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Merged
StrikerRUS merged 6 commits into from
Oct 12, 2025
Merged

[c++] default to C++17 for most builds #7016

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e95e089
[c++] default to C++17 for most builds
jameslamb Sep 1, 2025
e9c8f78
Merge branch 'master' into more-cpp17
jameslamb Sep 27, 2025
68cfb7e
Merge branch 'master' into more-cpp17
jameslamb Oct 9, 2025
88d3110
Merge branch 'master' into more-cpp17
jameslamb Oct 11, 2025
b25dce8
more updates
jameslamb Oct 11, 2025
78b52b7
fix formatting
jameslamb Oct 11, 2025
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2 changes: 1 addition & 1 deletion .pre-commit-config.yaml
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Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ repos:
- id: cpplint
args:
- --recursive
- --filter=-build/c++11,-build/include_subdir,-build/include_what_you_use,-build/header_guard,-whitespace/indent_namespace,-whitespace/line_length
- --filter=-build/include_subdir,-build/include_what_you_use,-build/header_guard,-whitespace/indent_namespace,-whitespace/line_length
- repo: local
hooks:
- id: check-omp-pragmas
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19 changes: 5 additions & 14 deletions CMakeLists.txt
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Expand Up @@ -36,13 +36,7 @@ endif()

project(lightgbm LANGUAGES C CXX)

if(USE_CUDA)
set(CMAKE_CXX_STANDARD 17)
elseif(BUILD_CPP_TEST)
set(CMAKE_CXX_STANDARD 14)
else()
set(CMAKE_CXX_STANDARD 11)
endif()
set(CMAKE_CXX_STANDARD 17)
set(CMAKE_CXX_STANDARD_REQUIRED ON)

list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake/modules")
Expand Down Expand Up @@ -72,22 +66,19 @@ endif()

if(CMAKE_CXX_COMPILER_ID STREQUAL "GNU")
if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS "4.8.2")
message(FATAL_ERROR "Insufficient gcc version")
message(FATAL_ERROR "Insufficient gcc version (${CMAKE_CXX_COMPILER_VERSION})")
endif()
elseif(CMAKE_CXX_COMPILER_ID STREQUAL "Clang")
if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS "3.8")
message(FATAL_ERROR "Insufficient Clang version")
message(FATAL_ERROR "Insufficient Clang version (${CMAKE_CXX_COMPILER_VERSION})")
endif()
elseif(CMAKE_CXX_COMPILER_ID STREQUAL "AppleClang")
if(CMAKE_CXX_COMPILER_VERSION VERSION_LESS "8.1.0")
message(FATAL_ERROR "Insufficient AppleClang version")
message(FATAL_ERROR "Insufficient AppleClang version (${CMAKE_CXX_COMPILER_VERSION})")
endif()
elseif(MSVC)
if(MSVC_VERSION LESS 1900)
message(
FATAL_ERROR
"The compiler ${CMAKE_CXX_COMPILER} doesn't support required C++11 features. Please use a newer MSVC."
)
message(FATAL_ERROR "Insufficient MSVC version (${MSVC_VERSION})")
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@jameslamb jameslamb Oct 11, 2025

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The previous message was probably technically still true, but this rewording is a bit simpler and is consistent with the other enforce-a-minimum-compiler-version errors.

It's enough for users to be told that the version of a compiler they're using is older than what LightGBM supports... saying for MSVC that that's because of "C++11 features" doesn't add much information.

endif()
endif()

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15 changes: 11 additions & 4 deletions R-package/README.md
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Expand Up @@ -67,13 +67,20 @@ The steps above should work on most systems, but users with highly-customized en

To change the compiler used when installing the CRAN package, you can create a file `~/.R/Makevars` which overrides `CC` (`C` compiler) and `CXX` (`C++` compiler).

For example, to use `gcc` instead of `clang` on Mac, you could use something like the following:
For example, to use `gcc-14` instead of `clang` on macOS, you could use something like the following:

```make
# ~/.R/Makevars
CC=gcc-8
CXX=g++-8
CXX11=g++-8
CC=gcc-14
CC17=gcc-14
CXX=g++-14
CXX17=g++-14
```
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@jameslamb jameslamb Oct 11, 2025

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I tested all of this on a Mac with R 4.4.2 tonight, confirmed it worked as expected.


To check the values R is using, run the following:

```shell
R CMD config --all
```

### Installing from Source with CMake <a id="install"></a>
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