Greek diacriticized letters without precomposed forms are not supported #17

Fonts

NotoSans-Regular.ttf
NotoSansMono-Regular.ttf
NotoSerif-Regular.ttf

Where the fonts came from, and when

Site: https://github.com/googlefonts/noto-fonts/blob/8f9bf04503f257b1f19bb472e9b8a06cae1caa60/hinted/ttf/NotoSans/NotoSans-Regular.ttf
Site: https://github.com/googlefonts/noto-fonts/blob/8f9bf04503f257b1f19bb472e9b8a06cae1caa60/hinted/ttf/NotoSansMono/NotoSansMono-Regular.ttf
Site: https://github.com/googlefonts/noto-fonts/blob/8f9bf04503f257b1f19bb472e9b8a06cae1caa60/hinted/ttf/NotoSerif/NotoSerif-Regular.ttf
Date: 2021-05-28

Font versions

Noto Sans: Version 2.005; ttfautohint (v1.8.3) -l 8 -r 50 -G 200 -x 14 -D latn -f none -a qsq -X ""
Noto Sans Mono: Version 2.006; ttfautohint (v1.8.3) -l 8 -r 50 -G 200 -x 14 -D latn -f none -a qsq -X ""
Noto Serif: Version 2.004; ttfautohint (v1.8.3) -l 8 -r 50 -G 200 -x 14 -D latn -f none -a qsq -X ""

Issue

According to Haralambous 2002 §§ 3.3–3.4, some combinations of letters and diacritics not used in modern Greek are attested in some dialects of Ancient Greek: epsilon and omicron with perispomeni, and capital upsilon with psili. (That source intentionally omits capital epsilon or omicron with perispomeni but no breathing mark, but I think those sequences should be supported too, in case they occur in epigraphy and because it is easy to support them.)

In Noto Sans, the perispomeni has no anchor point, and is therefore always positioned wrong in non-precomposed sequences.

In Noto Sans Mono and Noto Serif, in the sequence <uppercase epsilon/omicron, breathing mark, perispomeni>, the perispomeni is placed above the letter. It should be placed above the breathing mark.

In Noto Sans Mono and Noto Serif, in the sequence <lowercase epsilon/omicron, breathing mark, perispomeni>, there is a bit too much of a gap between the breathing mark and the perispomeni. Compare their relative position in precomposed characters like U+1F06 GREEK SMALL LETTER ALPHA WITH PSILI AND PERISPOMENI.

In all three fonts, the diacritics on capital upsilon are mispositioned. They should go to the left of the letter.

Character data

Ε͂Ἐ͂Ἑ͂ε͂ἐ͂ἑ͂Ο͂Ὀ͂Ὁ͂ο͂ὀ͂ὁ͂Υ̓Υ̓̀Υ̓́Υ̓͂

U+0395 GREEK CAPITAL LETTER EPSILON
U+0342 COMBINING GREEK PERISPOMENI

U+1F18 GREEK CAPITAL LETTER EPSILON WITH PSILI
U+0342 COMBINING GREEK PERISPOMENI

U+1F19 GREEK CAPITAL LETTER EPSILON WITH DASIA
U+0342 COMBINING GREEK PERISPOMENI

U+03B5 GREEK SMALL LETTER EPSILON
U+0342 COMBINING GREEK PERISPOMENI

U+1F10 GREEK SMALL LETTER EPSILON WITH PSILI
U+0342 COMBINING GREEK PERISPOMENI

U+1F11 GREEK SMALL LETTER EPSILON WITH DASIA
U+0342 COMBINING GREEK PERISPOMENI

U+039F GREEK CAPITAL LETTER OMICRON
U+0342 COMBINING GREEK PERISPOMENI

U+1F48 GREEK CAPITAL LETTER OMICRON WITH PSILI
U+0342 COMBINING GREEK PERISPOMENI

U+1F49 GREEK CAPITAL LETTER OMICRON WITH DASIA
U+0342 COMBINING GREEK PERISPOMENI

U+03BF GREEK SMALL LETTER OMICRON
U+0342 COMBINING GREEK PERISPOMENI

U+1F40 GREEK SMALL LETTER OMICRON WITH PSILI
U+0342 COMBINING GREEK PERISPOMENI

U+1F41 GREEK SMALL LETTER OMICRON WITH DASIA
U+0342 COMBINING GREEK PERISPOMENI

U+03A5 GREEK CAPITAL LETTER UPSILON
U+0313 COMBINING COMMA ABOVE

U+03A5 GREEK CAPITAL LETTER UPSILON
U+0313 COMBINING COMMA ABOVE
U+0300 COMBINING GRAVE ACCENT

U+03A5 GREEK CAPITAL LETTER UPSILON
U+0313 COMBINING COMMA ABOVE
U+0301 COMBINING ACUTE ACCENT

U+03A5 GREEK CAPITAL LETTER UPSILON
U+0313 COMBINING COMMA ABOVE
U+0342 COMBINING GREEK PERISPOMENI

Screenshots