The test programs used by _AC_PROG_CXX_CXX98 and _AC_PROG_CXX_CXX11
can take several seconds to compile, even on current-generation CPUs.
Each of them may be test-compiled up to six times as the configure
script searches for appropriate command-line switches. This is
reported to cancel out all of the other performance gains made since
2.69.
Replace these programs with simpler ones that do not exercise the C++
standard *library* and can be compiled in less than a second each.
On my computer, which is quite new, the minimal configure script
AC_INIT
AC_PROG_CXX
executes in 4.5 seconds (wall-clock) before this change and 0.5
seconds after.
* lib/autoconf/c.m4 (_AC_CXX_CXX98_TEST_HEADER, _AC_CXX_CXX98_TEST_BODY):
Rewrite to test only C++ 1998 language features, not library features.
(_AC_CXX_CXX11_TEST_HEADER, _AC_CXX_CXX11_TEST_BODY):
Similarly for C++ 2011.
* doc/autoconf.texi (AC_PROG_CXX): Document this change.
Problem reported by Ken Moffat (sr#110287); the problem was
introduced in 2016-12-21T16:15:46Z!daniel.kitta@gmail.com.
* bin/autoheader.in (templates_for_header):
When generating warnings about symbols lacking templates,
downgrade template read failure from a fatal error to a warning.
Also, don’t even try to read from a template file whose name has
shell metavariables (which Autoconf 2.50 withdrew support for);
just warn about that, too. These changes cause the Automake
tests to merely generate warnings that are ignored, instead
of failing.
* doc/autoconf.texi (Configuration Files, Configuration Headers)
(Configuration Commands, Configuration Links):
Also document here that the file names should not contain
shell metacharacters, to make this constraint more obvious.
* doc/autoconf.texi (Particular Functions): Point to Gnulib wherever Gnulib has
more workarounds than mentioned for the particular macro, namely for
AC_FUNC_CHOWN, AC_FUNC_FSEEKO, AC_FUNC_GETGROUPS, AC_FUNC_GETMNTENT,
AC_FUNC_MBRTOWC, AC_FUNC_STRERROR_R, AC_FUNC_STRTOLD.
* doc/autoconf.texi (Particular Functions): Point to Gnulib for all macros that
may call AC_LIBOBJ, namely AC_FUNC_ALLOCA, AC_FUNC_MALLOC, AC_FUNC_OBSTACK,
AC_FUNC_REALLOC, AC_FUNC_STRNLEN.
* NEWS, doc/autoconf.texi, lib/autoconf/fortran.m4:
Document 250, not 254.
* tests/fortran.at (AC_FC_LINE_LENGTH): Test lines with 250
columns not 253, since Oracle Studio 12.6 Fortran 95 8.8
2017/05/30 goes up only to 250.
- Better explanation of the additional tests performed by this macro,
once the tool has been located.
- Update advice re using Flex to generate a bundled lex.yy.c.
- Remove text describing a bug in Automake that has long since been
corrected.
* doc/autoconf.texi (Specifying Target Triplets): Describe the effects
of --host in more detail. Don't recommend to specify --build when
specifying --host. Add another example regarding MinGW.
Problem reported by Bruno Haible in:
https://savannah.gnu.org/support/?110266
* lib/autoconf/programs.m4 (AC_PROG_YACC):
Go back to using bison -y instead of bison -o y.tab.c.
Lots of http:// -> https:// conversions;
refer to XZ Utils instead of the obsolete LZMA Utils;
remove dead link to dbaspot.com;
replace mention of -fmudflap with -fsanitize=
and add a proper cross-reference to the GCC manual for that.
There are two errors caught by make syntax-check currently.
First, the recent make update-copyright
(d78a7dd95f) missed autoconf.texi, I
think because there are a bunch of .texi files in doc/ whose copyright
years should *not* be updated (e.g. standards.texi, fdl.texi) and the
exclusion pattern is too broad. I can't actually *find* the exclusion
pattern in the twisty maze of .mk files, all alike, so I just manually
updated autoconf.texi.
Second, it objects to an edit to an old section of NEWS. This is
because of d3dcd5895d, which is a
legitimate change (replacing http:// with https:// in a URL) so the
correct action is to change old_NEWS_hash to match.
* doc/autoconf.texi: Update copyright year.
* cfg.mk (old_NEWS_hash): Update to acknowledge commit
d3dcd5895d.
* doc/autoconf.texi (C and Posix Variants, System Services):
Remind user to include config.h first.
(Configuration Headers): Give another reason why config.h must be
first, and mention that only .c files need it.
Based on discussion on bugs.debian.org/158969
Signed-off-by: Eric Blake <eblake@redhat.com>
Several projects have a bootstrap script that invokes
'autoreconf -fi' as part of a fresh version control checkout,
in order to avoid storing common files in version control,
while also allowing contributors to rerun bootstrap to pick
up the benefits of any upgrade of one of the autotools.
However, the documentation did not make it obvious that such
a setup will overwrite any customizations to files like
INSTALL, if those files are stored in version control, when
automake still considers that file to be standard based on
AM_INIT_AUTOMAKE settings. In such a case, a mere
'autoreconf -i' is good for the bootstrap script, while a
separate 'autoreconf -f' is good for picking up on an upgrade
of any autotools.
