Commit
29ede6b96feee29c0c477d1659081bbdb82cd8b3 caused AC_PROG_LEX to
stop looking for a library that provides yywrap. This broke several
packages in a Debian archive rebuild.
Revert all the way to the 2.69 behavior, which was to set LEXLIB to
-ll or -lfl if that library defines yywrap, but allow AC_PROG_LEX to
succeed if neither -ll nor -lfl exists on the system, even if a lex
program that doesn't define yywrap would need it.
(This behavior was a bug, but people have come to depend on it.
See https://savannah.gnu.org/support/index.php?110269 and the
thread starting from
https://lists.gnu.org/r/autoconf-patches/2020-07/msg00013.html
for gory details.)
To provide a path away from bug-compatibility, AC_PROG_LEX now takes
one argument, documented as a whitespace-separated list of options.
Two options are defined: ‘yywrap’ means to look for yywrap and behave
as if lex is unavailable if it isn’t found; ‘noyywrap’ means to not
look for yywrap at all. These are mutually exclusive.
Fixes bug #110346.
* lib/autoconf/programs.m4 (AC_PROG_LEX): Add an argument which
can be either ‘yywrap’, meaning to look for yywrap in -ll, or
‘noyywrap’, meaning to not look for yywrap at all. In the
absence of either option, issue an obsoletion warning and
revert to behavior bug-compatible with 2.69.
* tests/semantics.at: Add more tests of AC_PROG_LEX.
* tests/mktests.sh: Exclude AC_PROG_LEX from autogenerated tests.
* doc/autoconf.texi: Update documentation of AC_PROG_LEX.
* NEWS: Update notes on AC_PROG_LEX.
AC_CHECK_FUNCS_ONCE, AC_CHECK_HEADERS, AC_CHECK_HEADERS_ONCE,
AC_CONFIG_MACRO_DIRS, AC_CONFIG_SUBDIRS, and AC_REPLACE_FUNCS.
-*** AC_PROG_LEX no longer looks for ‘yywrap’.
-
- LEXLIB will only be set to ‘-lfl’ or ‘-ll’ if a scanner that defines
- both ‘main’ and ‘yywrap’ itself still needs something else from that
- library.
-
- We recommend scanners define yywrap themselves, or use %noyywrap.
-
*** AC_FUNC_VFORK no longer ignores a signal-handling bug in Solaris 2.4.
This bug was being ignored because Emacs wanted to use ‘vfork’ on
specify the aux files you actually need, so that the check can be
effective.
+*** AC_PROG_LEX has an option to not look for yywrap.
+
+ AC_PROG_LEX now takes one argument, which may be either ‘yywrap’ or
+ ‘noyywrap’. If it is ‘noyywrap’, AC_PROG_LEX will only set LEXLIB
+ to ‘-lfl’ or ‘-ll’ if a scanner that defines both main and yywrap
+ itself still needs something else from that library. On the other
+ hand, if it is ‘yywrap’, AC_PROG_LEX will fail (setting LEX to ‘:’
+ and LEXLIB to nothing) if it can’t find a library that defines yywrap.
+
+ In the absence of arguments, AC_PROG_LEX’s behavior is bug-compatible
+ with 2.69, which did neither of the above things (see the manual for
+ details). This mode is deprecated.
+
+ We encourage all programs that use AC_PROG_LEX to use the new
+ ‘noyywrap’ mode, and to define yywrap themselves, or use %noyywrap.
+ The yywrap function in lib(f)l is trivial, and self-contained
+ scanners are easier to work with.
+
** Obsolete features and new warnings
*** Use of the long-deprecated name ‘configure.in’ for the autoconf
@end defmac
@anchor{AC_PROG_LEX}
-@defmac AC_PROG_LEX
+@defmac AC_PROG_LEX (@var{options})
@acindex{PROG_LEX}
@ovindex LEX
@ovindex LEXLIB
@cvindex YYTEXT_POINTER
@ovindex LEX_OUTPUT_ROOT
@caindex prog_LEX
-If @code{flex} is found, set output variable @code{LEX} to @samp{flex}.
