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jww
jww
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Optimize in CMake - optimize by default

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marmistrz
marmistrz
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I have a C++ project which uses CMake as its build system. I'd like the following behavior:

If cmake is invoked as cmake .., then CMAKE_CXX_FLAGS is -O3 -Wall -Wextra

If cmake is invoked as cmake .. -DCMAKE_BUILD_TYPE=Debug, then CMAKE_CXX_FLAGS is -g -Wall -Wextra

I tried the following

message(STATUS "Build type: ${CMAKE_BUILD_TYPE}")

set(CMAKE_CXX_STANDARD 14)
set(CMAKE_CXX_FLAGS "-O3 -Wall -Wextra")
set(CMAKE_CXX_FLAGS_DEBUG "-g -Wall -Wextra")

But this has a big problem. First of all, if the second invocation is used, then both -O3 and -g flags are passed to the compiler. Besides, if I use the second invocation and the first thereafter, CMAKE_BUILD_TYPE stays Debug although not explicitly ordered so - so I get a Debug build although I want an optimized build.

Why? What can I do to get the desired behavior?

I have a C++ project which uses CMake as its build system. I'd like the following behavior:

If cmake is invoked as cmake .., then CMAKE_CXX_FLAGS is -O3 -Wall -Wextra

If cmake is invoked as cmake .. -DCMAKE_BUILD_TYPE=Debug, then CMAKE_CXX_FLAGS is -g -Wall -Wextra

I tried the following

message(STATUS "Build type: ${CMAKE_BUILD_TYPE}")

set(CMAKE_CXX_STANDARD 14)
set(CMAKE_CXX_FLAGS "-O3 -Wall -Wextra")
set(CMAKE_CXX_FLAGS_DEBUG "-g -Wall -Wextra")

But this has a big problem. First of all, if the second invocation is used, then both -O3 and -g flags are passed to the compiler. Besides, if I use the second invocation and the first thereafter, CMAKE_BUILD_TYPE stays Debug although not explicitly ordered so - so I get a Debug build although I want an optimized build.

Why? What can I do to get the desired behavior?

I have a C++ project which uses CMake as its build system. I'd like the following behavior:

If cmake is invoked as cmake .., then CMAKE_CXX_FLAGS is -O3 -Wall -Wextra

If cmake is invoked as cmake .. -DCMAKE_BUILD_TYPE=Debug, then CMAKE_CXX_FLAGS is -g -Wall -Wextra

I tried the following

message(STATUS "Build type: ${CMAKE_BUILD_TYPE}")

set(CMAKE_CXX_FLAGS "-O3 -Wall -Wextra")
set(CMAKE_CXX_FLAGS_DEBUG "-g -Wall -Wextra")

But this has a big problem. First of all, if the second invocation is used, then both -O3 and -g flags are passed to the compiler. Besides, if I use the second invocation and the first thereafter, CMAKE_BUILD_TYPE stays Debug although not explicitly ordered so - so I get a Debug build although I want an optimized build.

Why? What can I do to get the desired behavior?

Source Link
marmistrz
marmistrz
  • 6.2k
  • 10
  • 47
  • 98

CMake - optimize by default

I have a C++ project which uses CMake as its build system. I'd like the following behavior:

If cmake is invoked as cmake .., then CMAKE_CXX_FLAGS is -O3 -Wall -Wextra

If cmake is invoked as cmake .. -DCMAKE_BUILD_TYPE=Debug, then CMAKE_CXX_FLAGS is -g -Wall -Wextra

I tried the following

message(STATUS "Build type: ${CMAKE_BUILD_TYPE}")

set(CMAKE_CXX_STANDARD 14)
set(CMAKE_CXX_FLAGS "-O3 -Wall -Wextra")
set(CMAKE_CXX_FLAGS_DEBUG "-g -Wall -Wextra")

But this has a big problem. First of all, if the second invocation is used, then both -O3 and -g flags are passed to the compiler. Besides, if I use the second invocation and the first thereafter, CMAKE_BUILD_TYPE stays Debug although not explicitly ordered so - so I get a Debug build although I want an optimized build.

Why? What can I do to get the desired behavior?