lemon-graph: fix build with GCC 15 and C++20 #477756

gonsolo · 2026-01-07T14:43:24Z

Fix 'std::iterator' deprecation warnings by defining iterator traits explicitly.
Fix 'std::allocator::construct' removal in C++20 using std::allocator_traits.
Resolve uninitialized variable warnings in dim2::Point.
Add [[fallthrough]] attributes to intentional switch case transitions.

bouk

not sure why you added me as a reviewer since I'm not a maintainer, but it doesn't seem a good idea to me to switch to a fork

gonsolo · 2026-01-07T15:38:44Z

not sure why you added me as a reviewer since I'm not a maintainer, but it doesn't seem a good idea to me to switch to a fork

There were two reviewers suggested in the corner top right. Sorry about that. I converted this PR to a draft since it is WIP.

gonsolo · 2026-01-07T16:27:16Z

but it doesn't seem a good idea to me to switch to a fork

Version 1.3.1 was released in 2014. The fork from OpenROAD is at least updated to compile.

gonsolo · 2026-01-07T17:03:44Z

Could you review, @eljamm?

eljamm · 2026-01-07T22:19:49Z

lemon-graph doesn't appear to be broken:

$ hydra-check lemon-graph
Build Status for nixpkgs.lemon-graph.x86_64-linux on jobset nixos/trunk-combined
https://hydra.nixos.org/job/nixos/trunk-combined/nixpkgs.lemon-graph.x86_64-linux
✔           lemon-graph-1.3.1  2025-12-31  https://hydra.nixos.org/build/317865215
✔           lemon-graph-1.3.1  2025-11-23  https://hydra.nixos.org/build/314192137
✔           lemon-graph-1.3.1  2025-11-13  https://hydra.nixos.org/build/313176240
✔           lemon-graph-1.3.1  2025-10-21  https://hydra.nixos.org/build/310404901
✔           lemon-graph-1.3.1  2025-10-07  https://hydra.nixos.org/build/309254064
✖ (Failed)  lemon-graph-1.3.1  2025-10-05  https://hydra.nixos.org/build/308844417
✔           lemon-graph-1.3.1  2025-09-11  https://hydra.nixos.org/build/306922703
✔           lemon-graph-1.3.1  2025-08-25  https://hydra.nixos.org/build/305602029
✔           lemon-graph-1.3.1  2025-07-27  https://hydra.nixos.org/build/303380753
✔           lemon-graph-1.3.1  2025-07-14  https://hydra.nixos.org/build/302408273

And I can indeed build it from the latest master:

nix build github:nixos/nixpkgs/master#lemon-graph -L

* Fix 'std::iterator' deprecation warnings by defining iterator traits explicitly.

* Fix 'std::allocator::construct' removal in C++20 using std::allocator_traits.

* Resolve uninitialized variable warnings in dim2::Point.

* Add [[fallthrough]] attributes to intentional switch case transitions.

If these are just warnings, I think we can probably ignore them for now since they don't appear to be breaking the build.

gonsolo · 2026-01-08T00:43:14Z

lemon-graph doesn't appear to be broken:

Ah, yes, it's more complicated than that; while trying to get Librelane into Nix, I had to update OpenROAD:
https://github.com/NixOS/nixpkgs/pull/477789/changes
This fails among other things because of lemon-graph.

If these are just warnings, I think we can probably ignore them for now since they don't appear to be breaking the build.

I fixed everything upstream in the OpenROAD fork:
The-OpenROAD-Project/lemon-graph#4

I also contacted the author of Lemon at lemon.cs.elte.hu, you may have received the email.
Hopefully he can incorporate the changes, or if development is abandoned we can switch to the OpenROAD fork.

Thanks anyway,
g

gonsolo · 2026-01-08T08:21:25Z

The error from an updated openroad is:

error: Cannot build '/nix/store/bg07lclj48imcsc95b2k8dq9nrqsyxqj-openroad-2.0-unstable-2026-01-07.drv'.
       Reason: builder failed with exit code 2.
       Output paths:
         /nix/store/p31xf1kl9rl0j8pyx1ahvmx07jmbp850-openroad-2.0-unstable-2026-01-07
       Last 25 log lines:
       >   289 |     virtual void erase(const std::vector<Key>& keys) {
       >       |                  ^~~~~
       > /nix/store/kdlh4zmf3ycdnx4pmi0fmgkn0mry04l6-lemon-graph-1.3.1/include/lemon/bits/array_map.h:292:19: error: 'lemon::ArrayMap<lemon::GraphExtender<lemon::ListGraphBase>, lemon::ListGraphBase::Node, odb::Point>::Allocator' {aka 'class std::allocator<odb::Point>'} has no member named 'destroy'
       >   292 |         allocator.destroy(&(values[id]));
       >       |         ~~~~~~~~~~^~~~~~~