-Otherwise set @code{LEX} to @samp{lex}, if found.
-If neither variant is available, set @code{LEX} to @samp{:};
+Search for a lexical analyzer generator, preferring @code{flex}
+to plain @code{lex}. Output variable @code{LEX} is set to whichever
+program is available. If neither program is available, @code{LEX}
+is set to @samp{:};
for packages that ship the generated @file{file.yy.c}
alongside the source @file{file.l}, this default allows users without a
lexer generator to still build the package even if the timestamp for
@file{file.l} is inadvertently changed.
-The result of this test can be influenced by setting the variable
-@code{LEX} or the cache variable @code{ac_cv_prog_LEX}.
+The name of the program to use can be overridden by setting the
+output variable @code{LEX} or the cache variable @code{ac_cv_prog_LEX}
+when running @command{configure}.
+
+If a lexical analyzer generator is found, this macro performs additional
+checks for common portability pitfalls. If these additional checks
+fail, @code{LEX} is reset to @samp{:}; otherwise the following
+additional macros and variables are provided.
-If either @code{flex} or @code{lex} is found, this macro performs
-additional checks for common portability pitfalls. If these additional
-checks fail, @code{LEX} is also set to @samp{:}.
+Preprocessor macro @code{YYTEXT_POINTER} is defined if the lexer
+skeleton, by default, declares @code{yytext} as a @samp{@w{char *}}
+rather than a @samp{@w{char []}}.
Output variable @code{LEX_OUTPUT_ROOT} is set to the base of the file
name that the lexer generates; this is usually either @file{lex.yy} or
-@file{lexyy}. Preprocessor macro @code{YYTEXT_POINTER} is defined if
-the lexer skeleton, by default, declares @code{yytext} as a @samp{char
-*} rather than a @samp{char []}. Finally, if generated lexers need a
-library to work, set output variable @code{LEXLIB} to an option for that
-library (e.g., @option{-ll}); otherwise define @code{LEXLIB} to empty.
-A library that merely defines @code{main} and @code{yywrap} placeholder
-functions is not considered to be needed.
+@file{lexyy}.
+
+If generated lexers need a library to work, output variable
+@code{LEXLIB} is set to a link option for that library (e.g.,
+@option{-ll}), otherwise it is set to empty.
+
+The @var{options} argument modifies the behavior of @code{AC_PROG_LEX}.
+It should be a whitespace-separated list of options. Currently there
+are only two options, and they are mutually exclusive:
+
+@table @code
+@item yywrap
+Indicate that the library in @code{LEXLIB} needs to define the function
+@code{yywrap}. If a library that defines this function cannot be found,
+@code{LEX} will be reset to @samp{:}.
+
+@item noyywrap
+Indicate that the library in @code{LEXLIB} does not need to define the
+function @code{yywrap}. @command{configure} will not search for it at
+all.
+@end table
+
+Prior to Autoconf 2.70, @code{AC_PROG_LEX} did not take any arguments,
+and its behavior was different from either of the above possibilities:
+it would search for a library that defines @code{yywrap}, and would set
+@code{LEXLIB} to that library if it finds one. However, if a library
+that defines this function could not be found, @code{LEXLIB} would be
+left empty and @code{LEX} would @emph{not} be reset. This behavior was
+due to a bug, but several packages came to depend on it, so
+@code{AC_PROG_LEX} still does this if neither the @code{yywrap} nor the
+@code{noyywrap} option is given.
+
+Usage of @code{AC_PROG_LEX} without choosing one of the @code{yywrap}
+or @code{noyywrap} options is deprecated. It is usually better to
+use @code{noyywrap} and define the @code{yywrap} function yourself,
+as this almost always renders the @code{LEXLIB} unnecessary.
