Re: -Wshift-negative-value

[Bruno H. <br...@cl...>]

Hi Sam,

> >> > As I said on 2017-02-08, diagnostics from -Wshift-negative-value are
> >> > most probably just noise.
> >> 
> >> Why not disable them then?
> >
> > Feel free to do so. Good idea.
> 
> Done.

On OpenBSD 6, with gcc 4.2.1, I now get the build error:
cc1: error: unrecognized command line option "-Wno-shift-negative-value"

Please, can you limit the use of this option to the compilers that support it?
Just tried it (I have all gcc releases installed separately): it's supported
starting with gcc 4.4.0, unsupported for older versions.

Using the same idiom that I used to protect the use of -Wno-invalid-offsetof:

    # g++ 3.4 introduced an annoying warning, but has a workaround:
    case "$XCC_GCC_VERSION" in
      2.* | 3.[1-3]*) ;;
      *)
        XCFLAGS=$XCFLAGS' -Wno-invalid-offsetof'
        ;;
    esac

Btw, why did you remove this version check? It is needed:

$ /arch/x86-linux/gnu-inst-gcc/3.4.4/bin/gcc -x c++ -Wno-invalid-offsetof -S hello.c

succeeds but

$ /arch/x86-linux/gnu-inst-gcc/3.3.6/bin/gcc -x c++ -Wno-invalid-offsetof -S hello.c
cc1plus: error: unrecognized option `-Wno-invalid-offsetof'

I tend to assume a gcc version >= 3.1.

Bruno