docs: Port docs/macros.txt to Markdown and update it

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

docs/macros.md

@@ -0,0 +1,73 @@
+GLib's configure options and corresponding macros
+=================================================
+
+The following Meson configure options will result in certain macros or options
+being defined at build time:
+
+`--buildtype={plain,release,minsize,custom}`
+ : No special macros or options
+`--buildtype={debug,debugoptimized}` (`debugoptimized` is the default)
+ : `-DG_ENABLE_DEBUG -g`
+`-Dglib_debug=disabled`
+ : Omits `G_ENABLE_DEBUG` when implied by `--buildtype`/`-Ddebug`
+`-Dglib_debug=enabled`
+ : Defines `G_ENABLE_DEBUG` regardless of `--buildtype`/`-Ddebug`
+`-Dglib_asserts=false`
+ : `-DG_DISABLE_ASSERT`
+`-Dglib_checks=false`
+ : `-DG_DISABLE_CHECKS`
+
+Besides these, there are some local feature specific options, but the main
+focus here is to concentrate on macros that affect overall GLib behaviour
+and/or third party code.
+
+
+GLib's internal and global macros
+=================================
+
+`G_DISABLE_ASSERT`
+---
+
+The `g_assert()` and `g_assert_not_reached()` macros become non-functional
+with this define. The motivation is to speed up end-user apps by
+avoiding expensive checks.
+
+This macro can affect third-party code. Defining it when building GLib
+will only disable the assertion macros for GLib itself, but third-party code
+that passes `-DG_DISABLE_ASSERT` to the compiler in its own build
+will end up with the non-functional variants after including `glib.h`
+as well.
+
+Note: Code inside the assertion macros should not have side effects
+that affect the operation of the program, as they may get compiled out.
+
+`G_DISABLE_CHECKS`
+---
+
+This macro is similar to `G_DISABLE_ASSERT`, it affects third-party
+code as mentioned above and the note about `G_DISABLE_ASSERT` applies
+too.
+
+The macros that become non-functional here are `g_return_if_fail()`,
+`g_return_val_if_fail()`, `g_return_if_reached()` and
+`g_return_val_if_reached()`.
+
+This macro also switches off certain checks in the GSignal code.
+
+`G_ENABLE_DEBUG`
+---
+
+Quite a bit of additional debugging code is compiled into GLib when this
+macro is defined, and since it is a globally visible define, third-party code
+may be affected by it similarly to `G_DISABLE_ASSERT`.
+
+The additional code executed/compiled for this macro currently includes the
+following, but this is not an exhaustive list:
+ - extra validity checks for `GDate`
+ - breakpoint abortion for fatal log levels in `gmessages.c` instead of
+   plain `abort()` to allow debuggers trapping and overriding them
+ - added verbosity of `gscanner.c` to catch deprecated code paths
+ - added verbosity of `gutils.c` to catch deprecated code paths
+ - object and type bookkeeping in `gobject.c`
+ - extra validity checks in `gsignal.c`
+ - support for tracking still-alive `GTask`s

docs/macros.txt

@@ -1,56 +0,0 @@
-GLib's configure options and corresponding macros
-=================================================
-
---buildtype={plain,release,minsize,custom}
-	none
---buildtype={debug,debugoptimized}	[debugoptimized is the default]
-	-DG_ENABLE_DEBUG -g
--Dglib_debug=disabled
-	Omits G_ENABLE_DEBUG when implied by --buildtype/-Ddebug
--Dglib_debug=enabled
-	Defines G_ENABLE_DEBUG regardless of --buildtype/-Ddebug
--Dglib_asserts=false
-	-DG_DISABLE_ASSERT
--Dglib_checks=false
-	-DG_DISABLE_CHECKS
-
-Besides these, there are some local feature specific options, but my main
-focus here is to concentrate on macros that affect overall GLib behaviour
-and/or third party code.
-
-
-Notes on GLib's internal and global macros
-==========================================
-
-G_DISABLE_ASSERT
-	The g_assert() and g_assert_not_reached() become non-functional
-	with this define. The motivation is to speed up end-user apps by
-	avoiding expensive checks.
-	This macro can affect third-party code. Defining it when building GLib
-	will only disable the assertion macros for GLib itself, but third-party code
-	that passes -DG_DISABLE_ASSERT to the compiler upon its own build
-	will end up with the non-functional variants after including glib.h
-	as well.
-	NOTE: Code inside the assertion macros should not have side effects
-	that affect the operation of the program.
-G_DISABLE_CHECKS
-	This macro is similar to G_DISABLE_ASSERT, it affects third-party
-	code as mentioned above and the NOTE about G_DISABLE_ASSERT applies
-	too. The macros that become non-functional here are
-	g_return_if_fail(), g_return_val_if_fail(), g_return_if_reached() and
-	g_return_val_if_reached().
-	Additionally the glib_mem_profiler_table and g_mem_profile() from
-	gmem.h become non-functional if this macro is supplied.
-	This macro also switches off certain checks in the GSignal code.
-G_ENABLE_DEBUG
-	Quite a bit of additional debugging code is compiled into GLib for this
-	macro, and since it is a globally visible define, third-party code may
-	be affected by it similar to G_DISABLE_ASSERT.
-	The additional code executed/compiled for this macro currently involve:
-	- extra validity checks for GDate
-	- BREAKPOINT abortion for fatal log levels in gmessage.c instead of
-	  plain abort() to allow debuggers trapping and overriding them
-	- added verbosity of gscanner.c to catch deprecated code paths
-	- added verbosity of gutils.c to catch deprecated code paths
-	- object and type bookkeeping in gobject.c
-	- extra validity checks in gsignal.c