@strong{Caution:} As a side-effect of the test, this macro may delete
any file in the configure script's current working directory named
AN_MAKEVAR([LEX], [AC_PROG_LEX])
AN_PROGRAM([lex], [AC_PROG_LEX])
AN_PROGRAM([flex], [AC_PROG_LEX])
-AC_DEFUN_ONCE([AC_PROG_LEX],
-[AC_CHECK_PROGS(LEX, flex lex, :)
-if test "x$LEX" != "x:"; then
- _AC_PROG_LEX_YYTEXT_DECL
-fi])
+AC_DEFUN([AC_PROG_LEX],
+[m4_case($#,
+ [0], [],
+ [1], [],
+ [m4_fatal([too many arguments to $0])])]dnl
+[_$0(m4_normalize([$1]))])
+
+AC_DEFUN([_AC_PROG_LEX],
+[m4_case([$1],
+ [yywrap], [],
+ [noyywrap], [],
+ [yywrap noyywrap],
+ [m4_fatal([AC_PROG_LEX: yywrap and noyywrap are mutually exclusive])],
+ [noyywrap yywrap],
+ [m4_fatal([AC_PROG_LEX: yywrap and noyywrap are mutually exclusive])],
+ [],
+ [m4_warn([obsolete],
+ [AC_PROG_LEX without either yywrap or noyywrap is obsolete])],
+ [m4_fatal([AC_PROG_LEX: unrecognized argument: $1])])]dnl
+dnl We can't use AC_DEFUN_ONCE because this macro takes arguments.
+dnl Silently skip a second invocation if the options match;
+dnl warn if they don't.
+[m4_ifdef([_AC_PROG_LEX_options],
+ [m4_if([$1], m4_defn([_AC_PROG_LEX_options]), [],
+ [m4_warn([syntax], [AC_PROG_LEX used twice with mismatched options])])],
+[dnl
+dnl _AC_PROG_LEX_options not defined: first use
+m4_define([_AC_PROG_LEX_options], [$1])dnl
+AC_CHECK_PROGS(LEX, flex lex, :)
+ if test "x$LEX" != "x:"; then
+ _AC_PROG_LEX_YYTEXT_DECL([$1])
+fi])])
# _AC_PROG_LEX_YYTEXT_DECL
# ------------------------
# Check for the Lex output root, the Lex library, and whether Lex
# declares yytext as a char * by default.
-m4_define([_AC_PROG_LEX_YYTEXT_DECL],
+AC_DEFUN([_AC_PROG_LEX_YYTEXT_DECL],
[cat >conftest.l <<_ACEOF[
%%
a { ECHO; }
AS_VAR_SET_IF([LEXLIB], [], [
AC_CACHE_CHECK([for lex library], [ac_cv_lib_lex], [
- ac_save_LIBS=$LIBS
+ ac_save_LIBS="$LIBS"
+ ac_found=false
for ac_cv_lib_lex in 'none needed' -lfl -ll 'not found'; do
- case $ac_cv_lib_lex in
- 'none needed') ;;
- 'not found') break;;
- *) LIBS="$ac_cv_lib_lex $ac_save_LIBS";;
- esac
+ AS_CASE([$ac_cv_lib_lex],
+ ['none needed'], [],
+ ['not found'], [break],
+ [*], [LIBS="$ac_cv_lib_lex $ac_save_LIBS"])
+
AC_LINK_IFELSE([AC_LANG_DEFINES_PROVIDED[`cat $LEX_OUTPUT_ROOT.c`]],
- [break])
+ [ac_found=:])
+ if $ac_found; then
+ break
+ fi
done
- LIBS=$ac_save_LIBS
+ LIBS="$ac_save_LIBS"
])
AS_IF(
[test "$ac_cv_lib_lex" = 'not found'],
[test "$ac_cv_lib_lex" = 'none needed'],
[LEXLIB=''],
[LEXLIB=$ac_cv_lib_lex])
+dnl
+dnl For compatibility with autoconf 2.69 and prior, if $1 is not `noyywrap',
+dnl and we didn't already set LEXLIB to -ll or -lfl, see if one of those
+dnl libraries provides yywrap and set LEXLIB to it if so. If $1 is `yywrap',
+dnl and we don't find a library that provides yywrap, we fail.