This is not triggered in lemon-graph since it is header only and not in test.

gonsolo · 2026-01-08T08:41:17Z

I took a different path now; just vendor the necessary patch from the OpenROAD fork.
I hope this is acceptible.
Since this is one of the last 7 PRs to merge Librelane, could you review, @eljamm @donn?

eljamm · 2026-01-08T11:00:00Z

`nixpkgs-review` result for #477756

Generated using nixpkgs-review-gha

Command: nixpkgs-review pr 477756
Commit: 7ba184ad35bea0ba7de54ae409a3238fc16bbe61 (subsequent changes)
Merge: e9d2d6ac06c55ddf79ec535580e0b8e268d504ee

Logs: https://github.com/eljamm/nixpkgs-review-gha/actions/runs/20813070935

`x86_64-linux`

❌ 2 packages failed to build:

coloquinte
openroad

✅ 2 packages built:

lemon-graph
openmvg

Error logs: `x86_64-linux`

coloquinte

@nix { "action": "setPhase", "phase": "buildPhase" }
build flags: -j4 SHELL=/nix/store/lw117lsr8d585xs63kx5k233impyrq7q-bash-5.3p3/bin/bash
[  2%] Building CXX object CMakeFiles/coloquinte.dir/src/coloquinte.cpp.o
[  8%] Building CXX object CMakeFiles/coloquinte.dir/src/place_global/net_model.cpp.o
[  8%] Building CXX object CMakeFiles/coloquinte.dir/src/parameters.cpp.o
[ 11%] Building CXX object CMakeFiles/coloquinte.dir/src/place_global/density_legalizer.cpp.o
[ 14%] Building CXX object CMakeFiles/coloquinte.dir/src/place_global/density_grid.cpp.o
[ 17%] Building CXX object CMakeFiles/coloquinte.dir/src/place_global/place_global.cpp.o
[ 20%] Building CXX object CMakeFiles/coloquinte.dir/src/place_detailed/legalizer.cpp.o
[ 22%] Building CXX object CMakeFiles/coloquinte.dir/src/place_detailed/abacus_legalizer.cpp.o
[ 25%] Building CXX object CMakeFiles/coloquinte.dir/src/place_detailed/tetris_legalizer.cpp.o
[ 28%] Building CXX object CMakeFiles/coloquinte.dir/src/place_detailed/row_legalizer.cpp.o
/build/source/src/place_detailed/tetris_legalizer.cpp: In member function 'std::pair<bool, int> coloquinte::TetrisLegalizer::attemptPlacement(int, int) const':
/build/source/src/place_detailed/tetris_legalizer.cpp:48:20: error: 'clamp' is not a member of 'std'
   48 |     int pos = std::clamp(x, b, e);
      |                    ^~~~~
make[2]: *** [CMakeFiles/coloquinte.dir/build.make:191: CMakeFiles/coloquinte.dir/src/place_detailed/tetris_legalizer.cpp.o] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [CMakeFiles/Makefile2:133: CMakeFiles/coloquinte.dir/all] Error 2
make: *** [Makefile:146: all] Error 2

openroad

 1325 |              block->dbuAreaToMicrons(stdInstsArea_));
      |                                      ^~~~~~~~~~~~~
/build/source/src/gpl/src/placerBase.cpp:1331:38: error: 'macroInstsArea_' was not declared in this scope
 1331 |              block->dbuAreaToMicrons(macroInstsArea_));
      |                                      ^~~~~~~~~~~~~~~
/build/source/src/gpl/src/placerBase.cpp: At global scope:
/build/source/src/gpl/src/placerBase.cpp:1345:9: error: no declaration matches 'int64_t gpl::PlacerBase::macroInstsArea() const'
 1345 | int64_t PlacerBase::macroInstsArea() const
      |         ^~~~~~~~~~
/build/source/src/gpl/src/placerBase.cpp:1345:9: note: no functions named 'int64_t gpl::PlacerBase::macroInstsArea() const'
/build/source/src/gpl/src/placerBase.h:378:7: note: 'class gpl::PlacerBase' defined here
  378 | class PlacerBase
      |       ^~~~~~~~~~
make[2]: *** [src/gpl/CMakeFiles/gpl.dir/build.make:161: src/gpl/CMakeFiles/gpl.dir/src/placerBase.cpp.o] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [CMakeFiles/Makefile2:5275: src/gpl/CMakeFiles/gpl.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....
[ 91%] Built target rmp
[ 94%] Built target drt_lib
make: *** [Makefile:146: all] Error 2

