Debug vs Release in CMake

Question

In a GCC compiled project    How do I run CMake for each target type  debug release   How do I specify debug and release C C   flags using CMake  How do I express that the main executable will be compiled with g   and one nested library with gcc

User · Answer

Instead of manipulating the CMAKE CXX FLAGS strings directly  which could be done more nicely using string APPEND CMAKE CXX FLAGS DEBUG   -g3   btw   you can use add compiler options   add compile options     -Wall   -Wpedantic   -Wextra   -fexceptions       lt   lt CONFIG DEBUG gt  -O0 -g3 -ggdb gt       This would add the specified warnings to all build types  but only the given debugging flags to the DEBUG build  Note that compile options are stored as a CMake list  which is just a string separating its elements by semicolons

User · Answer

A lot of the answers here are out of date bad  So I m going to attempt to answer it better  Granted I m answering this question in 2020  so it s expected things would change   How do I run CMake for each target type  debug release   First off Debug Release are called configurations in cmake  nitpick   If you are using a single configuration generator  Ninja Unix-Makefiles  Then you need a build folder for each configuration  Like this    Configure the build cmake -S   -B build Debug -D CMAKE BUILD TYPE Release    Actually build the binaries cmake --build build Debug  For multi-configuration generators it s slightly different  Ninja Multi-Config  Visual Studio    Configure the build cmake -S   -B build    Actually build the binaries cmake --build build --config Debug  If you are wondering why this is necessary it s because cmake isn t a build system  It s a meta-build system  IE a build system that build s build systems   This is basically the result of handling build systems that support multiple-configurations in 1 build  If you d like a deeper understanding I d suggest reading a bit about cmake in Craig Scott s book  quot Professional CMake  A Practical Guide  How do I specify debug and release C C   flags using CMake  The modern practice is to use target s and properties  Here is an example  add library foobar     Add this compile definition for debug builds  this same logic works for   target compile options  target link options  etc  target compile definitions foobar PRIVATE       lt   lt CONFIG Debug gt           FOOBAR DEBUG 1      gt     NOTE  How I m using generator expressions to specify the configuration  Using CMAKE BUILD TYPE will result in bad builds for any multi-configuration generator  Further more sometimes you need to set things globally and not just for one target  Use add compile definitions  add compile options  etc  Those functions support generator expressions  Don t use old style cmake unless you have to  that path is a land of nightmares   How do I express that the main executable will be compiled with g   and one nested library with gcc  Your last question really doesn t make sense

User · Answer

If you want to build a different configuration without regenerating if using you can also run cmake --build   PWD  --config  lt cfg gt  For multi-configuration tools  choose  lt cfg gt  ex  Debug  Release  MinSizeRel  RelWithDebInfo  https   cmake org cmake help v2 8 11 cmake html opt 3a--builddir

User · Answer

With CMake  it s generally recommended to do an  out of source  build  Create your CMakeLists txt in the root of your project  Then from the root of your project   mkdir Release cd Release cmake -DCMAKE BUILD TYPE Release    make   And for Debug  again from the root of your project    mkdir Debug cd Debug cmake -DCMAKE BUILD TYPE Debug    make   Release   Debug will add the appropriate flags for your compiler  There are also RelWithDebInfo and MinSizeRel build configurations     You can modify add to the flags by specifying a toolchain file in which you can add CMAKE  lt LANG gt  FLAGS  lt CONFIG gt  INIT variables  e g    set CMAKE CXX FLAGS DEBUG INIT  -Wall   set CMAKE CXX FLAGS RELEASE INIT  -Wall     See CMAKE BUILD TYPE for more details     As for your third question  I m not sure what you are asking exactly  CMake should automatically detect and use the compiler appropriate for your different source files

User · Answer

CMakeLists txt   release  set CMAKE CONFIGURATION TYPES  Release  CACHE STRING    FORCE       CMakeLists txt   debug  set CMAKE CONFIGURATION TYPES  Debug  CACHE STRING    FORCE

User · Answer

For debug release flags  see the CMAKE BUILD TYPE variable  you pass it as cmake -DCMAKE BUILD TYPE value   It takes values like Release  Debug  etc   https   gitlab kitware com cmake community wikis doc cmake Useful-Variables compilers-and-tools  cmake uses the extension to choose the compiler  so just name your files  c   You can override this with various settings   For example   set source files properties yourfile c LANGUAGE CXX     Would compile  c files with g    The link above also shows how to select a specific compiler for C C

[c++] Debug vs Release in CMake

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