xxx.build.board not passed to compiler(s)

[WestfW]

various choices in boards.txt carefully define a "build.board" platform variable:

CH32X035_EVT.menu.pnum.CH32X035G8U.build.board=CH32X035G8U
CH32V10x_EVT.build.board=CH32V10x_EVT
CH32V10x_EVT.menu.pnum.CH32V103R8T6.build.board=CH32V103R8T6
CH32V20x_EVT.build.board=CH32V20x_EVT
CH32V20x_EVT.menu.pnum.CH32V203RB.build.board=CH32V203RB
CH32V20x_EVT.menu.pnum.CH32V203G8.build.board=CH32V203G8
CH32V20x_EVT.menu.pnum.CH32V203G6.build.board=CH32V203G6
CH32V20x_EVT.menu.pnum.CH32V203C8.build.board=CH32V203C8
CH32V20x_EVT.menu.pnum.CH32V203C6.build.board=CH32V203C6
CH32V20x_EVT.menu.pnum.CH32V203G6_ADAFRUIT_QTPY.build.board=CH32V203G6_ADAFRUIT_QTPY
CH32V30x_EVT.build.board=CH32V30x_EVT
CH32V30x_EVT.menu.pnum.CH32V307VCT6.build.board=CH32V307VCT6
CH32L10x_EVT.build.board=CH32L10x_EVT

But in platforms.txt, while there are comments indicating that this should be passed to the various compilers:

# Build information's     
#####################-D{build.board} -DARDUINO_ARCH_{build.arch} -DBOARD_NAME="{build.board}" -DVARIANT_H="{build.variant_h}"

those are only comments, the actual "recipies" for the compiler invocations never actually pass the variables to any of the compiler steps.

This makes it difficult to add differnt board-name variants to a particular arduino "board" via the menus.
(For instance, adding the YD-CH32v307 board to the CH32V3xx ...)

[maxint-rd]

Hello @WestfW - Sounds like a useful suggestion. I'm not quite sure why that definition is commented out. Perhaps it's something the developers though of, but never incorporated. In the line below it, you can see other defines (eg. -D{build.chip}) are being passed.

For many boards build.board is the same as build.chip, but not for all.
I noticed that -DVARIANT_H="{build.variant_h} is passed and in board.txt it's set to include the build.board: CH32V20x_EVT.build.variant_h=variant_{build.board}.h.

All-over the use of build.chip, build.variant, build.board, build.series, etc. seems to lack some consistency.
In my own submissions for additional boards (such as PR #200), I did a quick copy/paste and never really looked into those definitions. (Whenever I get to it I should improve it...)

As a PR fixing this seems simple enough. (Unfortunately for this Arduino core the community is left to resolve things on their own and I don't expect WCH to merge PR's into a new release anytime soon).