-Wl,-O1 Did you know that you also have an optimization flag for the linker ? Now you know! Ages ago the linker on SUN used to compile templates. What is GCC doing/using this flag for?
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What Are Your GCC Flags?
21–30 of 117 posts
Re: What Are Your GCC Flags?
#22The use of 'bytecode' is strange when refering to gcc and C code, perhaps 'object code', or executable would've been better. Bytecode is usually reserved for things like the JVM, or other cases where an interpreter/JIT is needed to run your code.
Re: What Are Your GCC Flags?
#23-Wl,-O1 Did you know that you also have an optimization flag for the linker ? Now you know! Ages ago the linker on SUN used to compile templates. What is GCC doing/using this flag for?
"Optimising the linked output" seems a bit vague but that's about as clear as the man page.
If level is a numeric values greater than zero ld optimizes the output. This might take significantly longer and therefore probably should only be enabled for the final binary. At the moment this option only affects ELF shared library generation.Re: What Are Your GCC Flags?
#24This is probably an unpopular opinion, but: -Werror is fine on your dev machine, but is a very bad idea in the official build system, notably if you do it for a library that you want people to use. As soon as you want to compile with various compilers, systems, use cross-compilation and other funny things that makes it portable, you're going to have a bad time. New compilers will make new warnings, old compilers will…
Our experience is that it is actually an excellent sanitary decision. We are using multiple builders with fixed GCC releases (for RHEL5, RHEL6 etc. flavors), and yes it means fixing additional warnings when we have to introduce a new architecture. But I can not count the number of serious issues we avoided by spotting and investigating warnings.
That's fine and dandy. It's not fine when it's an open source project from three years and four compiler versions ago that you want to compile, and find -Werror on every line invocation in a Makefile.
What you build with in-house for development/test-farms is not what you should ship as default to users of your project.
Re: What Are Your GCC Flags?
#25The compiler flags for Ag[1] are rather strict these days:
-Wall -Wextra -Wformat=2 -Wno-format-nonliteral -Wshadow \
-Wpointer-arith -Wcast-qual -Wmissing-prototypes -Wno-missing-braces \
-std=gnu89 -D_GNU_SOURCE -O2
I also use scan-build[2] for static analysis and clang-format[3] to ensure a consistent style. It was frustrating when I first enabled all these options, but the warnings helped me discover bugs that had been lurking for years.
1. https://github.com/ggreer/the_silver_searcher
Re: What Are Your GCC Flags?
#26This is probably an unpopular opinion, but: -Werror is fine on your dev machine, but is a very bad idea in the official build system, notably if you do it for a library that you want people to use. As soon as you want to compile with various compilers, systems, use cross-compilation and other funny things that makes it portable, you're going to have a bad time. New compilers will make new warnings, old compilers will…
Our experience is that it is actually an excellent sanitary decision. We are using multiple builders with fixed GCC releases (for RHEL5, RHEL6 etc. flavors), and yes it means fixing additional warnings when we have to introduce a new architecture. But I can not count the number of serious issues we avoided by spotting and investigating warnings.
Hi Xavier
Kinda off-topic, but have you considered translating HTTrack comments and variable names to English ?
Re: What Are Your GCC Flags?
#27This is probably an unpopular opinion, but: -Werror is fine on your dev machine, but is a very bad idea in the official build system, notably if you do it for a library that you want people to use. As soon as you want to compile with various compilers, systems, use cross-compilation and other funny things that makes it portable, you're going to have a bad time. New compilers will make new warnings, old compilers will…
Marco Arment, John Siracusa and Casey Liss had a lengthy discussion about this in two last episodes of ATP[0] (but mostly in #54[1] and some follow-up in #55[2]).
[0]: http://atp.fm
Re: What Are Your GCC Flags?
#28We use quite a few flags to issue warnings for our code[1]. The linked autoconf macro will detect whether or not the flags are supported on the detected compiler, and automatically add the flags to the build. It works for clang, gcc, g++, and helps us spot errors that would otherwise be hard to detect and fix.
[1] https://github.com/rescrv/HyperDex/blob/master/m4/anal_warni...
Re: What Are Your GCC Flags?
#29That's a very easy question. It's usually made of green, white, red and black.
Details here: http://ncusar.org/email_graphics/images/gcc-flags.gif
Re: What Are Your GCC Flags?
#30The compiler flags for Ag[1] are rather strict these days: -Wall -Wextra -Wformat=2 -Wno-format-nonliteral -Wshadow \ -Wpointer-arith -Wcast-qual -Wmissing-prototypes -Wno-missing-braces \ -std=gnu89 -D_GNU_SOURCE -O2 Note that -Wall and -Wextra do not enable all warnings. To keep backwards compatibility, -Wall is basically, "All warnings as of 1990." -Wextra covers a lot of the newer warnings, but still misses a few…
-pedantic-errors is also a very useful flag.
-Wstrict-aliasing=1/-Wsuggest-attribute= can give good suggestions during development.
Probably not useful for Ag: But I do a lot of numeric stuff so -Wfloat-equal is handy for me. For code using float this should be mandatory: -Wdouble-promotion.