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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Thu, 3 Aug 2023 11:28:04 +0900
Message-ID: <CAK7LNAS=da_jTF77hF0+Est-orBybwReZAkqWLH5sGTp59eH9g@mail.gmail.com>
Subject: Re: [PATCH v2 1/1] kconfig: port qconf to work with Qt6 in addition
 to Qt5
To:     Boris Kolpackov <boris@codesynthesis.com>
Cc:     linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org
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On Tue, Aug 1, 2023 at 11:07=E2=80=AFPM Boris Kolpackov <boris@codesynthesi=
s.com> wrote:
>
> Tested with Qt5 5.15 and Qt6 6.4. Note that earlier versions of Qt5
> are no longer guaranteed to work.
>
> Signed-off-by: Boris Kolpackov <boris@codesynthesis.com>
> ---


$ make xconfig
  HOSTCC  scripts/basic/fixdep
  HOSTCC  scripts/kconfig/images.o
  HOSTCC  scripts/kconfig/confdata.o
  HOSTCC  scripts/kconfig/expr.o
  LEX     scripts/kconfig/lexer.lex.c
  YACC    scripts/kconfig/parser.tab.[ch]
  HOSTCC  scripts/kconfig/lexer.lex.o
  HOSTCC  scripts/kconfig/menu.o
  HOSTCC  scripts/kconfig/parser.tab.o
  HOSTCC  scripts/kconfig/preprocess.o
  HOSTCC  scripts/kconfig/symbol.o
  HOSTCC  scripts/kconfig/util.o
  HOSTCXX scripts/kconfig/qconf.o
In file included from /usr/include/x86_64-linux-gnu/qt6/QtGui/qtguiglobal.h=
:7,
                 from /usr/include/x86_64-linux-gnu/qt6/QtGui/qaction.h:7,
                 from /usr/include/x86_64-linux-gnu/qt6/QtGui/QAction:1,
                 from scripts/kconfig/qconf.cc:7:
/usr/include/x86_64-linux-gnu/qt6/QtCore/qglobal.h:106:6: error:
#error "Qt requires a C++17 compiler"
  106 | #    error "Qt requires a C++17 compiler"
      |      ^~~~~
/usr/include/x86_64-linux-gnu/qt6/QtCore/qglobal.h:491:11: warning:
inline variables are only available with =E2=80=98-std=3Dc++17=E2=80=99 or
=E2=80=98-std=3Dgnu++17=E2=80=99 [-Wc++17-extensions]
  491 | constexpr inline Deprecated_t Deprecated =3D {};
      |           ^~~~~~
/usr/include/x86_64-linux-gnu/qt6/QtCore/qglobal.h:1009:26: error:
=E2=80=98enable_if_t=E2=80=99 in namespace =E2=80=98std=E2=80=99 does not n=
ame a template type
 1009 |          typename =3D std::enable_if_t<std::is_arithmetic_v<T>
&& std::is_arithmetic_v<U> &&
      |                          ^~~~~~~~~~~
/usr/include/x86_64-linux-gnu/qt6/QtCore/qglobal.h:1009:21: note:
=E2=80=98std::enable_if_t=E2=80=99 is only available from C++14 onwards
 1009 |          typename =3D std::enable_if_t<std::is_arithmetic_v<T>
&& std::is_arithmetic_v<U> &&
      |                     ^~~
[ snip tons of errors]


The first error says,  #error "Qt requires a C++17 compiler"


Right, g++ defaults to this:

$ g++ --version
g++ (Debian 12.2.0-14) 12.2.0
Copyright (C) 2022 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


It worked for me with the following fix-up applied.


diff --git a/scripts/kconfig/qconf-cfg.sh b/scripts/kconfig/qconf-cfg.sh
index a1b718a7366c..a5d5ed008dc3 100755
--- a/scripts/kconfig/qconf-cfg.sh
+++ b/scripts/kconfig/qconf-cfg.sh
@@ -17,6 +17,8 @@ fi

 if ${HOSTPKG_CONFIG} --exists $PKG6; then
        ${HOSTPKG_CONFIG} --cflags ${PKG6} > ${cflags}
+       # Qt6 requires a C++17 compiler
+       echo -std=3Dc++17 >> ${cflags}
        ${HOSTPKG_CONFIG} --libs ${PKG6} > ${libs}
        ${HOSTPKG_CONFIG} --variable=3Dlibexecdir Qt6Core > ${bin}
        exit 0


--
Best Regards
Masahiro Yamada