+ m4_case([$1],
+ [noyywrap],
+ [],
+ [yywrap],
+ [ac_save_LIBS="$LIBS"
+ AS_IF([test -n "$LEXLIB"],
+ [LIBS="$LEXLIB"
+ AC_CHECK_FUNC([yywrap],
+ [:],
+ [AC_MSG_WARN([$LEXLIB does not contain yywrap; giving up on $LEX])
+ LEX=: LEXLIB=])
+ ],
+ [LIBS=
+ AC_SEARCH_LIBS([yywrap], [fl l], [LEXLIB="$LIBS"])
+ AS_IF([test x"$ac_cv_search_yywrap" = xno],
+ [AC_MSG_WARN([yywrap not found; giving up on $LEX])
+ LEX=: LEXLIB=])])
+ LIBS="$ac_save_LIBS"],
+ [],
+ [ac_save_LIBS="$LIBS"
+ LIBS=
+ AC_SEARCH_LIBS([yywrap], [fl l], [LEXLIB="$LIBS"])
+ LIBS="$ac_save_LIBS"])dnl
])
AC_SUBST(LEXLIB)
+dnl This test is done last so that we don't define YYTEXT_POINTER if
+dnl any of the above tests gave up on lex.
AS_IF([test "$LEX" != :], [
AC_CACHE_CHECK(whether yytext is a pointer, ac_cv_prog_lex_yytext_pointer,
[# POSIX says lex can declare yytext either as a pointer or an array; the
# default is implementation-dependent. Figure out which it is, since
# not all implementations provide the %pointer and %array declarations.
ac_cv_prog_lex_yytext_pointer=no
-ac_save_LIBS=$LIBS
-LIBS="$LEXLIB $ac_save_LIBS"
-AC_LINK_IFELSE([AC_LANG_DEFINES_PROVIDED
+AC_COMPILE_IFELSE([AC_LANG_DEFINES_PROVIDED
[#define YYTEXT_POINTER 1
`cat $LEX_OUTPUT_ROOT.c`]],
[ac_cv_prog_lex_yytext_pointer=yes])
-LIBS=$ac_save_LIBS
])
dnl
if test $ac_cv_prog_lex_yytext_pointer = yes; then
/^AC_(PROG_CC|C_CONST|C_VOLATILE)$/ {next}
/^AC_PATH_XTRA$/ {next}
+ # Use without an argument is obsolete.
+ # Checked in semantics.
+ /^AC_PROG_LEX$/ {next}
+
# Requires a working C++ compiler, which is not a given.
/^AC_PROG_CXX_C_O$/ {next}
]])
AT_CLEANUP
+
+
+## ------------------------------------- ##
+## AC_PROG_LEX with and without yywrap. ##
+## ------------------------------------- ##
+
+# We don't currently have a good way of verifying that each mode
+# does what it's supposed to, but we can at least put them through
+# their paces as much as the autogenerated AT_CHECK_MACRO invocation
+# used to, back when AC_PROG_LEX took no arguments.
+
+AT_CHECK_MACRO([AC_PROG_LEX with yywrap], [AC_PROG_LEX([yywrap])])
+AT_CHECK_MACRO([AC_PROG_LEX with noyywrap], [AC_PROG_LEX([noyywrap])])
+
+AT_SETUP([AC_PROG_LEX in legacy mode])
+
+AT_CONFIGURE_AC([[AC_PROG_LEX]])
+AT_CHECK_AUTOHEADER([], [ignore])
+AT_CHECK_AUTOCONF([], [], [],
+[[configure.ac:4: warning: AC_PROG_LEX without either yywrap or noyywrap is obsolete
+programs.m4: _AC_PROG_LEX is expanded from...
+programs.m4: AC_PROG_LEX is expanded from...
