Have just worked through this and I think in short there is no *good* way. The method I decided to live with is caching the CFLAGS in the toolchain file.
If you don't have a custom toolchain file for that project, create one.
Assuming you're using a GNU-derived toolchain try this:
set(CMAKE_C_FLAGS_RELEASE "-O2" CACHE STRING "Some description")
include(Compiler/GNU)
Pass the toolchain file to cmake:
cmake -DCMAKE_TOOLCHAIN_FILE=/path/to/my/toolchain-file.cmake ...
The downside is you can no longer change the C_FLAGS from a cmake UI
(like ccmake) though you *can* change them from the command line.
( cmake -DCMAKE_C_FLAGS_RELEASE=... )
What doesn't work and why:
* Setting CMAKE_CFLAGS_RELEASE in a CMakeLists.txt
-> Obviously. It's too late, we're past toolchain
determination and try_compile
* Setting CMAKE_CFLAGS_RELEASE_INIT in a toolchain file
-> GNU compiler determination appends -O3 and -NDEBUG
ciao
Mark
On Mon, 10 Sep 2018 14:34:26 +0200, Stéphane Ancelot wrote:
> Hi,
>
> In one project I need to compile with -O2 option , how to set it and remove
> -O3 -DNDEBUG flags for this project ?
>
> Regards,
>
> Steph
>
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