[ARROW-18231] [C++] Cannot override optimization level using CXXFLAGS

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 11.0.0
• Component/s: C++
• Labels: pull-request-available
• External issue URL: https://github.com/apache/arrow/issues/33416
• Assignee: Kouhei Sutou
• Reporter: Antoine Pitrou
• Created: 02/Nov/22 20:37
• Updated: 11/Jan/23 11:58
• Resolved: 24/Dec/22 20:20

Description

In release mode, Arrow C++ unconditionally adds -O2 at the end of the compiler flags.
So, if you do something like:

export CXXFLAGS=-O0
cmake ...

the final compilation flags will look like -O0 -O2, meaning the user-provided optimization level is ignored.

One can instead use the ARROW_CXXFLAGS CMake variable, but it only overrides the flags for Arrow itself, not the bundled dependencies.

Issue Links

• links to: GitHub Pull Request #15022