Cannot infer the value of static parameters in certain cases (regression 2.1.1 → 2.2.0)

[xigoi]

Description

The following program works correctly in Nim 2.1.1:

type Matrix[m, n: static int] = array[m * n, float]

func `[]`(A: Matrix, i, j: int): float =
  A[A.n * i + j]

func `[]`(A: var Matrix, i, j: int): var float =
  A[A.n * i + j]

func `*`[m, n, p: static int](A: Matrix[m, n], B: Matrix[n, p]): Matrix[m, p] =
  for i in 0 ..< m:
    for k in 0 ..< p:
      for j in 0 ..< n:
        result[i, k] += A[i, j] * B[j, k]

let A: Matrix[2, 2] = [-1, 1, 0, -1]
echo(A * A)

However, in Nim 2.2.0 it fails to compile with the error shown below.

Nim Version

Nim Compiler Version 2.2.0 [Linux: amd64]
Compiled at 2024-10-02
Copyright (c) 2006-2024 by Andreas Rumpf

git hash: 78983f1876726a49c69d65629ab433ea1310ece1
active boot switches: -d:release

Current Output

Hint: used config file '/home/xigoi/.choosenim/toolchains/nim-2.2.0/config/nim.cfg' [Conf]
Hint: used config file '/home/xigoi/.choosenim/toolchains/nim-2.2.0/config/config.nims' [Conf]
Hint: used config file '/home/xigoi/.config/nim/nim.cfg' [Conf]
.....................................................................
/home/xigoi/sandbox/program.nim(16, 8) template/generic instantiation of `*` from here
/home/xigoi/.choosenim/toolchains/nim-2.2.0/lib/system/arithmetics.nim(10, 6) Error: cannot infer the value of the static param 'm'

Expected Output

[1.0, -2.0, 0.0, 1.0]

Known Workarounds

No response

Additional Information

No response

[metagn]

Happens in checkGeneric thankfully, disambiguation of []

Still bisecting just in case there's a deeper issue

[metagn]

!nim c

type Matrix[m, n: static int] = array[m * n, float]

func `[]`(A: Matrix, i, j: int): float =
  A[A.n * i + j]

func `[]`(A: var Matrix, i, j: int): var float =
  A[A.n * i + j]

func `*`[m, n, p: static int](A: Matrix[m, n], B: Matrix[n, p]): Matrix[m, p] =
  for i in 0 ..< m:
    for k in 0 ..< p:
      for j in 0 ..< n:
        result[i, k] += A[i, j] * B[j, k]

let A: Matrix[2, 2] = [-1, 1, 0, -1]
echo(A * A)

[github-actions]

🐧 Linux bisect by @metagn (collaborator)

devel 👎 FAIL

Output

Filesize 0 (0 bytes)
Duration

stable 👎 FAIL

Output

Filesize 0 (0 bytes)
Duration

2.2.2 👎 FAIL

Output

Filesize 0 (0 bytes)
Duration

2.0.0 👍 OK

Output

Filesize 96.27 Kb (98,584 bytes)
Duration 1 mins

1.6.20 👍 OK

Output

Filesize 104.98 Kb (107,504 bytes)
Duration

1.4.8 👎 FAIL

Output

Filesize 104.98 Kb (107,504 bytes)
Duration

1.2.18 👎 FAIL

Output

Filesize 104.98 Kb (107,504 bytes)
Duration

1.0.10 👎 FAIL

Output

Filesize 104.98 Kb (107,504 bytes)
Duration

#ccc7c45d7 ➡️ 🐛

Diagnostics

ryan mcconnell introduced a bug at 2023-12-31 16:52:52 +0000 on commit #ccc7c45d7 with message:

The bug is in the files:

The bug can be in the commits:

• #b28010049
• #ccc7c45d7
• #9659da903
• #9483b1126
• #b92163180
• #fd253a08b
• #d8a5cf422
• #15c7b76c6
• #1324d2e04

(Diagnostics sometimes off-by-one).

Stats

• GCC 13.3.0
• Clang 18.1.3
• NodeJS 18.2
• Created 2025-02-21T14:08:36Z
• Comments 2
• Commands nim c --run -d:nimDebug -d:nimDebugDlOpen -d:ssl -d:nimDisableCertificateValidation --forceBuild:on --colors:off --verbosity:0 --hints:off --lineTrace:off --nimcache:/home/runner/work/Nim/Nim --out:/home/runner/work/Nim/Nim/temp /home/runner/work/Nim/Nim/temp.nim

🤖 Bug found in 34 mins bisecting 1179 commits at 34 commits per second