2.0 C compilation error when using seq of array with enum indices

stoneface86 commented 2 months ago

Description

The following nim code results in an error when compiling the generated C code:

type
  ChannelId = enum
    ch1, ch2, ch3, ch4

  OrderRow = array[ChannelId, uint8]
  Order = seq[OrderRow]

func test(o: Order) =
  discard

let order = @[ [0u8, 0, 0, 0], [1u8, 1, 1, 1] ]
test(order)

The generated C code fails to compile when using Nim 2.0.0 or 2.0.2, Nim 1.6.16 results in no errors whatsoever.

Nim Version

git hash: a488067a4130f029000be4550a0fb1b39e0e9e7c active boot switches: -d:release

Current Output

nim r issue.nim
Hint: used config file '/home/bit/.choosenim/toolchains/nim-2.0.0/config/nim.cfg' [Conf]
Hint: used config file '/home/bit/.choosenim/toolchains/nim-2.0.0/config/config.nims' [Conf]
Hint: used config file '/home/bit/.config/nim/config.nims' [Conf]
......................................................................
CC: ../../home/bit/.choosenim/toolchains/nim-2.0.0/lib/system/exceptions.nim
CC: ../../home/bit/.choosenim/toolchains/nim-2.0.0/lib/std/private/digitsutils.nim
CC: ../../home/bit/.choosenim/toolchains/nim-2.0.0/lib/system/dollars.nim
CC: ../../home/bit/.choosenim/toolchains/nim-2.0.0/lib/system.nim
CC: issue.nim
/mnt/ramdisk/nimcache/2.0.0/d/issue/@missue.nim.c: In function ‘NimMainModule’:
/mnt/ramdisk/nimcache/2.0.0/d/issue/@missue.nim.c:164:25: error: incompatible type for argument 1 of ‘test__issue_u11’
  164 |         test__issue_u11(order__issue_u17);
      |                         ^~~~~~~~~~~~~~~~
      |                         |
      |                         tySequence__atzPT9bqVZh26epu1UBlGdg
/mnt/ramdisk/nimcache/2.0.0/d/issue/@missue.nim.c:101:84: note: expected ‘tySequence__puy72L9c7VseAknjAniYCWg’ but argument is of type ‘tySequence__atzPT9bqVZh26epu1UBlGdg’
  101 | N_LIB_PRIVATE N_NIMCALL(void, test__issue_u11)(tySequence__puy72L9c7VseAknjAniYCWg o_p0) {
      |                                                ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~
Error: execution of an external compiler program 'gcc -c  -w -fmax-errors=3 -pthread   -I/home/bit/.choosenim/toolchains/nim-2.0.0/lib -I/mnt/ramdisk -o /mnt/ramdisk/nimcache/2.0.0/d/issue/@missue.nim.c.o /mnt/ramdisk/nimcache/2.0.0/d/issue/@missue.nim.c' failed with exit code: 1

Expected Output

# when compiling with nim 1.6.16
nim r issue.nim
Hint: used config file '/home/bit/.choosenim/toolchains/nim-1.6.16/config/nim.cfg' [Conf]
Hint: used config file '/home/bit/.choosenim/toolchains/nim-1.6.16/config/config.nims' [Conf]
Hint: used config file '/home/bit/.config/nim/config.nims' [Conf]
..........................................................
CC: issue.nim
Hint:  [Link]
Hint: gc: refc; opt: none (DEBUG BUILD, `-d:release` generates faster code)
50844 lines; 0.145s; 61.125MiB peakmem; proj: /mnt/ramdisk/issue.nim; out: /mnt/ramdisk/nimcache/1.6.16/d/issue/issue_4A2D8CE6202E3A7174E40689BBC6A80A83C99581 [SuccessX]
Hint: /mnt/ramdisk/nimcache/1.6.16/d/issue/issue_4A2D8CE6202E3A7174E40689BBC6A80A83C99581  [Exec]

Possible Solution

Should this be a nim compile error? In the example, the type of order is seq[array[0..3, uint8]], however, the type of Order is seq[array[ChannelId, uint8]], which I believe is what results in two instances of seq being generated in the C code.

Additional Information

Declaring order as type Order in the let statement does not result in any error.

This might be an ARC/ORC issue: compiling with --mm:arc or --mm:orc on 1.6.16 also results in the same error

ringabout commented 2 months ago

Araq commented 2 months ago

This should not be allowed by the compiler, the types are not compatible.

beef331 commented 2 months ago

There is a type bug here. Even if one corrects the arrays, incorrect C is generated unless one explicitly converts to a type alias.

type
  ChannelId = enum
    ch1, ch2, ch3, ch4

  OrderRow = array[ChannelId, uint8]
  Order = seq[OrderRow]

let order = @[ [ch1: 0u8, 0, 0, 0], [ch1: 1u8, 1, 1, 1]  ]#.Order # Explicitly converting stops the cgen error
static: assert order is Order

proc test(_: Order) = discard
test(order)

nim-lang / Nim