeVars, s: PSym, t: PType): PSym
 proc replaceTypeVarsN*(cl: var TReplTypeVars, n: PNode; start=0; expectedType: PType = nil): PNode
 
 proc initLayeredTypeMap*(pt: TIdTable): LayeredIdTable =
@@ -129,7 +129,12 @@ proc prepareNode(cl: var TReplTypeVars, n: PNode): PNode =
            else: t.n
   result = copyNode(n)
   result.typ = t
-  if result.kind == nkSym: result.sym = replaceTypeVarsS(cl, n.sym)
+  if result.kind == nkSym:
+    result.sym =
+      if n.typ != nil and n.typ == n.sym.typ:
+        replaceTypeVarsS(cl, n.sym, result.typ)
+      else:
+        replaceTypeVarsS(cl, n.sym, replaceTypeVarsT(cl, n.sym.typ))
   let isCall = result.kind in nkCallKinds
   for i in 0..<n.safeLen:
     # XXX HACK: ``f(a, b)``, avoid to instantiate `f`
@@ -224,7 +229,11 @@ proc replaceTypeVarsN(cl: var TReplTypeVars, n: PNode; start=0; expectedType: PT
     discard
   of nkOpenSymChoice, nkClosedSymChoice: result = n
   of nkSym:
-    result.sym = replaceTypeVarsS(cl, n.sym)
+    result.sym =
+      if n.typ != nil and n.typ == n.sym.typ:
+        replaceTypeVarsS(cl, n.sym, result.typ)
+      else:
+        replaceTypeVarsS(cl, n.sym, replaceTypeVarsT(cl, n.sym.typ))
     if result.sym.typ.kind == tyVoid:
       # don't add the 'void' field
       result = newNodeI(nkRecList, n.info)
@@ -266,7 +275,7 @@ proc replaceTypeVarsN(cl: var TReplTypeVars, n: PNode; start=0; expectedType: PT
       for i in start..<n.len:
         result[i] = replaceTypeVarsN(cl, n[i])
 
-proc replaceTypeVarsS(cl: var TReplTypeVars, s: PSym): PSym =
+proc replaceTypeVarsS(cl: var TReplTypeVars, s: PSym, t: PType): PSym =
   if s == nil: return nil
   # symbol is not our business:
   if cl.owner != nil and s.owner != cl.owner:
@@ -307,7 +316,7 @@ proc replaceTypeVarsS(cl: var TReplTypeVars, s: PSym): PSym =
   incl(result.flags, sfFromGeneric)
   #idTablePut(cl.symMap, s, result)
   result.owner = s.owner
-  result.typ = replaceTypeVarsT(cl, s.typ)
+  result.typ = t
   if result.kind != skType:
     result.ast = replaceTypeVarsN(cl, s.ast)
 

tests/generics/tgenerics_various.nim

@@ -231,3 +231,17 @@ doSomething(identity((1, 2)))
 proc myProc[T, U](x: T or U) = discard
 
 myProc[int, string](x = 2)
+
+
+block: # issue #9381
+  var evalCount {.compileTime.} = 0
+
+  macro test(t: typed): untyped =
+    inc evalCount
+    t
+
+  type GenericObj[T] = object
+    f: test(T)
+
+  var x: GenericObj[int]
+  static: doAssert evalCount == 1