GCC Warnings
GCC can warn you about a lot of things that might be problematic in your code.
You can read up on the specific warnings in the documentation, but it is quite
a pain to make a selection that includes as much as possible, because unlike
the name suggests, -Wall does not enable all warnings and neither do the
well known shorthands -Wextra and -Wpedantic, although -Wpedantic already
includes some very strict code checks.
Anyways, here is a list of warning flags that I like to use for C coding, which
is quite a bit more complete than the formentioned three:
-Wall
-Wextra
-Wpedantic
-Winline
-Wundef
-Wshadow
-Winit-self
-Wformat-nonliteral
-Wcast-qual
-Wcast-align
-Wsign-conversion
-Wpointer-arith
-Wbad-function-cast
-Wmissing-prototypes
-Wmissing-include-dirs
-Wmissing-declarations
-Wstrict-prototypes
-Wstrict-overflow=5
-Wnested-externs
-Wwrite-strings
-Wfloat-equal
-Wdisabled-optimization
-Wformat=2
-Wformat-extra-args
-Wformat-security
-Wformat-nonliteral
-Wformat-signedness
-Wlogical-op
-Wredundant-decls
-Wswitch-default
-Wunused-function
-Wunused-label
-Wunused-value
-Wunused-variable
-Wunused-parameter
-Wnull-dereference
Last but not least, there is the -ansi flag, which makes GCC enforce ANSI C code.
In my mind, this is just a tad too pedantic, since it enforces quite uncomfortable
code format rules. For example you have to declare all variables at the top of the
function and can not declare them in the middle.
This for example would be not valid with the -ansi flag enabled:
int main(){
printf("Hello, World!");
int a = 1;
return 0;
}
Also note that for other languages, like C++, there are even more and other flags.