qt5base-lts/cmake/modulecppexports.h.in
Marc Mutz 8602a224b6 QT_INLINE_SINCE: never inline for static Qt builds
Static Qt builds are not covered by BC guarantees, but since all
'libraries' are linked into a single executable, we face in all users
of the library the same ODR violation that we faced within the
implementation DLL: we can't define the same symbol as inline in some
TUs and out-of-line in others.

In the past, we decided to always inline in static builds, but that
breaks users which, by Hyrum's Law, have come to depend on the
non-existent BC guarantees for static Qt builds.

By switching to never inline¹ in static builds, we restore BC for such
users. The performance issues should be minimal, since LTO will anyway
inline whatever it wants, independent on how it was declared.

¹ except when the deprecation point has passed over the Qt version the
  API was inlined (-disable-deprecated-up-to configure switch).

[ChangeLog][QtCore] Restored binary compatibility for static Qt
builds broken by the QT_INLINE_SINCE mechanism. Qt still does not
guarantee BC for static build configurations otherwise.

Fixes: QTBUG-109449
Pick-to: 6.5 6.4
Change-Id: Ie3fa62621b74dc5e9dac301b9882c0e3c3999eaf
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
2022-12-16 17:21:56 +00:00

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C

// Copyright (C) 2022 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
#include <QtCore/qglobal.h>
#ifndef @header_base_name_upper@_H
#define @header_base_name_upper@_H
#if defined(QT_SHARED) || !defined(QT_STATIC)
# if defined(QT_BUILD_@module_define_infix@_LIB)
# define Q_@module_define_infix@_EXPORT Q_DECL_EXPORT
# else
# define Q_@module_define_infix@_EXPORT Q_DECL_IMPORT
# endif
#else
# define Q_@module_define_infix@_EXPORT
#endif
#if !defined(QT_BUILD_@module_define_infix@_LIB) && !defined(QT_STATIC)
/* outside library → inline decl + defi */
/* static builds treat everything as part of the library, so they never inline */
# define QT_@module_define_infix@_INLINE_SINCE(major, minor) inline
# define QT_@module_define_infix@_INLINE_IMPL_SINCE(major, minor) 1
#elif defined(QT_@module_define_infix@_BUILD_REMOVED_API)
/* inside library, inside removed_api.cpp:
* keep deprecated API → non-inline decl;
* remove deprecated API → inline decl;
* definition is always available */
# define QT_@module_define_infix@_INLINE_SINCE(major, minor) \
QT_IF_DEPRECATED_SINCE(major, minor, inline, /* not inline */)
# define QT_@module_define_infix@_INLINE_IMPL_SINCE(major, minor) 1
#else
/* inside library, outside removed_api.cpp:
* keep deprecated API → non-inline decl, no defi;
* remove deprecated API → inline decl, defi */
# define QT_@module_define_infix@_INLINE_SINCE(major, minor) \
QT_IF_DEPRECATED_SINCE(major, minor, inline, /* not inline */)
# define QT_@module_define_infix@_INLINE_IMPL_SINCE(major, minor) \
QT_IF_DEPRECATED_SINCE(major, minor, 1, 0)
#endif
#ifdef QT_@module_define_infix@_BUILD_REMOVED_API
# define QT_@module_define_infix@_REMOVED_SINCE(major, minor) QT_DEPRECATED_SINCE(major, minor)
#else
# define QT_@module_define_infix@_REMOVED_SINCE(major, minor) 0
#endif
#endif // @header_base_name_upper@_H