Document Really Ugly Bugs (coredumps, assert fails, etc) \score{ \melodic{ [a8 a-2] /bla } } koor.ly: 4: error: parse error, expecting `DIGIT' or `UNSIGNED': [a8 a-2] /bla koor.ly: 5: error: Have to be in Lyric mode for lyrics: } lilypond: parser.y:765: int yyparse(void *): Assertion `((My_lily_parser *) my_lily_parser_l)->post_reqs.empty ()' failed. Aborted (core dumped) [gcc 2.8.x/libstdc++ 2.8.x/libg++ 2.8.0] The latest gcc release causes lily to crash just after Interpreting music: stacktrace looks something like: __DTOR_END__ () __malloc () [GNU libc] The GNU extension memmem() is known to be buggy on linux libc 5.0.9 and before. Glibc upto 2.0.5 also has problems with memmem (), but these should not affect LilyPond. [IRIX (5.3?)] coredump from strstream::strstream () upon the first read of a file [Linux Intel] LilyPond occasionally crashes while parsing the initialisation files. This is a very obscure bug, and usually entering the commandline differently "fixes" it. lilypond input.ly and lilypond -I. ./input.ly makes a difference Typical stacktrace: SIGSEGV __libc_malloc (bytes=16384) ?? () yyFlexLexer::yy_create_buffer () Includable_lexer::new_input (this=0x8209a00, s={strh_ = { : I get bitten by this every once in a while, and I am very interested in hints what might be wrong. This problem has only been identified with libc-5.3 and libc-5.4 platforms, so you might try upgrading to 6.0, ie. GNU libc-2. [Linux Intel] A problem resembling the previous: usage of libg++.2.8.x with the wrong version of libc results in a coredump from the scanner while reading the init files. Stacktrace: ios::eof (this=0x0) yyFlexLexer::LexerInput (this=0x8294848, buf=0x82955f0 "", max_size=8192) yyFlexLexer::yy_get_next_buffer (this=0x8294848) My_lily_lexer::yylex (this=0x8294848) Fix: follow the install instructions of libg++: match the right library versions.