Many toolchain did not change the definition of NULL to avoid introducing
breaking changes in existing codebases. For example, on Windows NULL is
0 (int) regardless of the C++ standard in use.
Fixes the following warnings on CLang when compiling for Windows:
../glib/glib/tests/cxx.cpp:539:34: warning: missing sentinel in function call [-Wsentinel]
g_test_init (&argc, &argv, NULL);
^
, nullptr
../glib/glib/gtestutils.h:298:9: note: function has been explicitly marked sentinel here
void g_test_init (int *argc,
^
../glib/gio/tests/cxx.cpp:62:34: warning: missing sentinel in function call [-Wsentinel]
g_test_init (&argc, &argv, NULL);
^
, nullptr
../glib/glib/gtestutils.h:298:9: note: function has been explicitly marked sentinel here
void g_test_init (int *argc,
^
Wrap the logic into a G_ALWAYS_INLINE function, instead of using a
complex statement-expression which is not allowed in braced initializer
lists and expanded into some bad thing when it's used as
`::g_strdup(...)`.
We cannot use `__builtin_constant_p (str)` because GCC documentation
clearly states that it always produces 0 when str is a const char *
argument of an inline function. But `__builtin_constant_p (!str)`,
`__builtin_constant_p (!!str)`, and
`__builtin_constant_p (strlen (str))` functions properly with `-O1` or
above enabled.
Fixes#2936.
...much like g_string_free_and_steal () does; by redirecting
g_string_free (_, FALSE) calls (when we can detect them) to
g_string_free_and_steal ().
This relies on some unpretty macros, but should be entirely transparent
to any users of g_string_free (). In particular, the macro only
evaluates its arguments once, no matter which branch ends up being
taken. The ternary operator the macro expands to always gets optimized
out, even at -O0: there is only one call to either g_string_free () or
g_string_free_and_steal () in the compiled code, with no run-time
branching.
Add a test for ensuring this works as expected in C++ too.
Signed-off-by: Sergey Bugaev <bugaevc@gmail.com>
g_strdup() is often used to duplicate static strings, in these cases the
compiler could use a faster path because it knows the length of the
string at compile time, but this cannot happen because our g_strdup()
implementation is hidden.
To improve this case, we add a simple implementation of g_strdup() when
it is used with static or NULL strings that explicitly uses strlen,
g_malloc and memcpy to give hints to the compiler how to behave better.
This has definitely some benefits in terms of performances, causing an
iteration of 1000000 string duplication to drop from 2.7002s to 1.9428s
for a static string and from ~0.6584s to ~0.4408 for a NULL one.
Since compiler can optimize these cases quite a bit, the generated code
[2] is not increasing a lot, given that it can now avoid generating some
code or do it in few simpler steps.
Update tests to cover both inlined and non inlined cases.
[1] https://gitlab.gnome.org/GNOME/glib/-/merge_requests/3209#note_1644383
[2] https://gitlab.gnome.org/GNOME/glib/-/merge_requests/3209#note_1646662
We could have unguarded crashes when calling strlen (NULL) or when passing
invalid GString's.
Also ensure that we are not using the macro `val` argument multiple times as
it may lead to an unwanted behavior when passing to it a variable value such
as `str[++i]`, as the value may be called multiple times.
C++ tests and Coverity were both underlining this.
Fixes: #2890
Further to commit bcd364afef984da894045, fix the types accepted by the
`g_str_equal()` macro for C++ too. C++ is more restrictive about
const-correctness.
Add unit tests.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Fixes: #2820
Sadly, in C++ there's not an universal way to get what language standard
is used to compile GLib-based programs, in fact while most compilers
relies on `__cplusplus`, MSVC is defining that, but it does not use it
to expose such information (unless `/Zc:__cplusplus` arg is used).
On the other side, MSVC reports the language standard via _MSVC_LANG [1].
This complication makes us defining some macros in a very complex way
(such as glib_typeof()), because we need to perform many checks just to
understand if a C++ compiler is used and what standard is expecting.
To avoid this, define multiple macros that can be used to figure out
what C++ standard is being used.
[1] https://docs.microsoft.com/en-us/cpp/build/reference/zc-cplusplus?view=msvc-170
These functions may be defined as macros with different behaviors in
different c++ versions (as they rely on glib_typeof), so let's ensure
they work and compile everywhere.
We had gcc-only implementations for them while both can be used in all
the supported platforms we have.
So let's just provide generic definitions, while we keep the old ones
for both consistency and retro-compatibility.
Atomic primitives allow to do conditional compare and exchange but also
to get the value that was previously stored in the atomic variable.
Now, we provided an exchange function that allows to do an exchange if
the atomic value matches an expected value but we had no way to know
at the same time what was the value in the atomic at the moment of the
exchange try, an this can be useful in case that the operation fails,
for example if the current value is still acceptable for us, allowing
to do a kind of "OR" check:
gint old_value;
gint valid_value = 222;
while (!g_atomic_pointer_compare_and_exchange_value (&atomic,
valid_value, 555,
&old_value)
{
if (old_value == 555 || old_value == 222)
valid_value = old_value;
}
Atomic APIs provide a way to exchange values only if we compare a value
that is equal to the old value, but not to just exchange the value
returning the old one.
However, compilers provide such built-in functions, so we can use them
to expose such functionality to GLib.
The only drawback is that when using an old version of gcc not providing
atomic APIs to swap values, we need to re-implement it with an
implementation that may not be fully atomic, but that is safe enough.
However this codepath should really not be used currently as gcc
introduced __atomic_exchange_n() at version 4.7.4, so 8 years ago.
These have all been added manually, as I’ve finished all the files which
I can automatically detect.
All the license headers in this commit are for LGPL-2.1-or-later, and
all have been double-checked against the license paragraph in the file
header.
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #1415
The tests have to be conditional on C++11 being enabled, as the default
C++ standard on macOS is (for some reason), C++97 (`__cplusplus` is
defined as `199711L`).
Signed-off-by: Philip Withnall <pwithnall@endlessos.org>
Helps: #2625
There are various places glib uses __typeof__ for type safety, but
that's a GNUC extension. C++11 has standard decltype() that does a
similar job, at least for cases we care about.
This avoids C++ code to always have to cast return value of
g_object_ref() which was causing type kind of error:
error: invalid conversion from ‘gpointer’ {aka ‘void*’} to
‘GstElementFactory*’ {aka ‘_GstElementFactory*’} [-fpermissive]
There are various places glib uses __typeof__ for type safety, but
that's a GNUC extension. C++11 has standard decltype() that does a
similar job, at least for cases we care about.
This avoids C++ code to always have to cast return value of
g_object_ref() which was causing type kind of error:
error: invalid conversion from ‘gpointer’ {aka ‘void*’} to
‘GstElementFactory*’ {aka ‘_GstElementFactory*’} [-fpermissive]
