[jira] [Commented] (ARROW-17580) [Doc][C++][Python] Unclear how to influence compilation flags

["Kouhei Sutou (Jira)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/ARROW-17580?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17598685#comment-17598685 ] 

Kouhei Sutou commented on ARROW-17580:
--------------------------------------

{quote}
For Arrow C++, it seems {{ARROW_CXXFLAGS}} should be passed to CMake, while the {{CXXFLAGS}} environment variable is ignored (it probably shouldn't?).
{quote}

Really? {{CXXFLAGS}} environment variable should be respected because we don't override {{CMAKE_CXX_FLAGS}} that is initialized with {{CXXFLAGS}} environment variable.
See also:
* https://github.com/apache/arrow/blob/master/cpp/CMakeLists.txt#L555
* https://cmake.org/cmake/help/latest/envvar/CXXFLAGS.html

For PyArrow:
* We should unify {{python/CMakeLists.txt}} and {{python/pyarrow/src/CMakeLists.txt}}.
* We need to look into why {{CXXFLAGS}} environment variable is ignored.

> [Doc][C++][Python] Unclear how to influence compilation flags
> -------------------------------------------------------------
>
>                 Key: ARROW-17580
>                 URL: https://issues.apache.org/jira/browse/ARROW-17580
>             Project: Apache Arrow
>          Issue Type: Bug
>          Components: C++, Documentation, Python
>            Reporter: Antoine Pitrou
>            Priority: Critical
>
> Frequently people need to customize compilation flags for C++ and/or C files.
> Unfortunately, both for Arrow C++ and PyArrow, it is very difficult to find out the proper way to do this.
> For Arrow C++, it seems {{ARROW_CXXFLAGS}} should be passed to CMake, while the {{CXXFLAGS}} environment variable is ignored (it probably shouldn't?).
> For PyArrow, I have not found a way to do it. The {{CXXFLAGS}} environment variable is ignored, and the {{PYARROW_CXXFLAGS}} CMake variable has two problems:
> * it is only recognized for Cython-generated files, not for PyArrow C++ sources
> * it only affects linker calls, while it should actually affect compiler calls



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