问题
I'm using qmake and Visual Studio. In release build qmake adds /GL and /O2 flags to all projects, and I need to remove those two flags for certain libraries within my whole Qt project. Is there a way?
回答1:
The only way this could work is
QMAKE_CFLAGS -= /GL /O2
but I doubt this works for QMAKE_CFLAGS.
Alternatively, you could redefine QMAKE_CFLAGS, forgetting its previous value:
QMAKE_CFLAGS = $$CFLAGS_WITHOUT_GL_O2
回答2:
I had a similar problem and I solved it by adding the following directive in the .pro file:
QMAKE_CXXFLAGS_RELEASE -= -g
Observe the _RELEASE suffix, otherwise don't work.
回答3:
I edited my .pro file by using this, and it worked!
QMAKE_CXXFLAGS_RELEASE -= -Zc:strictStrings
QMAKE_CXXFLAGS_RELEASE_WITH_DEBUGINFO -= -Zc:strictStrings
It does not work:
QMAKE_CFLAGS_RELEASE -= -Zc:strictStrings
QMAKE_CFLAGS_RELEASE_WITH_DEBUGINFO -= -Zc:strictStrings
You can try:
QMAKE_CXXFLAGS_RELEASE -= -GL -O2
QMAKE_CXXFLAGS_RELEASE_WITH_DEBUGINFO -= -GL -O2
Take a look in:
your Qt dir\compiler\mkspecs\win32-msvc2013\qmake.conf
回答4:
You can edit the qmakespec which is used by your configuration.
The easiest way to find it is by opening
%QTDIR%\mkspecs\%QMAKESPEC%
assuming the environment variables are set (they should be)
Just in case it's not working, it will be something like C:\Qt\4.x.x\mkspecs\win32-msvc2010
In the qmake.conf file you can adjust the folling two lines (they are in different places in the file)
QMAKE_CFLAGS_RELEASE = -O2 -MT
QMAKE_CFLAGS_LTCG = -GL
to
QMAKE_CFLAGS_RELEASE = -MT
QMAKE_CFLAGS_LTCG =
However note that you will have to do this for every Qt Version you are using (and for every future update you will do).
[Edit]
If you want to have -O2 -GL options for certain projects you will have to add
QMAKE_CFLAGS_RELEASE += -O2
QMAKE_CFLAGS_LTCG += -GL
to the .pro file of the projects which need those options.
Dependent on the amount of projects which use it and the ones which don't, either this approach or redefining QMAKE_CFLAGS will be more convenient.
回答5:
If -= does not work
try in your .pro file
QMAKE_CFLAGS = $$replace(QMAKE_CFLAGS, "-GL ", "")
QMAKE_CFLAGS = $$replace(QMAKE_CFLAGS, "-O2 ", "")
回答6:
Recently I faced the same problem. I had to remove the Zc:strictStrings compiler flag. I've learned immediately that just removing does not work. So, the solution is to override the flag by including this string into .pro file
QMAKE_CXXFLAGS+=-Zc:strictStrings-
Like this the compiler prints a warning: cl : Command line warning D9025 : overriding '/Zc:strictStrings' with '/Zc:strictStrings-' but still it does the job.
来源：https://stackoverflow.com/questions/8241567/qmake-how-to-remove-compiler-flag-for-a-certain-project-without-changing-qmake