[makeotfexe] Using .notdef glyph in a class causes error

[khaledhosny]

Given a feature file containing:

table GDEF {
  GlyphClassDef [.notdef], , , ;
} GDEF;

Processing it with makeotf causes:

makeotf [Warning] Could not find FontMenuNameDB file. Font will be built with menu names derived from PostScript name.
makeotfexe [WARNING] FontMenuNameDB file was not specified or not found. [Foo]
makeotfexe [FATAL] <Foo> aborting because of errors
makeotf [Error] Failed to build output font file 'Foo.otf'.

(ignoring the irrelevant warnings), there is no explanation for the cause of error and I had to debug the C code to find the root cause:

afdko/c/makeotf/makeotf_lib/source/hotconv/featgram.c

Lines 173 to 182 in f10db2e

	if (secondPart != NULL) {
	*secondPart = '\0';
	secondPart++;
	gid = featMapGName2GID(g, firstPart, FALSE);
	endgid = featMapGName2GID(g, secondPart, FALSE);
	if (gid != 0 && endgid != 0) {
	gcAddRange(gid, endgid, firstPart, secondPart);
	} else {
	hotMsg(g, hotFATAL, "aborting because of errors");
	}

Further more I think using .notdef here is valid and several other tools allow generating GDEF tables with .notdef assigned a glyph class.

[readroberts]

@mousa @cjchapman
I agree that .notdef should be allowed to be part of glyph classes. The change needs to be from testing against gid== 0 to gid == GID_UNDEF in line 178. However, featgram.c is a file derived from running the ANTLR parse against featgram.g; edits should be made in afdko/c/makeotf/makeotf_lib/build/hotpccts/featgram.g.