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examples: beware of the portability of flex --header-file

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The option --header was introduced in version 2.5.6.
The option --header-file was introduced in version 2.6.4.
Reported by Bruno Haible.
https://lists.gnu.org/r/bug-bison/2020-05/msg00013.html

So use --header, and do bother with versions that don't support it.

* m4/flex.m4: Check whether flex supports --header.
* configure.ac (FLEX_WORKS, FLEX_CXX_WORKS): Set to false if it doesn't.
* * examples/c/reccalc/local.mk, examples/c/reccalc/Makefile:
Use --header rather than --header-file.
This commit is contained in:
Akim Demaille
2020-05-03 09:51:18 +02:00
parent ccaa8e29f9
commit 392f3caef6
4 changed files with 22 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
configure.ac
View File

@@ -261,9 +261,8 @@ if ! "$LEX_IS_FLEX" || test "X$LEX" = X:; then
AC_MSG_WARN([bypassing lex because flex is required])
LEX=:
fi
AM_CONDITIONAL([FLEX_WORKS], [$LEX_IS_FLEX])
AM_CONDITIONAL([FLEX_CXX_WORKS],
[$LEX_IS_FLEX && test $bison_cv_cxx_works = yes])
AM_CONDITIONAL([FLEX_WORKS], [$LEX_IS_FLEX && $FLEX_SUPPORTS_HEADER_OPT])
AM_CONDITIONAL([FLEX_CXX_WORKS], [$LEX_WORKS && test $bison_cv_cxx_works = yes])
AC_PROG_YACC
AC_PROG_RANLIB
AC_PROG_GNU_M4

2
examples/c/reccalc/Makefile
View File

@@ -12,7 +12,7 @@ all: $(BASE)
$(BISON) $(BISONFLAGS) --defines --xml --graph=$*.gv -o $*.c $<
%.c %.h: %.l
$(FLEX) $(FLEXFLAGS) -o$*.c --header-file=$*.h $<
$(FLEX) $(FLEXFLAGS) -o$*.c --header=$*.h $<
scan.o: parse.h
parse.o: scan.h

4
examples/c/reccalc/local.mk
View File

@@ -69,7 +69,9 @@ DASH = -
$(AM_V_LEX)rm -f $@ $@.tmp
$(AM_V_at)$(MKDIR_P) %D%
$(AM_V_at)touch $@.tmp
$(AM_V_at)$(LEX) $(AM_LFLAGS) $(LFLAGS) -o%D%/scan.c --header-file=%D%/scan.h $(srcdir)/%D%/scan.l
## --header introduced in 2.5.6, renamed as --header-file in 2.6.4.
## Backward compatibility ensured since --header is an unambiguous prefix.
$(AM_V_at)$(LEX) $(AM_LFLAGS) $(LFLAGS) -o%D%/scan.c --header=%D%/scan.h $(srcdir)/%D%/scan.l
$(AM_V_at)mv $@.tmp $@

16
m4/flex.m4
View File

@@ -41,6 +41,22 @@ else
fi
])
AC_CACHE_CHECK([whether flex supports --header=FILE],
[ac_cv_prog_lex_supports_header_opt],
[if _AC_DO_VAR([LEX --header=conftest.h conftest.l]); then
ac_cv_prog_lex_supports_header_opt=yes
else
ac_cv_prog_lex_supports_header_opt=no
fi
])
if test "$ac_cv_prog_lex_supports_header_opt" = yes; then
FLEX_SUPPORTS_HEADER_OPT=true
else
FLEX_SUPPORTS_HEADER_OPT=false
fi
cat >conftest.l <<_ACEOF[
%%
a { ECHO; }