Tuplanolla Sampsa Kiiskinen


This project is merely a collection of useful options. Get it on GitHub.

Warnings for GCC

Clang has a handy option called -Weverything, which enables every warning built into the compiler. GCC does not. This project provides -Weverything for compiling C files with GCC.

Both compilers of course have -Wall and -Wextra, but their names are misleading: they only offer a few of the most commonly used warnings.

Table of Contents


The file extract.scm contains sloppy code for extracting all of the -W options from the source code of any version of GCC. That includes undocumented options, which are actually quite common. Those willing to try it need CHICKEN and some eggs, a Scheme implementation and a bunch of libraries, to run it. It is safe to use in the sense that it does not do any destructive operations like writing files.

The file checkout.sh contains equally sloppy code for checking out various GCC versions from a local Git repository, which has to be downloaded separately. It exists to automate using extract.scm and contains all of the potentially harmful operations, so one should proceed with caution.

The rest of the files inside the tags directory contain the warning options for each of the tagged versions of GCC. For example gcc-4_8_0-release contains 124 warnings of which 23 are undocumented.


The closest thing to an installation is downloading the option listings.

[user@computer:~]$ wget https://github.com/Tuplanolla/gcc-weverything/blob/master/tags/gcc-4_8_0-release


It is easy to integrate -Weverything with make by fixing the version

CFLAGS=`cat gcc-4_8_0-release`

or detecting it automatically.

CFLAGS=gcc-`gcc --version | grep -o "[0-9]\+\(\.[0-9]\)*" | head -n 1 | tr . _`-release

Bugs and Limitations

Throughout history GCC has used three kinds of option specification systems, so there can be small variations in the extracted output. For example -Wformat was changed to -Wformat= when version 3.4.0 was released. Such options have to be tweaked by hand or removed.

Since everything really means everything here, -Werror and warnings like, say, -Wtraditional are also included. Therefore it is almost impossible to compile files without disabling some of them with -Wno-.

CFLAGS=`cat gcc-4_8_0-release` -Wno-error