+configure.ac:4: the top level
+]])
+
+AT_CHECK_CONFIGURE
+
+AT_CLEANUP
+
+
+## ---------------------------------- ##
+## Invalid arguments to AC_PROG_LEX. ##
+## ---------------------------------- ##
+
+AT_SETUP([Invalid arguments to AC_PROG_LEX])
+
+AT_CONFIGURE_AC(
+[[AC_PROG_LEX([nonsense])
+]])
+AT_CHECK_AUTOCONF([], [1], [],
+[[configure.ac:4: error: AC_PROG_LEX: unrecognized argument: nonsense
+programs.m4: _AC_PROG_LEX is expanded from...
+programs.m4: AC_PROG_LEX is expanded from...
+configure.ac:4: the top level
+autom4te: error: m4 failed with exit status: 1
+]])
+
+AT_CONFIGURE_AC(
+[[AC_PROG_LEX([too],[many])
+]])
+AT_CHECK_AUTOCONF([], [1], [],
+[[configure.ac:4: error: too many arguments to AC_PROG_LEX
+programs.m4: AC_PROG_LEX is expanded from...
+configure.ac:4: the top level
+autom4te: error: m4 failed with exit status: 1
+]])
+
+AT_CONFIGURE_AC(
+[[AC_PROG_LEX([yywrap noyywrap])
+]])
+AT_CHECK_AUTOCONF([], [1], [],
+[[configure.ac:4: error: AC_PROG_LEX: yywrap and noyywrap are mutually exclusive
+programs.m4: _AC_PROG_LEX is expanded from...
+programs.m4: AC_PROG_LEX is expanded from...
+configure.ac:4: the top level
+autom4te: error: m4 failed with exit status: 1
+]])
+
+AT_CONFIGURE_AC(
+[[AC_PROG_LEX([noyywrap yywrap])
+]])
+AT_CHECK_AUTOCONF([], [1], [],
+[[configure.ac:4: error: AC_PROG_LEX: yywrap and noyywrap are mutually exclusive
+programs.m4: _AC_PROG_LEX is expanded from...
+programs.m4: AC_PROG_LEX is expanded from...
+configure.ac:4: the top level
+autom4te: error: m4 failed with exit status: 1
+]])
+
+AT_CONFIGURE_AC(
+[[AC_PROG_LEX([yywrap nonsense])
+]])
+AT_CHECK_AUTOCONF([], [1], [],
+[[configure.ac:4: error: AC_PROG_LEX: unrecognized argument: yywrap nonsense
+programs.m4: _AC_PROG_LEX is expanded from...
+programs.m4: AC_PROG_LEX is expanded from...
+configure.ac:4: the top level
+autom4te: error: m4 failed with exit status: 1
+]])
+
+AT_CONFIGURE_AC(
+[[AC_PROG_LEX([nonsense noyywrap])
+]])
+AT_CHECK_AUTOCONF([], [1], [],
+[[configure.ac:4: error: AC_PROG_LEX: unrecognized argument: nonsense noyywrap
+programs.m4: _AC_PROG_LEX is expanded from...
+programs.m4: AC_PROG_LEX is expanded from...
+configure.ac:4: the top level
+autom4te: error: m4 failed with exit status: 1
+]])
+
+# A double invocation with matching arguments should be accepted
+# without complaint. FIXME: verify that it runs the test only once.
+AT_CONFIGURE_AC(
+[[AC_PROG_LEX([noyywrap])
+AC_PROG_LEX([noyywrap])
+]])
+AT_CHECK_AUTOCONF
+
+# A double invocation with matching arguments should trigger a warning.
+AT_CONFIGURE_AC(
+[[AC_PROG_LEX([yywrap])
+AC_PROG_LEX([noyywrap])
+]])
+AT_CHECK_AUTOCONF([], [0], [],
+[[configure.ac:5: warning: AC_PROG_LEX used twice with mismatched options
+programs.m4: _AC_PROG_LEX is expanded from...
+programs.m4: AC_PROG_LEX is expanded from...
+configure.ac:5: the top level
+]])
+
+AT_CLEANUP
projects / thirdparty / autoconf.git / commitdiff
