Premature gameover on line clear

[0xjmux]

I'm going to try out issues for bug resolution just to get the hang of it.

So far, this seems to happen most with I_PIECE, but idk if that's a necessary part of it.

game.log from a game where this happened:

Global piece locations are: {[24, 7] [25, 7] [26, 7] [27, 7] }
Gravity tick activated systime=200069, last tick=16: piece moved down
display_board()
display_board()
display_board()
display_board()
display_board()
display_board()
display_board()
display_board()
Global piece locations are: {[25, 7] [26, 7] [27, 7] [28, 7] }
Gravity tick activated systime=400097, last tick=200069: piece moved down
display_board()
display_board()
display_board()
display_board()
display_board()
display_board()
display_board()
display_board()
Global piece locations are: {[26, 7] [27, 7] [28, 7] [29, 7] }
Gravity tick activated: move down failed
Piece stopped falling at loc row=26, col=7
check_and_clear: checking row 26
check_and_clear: checking row 27
check_and_clear: checking row 28
check_and_clear: checking row 29
smallest value in array {26, 28, 29, } is 26!
clearing 3 rows with top_row=26
Score updated for 3 lines cleared. Score = 4300, Level = 3     Lines cleared since last level=2
Global piece locations are: {[1, 9] [2, 8] [2, 9] [3, 8] }

Gravity tick activated: move down failed

Piece stopped falling at loc row=1, col=8
check_and_clear: checking row 1
check_and_clear: checking row 2
check_and_clear: checking row 2
check_and_clear: checking row 3
smallest value in array {2, 2, } is 2!
clearing 2 rows with top_row=2
Score updated for 2 lines cleared. Score = 5200, Level = 3     Lines cleared since last level=4
game over detected, returning false from tg_tick
Deallocating tetris game

The first sign of a problem is that "Gravity tick activated" line - for some reason it thinks it can't move the piece down when it's at the top of the board, and that causes the crash.

That print statement is in check_do_piece_gravity(), but the source of the problem has to be at/near check_valid_move(tg, T_DOWN).

[0xjmux]

Not resolved - similar crash occurred on a 4 row clear in a game a couple minutes ago - see test/files/final-gamestate-4row-clear-premat-gameover.ini

It looks like some weirdness is causing incorrect bit values to show up at the top of the file, which prevents the new piece from moving down - triggering the game over condition. Need to figure out what is causing the corruption in the first place.

[0xjmux]

• possible cause might be clearing lines down to row 31
• it seems to happen right around when the level increases, so maybe it's the change in level that's doing it?

[0xjmux]

Issue possibly fixed in 6a23430, but until i've gone through several rounds of testing trying to break it will leave this open.

[0xjmux]

Commit 6a2340 fixed this issue.
As I stated in the commit, the problem and fix were:

* clear_rows modified so it won't try to move rows above the top of the
  board down, which is a possible cause of the premature crash as a
  result of garbage data I've been seeing (Issue https://github.com/0xjmux/tetris/pull/2). Garbage data ends up in the
  first few rows, pieces can't move down into it, they stop falling, and
  then the game_over condition activates.
    * to fix this, added another loop to clear_rows() so that it stops
      once it would start touching the top of the board, and will fill
      rows at the top with BG_COLOR without trying to read OOB