Bug#21029 (Dependencies between sql_yacc.cc and dependent headers not detected)

The build scripts in general, using automake, autoconf, etc, contain several
special commands and work around all related to the way the bison code in the
parser is built, for sql/sql_yacc.yy. These work arounds, accumulated over
time during development, ultimately cause the build scripts to be unstable
and cause build defects by not enforcing dependencies.

This fix simplifies the build process and aligns it with the automake tooling,
which provides native support for bison and *.yy files.

In particular, the following problem have been fixed:
- dependencies with sql_yacc.cc were not honored (Bug 21029), leading to
  corrupted builds,
- the work around introduced by Bug 24557, to cleanup the generated files
  sql_yacc.h and sql_yacc.cc, has been removed,
- the generated makefile, in a source distribution, used to destroy the files
  sql_yacc.h and sql_yacc.cc on a 'make clean' target. This has been fixed:
  these files are now removed by make maintainer-clean.
- The root cause of the problem found with gcc 4.1 (see Bug 24619) has been
  clearly documented, and the "sed" hack has been replaced by a cleaner
  work around, when building the code with bison 1.875.
- Removed the file sql/sql_yacc.yy.bak, added by WL 3031 by accident.
- Removed the unnecessary AM_YFLAG= --debug introduced by WL 3432, since
  the compiling option DBUG_OFF takes precedence when setting YYDEBUG.

Makefile.am

@@ -41,14 +41,6 @@ BUILT_SOURCES = linked_client_sources linked_server_sources \
 CLEANFILES = $(BUILT_SOURCES)
 DISTCLEANFILES = ac_available_languages_fragment
 
-# Our current filtering of "sql_yacc.cc" in "sql/Makefile.am" creates
-# a problem, if a VPATH build and "sql_yacc.cc" was part of the source
-# distribution we end up with one "sql_yacc.cc" in the source tree,
-# and one in the build tree. This breaks "distcleancheck", until this
-# is sorted out we redefine the find that scans for files not removed
-
-distcleancheck_listfiles = find . -name sql_yacc.cc -o -type f -print
-
 linked_include_sources:
 	cd include; $(MAKE) link_sources
 	echo timestamp > linked_include_sources

sql/Makefile.am

@@ -121,13 +121,14 @@ DEFS =			-DMYSQL_SERVER \
 			-DLIBDIR="\"$(MYSQLLIBdir)\"" \
 			@DEFS@
 
-BUILT_DIST_SRC =	sql_yacc.cc sql_yacc.h
-BUILT_SOURCES =		$(BUILT_DIST_SRC) lex_hash.h
-EXTRA_DIST =		udf_example.c udf_example.def $(BUILT_DIST_SRC) \
+BUILT_MAINT_SRC =	sql_yacc.cc sql_yacc.h
+BUILT_SOURCES =		$(BUILT_MAINT_SRC) lex_hash.h
+EXTRA_DIST =		udf_example.c udf_example.def $(BUILT_MAINT_SRC) \
 			nt_servc.cc nt_servc.h message.mc CMakeLists.txt \
 			udf_example.c udf_example.def
-CLEANFILES =        	lex_hash.h sql_yacc.cc sql_yacc.h sql_yacc.output
-AM_YFLAGS =		-d --debug --verbose
+CLEANFILES =        	lex_hash.h sql_yacc.output
+MAINTAINERCLEANFILES =  $(BUILT_MAINT_SRC)
+AM_YFLAGS =		-d --verbose
 
 mysql_tzinfo_to_sql.cc:
 	rm -f mysql_tzinfo_to_sql.cc
@@ -148,23 +149,6 @@ link_sources: mysql_tzinfo_to_sql.cc
 mysql_tzinfo_to_sql.o:	$(mysql_tzinfo_to_sql_SOURCES)
 			$(CXXCOMPILE) -c $(INCLUDES) -DTZINFO2SQL $<
 
-# Try to get better dependencies for the grammar. Othervise really bad
-# things like different grammars for different pars of MySQL can
-# happen if you are unlucky.
-sql_yacc.cc:	sql_yacc.yy
-
-sql_yacc.h:	sql_yacc.yy
-
-# Be careful here, note that we use VPATH and might or might not have
-# a pregenerated "sql_yacc.cc" in $(srcdir) or one we just built in
-# $(builddir). And it has to work if $(srcdir) == $(builddir).
-sql_yacc.o:	sql_yacc.cc sql_yacc.h $(HEADERS)
-		@SED@ -e 's/__attribute__ ((__unused__))//' $< > sql_yacc.cc-new
-		@MV@ sql_yacc.cc-new sql_yacc.cc
-		@echo "Note: The following compile may take a long time."
-		@echo "If it fails, re-run configure with --with-low-memory"
-		$(CXXCOMPILE) $(LM_CFLAGS) -c sql_yacc.cc
-
 # FIXME seems like now "lex_hash.h" differs depending on configure
 # flags, so can't pregenerate and include in source TAR. Revert to
 # dist pregenerated if this changes, so the file doesn't differ.

sql/sql_yacc.yy

@@ -54,6 +54,28 @@ const LEX_STRING null_lex_str={0,0};
     YYABORT;				\
   }
 
+/*
+  Work around for broken code generated by bison 1.875.
+
+  The code generated by bison 1.875a and later, bison 2.1 and bison 2.2 is ok.
+  With bison 1.875 however, the generated code contains:
+<pre>
+  yyerrlab1:
+  #if defined (__GNUC_MINOR__) && 2093 <= (__GNUC__ * 1000 + __GNUC_MINOR__)
+    __attribute__ ((__unused__))
+  #endif
+</pre>
+  This usage of __attribute__ is illegal, so we remove it.
+  See the following references for details:
+  http://lists.gnu.org/archive/html/bug-bison/2004-02/msg00014.html
+  http://gcc.gnu.org/bugzilla/show_bug.cgi?id=14273
+*/
+
+#if defined (__GNUC_MINOR__) && 2093 <= (__GNUC__ * 1000 + __GNUC_MINOR__)
+#undef __attribute__
+#define __attribute__(X)
+#endif
+
 /* Helper for parsing "IS [NOT] truth_value" */
 inline Item *is_truth_value(THD *thd, Item *A, bool v1, bool v2)
 {