问题
The project that I am trying to build has default flags
CFLAGS = -Wall -g -O2
CXXFLAGS = -g -O2
I need to append a flag -w to both these variables (to remove: 'consider all warnings as errors')
I have a method to work it out, give
make 'CFLAGS=-Wall -g -O2 -w'; 'CXXFLAGS=-g -O2 -w'
OR
Run ./configure and statically modify Makefile
But I want to append my options with the existing options while running configure or make
The post Where to add a CFLAG, such as -std=gnu99, into an autotools project conveniently uses a macro to achieve this.
回答1:
You almost have it right; why did you add the semicolon?
To do it on the configure line:
./configure CFLAGS='-g -O2 -w' CXXFLAGS='-g -O2 -w'
To do it on the make line:
make CFLAGS='-g -O2 -w' CXXFLAGS='-g -O2 -w'
However, that doesn't really remove consider all warnings as errors; that removes all warnings. So specifying both -Wall and -w doesn't make sense. If you want to keep the warnings but not have them considered errors, use the -Wall -Wno-error flags.
Alternatively, most configure scripts which enable -Werror by default also have a flag such as --disable-werror or similar. Run ./configure --help and see if there's something like that.
来源：https://stackoverflow.com/questions/23407635/append-compile-flags-to-cflags-and-cxxflags-while-configuration-make