some typeclasses don't work with typed, macros.symBodyHash crashes with ptr, ref

[timotheecour]

Example

when true:
  import std/macros

  macro repr2(s: typed): string = 
    result = newLit(s.repr)

  macro symHash(s: typed): string = 
    result = newLit(symBodyHash(s))

  type A[T] = object
    x: T

  proc fn1(x: seq) = discard
  proc fn2(x: ref) = discard
  proc fn2b(x: ptr) = discard
  proc fn3(x: pointer | ref | ptr) = discard
  proc fn4(x: A) = discard

  proc fn0(x: pointer) = discard
  proc fn5[T](x: A[T]) = discard
  proc fn6(x: tuple) = discard
  proc fn7(x: pointer | tuple) = discard

  # ok
  discard symHash(fn0)
  discard symHash(fn5)
  discard symHash(fn6)
  discard symHash(fn7)

  # ok
  discard repr2(fn2)
  discard repr2(fn2b)
  discard repr2(fn3)

  # BUG D20210415T162824: Error: 'fn4' doesn't have a concrete type, due to unspecified generic parameters.
  # discard symHash(fn4)
  # discard symHash(fn1) # ditto

  # BUG D20210415T162832: Error: unhandled exception: index out of bounds, the container is empty [IndexDefect]
  # discard symHash(fn3)
  # discard symHash(fn2) # ditto
  # discard symHash(fn2b) # ditto

#[
/Users/timothee/git_clone/nim/Nim_prs/compiler/semexprs.nim(2793) semExpr /Users/timothee/git_clone/nim/timn/tests/nim/all/t12171.nim(50, 18) nkCall
/Users/timothee/git_clone/nim/Nim_prs/compiler/semexprs.nim(1037) semDirectOp
/Users/timothee/git_clone/nim/Nim_prs/compiler/semexprs.nim(919) afterCallActions
/Users/timothee/git_clone/nim/Nim_prs/compiler/sem.nim(472) semMacroExpr
/Users/timothee/git_clone/nim/Nim_prs/compiler/vm.nim(2330) evalMacroCall
/Users/timothee/git_clone/nim/Nim_prs/compiler/vm.nim(1213) rawExecute
/Users/timothee/git_clone/nim/Nim_prs/compiler/vmops.nim(242) :anonymous
/Users/timothee/git_clone/nim/Nim_prs/compiler/sighashes.nim(378) symBodyDigest
/Users/timothee/git_clone/nim/Nim_prs/compiler/sighashes.nim(221) hashType
/Users/timothee/git_clone/nim/Nim_prs/compiler/sighashes.nim(240) hashType
/Users/timothee/git_clone/nim/Nim_prs/compiler/sighashes.nim(240) hashType
/Users/timothee/git_clone/nim/Nim_prs/compiler/sighashes.nim(186) hashType
/Users/timothee/git_clone/nim/Nim_prs/compiler/ast.nim(1342) lastSon
/Users/timothee/git_clone/nim/Nim_prs/lib/system.nim(2647) []
/Users/timothee/git_clone/nim/Nim_prs/lib/system/fatal.nim(53) sysFatal
Error: unhandled exception: index out of bounds, the container is empty [IndexDefect]

]#

Current Output

uncomment discard symHash(fn4):
Error: 'fn4' doesn't have a concrete type, due to unspecified generic parameters.

uncomment discard symHash(fn3):
Error: unhandled exception: index out of bounds, the container is empty [IndexDefect]

Expected Output

these should all work

• both fn5 and fn4 should be typed (a typeclass should be valid)
• there's no reason proc fn(a: ref) should be typed but not proc fn(a: seq) (etc)
• the crash with fn3 shouldn't happen

Additional Information

• 1.5.1 d6242d7
• I hit this bug in std/hashes: hash(ref|ptr|pointer) + other improvements #17731:
  the innocent looking signature proc hash*(x: pointer | ref | ptr): Hash {.inline.} = caused a test to crash, tests/macros/tincremental.nim, because it somehow calls symBodyHash on hash, which results in this bug