`aarch64-linux`

❌ 2 packages failed to build:

coloquinte
openroad

✅ 2 packages built:

lemon-graph
openmvg

Error logs: `aarch64-linux`

coloquinte

@nix { "action": "setPhase", "phase": "buildPhase" }
build flags: -j4 SHELL=/nix/store/q1lr86rzsxxbbqdz8m6bcv94saaz8wlv-bash-5.3p3/bin/bash
[  2%] Building CXX object CMakeFiles/coloquinte.dir/src/parameters.cpp.o
[  5%] Building CXX object CMakeFiles/coloquinte.dir/src/coloquinte.cpp.o
[  8%] Building CXX object CMakeFiles/coloquinte.dir/src/place_global/density_legalizer.cpp.o
[ 11%] Building CXX object CMakeFiles/coloquinte.dir/src/place_global/net_model.cpp.o
[ 14%] Building CXX object CMakeFiles/coloquinte.dir/src/place_global/density_grid.cpp.o
[ 17%] Building CXX object CMakeFiles/coloquinte.dir/src/place_global/place_global.cpp.o
[ 20%] Building CXX object CMakeFiles/coloquinte.dir/src/place_detailed/legalizer.cpp.o
[ 22%] Building CXX object CMakeFiles/coloquinte.dir/src/place_detailed/abacus_legalizer.cpp.o
[ 25%] Building CXX object CMakeFiles/coloquinte.dir/src/place_detailed/tetris_legalizer.cpp.o
[ 28%] Building CXX object CMakeFiles/coloquinte.dir/src/place_detailed/row_legalizer.cpp.o
/build/source/src/place_detailed/tetris_legalizer.cpp: In member function 'std::pair<bool, int> coloquinte::TetrisLegalizer::attemptPlacement(int, int) const':
/build/source/src/place_detailed/tetris_legalizer.cpp:48:20: error: 'clamp' is not a member of 'std'
   48 |     int pos = std::clamp(x, b, e);
      |                    ^~~~~
make[2]: *** [CMakeFiles/coloquinte.dir/build.make:191: CMakeFiles/coloquinte.dir/src/place_detailed/tetris_legalizer.cpp.o] Error 1
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [CMakeFiles/Makefile2:133: CMakeFiles/coloquinte.dir/all] Error 2
make: *** [Makefile:146: all] Error 2

openroad

      |                              nonPlaceInsts_
/build/source/src/gpl/src/placerBase.cpp:1325:38: error: 'stdInstsArea_' was not declared in this scope
 1325 |              block->dbuAreaToMicrons(stdInstsArea_));
      |                                      ^~~~~~~~~~~~~
/build/source/src/gpl/src/placerBase.cpp:1331:38: error: 'macroInstsArea_' was not declared in this scope
 1331 |              block->dbuAreaToMicrons(macroInstsArea_));
      |                                      ^~~~~~~~~~~~~~~
/build/source/src/gpl/src/placerBase.cpp: At global scope:
/build/source/src/gpl/src/placerBase.cpp:1345:9: error: no declaration matches 'int64_t gpl::PlacerBase::macroInstsArea() const'
 1345 | int64_t PlacerBase::macroInstsArea() const
      |         ^~~~~~~~~~
/build/source/src/gpl/src/placerBase.cpp:1345:9: note: no functions named 'int64_t gpl::PlacerBase::macroInstsArea() const'
/build/source/src/gpl/src/placerBase.h:378:7: note: 'class gpl::PlacerBase' defined here
  378 | class PlacerBase
      |       ^~~~~~~~~~
make[2]: *** [src/gpl/CMakeFiles/gpl.dir/build.make:161: src/gpl/CMakeFiles/gpl.dir/src/placerBase.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:5275: src/gpl/CMakeFiles/gpl.dir/all] Error 2
make[1]: *** Waiting for unfinished jobs....
[ 94%] Built target drt_lib
make: *** [Makefile:146: all] Error 2

`x86_64-darwin` (sandbox = relaxed)

✅ 1 package built:

lemon-graph

`aarch64-darwin` (sandbox = relaxed)

❌ 1 package failed to build:

openroad

✅ 2 packages built:

lemon-graph
openmvg

eljamm

I took a different path now; just vendor the necessary patch from the OpenROAD fork.
I hope this is acceptible.

