configure on master checks for C++ compiler

configure on master checks for C++ compiler

[Eli Zaretskii]

I've noticed that the configure script now checks for a C++ compiler:

  checking for g++... g++
  checking whether we are using the GNU C++ compiler... yes
  checking whether g++ accepts -g... yes
  checking for g++ option to enable C++11 features... none needed
  checking how to run the C++ preprocessor... g++ -E

However, AFAIU the C++ compiler is really needed only for two builds:
Android and Haiku.  If that is correct, could we please limit these
tests only to those two builds, so that people who build for other
configurations won't need to have a C++ compiler installed?

Thanks.

Re: configure on master checks for C++ compiler

[Andreas Schwab]

On Aug 10 2023, Eli Zaretskii wrote:

> However, AFAIU the C++ compiler is really needed only for two builds:
> Android and Haiku.  If that is correct, could we please limit these
> tests only to those two builds, so that people who build for other
> configurations won't need to have a C++ compiler installed?

The configure script does not complain if it doesn't find a C++
compiler.

-- 
Andreas Schwab, SUSE Labs, schwab@suse.de
GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE  1748 E4D4 88E3 0EEA B9D7
"And now for something completely different."

Re: configure on master checks for C++ compiler

[Po Lu]

Eli Zaretskii <eliz@gnu.org> writes:

> I've noticed that the configure script now checks for a C++ compiler:
>
>   checking for g++... g++
>   checking whether we are using the GNU C++ compiler... yes
>   checking whether g++ accepts -g... yes
>   checking for g++ option to enable C++11 features... none needed
>   checking how to run the C++ preprocessor... g++ -E
>
> However, AFAIU the C++ compiler is really needed only for two builds:
> Android and Haiku.  If that is correct, could we please limit these
> tests only to those two builds, so that people who build for other
> configurations won't need to have a C++ compiler installed?
>
> Thanks.

A C++ compiler isn't required unless you are actually building for
Haiku, or Android with C++ dependencies (such as icu4c, a prerequisite
of libxml2.)

And unfortunately this is because of a well-known limitation in
Autoconf: the two distinct checks for C++ compilers both AC_REQUIRE a
C++ compiler, leading M4 to place the check at the top of the macro
expansion stack.  The result of the check remains unused unless one of
the two conditions above are satisfied.

Re: configure on master checks for C++ compiler

[Richard Stallman]

[[[ To any NSA and FBI agents reading my email: please consider    ]]]
[[[ whether defending the US Constitution against all enemies,     ]]]
[[[ foreign or domestic, requires you to follow Snowden's example. ]]]

  > And unfortunately this is because of a well-known limitation in
  > Autoconf: the two distinct checks for C++ compilers both AC_REQUIRE a
  > C++ compiler, leading M4 to place the check at the top of the macro
  > expansion stack.  The result of the check remains unused unless one of
  > the two conditions above are satisfied.

Since the failure of the check for a C++ compiler causes no problem
on platforms which don't need a C++ compiler, I think we can
live with this.  It is inelegant but no worse.

-- 
Dr Richard Stallman (https://stallman.org)
Chief GNUisance of the GNU Project (https://gnu.org)
Founder, Free Software Foundation (https://fsf.org)
Internet Hall-of-Famer (https://internethalloffame.org)