Remove `spdlog` from `libmamba`, provide `libmamba-spdlog` library #4082

Klaim · 2025-10-20T15:14:05Z

Description

removes spdlog from libmamba dependencies;
adds a new library libmamba-spdlog which provides the spdlog-based LogHandler for mamba;
libmambapy and mamba/micromamba now depends on libmamba-spdlog to keep using spdlog as a log handler;

For simplicity, libmamba-spdlog is a header-only library. This avoids many possible variations of libmamba usage to get in the way of easy packaging. As we always use spdlog as a header-only library and we just wrapps it, it shouldnt impact usage much. Also only end-user targets (usually executables) will need to decide which LogHandler to use so this header will probably only be compiled once.

Notes:

this does not provide the necessary work to package libmamba-spdlog (next pr?);
this is essentially solving what maint: Make spdlog a private dependency #3945 solves but relies on Logging impl separation #4016 and completely removes spdlog as a dependency of libmamba;
this does not provide a way for libmambapy to use another logging implementation.

Type of Change

Bugfix
Feature / enhancement
CI / Documentation
Maintenance

Checklist

My code follows the general style and conventions of the codebase, ensuring consistency
I have performed a self-review of my code
I have commented my code, particularly in hard-to-understand areas
My changes generate no new warnings
I have run pre-commit run --all locally in the source folder and confirmed that there are no linter errors.
I have added tests that prove my fix is effective or that my feature works
New and existing tests pass locally with my changes

…ly) libraries

…(used by libmambapy anb mamba/micromamba)

…ilities

jjerphan

I think that one could create a PR on mamba-feedstock with the patch to anticipate packaging changes.

Klaim · 2025-11-25T17:51:43Z

I think that one could create a PR on mamba-feedstock with the patch to anticipate packaging changes.

I agree, I'll take a look there. I will probably need your help with details @jjerphan 🙏🏽

jjerphan · 2025-11-26T14:31:50Z

We can iterate on conda-forge/mamba-feedstock#368.

JohanMabille · 2025-11-27T07:38:14Z

cmake/CompilerWarnings.cmake

+    get_target_property(type ${target} TYPE)
+    if(NOT ${type} STREQUAL "INTERFACE_LIBRARY")
+        target_compile_options("${target}" PRIVATE ${warnings})
+    endif()


What is the issue with adding warnings to an Interface library?

PRIVATE cannot be used with target_compile_options when the target is INTERFACE_LIBRARY (header-only). (that triggers a cmake error, to be clear)

I fixed it by not adding the warnings because usually warnings flags should be set for the target having the translation units to compile these warnings with, that's why PRIVATE is used here to not pollute the flags for the user of the library. But because we have a header-only library, we don't have translation units. We never want to pollute the user build with flags added to headers they will include. In the case of header-only libraries, warnings should be set only on the test executables.

If we wanted to, we could change the PRIVATE to INTERFACE if the target is an interface library, but then we impose our warnings to all the code using these headers.

Thanks for the explanation. I agree we should not impose our warnings to the user, so let's keep it as is.

JohanMabille · 2025-11-27T07:41:38Z

libmamba-spdlog/cmake/libmamba-spdlogConfig.cmake.in

+@PACKAGE_INIT@
+
+include("${CMAKE_CURRENT_LIST_DIR}/@[email protected]")
+check_required_components("@PROJECT_NAME@")


This file should also contain calls to find_dependency for libmamba and spdlog

jjerphan

Thanks! Just minor nipicks.

this does not provide the necessary work to package libmamba-spdlog (next pr?);

What do you think of adding changes in this PR to be able to package libmamba-spdlog to test everything with conda-forge/mamba-feedstock#368?

jjerphan · 2025-11-27T08:50:58Z

CMakeLists.txt

 option(BUILD_SHARED "Build shared libmamba library" OFF)
 option(BUILD_STATIC "Build static libmamba library with static linkage to its dependencies" OFF)
 option(BUILD_LIBMAMBA "Build libmamba library" OFF)
+option(BUILD_LIBMAMBA_SPDLOG_TESTS "Build libmamba-spdlog library tests" OFF)


I think that we would need this to be able to distribute libmamba-spdlog independently.

Suggested change

option(BUILD_LIBMAMBA_SPDLOG_TESTS "Build libmamba-spdlog library tests" OFF)

option(BUILD_LIBMAMBA_SPDLOG "Build libmamba-spdlog library" OFF)

option(BUILD_LIBMAMBA_SPDLOG_TESTS "Build libmamba-spdlog library tests" OFF)

I initially had that but realized it made no sense in the context of mamba and libmambapy and also that library is header-only so it doesnt make sense to "build" it. But we can use it as en enable/disable thing, sure, in particular if it helps with packaging.

.gitignore

jjerphan · 2025-11-27T08:56:47Z

libmamba-spdlog/include/mamba/spdlog/logging_spdlog.hpp

+#ifndef MAMBA_LOGGING_SPDLOG_HPP
+#define MAMBA_LOGGING_SPDLOG_HPP


How about using?

Suggested change

#ifndef MAMBA_LOGGING_SPDLOG_HPP

#define MAMBA_LOGGING_SPDLOG_HPP

#pragma once

I'm fine with it, although note that it is not the policy for libmamba/.

I'll do it in a separate commit to remove the endif too

I think we should keep the codebase homogeneous. If we decide to replace the inclusion guards with pragma once statements, that should be done for the whole codebase in a dedicated PR.

