Generic pointer procs now error if no types supplied (#18832)

* more precise logic for pointer procs

* added test for generic pointer procs

* Fixed generic getting bracket expr if erroring

compiler/semexprs.nim

@@ -1511,7 +1511,7 @@ proc maybeInstantiateGeneric(c: PContext, n: PNode, s: PSym): PNode =
   else:
     result = explicitGenericInstantiation(c, n, s)
     if result == n:
-      n[0] = copyTree(result)
+      n[0] = copyTree(result[0])
     else:
       n[0] = result
 

compiler/semstmts.nim

@@ -553,7 +553,7 @@ proc semVarOrLet(c: PContext, n: PNode, symkind: TSymKind): PNode =
           typ = typ.lastSon
         if hasEmpty(typ):
           localError(c.config, def.info, errCannotInferTypeOfTheLiteral % typ.kind.toHumanStr)
-        elif typ.kind == tyProc and hasUnresolvedParams(def, {}):
+        elif typ.kind == tyProc and def.kind == nkSym and isGenericRoutine(def.sym.ast):
           # tfUnresolved in typ.flags:
           localError(c.config, def.info, errProcHasNoConcreteType % def.renderTree)
         when false:

tests/generics/tpointerprocs.nim

@@ -0,0 +1,28 @@
+discard """
+cmd: "nim check $options --hints:off $file"
+action: "reject"
+nimout:'''
+tpointerprocs.nim(15, 11) Error: 'foo' doesn't have a concrete type, due to unspecified generic parameters.
+tpointerprocs.nim(27, 11) Error: cannot instantiate: 'foo[int]'; got 1 typeof(s) but expected 2
+tpointerprocs.nim(27, 14) Error: expression 'foo[int]' has no type (or is ambiguous)
+tpointerprocs.nim(28, 11) Error: expression 'bar' has no type (or is ambiguous)
+'''
+"""
+
+block:
+  proc foo(x: int | float): float = result = 1.0
+  let
+    bar = foo
+    baz = bar
+
+block:
+  proc foo(x: int | float): float = result = 1.0
+  let
+    bar = foo[int]
+    baz = bar
+
+block:
+  proc foo(x: int | float, y: int or string): float = result = 1.0
+  let
+    bar = foo[int]
+    baz = bar