* bin/autoreconf.in (help): Mention standard files.
* doc/autoconf.texi (autoreconf Invocation): Add more text, including
warning that mixing --force and --install may undo customizations,
and that the set of files impacted is controlled by automake.
Reported by Emil Laine <laine.emil@gmail.com>
Signed-off-by: Eric Blake <eblake@redhat.com>
The example text regarding a desired literal AC_DC in output
claimed that the result would trigger a warning if one does
not use creative quoting; but in reality, autoconf's use of
m4_pattern_forbid to reserve the entire AC_ namespace makes
it a hard error. Reword the section to mention the use of
m4_pattern_allow() as the fix, and beef up the example to
better demonstrate the problem.
* doc/autoconf.texi (Autoconf Language): Improve AC_DC example.
Reported by Gavin Smith <gavinsmith0123@gmail.com>.
Signed-off-by: Eric Blake <eblake@redhat.com>
The "single" macro infinitely recurses because its expansion contains
the unquoted text " single-". The "double" macro almost has the same
problem, but it is protected by extra quotes. In any case, the macro
names being repeated in the macro definitions is not necessary.
This commit changes the macro names to "foo" and "bar", which are taken
from a very similar example in the GNU M4 1.4.17 manual. See lines 1971
to 1980 of v1.4.17:doc/m4.texi in the GNU M4 Git repository.
* doc/autoconf.texi (Quoting and Parameters): Fix broken example.
* doc/autoconf.texi (C and Posix Variants): Rename from "Posix
Variants", and document updated behavior.
* lib/autoconf/specific.m4 (AC_USE_SYSTEM_EXTENSIONS): Also define
__STDC_WANT_IEC_60559_ATTRIBS_EXT__,
__STDC_WANT_IEC_60559_DFP_EXT__,
__STDC_WANT_IEC_60559_TYPES_EXT__, and
__STDC_WANT_MATH_SPEC_FUNCS__. From a suggestion by Joseph Myers in:
http://lists.gnu.org/archive/html/autoconf-patches/2016-09/msg00011.html
glibc 2.25 is deprecating the namespace pollution of <sys/types.h>
injecting major(), minor(), and makedev() into the compilation
environment, with a warning that insists that users include
<sys/sysmacros.h> instead. However, because the expansion of
AC_HEADER_MAJOR didn't bother checking sys/sysmacros.h until
after probing whether sys/types.h pollutes the namespace, it was
not defining MAJOR_IN_SYSMACROS, with the result that code
compiled with -Werror chokes on the deprecation warnings because
it was not including sysmacros.h.
In addition to fixing autoconf (which only benefits projects
that rebuild configure after this fix is released), we can also
give a hint to distros on how they can populate config.site with
a cache variable to force pre-existing configure scripts without
the updated macro to behave sanely in the presence of glibc 2.25
(the documentation is especially useful since that cache variable
is no longer present in autoconf after this patch).
Note that mingw lacks major/minor/makedev in any of its standard
headers; for that platform, the behavior of this macro is unchanged
(code using the recommended include formula will get a compile error
when trying to use major(), whether before or after this patch); but
for now, it is assumed that programs actually concerned with
creating devices are not worried about portability to mingw. If
desired, a later patch could tighten AC_HEADER_MAJOR to fail at
configure time if the macros are unavailable in any of the three
system headers, but that semantic change is not worth mixing into
this patch.
* lib/autoconf/headers.m4 (AC_HEADER_MAJOR): Drop check for
major within sys/types.h; it interferes with the need to check
sysmacros.h first.
* doc/autoconf.texi (Particular Headers) <AC_HEADER_MAJOR>: Expand
details on usage, and on workarounds for non-updated projects.
Signed-off-by: Eric Blake <eblake@redhat.com>
* lib/autoconf/specific.m4 (AC_USE_SYSTEM_EXTENSIONS):
Also define __STDC_WANT_IEC_60559_BFP_EXT__,
__STDC_WANT_IEC_60559_FUNCS_EXT__, and __STDC_WANT_LIB_EXT2__.
* NEWS, doc/autoconf.texi (Posix Variants):
Document this. Also, document other changes in this area
that were not properly documented before.
Silences this warning from new-enough texinfo:
./doc/autoconf.texi:14236: warning: @xref node name should not contain `.'
* doc/autoconf.texi (Macro Definitions): No need for .info.
Signed-off-by: Eric Blake <eblake@redhat.com>
Based on a report by Michael Felt, via Paul Eggert on the
coreutils list.
* doc/autoconf.texi (Limitations of Builtins) <for>: Document
problem with 'for var in ;'.
Signed-off-by: Eric Blake <eblake@redhat.com>
* lib/autoconf/general.m4 (_AC_UNDECLARED_WARNING): New macro.
(_AC_CHECK_DECL_BODY): Call it once per language; treat warnings as
errors when its verdict indicates that.
* tests/semantics.at (AC_CHECK_DECLS): Add a macro call that relies on
the new semantics. Avoid -Wmissing-variable-declarations warnings.
* doc/autoconf.texi (Generic Declarations): Document the implications.
* NEWS: Mention this change.
Give a more concrete description of what the m4_pattern_forbid
thingy that pretends it is a macro accepts as an argument.
Copyright-paper-exempt: Yes
Signed-off-by: Eric Blake <eblake@redhat.com>
