Compiling with tcc needs -DNIM_EmulateOverflowChecks [nim 1.2.x+]

[kaushalmodi]

Compilations break when compiling with --cc:tcc.

Example

echo 0

Current Output

CC: stdlib_io.nim
CC: stdlib_system.nim
CC: t.nim
/tmp/kmodi/.cache/nim/t_d/stdlib_io.nim.c:56: error: invalid type
Error: execution of an external compiler program 'tcc -c -w   -I/home/kmodi/usr_local/apps/6/nim/devel/lib -I/home/kmodi/sandbox/nim/tcc -o /tmp/kmodi/.cache/nim/t_d/stdlib_io.nim.c.o /tmp/kmodi/.cache/nim/t_d/stdlib_io.nim.c' failed with exit code: 1

/tmp/kmodi/.cache/nim/t_d/stdlib_system.nim.c:457: error: invalid type

Here is the full stdlib_io.nim.c.

Expected Output

0

Possible Solution

• Change the tcc.options.always in nim's default nim.cfg to tcc.options.always = "-w -DNIM_EmulateOverflowChecks" (Credit: @c-blake )

Additional Information

• Apparently compilations using tcc worked just fine earlier, but it probably broke in nim 1.2.0+ (based on its release notes).
• Discovered this as I was trying to get the fastest possible nim compilations in https://github.com/c-blake/cligen/issues/139#issuecomment-621883694

$ nim -v
Nim Compiler Version 1.3.1 [Linux: amd64]
Compiled at 2020-04-30
Copyright (c) 2006-2020 by Andreas Rumpf

git hash: d6e1b5c070bf58449bf4af210ec099418d496aa5
active boot switches: -d:release

[c-blake]

I would recommend just fixing the ifdef switching at the bottom of nimbase.h with an || defined(__TINYC__). Realistically, tcc is never going to grow all those gcc/clang __builtin_*s.

[cooldome]

yes, please fix nimbase.h instead

[kaushalmodi]

@c-blake I tried building nim locally with https://github.com/kaushalmodi/Nim/commit/dba6ec7b69a4472b4324834b2cfd3fe5e6a24cc7, but this issue doesn't get fixed.

Do you want to bring a closure to this issue with a verified PR?

[kaushalmodi]

ok.. seeing the diff again, may be I need to put the tinycc outside that wrapped OR condition

[c-blake]

I commented on the PR, too. But I think you figured it out.

[kaushalmodi]

But I think you figured it out.

Yep :). I also verified that that PR works fine locally.

[c-blake]

Works for me with both tcc and gcc. Should pass the CI no problem, I'd expect.