fix erroring invoke type (#1161)

fixes #1160

Author: metagn

src/nimony/sem.nim

@@ -3066,11 +3066,17 @@ proc semObjConstr(c: var SemContext, it: var Item) =
     if decl.kind != TypeY:
       # includes typevar case
       c.buildErr info, "expected type for object constructor"
+      skipToEnd it.n
       return
     objType = decl.objBody
     if objType.typeKind != ObjectT:
       c.buildErr info, "expected object type for object constructor"
+      skipToEnd it.n
       return
+  else:
+    c.buildErr info, "expected type symbol for object constructor"
+    skipToEnd it.n
+    return
   # build bindings for invoked object type to get proper types for fields:
   let bindings = bindInvokeArgs(decl, invokeArgs)
   var fieldBuf = createTokenBuf(16)

src/nimony/semtypes.nim

@@ -299,7 +299,7 @@ proc semInvoke(c: var SemContext; n: var Cursor) =
     decl = getTypeSection(headId)
     if decl.kind != TypeY:
       c.buildErr info, "cannot attempt to instantiate a non-type"
-    if decl.typevars.substructureKind != TypevarsU:
+    elif decl.typevars.substructureKind != TypevarsU:
       c.buildErr info, "cannot attempt to instantiate a concrete type"
     else:
       ok = true
@@ -316,8 +316,10 @@ proc semInvoke(c: var SemContext; n: var Cursor) =
     else:
       c.buildErr info, "cannot attempt to instantiate a non-type"
 
-  var params = decl.typevars
-  inc params
+  var params = default(Cursor)
+  if decl.kind == TypeY:
+    params = decl.typevars
+    inc params
   var paramCount = 0
   var argCount = 0
   var m = createMatch(addr c)
@@ -332,7 +334,7 @@ proc semInvoke(c: var SemContext; n: var Cursor) =
     semLocalTypeImpl c, n, AllowValues
     swap c.dest, argBuf
     var addArg = true
-    if params.kind == ParRi:
+    if cursorIsNil(params) or params.kind == ParRi:
       # will error later from param/arg count not matching
       discard
     else:
@@ -349,7 +351,7 @@ proc semInvoke(c: var SemContext; n: var Cursor) =
       c.dest.add argBuf
   swap c.usedTypevars, genericArgs
   takeParRi c, n
-  if paramCount != argCount:
+  if ok and paramCount != argCount:
     c.dest.shrink typeStart
     c.buildErr info, "wrong amount of generic parameters for type " & pool.syms[headId] &
       ", expected " & $paramCount & " but got " & $argCount

tests/nimony/errmsgs/twronginvoke.msgs

@@ -0,0 +1,3 @@
+tests/nimony/errmsgs/twronginvoke.nim(9, 13) Error: undeclared identifier
+tests/nimony/errmsgs/twronginvoke.nim(9, 18) Error: cannot attempt to instantiate a non-type
+tests/nimony/errmsgs/twronginvoke.nim(9, 26) Error: expected type symbol for object constructor

tests/nimony/errmsgs/twronginvoke.nim

@@ -0,0 +1,15 @@
+type
+  GObj[T] = ref object
+    data: T
+
+  AObj = ref object
+    data: string
+
+proc main =
+  var obj = BGObj[string](data: "abc")
+
+  var a = AObj(data: "abc")
+
+  var objB = GObj[int](data: 456)
+
+main()