fix #18823 Passing Natural to bitops.BitsRange[T] parameter in generi… (#20683)

* fix #18823 Passing Natural to bitops.BitsRange[T] parameter in generic proc is compile error

(cherry picked from commit 37d8f32ae9)

compiler/ast.nim

@@ -2023,10 +2023,12 @@ proc skipColon*(n: PNode): PNode =
     result = n[1]
 
 proc findUnresolvedStatic*(n: PNode): PNode =
-  # n.typ == nil: see issue #14802
   if n.kind == nkSym and n.typ != nil and n.typ.kind == tyStatic and n.typ.n == nil:
     return n
-
+  if n.typ != nil and n.typ.kind == tyTypeDesc:
+    let t = skipTypes(n.typ, {tyTypeDesc})
+    if t.kind == tyGenericParam and t.len == 0:
+      return n
   for son in n:
     let n = son.findUnresolvedStatic
     if n != nil: return n

compiler/semtypinst.nim

@@ -89,7 +89,7 @@ type
 
 proc replaceTypeVarsTAux(cl: var TReplTypeVars, t: PType): PType
 proc replaceTypeVarsS(cl: var TReplTypeVars, s: PSym): PSym
-proc replaceTypeVarsN*(cl: var TReplTypeVars, n: PNode; start=0): PNode
+proc replaceTypeVarsN*(cl: var TReplTypeVars, n: PNode; start=0; expectedType: PType = nil): PNode
 
 proc initLayeredTypeMap*(pt: TIdTable): LayeredIdTable =
   result = LayeredIdTable()
@@ -213,7 +213,7 @@ proc hasValuelessStatics(n: PNode): bool =
         return true
     false
 
-proc replaceTypeVarsN(cl: var TReplTypeVars, n: PNode; start=0): PNode =
+proc replaceTypeVarsN(cl: var TReplTypeVars, n: PNode; start=0; expectedType: PType = nil): PNode =
   if n == nil: return
   result = copyNode(n)
   if n.typ != nil:
@@ -255,8 +255,8 @@ proc replaceTypeVarsN(cl: var TReplTypeVars, n: PNode; start=0): PNode =
     when false:
       n = reResolveCallsWithTypedescParams(cl, n)
     result = if cl.allowMetaTypes: n
-             else: cl.c.semExpr(cl.c, n)
-    if not cl.allowMetaTypes:
+             else: cl.c.semExpr(cl.c, n, {}, expectedType)
+    if not cl.allowMetaTypes and expectedType != nil:
       assert result.kind notin nkCallKinds
   else:
     if n.len > 0:
@@ -692,12 +692,13 @@ proc initTypeVars*(p: PContext, typeMap: LayeredIdTable, info: TLineInfo;
   result.owner = owner
 
 proc replaceTypesInBody*(p: PContext, pt: TIdTable, n: PNode;
-                         owner: PSym, allowMetaTypes = false): PNode =
+                         owner: PSym, allowMetaTypes = false,
+                         fromStaticExpr = false, expectedType: PType = nil): PNode =
   var typeMap = initLayeredTypeMap(pt)
   var cl = initTypeVars(p, typeMap, n.info, owner)
   cl.allowMetaTypes = allowMetaTypes
   pushInfoContext(p.config, n.info)
-  result = replaceTypeVarsN(cl, n)
+  result = replaceTypeVarsN(cl, n, expectedType = expectedType)
   popInfoContext(p.config)
 
 when false:

compiler/sigmatch.nim

@@ -810,7 +810,8 @@ proc maybeSkipDistinct(m: TCandidate; t: PType, callee: PSym): PType =
     result = t
 
 proc tryResolvingStaticExpr(c: var TCandidate, n: PNode,
-                            allowUnresolved = false): PNode =
+                            allowUnresolved = false,
+                            expectedType: PType = nil): PNode =
   # Consider this example:
   #   type Value[N: static[int]] = object
   #   proc foo[N](a: Value[N], r: range[0..(N-1)])
@@ -1167,9 +1168,12 @@ proc typeRel(c: var TCandidate, f, aOrig: PType,
       if result notin {isNone, isGeneric}:
         # resolve any late-bound static expressions
         # that may appear in the range:
+        let expectedType = base(f)
         for i in 0..1:
           if f.n[i].kind == nkStaticExpr:
-            f.n[i] = tryResolvingStaticExpr(c, f.n[i])
+            let r = tryResolvingStaticExpr(c, f.n[i], expectedType = expectedType)
+            if r != nil:
+              f.n[i] = r
         result = typeRangeRel(f, a)
     else:
       let f = skipTypes(f, {tyRange})

tests/generics/t18823.nim

@@ -0,0 +1,6 @@
+type BitsRange[T] = range[0..sizeof(T)*8-1]
+
+proc bar[T](a: T; b: BitsRange[T]) =
+  discard
+
+bar(1, 2.Natural)