I'll replace the pragma once in the impl header and we can change everything in that future pr

Klaim · 2025-11-27T13:57:20Z

Thanks! Just minor nipicks.

this does not provide the necessary work to package libmamba-spdlog (next pr?);

What do you think of adding changes in this PR to be able to package libmamba-spdlog to test everything with conda-forge/mamba-feedstock#368?

We had a short discussion with @JohanMabille about that when I started, as stated in the pr description the goal was not to prepare for packaging.
But if the changes necessary are not too involved, I guess we can, I wouldnt mind as long as it doesnt add to the cmake noise.

jjerphan

OK, as you prefer; I think that we will need to have the packaging change in also if we have to make a release (are those significant?).

LGTM once the threads with Johan are resolved.

See mamba-org/mamba#4082

jjerphan

One last suggestion.

libmamba-spdlog/CMakeLists.txt

github-actions bot added the release::maintenance For PRs related to maintenance label Oct 20, 2025

Klaim force-pushed the libmamba-splog branch from ca64ba1 to c83e586 Compare November 17, 2025 14:26

jjerphan mentioned this pull request Nov 19, 2025

maint: Make spdlog a private dependency #3945

Closed

Klaim force-pushed the libmamba-splog branch from c83e586 to 2a12e45 Compare November 19, 2025 13:52

Klaim added 13 commits November 21, 2025 15:58

cmake: dont force warning compilation options on interface (header-on…

73de6d6

…ly) libraries

remove spdlog log-handler from libmamba, moved into it's own library …

9d33727

…(used by libmambapy anb mamba/micromamba)

attempt to enable libmamba-spdlog testing

b92d16f

added missing file that was ignored by git

de81483

removed problematic git ignore

df06ad9

ci: fixed name of the new tests to run

7067dc3

cmake fixes to link libmamba-spdlog

092ccb7

makes sure targets requireing libmamba-spdlog also gets threading fac…

bca7709

…ilities

fixed missing Threads dependency

ae9ce5d

only build libmamba-spdlog tests for test builds on ci

7465127

attempt to fix libmambapy not finding libmamba-spdlog

448511e

install setup for libmamba-spdlog

f06aeb4

(micro)mamba and libmambapy uses spdlog based logging

cbd6ef2

Klaim force-pushed the libmamba-splog branch from c2bc269 to cbd6ef2 Compare November 21, 2025 14:58

Klaim added 12 commits November 21, 2025 16:14

fixup

11c100d

fixup

3db2352

woops

00a7113

fix install

a10f81c

not sure if it's visible that I dont like cmake at all

1254f18

fix from @jjerphan

1a6801b

fix config cmake location after install

b6b401a

fix attempts

157e30c

fixup form @jjerphan

b4770f2

fixup from @jjerphan

c304af7

fixup libmambapy

9b05c2e

ci debug info

1009c50

Klaim and others added 12 commits November 24, 2025 16:27

potential tests fixup

e12d289

fix attempt test_libmamba_logging_spdlog

df156d4

ci debug info

0fbe8f3

more debug info

bcbab18

more info

a60c9e1

debug info

cc9652f

more cmake info

e680bcb

fix attempt

0c3275f

removed debug info ci

a06ac6e

formatting

9715774

tweak

be9628b

updates Context documentation to new behavior

5297af2

jjerphan reviewed Nov 25, 2025

View reviewed changes

jjerphan mentioned this pull request Nov 26, 2025

test: libmamba-spdlog distribution conda-forge/mamba-feedstock#368

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5 tasks

JohanMabille reviewed Nov 27, 2025

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jjerphan reviewed Nov 27, 2025

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jjerphan approved these changes Nov 27, 2025

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Klaim added 4 commits November 27, 2025 17:29

ignore cmake files only in the root dir + revert ignoring "Testing" dir

1dfd8d8

cmake generated config file dependencies fix

26d430f

use header guards instead of pragma once for now

7433dff

libmamba-spdlog build on/off through cmake config

f74d324

Klaim added a commit to Klaim/micromamba-feedstock that referenced this pull request Dec 2, 2025

Prepare for libmamba-spdlog

e4edc60

See mamba-org/mamba#4082

Klaim mentioned this pull request Dec 2, 2025

Prepare for libmamba-spdlog conda-forge/micromamba-feedstock#278

Merged

5 tasks

jjerphan reviewed Dec 9, 2025

View reviewed changes

libmamba-spdlog/CMakeLists.txt Show resolved Hide resolved

	option(BUILD_LIBMAMBA_SPDLOG_TESTS "Build libmamba-spdlog library tests" OFF)
	option(BUILD_LIBMAMBA_SPDLOG "Build libmamba-spdlog library" OFF)
	option(BUILD_LIBMAMBA_SPDLOG_TESTS "Build libmamba-spdlog library tests" OFF)

		#ifndef MAMBA_LOGGING_SPDLOG_HPP
		#define MAMBA_LOGGING_SPDLOG_HPP

	#ifndef MAMBA_LOGGING_SPDLOG_HPP
	#define MAMBA_LOGGING_SPDLOG_HPP
	#pragma once

Remove spdlog from libmamba, provide libmamba-spdlog library #4082

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Remove spdlog from libmamba, provide libmamba-spdlog library #4082

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Klaim commented Oct 20, 2025

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Remove `spdlog` from `libmamba`, provide `libmamba-spdlog` library #4082

Remove `spdlog` from `libmamba`, provide `libmamba-spdlog` library #4082

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