fixes #11941 (#12079)

compiler/sem.nim

@@ -403,7 +403,13 @@ proc semAfterMacroCall(c: PContext, call, macroResult: PNode,
   if s.typ.sons[0] == nil:
     result = semStmt(c, result, flags)
   else:
-    case s.typ.sons[0].kind
+    var retType = s.typ.sons[0]
+    if retType.kind == tyTypeDesc and tfUnresolved in retType.flags and
+        retType.len == 1:
+      # bug #11941: template fails(T: type X, v: auto): T
+      # does not mean we expect a tyTypeDesc.
+      retType = retType[0]
+    case retType.kind
     of tyUntyped:
       # Not expecting a type here allows templates like in ``tmodulealias.in``.
       result = semExpr(c, result, flags)
@@ -421,7 +427,6 @@ proc semAfterMacroCall(c: PContext, call, macroResult: PNode,
         result.typ = makeTypeDesc(c, typ)
       #result = symNodeFromType(c, typ, n.info)
     else:
-      var retType = s.typ.sons[0]
       if s.ast[genericParamsPos] != nil and retType.isMetaType:
         # The return type may depend on the Macro arguments
         # e.g. template foo(T: typedesc): seq[T]

compiler/semtypes.nim

@@ -1799,7 +1799,7 @@ proc semTypeNode(c: PContext, n: PNode, prev: PType): PType =
   of nkStmtListType: result = semStmtListType(c, n, prev)
   of nkBlockType: result = semBlockType(c, n, prev)
   else:
-    localError(c.config, n.info, errTypeExpected)
+    localError(c.config, n.info, "type expected, but got: " & renderTree(n))
     result = newOrPrevType(tyError, prev, c)
   n.typ = result
   dec c.inTypeContext

tests/template/template_issues.nim

@@ -6,6 +6,7 @@ output: '''
 a
 hi
 Hello, World!
+(e: 42)
 '''
 """
 
@@ -220,3 +221,17 @@ block t5235:
 
   outer:
     test("Hello, World!")
+
+
+# bug #11941
+type X = object
+  e: int
+
+proc works(T: type X, v: auto): T = T(e: v)
+template fails(T: type X, v: auto): T = T(e: v)
+
+var
+  w = X.works(42)
+  x = X.fails(42)
+
+echo x