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| author | Akim Demaille <akim@lrde.epita.fr> | 2013-03-27 09:18:32 +0100 |
|---|---|---|
| committer | Akim Demaille <akim@lrde.epita.fr> | 2013-04-09 14:07:52 +0200 |
| commit | 1fa19a769721658bb53177596531afbbea8b4e1c (patch) | |
| tree | 4b7aee891add899b68c2c2d9b226f75dde8eadf8 /NEWS | |
| parent | d1a07886ee63d7346d585d34190162b79a30fdfb (diff) | |
| download | bison-1fa19a769721658bb53177596531afbbea8b4e1c.tar.gz | |
api.value.type: diagnose guaranteed failure with --yacc
Instead of generating invalid C code, generate an error when --yacc and
'%define api.value.type union' are used together.
* data/bison.m4: Issue an error in this case.
* tests/types.at (%yacc vs. %define api.value.type union): New, check this
error.
* doc/bison.texi (Type Generation): Document it.
* tests/output.at: Check that '-o y.tab.c' and '-y' behave equally
wrt generated file names.
* NEWS (Use of YACC='bison -y'): New.
Promote the use of 'bison -o y.tab.c'.
Diffstat (limited to 'NEWS')
| -rw-r--r-- | NEWS | 23 |
1 files changed, 22 insertions, 1 deletions
@@ -23,6 +23,26 @@ GNU Bison NEWS Missing semicolons at the end of actions are no longer added (as announced in the release 2.5). +*** Use of YACC='bison -y' + + TL;DR: With Autoconf <= 2.69, pass -Wno-yacc to (AM_)YFLAGS if you use + Bison extensions. + + Traditional Yacc generates 'y.tab.c' whatever the name of the input file. + Therefore Makefiles written for Yacc expect 'y.tab.c' (and possibly + 'y.tab.h' and 'y.outout') to be generated from 'foo.y'. + + To this end, for ages, AC_PROG_YACC, Autoconf's macro to look for an + implementation of Yacc, was using Bison as 'bison -y'. While it does + ensure compatible output file names, it also enables warnings for + incompatibilities with POSIX Yacc. In other words, 'bison -y' triggers + warnings for Bison extensions. + + Autoconf 2.70+ fixes this incompatibility by using YACC='bison -o y.tab.c' + (which also generates 'y.tab.h' and 'y.output' when needed). + Alternatively, disable Yacc warnings by passing '-Wno-yacc' to your Yacc + flags (YFLAGS, or AM_YFLAGS with Automake). + ** Bug fixes *** The epilogue is no longer affected by internal #defines (glr.c) @@ -276,7 +296,8 @@ GNU Bison NEWS The %define variable api.value.type supports several special values. The value "union" means that the user provides genuine types, not union member - names such as "ival" and "sval" above. + names such as "ival" and "sval" above (WARNING: will fail if + -y/--yacc/%yacc is enabled). %define api.value.type "union" %token <int> INT "integer" |