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Reduce scope of a hack using volatile in favor of viewAt()

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We can now get qt_configure_strs to tell us the size of the string, as
well as its start, bypassing the strlen()-calling branch of
fromLocal8Bit() that caused the need for a hack using a volatile
variable. However, QT_CONFIGURE_SETTINGS_PATH still needs the volatile
hack.

Change-Id: I0181abf512123e6355acdd506d6845c3fb75c0e3
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
This commit is contained in:
Edward Welbourne 2021-11-18 12:17:47 +01:00
parent 4d4aa6e21c
commit 4ef8e9427c
1 changed files with 7 additions and 11 deletions
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18
src/corelib/global/qlibraryinfo.cpp
View File

@ -602,24 +602,20 @@ QString QLibraryInfo::path(LibraryPath p)
#endif // settings #endif // settings
if (!fromConf) { if (!fromConf) {
// "volatile" here is a hack to prevent compilers from doing a
// compile-time strlen() on "path". The issue is that Qt installers
// will binary-patch the Qt installation paths -- in such scenarios, Qt
// will be built with a dummy path, thus the compile-time result of
// strlen is meaningless.
const char * volatile path = nullptr;
if (loc == PrefixPath) { if (loc == PrefixPath) {
ret = getPrefix(); ret = getPrefix();
} else if (int(loc) <= qt_configure_strs.count()) { } else if (int(loc) <= qt_configure_strs.count()) {
path = qt_configure_strs[loc - 1]; ret = QString::fromLocal8Bit(qt_configure_strs.viewAt(loc - 1));
#ifndef Q_OS_WIN // On Windows we use the registry #ifndef Q_OS_WIN // On Windows we use the registry
} else if (loc == SettingsPath) { } else if (loc == SettingsPath) {
path = QT_CONFIGURE_SETTINGS_PATH; // Use of volatile is a hack to discourage compilers from calling
// strlen(), in the inlined fromLocal8Bit(const char *)'s body, at
// compile-time, as Qt installers binary-patch the path, replacing
// the dummy path seen at compile-time, typically changing length.
const char *volatile path = QT_CONFIGURE_SETTINGS_PATH;
ret = QString::fromLocal8Bit(path);
#endif #endif
} }
if (path)
ret = QString::fromLocal8Bit(path);
} }
if (!ret.isEmpty() && QDir::isRelativePath(ret)) { if (!ret.isEmpty() && QDir::isRelativePath(ret)) {