Re: build failures on Solaris

[Guy Harris via tcpdump-workers <tcpdump-workers () lists tcpdump org>]

> --- Begin Message ---
>
>
> From: Guy Harris <gharris () sonic net>
>
> Date: Sun, 8 Aug 2021 12:02:53 -0700
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> On Aug 8, 2021, at 2:26 AM, Denis Ovsienko <denis () ovsienko info> wrote:
>
> > GCC+CMake fails early now (see attached).
>
> Good!  That reveals the *underlying* problem:
>
> 1) CMake, by default, checks for both a C *and* a C++ compiler;
>
> 2) if it's checking for both compilers, the way CMake determines CMAKE_SIZEOF_VOID_P is to:
>
>         check for a C compiler;
>
>         set CMAKE_C_SIZEOF_DATA_PTR to the size of data pointers in that C compiler with whatever C flags are being 
> used;
>
>         set CMAKE_SIZEOF_VOID_P to CMAKE_C_SIZEOF_DATA_PTR;
>
>         check for a C++ compiler;
>
>         set CMAKE_CXX_SIZEOF_DATA_PTR to the size of data pointers in that C++ compiler with whatever C++ flags are 
> being used;
>
>         set CMAKE_SIZEOF_VOID_P to CMAKE_CXX_SIZEOF_DATA_PTR;
>
> 3) Sun/Oracle's C and C++ compilers default to building *32-bit* code;
>
> 4) the version of GCC installed on the Solaris 11 builder appears to default to building 64-bit code;
>
> 5) there does not appear to be a version of G++ installed, so CMake finds "/usr/bin/CC", which is the Sun/Oracle C++ 
> compiler;
>
> 6) as a result of the above, CMake ends up setting CMAKE_SIZEOF_VOID_P to 4, which can affect the process of finding 
> libraries;
>
> 7) nevertheless, the C code (which is *all* the code - ain't no C++ in tcpdump) is compiled 64-bit;
>
> 8) hilarity ensues.
>
> I've checked in a change to explicitly tell CMake "this is a C-only project, don't check for a C++ compiler", so it 
> should now think it's building 64-bit when building with GCC.
>
> See whether that fixes things.
>
> --- End Message ---
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