Subtable overflow in AALT feature

Glyphs
#1

I have some fonts with a ton of features and the aalt feature has 34 lines (features) in it. This is apparently causing a subtable overflow:

MakeOTF error
GSUB feature ‘aalt’ causes overflow of offset to a subtable (0x11924 3)

I’ve never seen overflows like this other than with with kerning… Is there any work around for this – besides possibly deleting features?

#2

Can you send us the .glyphs file?

#3

Sent! Thanks Rainer!

#4

I am having the same issue that @robkeller have you found a way to avoid this?

Best,

Nicolás

#5

IIRC it was because there were repeating features instead of reusing lookups.

#6

I could solved it using extensions:

feature aalt useExtension {
  feature <feat>…
}  aalt;

I have a trad (traditional Chinese) feature that use around 2614 substitutions in one lookup. So aalt is not only calling that lookup but also others.

Now I wonder what is the proper way to use extension when you are using Replace feature custom parameter?

aalt useExtension; feature locl; feature c2sc; feature smcp; feature case;
#7

I just confirm that the previous syntax doesn’t work. That would generate this

feature aalt {
useExtension; feature locl; feature c2sc; feature smcp; 
} aalt ;

instead of this

feature aalt useExtension {
 feature locl; feature c2sc; feature smcp; 
} aalt ;
#8

You can write the feature (in this syntax) into the prefix and disable the aalt feature.

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