Michael, Thx a lot for your research!
My summary: OpenBSD's yacc * works correctly * based on byacc: https://invisible-island.net/byacc/byacc.html Plan 9's yacc * utf * should be used with -S flag (for unix like) * usually works, but has some problems: https://github.com/gittup/binutils/blob/gittup/ld/ldgram.y#L1120 miniyacc * output code is optimized for low memory usage and small binary size * a piece of beautiful code, but it doesn't work very often: • "={" • missing semicolon • lack of {% and %} which is quite common (license): https://github.com/openbsd/src/blob/master/usr.bin/awk/awkgram.y • doesn't seem to handle escape sequences in literals ('\n') • I don't even know what else: https://github.com/9fans/plan9port/blob/master/src/cmd/hoc/hoc.y#L32 miniyacc looks really very promising, unfortunately since 2015 isn't actively developed: https://c9x.me/git/miniyacc.git/log/ mpu devotes most of his time to developing qbe. Daniel śr., 8 maj 2019 o 10:36 Michael Forney > > On 2019-05-07, Daniel Cegiełka > > Hi, > > > > I'm going to use Quentin's miniyacc with (for example) bc.y from Plan 9: > > https://github.com/9fans/plan9port/blob/master/src/cmd/bc.y > > > > Of course, I had to modify the code (a bit), but unfortunately I still > > get an error when using miniyacc - works correctly with yacc from > > OpenBSD and Plan 9. > > > > I'm getting a message from this place ("production rule too long"): > > https://c9x.me/git/miniyacc.git/tree/yacc.c#n1110 > > > > I tried to increase the value of IdntSz and MaxRhs, but it didn't help > > in any way. > > It looks like this error is caused when miniyacc encounters a > character that it doesn't recognize as a token. nexttk() returns a > zero-length TIdnt token, causing an infinite loop, filling up r->rhs. > > Try the attached patch, which makes it fail on invalid tokens. > > In the example bc.y you linked, I think the '={' is causing problems, > and is from an obsolete yacc syntax: > > Some implementations recognize "={" as equivalent to '{' because it > appears in historical documentation. This construction was recognized > and documented as obsolete as long ago as 1978, in the referenced > Yacc: Yet Another Compiler-Compiler. This volume of POSIX.1-2017 chose > to leave it as obsolete and omit it. > > I also ran into this problem on some other grammar files containing > comments. One other issue I noticed is miniyacc doesn't seem to handle > escape sequences in literals (i.e. '\n'). > > After working around those issues, I get a different error > > $n has no type (on line 171) > > I think this is due to the usage of $2 referring to a token (EQOP in > this case) rather than a non-terminal. I haven't investigated this > further.
