Replace deprecated placement=map_overwrite

[Wedge009]

I think deprecation notifications are only being shown in 1.17 but not 1.16. I noticed the map_overwrite deprecation message when testing the former.

I checked the change in SotA S17, no apparent regressions. I don't see any other instances of map_overwrite.

Info: https://wiki.wesnoth.org/SingleUnitWML#placement

[stevecotton]

I think deprecation notifications are only being shown in 1.17 but not 1.16.

There's a setting in advanced preferences, "show deprecation messages in-game". If it hasn't been set by the user, then it currently defaults to "no" in 1.16, "yes" in canonical 1.17.0 and 1.17.1, but "no" for 1.17.x+dev (debate about that might start up in #5084, and I've been wondering about it in #6512).

[Wedge009]

Funnily enough I was just re-reading #5084 when you wrote that. What's 'canonical 1.17.0 and 1.17.1', though? I wasn't aware we had any releases for 1.17 yet. And I don't recall setting any deprecation message preferences so that doesn't really explain how I saw the messages in 1.17.0+dev...

[Wedge009]

Update: preferences file is shared across versions by default on Linux, and I just confirmed I don't have 'show deprecation messages' enabled. Well, I suppose it's just as well I saw the message regardless - like with a lot of these recent deprecation-related issues, it's been deprecated since 1.13.x days.

[stevecotton]

Interesting, I might have misunderstood what turns on and off the deprecation messages' default. I thought it was is_dev_version():

wesnoth/src/game_version.cpp

Lines 170 to 176 in 02cdde9

	bool version_info::is_canonical() const {
	return nums_.size() <= 3;
	}
	bool version_info::is_dev_version() const {
	return is_canonical() && is_odd(minor_version());
	}

[Wedge009]

Well, I've enabled it now so if I run into more deprecated code in the bundled campaigns, etc, I can do something about it.

[Elvish-Hunter]

Regarding the deprecated [unit] placement= values, wmllint can automatically convert them since commits cde990a (master) and a7b22f5 (1.16), which I pushed yesterday.