Yes, I think that's a much better solution.

x86_64-linux

❌ 2 packages failed to build:
* coloquinte

* openroad

Openroad is already broken with an open PR to fix it and Coloquinte will potentially work after it's been updated:

This PR looks good to me now, but let's wait until these 2 are fixed before we merge.

gonsolo · 2026-01-09T17:44:32Z

`nixpkgs-review` result

Generated using nixpkgs-review.

Command: nixpkgs-review pr 477756
Commit: 9427e76a5a4b044e7dde61dfe79962b3b4b06afe

`x86_64-linux`

✅ 4 packages built:

coloquinte
lemon-graph
openmvg
openroad

gonsolo · 2026-01-09T17:46:45Z

I think this is ready, maybe @eljamm @imincik @GaetanLepage?

GaetanLepage · 2026-01-09T23:15:44Z

`nixpkgs-review` result

Generated using nixpkgs-review.

Command: nixpkgs-review pr 477756 --package lemon-graph
Commit: 9427e76a5a4b044e7dde61dfe79962b3b4b06afe

`x86_64-linux`

✅ 1 package built:

lemon-graph

`aarch64-linux`

✅ 1 package built:

lemon-graph

`x86_64-darwin`

✅ 1 package built:

lemon-graph

`aarch64-darwin`

✅ 1 package built:

lemon-graph

GaetanLepage · 2026-01-09T23:16:04Z

`nixpkgs-review` result

Generated using nixpkgs-review.

Command: nixpkgs-review pr 477756
Commit: 9427e76a5a4b044e7dde61dfe79962b3b4b06afe

`x86_64-linux`

✅ 4 packages built:

coloquinte
lemon-graph
openmvg
openroad

gonsolo requested review from bouk and flokli and removed request for flokli January 7, 2026 14:43

nixpkgs-ci bot requested a review from trepetti January 7, 2026 14:48

nixpkgs-ci bot added 10.rebuild-linux: 1-10 This PR causes between 1 and 10 packages to rebuild on Linux. 10.rebuild-darwin: 1-10 This PR causes between 1 and 10 packages to rebuild on Darwin. labels Jan 7, 2026

bouk suggested changes Jan 7, 2026

View reviewed changes

gonsolo marked this pull request as draft January 7, 2026 15:37

gonsolo force-pushed the lemon-graph branch from 081fc4d to 9534336 Compare January 7, 2026 16:06

gonsolo marked this pull request as ready for review January 7, 2026 16:06

gonsolo force-pushed the lemon-graph branch from 9534336 to 3da166b Compare January 7, 2026 16:17

gonsolo force-pushed the lemon-graph branch from 3da166b to 7ba184a Compare January 8, 2026 08:38

gonsolo mentioned this pull request Jan 8, 2026

coloquinte: 0.3.1 -> 0.4.3 #477801

Closed

13 tasks

eljamm approved these changes Jan 8, 2026

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eljamm mentioned this pull request Jan 8, 2026

Support packaging dependencies for Borg in Nixpkgs ngi-nix/ngipkgs#1941

Open

nixpkgs-ci bot added the 12.approvals: 1 This PR was reviewed and approved by one person. label Jan 8, 2026

gonsolo mentioned this pull request Jan 8, 2026

Librelane #471712

Open

2 tasks

gonsolo force-pushed the lemon-graph branch from 7ba184a to 2010b5e Compare January 9, 2026 16:54

lemon-graph: add patch for C++20 compatibility

9427e76

gonsolo force-pushed the lemon-graph branch from 2010b5e to 9427e76 Compare January 9, 2026 17:07

SuperSandro2000 approved these changes Jan 9, 2026

View reviewed changes

GaetanLepage approved these changes Jan 9, 2026

View reviewed changes

nixpkgs-ci bot added 12.approvals: 3+ This PR was reviewed and approved by three or more persons. 2.status: merge-bot eligible This PR can be merged by commenting "@NixOS/nixpkgs-merge-bot merge". and removed 12.approvals: 1 This PR was reviewed and approved by one person. labels Jan 9, 2026

GaetanLepage added this pull request to the merge queue Jan 9, 2026

Merged via the queue into NixOS:master with commit ff0e0b1 Jan 9, 2026
30 of 34 checks passed

gonsolo deleted the lemon-graph branch January 10, 2026 07:16

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lemon-graph: fix build with GCC 15 and C++20 #477756

lemon-graph: fix build with GCC 15 and C++20 #477756

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