fixes #25231; print better error messages when generics instantiation… (#25460)

… has no params

(cherry picked from commit abf434a336)

compiler/semexprs.nim

@@ -1658,6 +1658,9 @@ proc semDeref(c: PContext, n: PNode, flags: TExprFlags): PNode =
     n[0] = a
   result = n
   var t = skipTypes(n[0].typ, {tyGenericInst, tyVar, tyLent, tyAlias, tySink, tyOwned})
+  if t.kind == tyTypeDesc:
+    localError(c.config, n.info, "missing generic parameter")
+    return nil
   case t.kind
   of tyRef, tyPtr: n.typ() = t.elementType
   of tyMetaTypes, tyFromExpr:

compiler/semtypes.nim

@@ -1109,7 +1109,7 @@ proc semAnyRef(c: PContext; n: PNode; kind: TTypeKind; prev: PType): PType =
       let t = newTypeS(tySink, c, result)
       result = t
     else: discard
-    if result.kind == tyRef and 
+    if result.kind == tyRef and
         c.config.selectedGC in {gcArc, gcOrc, gcAtomicArc} and
         tfTriggersCompileTime notin result.flags:
       result.flags.incl tfHasAsgn
@@ -2176,7 +2176,8 @@ proc semTypeNode(c: PContext, n: PNode, prev: PType): PType =
     else:
       result = semTypeNode(c, whenResult, prev)
   of nkBracketExpr:
-    checkMinSonsLen(n, 2, c.config)
+    # Actually len >= 2 is required, but it doesn't print errors nicely with empty brackets
+    checkMinSonsLen(n, 1, c.config)
     var head = n[0]
     var s = if head.kind notin nkCallKinds: semTypeIdent(c, head)
             else: symFromExpectedTypeNode(c, semExpr(c, head))
@@ -2194,10 +2195,21 @@ proc semTypeNode(c: PContext, n: PNode, prev: PType): PType =
         incl result.flags, tfHasAsgn
     of mVarargs: result = semVarargs(c, n, prev)
     of mTypeDesc, mType, mTypeOf:
-      result = makeTypeDesc(c, semTypeNode(c, n[1], nil))
-      result.flags.incl tfExplicit
+      if n.len != 2:
+        let name = case s.magic:
+                   of mTypeDesc: "typedesc"
+                   of mType: "type"
+                   of mTypeOf: "typeof"
+                   else: ""
+        localError(c.config, n.info, errXExpectsOneTypeParam % name)
+      else:
+        result = makeTypeDesc(c, semTypeNode(c, n[1], nil))
+        result.flags.incl tfExplicit
     of mStatic:
-      result = semStaticType(c, n[1], prev)
+      if n.len != 2:
+        localError(c.config, n.info, errXExpectsOneTypeParam % "static")
+      else:
+        result = semStaticType(c, n[1], prev)
     of mExpr:
       result = semTypeNode(c, n[0], nil)
       if result != nil:
@@ -2207,9 +2219,11 @@ proc semTypeNode(c: PContext, n: PNode, prev: PType): PType =
         for i in 1..<n.len:
           result.rawAddSon(semTypeNode(c, n[i], nil))
     of mDistinct:
+      checkSonsLen(n, 2, c.config)
       result = newOrPrevType(tyDistinct, prev, c)
       addSonSkipIntLit(result, semTypeNode(c, n[1], nil), c.idgen)
     of mVar:
+      checkSonsLen(n, 2, c.config)
       result = newOrPrevType(tyVar, prev, c)
       var base = semTypeNode(c, n[1], nil)
       if base.kind in {tyVar, tyLent}: