In reality, who cares of what the C spec says? Unless you have to port code on different compilers (which is very unlikely, unless you are building a library me

In reality, who cares of what the C spec says? Unless you have to port code on different compilers (which is very unlikely, unless you are building a library meant to be shared with different projects) you only care about the fact that the code works correctly with the compiler you choose to use. I don't get all the programmers that scandalize if you use GNU extensions, they are fine, and mostly useful, so if you are using GCC to program I don't see why not use -std=gnu11 instead of -std=c11... who cares if the program is not compliant? Even if you want to be compliant to share code, the C standard is you last problem, the thing is that you probably use a ton of libraries and header files specific to that implementation (such as POSIX or even worse Linux-specific stuff), so your code is 99% not portable anyway without rewriting most of it.