Best compiler warning level for C/C++ compilers?

Question

What compiler warning level do you recommend for different C/C++ compilers?

gcc and g++ will let you get away with a lot on the default level. I find the best warning level for me is '-Wall'. And I always try to remove fix the code for the warnings it generates. (Even the silly ones about using parenthesis for logical precedence rules or to say I really mean 'if (x = y)')

What are your favorite levels for the different compilers, such as Sun CC, aCC (HPUX ?), Visual Studio, intel?

Edit:

I just wanted to point out that I don't use "-Werror" (but I do understand it's utility) on gcc/g++ because, I use:

#warning "this is a note to myself"

in a few places in my code. Do all the compilers understand the #warning macro?

Answer 1

no one has mentioned the Intel compiler yet:

https://software.intel.com/sites/products/documentation/doclib/iss/2013/compiler/cpp-lin/GUID-D060680A-1A18-4574-8291-5C74E6E31335.htm

-w3 is pretty chatty, so I would suggest -w2

Answer 2

I believe VC also supports

#pragma message ("note to self")

But as the system grows and grows, and you get a nightly build 30 developers work on simultaneously, it takes days to read all the notes to self, even in that amount that self is going to be do nothing but note reading and finally going to break under the stress not being able to keep up and have to resign...

No really, the amount of warnings is quickly going to grow if you allow them, and you won't be able to spot the really important ones (uninitialized variables, this pointer used in constructor, ...).

That's why I try to treat warnings as errors: most of the time, the compiler is right warning me, and if he isn't, I document it in the code and prepend

#pragma warning ( push )
#pragma warning ( 4191 : disable )
// violent code, properly documented
#pragma warning ( pop )

I just read they have a warning ( N : suppress ) pragma, too.