Invalid C code generation with templates

[tersec]

Nim Version

Nim Compiler Version 2.2.4 [Linux: amd64]
Compiled at 2025-06-08
Copyright (c) 2006-2025 by Andreas Rumpf

git hash: f7145dd26efeeeb6eeae6fff649db244d81b212d
active boot switches: -d:release

Nim Compiler Version 2.3.1 [Linux: amd64]
Compiled at 2025-06-10
Copyright (c) 2006-2025 by Andreas Rumpf

git hash: 638a8bf84d35c6be54cd7e4b4642ce77ae83da39
active boot switches: -d:release

Description

proc w(_: int): bool = discard
proc b() =
  template m(c: int) =
    if w(c): discard w(c)
  m((; let _ = 0; if true: 0 else: 0))
b()

Current Output

/tmp/tmp.iokGrWTR6P/@ms.nim.c: In function ‘b__s_u4’:
/tmp/tmp.iokGrWTR6P/@ms.nim.c:77:20: error: redeclaration of ‘__1’ with no linkage
   77 |                 NI __1;
      |                    ^~~
/tmp/tmp.iokGrWTR6P/@ms.nim.c:75:20: note: previous declaration of ‘__1’ with type ‘NI’ {aka ‘long int’}
   75 |                 NI __1;
      |                    ^~~

Expected Output

No invalid C code generation

Known Workarounds

No response

Additional Information

No response

[ringabout]

!nim c --gc:refc

proc w(_: int): bool = discard
proc b() =
  template m(c: int) =
    if w(c): discard w(c)
  m((; let _ = 0; if true: 0 else: 0))
b()

[github-actions[bot]]

:penguin: Linux bisect by @ringabout (member)

devel :-1: FAIL

Output

Filesize 0 (0 bytes) Duration

stable :-1: FAIL

Output

Filesize 0 (0 bytes) Duration

2.2.2 :-1: FAIL

Output

Filesize 0 (0 bytes) Duration

2.0.0 :-1: FAIL

Output

Filesize 0 (0 bytes) Duration

1.6.20 :-1: FAIL

Output

Filesize 0 (0 bytes) Duration

1.4.8 :-1: FAIL

Output

Filesize 0 (0 bytes) Duration

1.2.18 :-1: FAIL

Output

Filesize 0 (0 bytes) Duration

1.0.10 :-1: FAIL

Output

Filesize 0 (0 bytes) Duration

Stats

• GCC 13.3.0
• Clang 18.1.3
• NodeJS 19.2
• Created 2025-06-10T14:51:55Z
• Comments 1
• Commands nim c --gc:refc --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

:robot: Bug found in 21 mins bisecting 8 commits at 0 commits per second

[ringabout]

Duplicates of https://github.com/nim-lang/Nim/issues/15637