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b02e29558f
As per https://gitlab.gnome.org/GNOME/glib/-/issues/3421#note_2206315: It seems like there’s agreement that glib_debug should be enabled for developers and disabled for distros; and it also seems like there’s no reliable way to figure this out magically (because not everyone ties things to `-Dbuildtype=*`). So, we’re left with forcing some group of people to manually set the value of `glib_debug`. There are more developers/contributors than there are distros, and distros are more likely to notice an accidentally-slow GLib package than developers are likely to notice an accidentally-not-asserting-hard-enough local build, so let’s say: The default should be `-Dglib_debug=enabled`, and distros should probably all override that to `-Dglib_debug=disabled`. Signed-off-by: Philip Withnall <pwithnall@gnome.org> Fixes: #3421
78 lines
2.8 KiB
Markdown
78 lines
2.8 KiB
Markdown
GLib's configure options and corresponding macros
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=================================================
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The following Meson configure options will result in certain macros or options
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being defined at build time:
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`--buildtype={plain,release,minsize,custom}`
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: No special macros or options
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`--buildtype={debug,debugoptimized}` (`debugoptimized` is the default)
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: `-DG_ENABLE_DEBUG -g`
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`-Dglib_debug=disabled`
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: Omits `G_ENABLE_DEBUG` when implied by `--buildtype`/`-Ddebug`
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`-Dglib_debug=enabled`
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: Defines `G_ENABLE_DEBUG` regardless of `--buildtype`/`-Ddebug`
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`-Dglib_asserts=false`
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: `-DG_DISABLE_ASSERT`
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`-Dglib_checks=false`
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: `-DG_DISABLE_CHECKS`
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Besides these, there are some local feature specific options, but the main
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focus here is to concentrate on macros that affect overall GLib behaviour
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and/or third party code.
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GLib's internal and global macros
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=================================
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`G_DISABLE_ASSERT`
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---
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The `g_assert()` and `g_assert_not_reached()` macros become non-functional
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with this define. The motivation is to speed up end-user apps by
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avoiding expensive checks.
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This macro can affect third-party code. Defining it when building GLib
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will only disable the assertion macros for GLib itself, but third-party code
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that passes `-DG_DISABLE_ASSERT` to the compiler in its own build
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will end up with the non-functional variants after including `glib.h`
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as well.
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Note: Code inside the assertion macros should not have side effects
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that affect the operation of the program, as they may get compiled out.
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`G_DISABLE_CHECKS`
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---
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This macro is similar to `G_DISABLE_ASSERT`, it affects third-party
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code as mentioned above and the note about `G_DISABLE_ASSERT` applies
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too.
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The macros that become non-functional here are `g_return_if_fail()`,
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`g_return_val_if_fail()`, `g_return_if_reached()` and
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`g_return_val_if_reached()`.
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This macro also switches off certain checks in the GSignal code.
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`G_ENABLE_DEBUG`
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---
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Quite a bit of additional debugging code is compiled into GLib when this
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macro is defined, and since it is a globally visible define, third-party code
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may be affected by it similarly to `G_DISABLE_ASSERT`.
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Some of these checks can be relatively expensive at runtime, as they affect
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every GObject type cast. Distributions are recommended to disable
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`G_ENABLE_DEBUG` in stable release builds.
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The additional code executed/compiled for this macro currently includes the
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following, but this is not an exhaustive list:
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- extra validity checks for `GDate`
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- breakpoint abortion for fatal log levels in `gmessages.c` instead of
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plain `abort()` to allow debuggers trapping and overriding them
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- added verbosity of `gscanner.c` to catch deprecated code paths
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- added verbosity of `gutils.c` to catch deprecated code paths
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- object and type bookkeeping in `gobject.c`
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- extra validity checks in `gsignal.c`
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- support for tracking still-alive `GTask`s
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