fixes #22902; borrow from proc return type mismatch (#22908)

fixes #22902

(cherry picked from commit 95e5ad6927)

compiler/semcall.nim

@@ -809,7 +809,7 @@ proc searchForBorrowProc(c: PContext, startScope: PScope, fn: PSym): tuple[s: PS
     if resolved != nil:
       result.s = resolved[0].sym
       result.state = bsMatch
-      if not compareTypes(result.s.typ[0], fn.typ[0], dcEqIgnoreDistinct):
+      if not compareTypes(result.s.typ[0], fn.typ[0], dcEqIgnoreDistinct, {IgnoreFlags}):
         result.state = bsReturnNotMatch
       elif result.s.magic in {mArrPut, mArrGet}:
         # cannot borrow these magics for now

compiler/types.nim

@@ -991,6 +991,7 @@ type
     ExactGcSafety
     AllowCommonBase
     PickyCAliases  # be picky about the distinction between 'cint' and 'int32'
+    IgnoreFlags          # used for borrowed functions; ignores the tfVarIsPtr flag
 
   TTypeCmpFlags* = set[TTypeCmpFlag]
 
@@ -1312,7 +1313,7 @@ proc sameTypeAux(x, y: PType, c: var TSameTypeClosure): bool =
     cycleCheck()
     if a.kind == tyUserTypeClass and a.n != nil: return a.n == b.n
     result = sameChildrenAux(a, b, c)
-    if result:
+    if result and IgnoreFlags notin c.flags:
       if IgnoreTupleFields in c.flags:
         result = a.flags * {tfVarIsPtr, tfIsOutParam} == b.flags * {tfVarIsPtr, tfIsOutParam}
       else:

tests/distinct/typeclassborrow.nim

@@ -1,3 +1,5 @@
+import std/tables
+
 type
   Foo = distinct seq[int]
   Bar[N: static[int]] = distinct seq[int]
@@ -46,3 +48,9 @@ proc `==`*(x, y: Fine): bool {.borrow.} =
 var x = Fine("1234")
 var y = Fine("1234")
 doAssert x == y
+
+block: # bug #22902
+  type
+    DistinctTable = distinct Table[int, int]
+
+  proc `[]`(t: DistinctTable; key: int): lent int {.borrow.}