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build: flex.m4: check for Flex.

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* m4/flex.m4 (_AC_PROG_LEX_YYTEXT_DECL): Check that $LEX
supports some of the Flex options, and exclusive start conditions.
Define FLEX to 'yes'/'', as AC_PROG_CC does for GCC.
This commit is contained in:
Akim Demaille
2012-04-10 21:36:19 +02:00
parent a4e4295ad2
commit 0d49053a75
1 changed files with 21 additions and 2 deletions
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23
m4/flex.m4
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@@ -20,10 +20,29 @@ fi])
# _AC_PROG_LEX_YYTEXT_DECL
# ------------------------
# Check for the Lex output root, the Lex library, and whether Lex
# declares yytext as a char * by default.
# Check whether this is Flex, for the Lex output root, the Lex library,
# and whether Lex declares yytext as a char * by default.
m4_define([_AC_PROG_LEX_YYTEXT_DECL],
[AC_CACHE_CHECK([whether lex is flex],
[ac_cv_prog_flex],
[cat >conftest.l <<_ACEOF[
%option debug nodefault noinput nounput noyywrap never-interactive
%x SC_CONF_TEST
%%
a { BEGIN SC_CONF_TEST; }
]_ACEOF
if _AC_DO_VAR([LEX conftest.l]); then
ac_cv_prog_flex=yes
else
ac_cv_prog_flex=no
fi
])
FLEX=
if test $ac_cv_prog_flex = yes; then
AC_SUBST([FLEX], [yes])dnl
fi
cat >conftest.l <<_ACEOF[
%%
a { ECHO; }
b { REJECT; }