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INSTALL revision 1.1.1.3.4.1
      1 Copyright 1999-2018 Free Software Foundation, Inc.
      2 Contributed by the AriC and Caramba projects, INRIA.
      3 
      4 This file is part of the GNU MPFR Library.
      5 
      6 The GNU MPFR Library is free software; you can redistribute it and/or modify
      7 it under the terms of the GNU Lesser General Public License as published by
      8 the Free Software Foundation; either version 3 of the License, or (at your
      9 option) any later version.
     10 
     11 The GNU MPFR Library is distributed in the hope that it will be useful, but
     12 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
     13 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
     14 License for more details.
     15 
     16 You should have received a copy of the GNU Lesser General Public License
     17 along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
     18 http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
     19 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
     20 
     21 
     22 
     23                         Installing GNU MPFR
     24                         ===================
     25 
     26 Note: In case of problem, please read this INSTALL file carefully before
     27 reporting a bug, in particular Section "In case of problem" below. Some
     28 problems are due to bad configuration on the user side (not specific to
     29 MPFR).
     30 
     31 0. You first need to install GMP. See <http://www.gnu.org/software/gmp/>.
     32    MPFR requires GMP version 4.1 or later.
     33 
     34 1. Extract the files from the archive.
     35 
     36 2. It is strongly advised to apply the latest patches if this has
     37    not been done yet and if patches are available. You can check
     38    on the release page:
     39 
     40      http://www.mpfr.org/mpfr-4.0.1/
     41 
     42    which may have additional information. The patches can be applied
     43    with commands like:
     44 
     45      wget http://www.mpfr.org/mpfr-4.0.1/allpatches
     46      patch -N -Z -p1 < allpatches
     47 
     48    or
     49 
     50      curl http://www.mpfr.org/mpfr-4.0.1/allpatches | patch -N -Z -p1
     51 
     52    (Those instructions are for the GNU patch command, for example
     53    /usr/bin/gpatch on Solaris.)
     54 
     55 3. In the MPFR directory, to detect your system, type:
     56      ./configure
     57    possibly with options (see below, in particular if this step or
     58    one of the following fails). You should also check whether WARNING
     59    lines have been output (such a problem may cause a failure in one
     60    of the following steps).
     61    Note: paths provided in configure options must always be absolute
     62    (relative paths are not supported).
     63 
     64 4. To build the library, type:
     65      make
     66 
     67    [optional] if you want to tune MPFR for your specific architecture, see
     68    the section "Tuning MPFR" below. Note that for most common architectures,
     69    MPFR includes some default tuning parameters which should be near from
     70    optimal.
     71 
     72 5. To check the built library (runs the test files), type:
     73      make check
     74 
     75    Note: If any test fails, information about this failure can be found in
     76    the tests/test-suite.log file; you should provide this file in your bug
     77    reports (in addition to other useful information, as mentioned later).
     78    If you want the contents of this file to be automatically output in case
     79    of failure, you can set the VERBOSE environment variable to 1 before
     80    running "make check", for instance by typing:
     81      VERBOSE=1 make check
     82 
     83 6. [Optional / experimental] Binary distributions may also want to run:
     84      make check-gmp-symbols
     85 
     86    This will check that MPFR does not use GMP internal symbols, which
     87    could yield failures in case of GMP upgrade without a MPFR rebuild.
     88    But note that this is a heuristic and might give false positives or
     89    false negatives. Please report any problem to the MPFR developers.
     90    End users may also be interested in this check, unless they have
     91    allowed GMP internals with configure options (see below).
     92 
     93 7. To install it (default "/usr/local" | see "--prefix" option), type:
     94      make install
     95 
     96 If you installed MPFR (header and library) in directories that are
     97 not searched by default by the compiler and/or linking tools, then,
     98 like with other libraries, you may need to set up some environment
     99 variables such as C_INCLUDE_PATH (to find the header mpfr.h),
    100 LIBRARY_PATH (to find the library), and if the shared library has
    101 been installed, LD_LIBRARY_PATH (before execution) or LD_RUN_PATH
    102 (before linking); this list is not exhaustive and some environment
    103 variables may be specific to your system. "make install" gives some
    104 instructions; please read them. You can also find more information
    105 in the manuals of your compiler and linker. The MPFR FAQ may also
    106 give some information.
    107 
    108 Remember that if you have several MPFR (or GMP) versions installed
    109 (e.g., one with the system, and one, newer, by you), you will not
    110 necessarily get a compilation/linking error if a wrong library is
    111 used (e.g., because LD_LIBRARY_PATH has not been set correctly).
    112 But unexpected results may occur.
    113 
    114 Under Mac OS X, if the shared library was not installed and you use
    115 Apple's linker (this is the default), you will also need to provide
    116 the -search_paths_first linker flag ("-Wl,-search_paths_first" when
    117 you link via gcc) to make sure that the right library is selected,
    118 as by default, Apple's linker selects a shared library preferably,
    119 even when it is farther in the library paths. We recall that if a
    120 wrong library is selected due to this behavior, unexpected results
    121 may occur.
    122 
    123 
    124 Building the documentation
    125 ==========================
    126 
    127 To build the documentation in various formats, you may first need to
    128 install recent versions of some utilities such as texinfo.
    129 
    130 * Type "make info" to produce the documentation in the info format.
    131 
    132 * Type "make pdf" to produce the documentation in the PDF format.
    133 
    134 * Type "make dvi" to produce the documentation in the DVI format.
    135 
    136 * Type "make ps" to produce the documentation in the Postscript format.
    137 
    138 * Type "make html" to produce the documentation in the HTML format
    139   (in several pages); if you want only one output HTML file, then
    140   type "makeinfo --html --no-split mpfr.texi" from the doc directory
    141   instead.
    142 
    143 
    144 Building MPFR with internal GMP header files
    145 ============================================
    146 
    147 MPFR built with internal GMP header files is a bit faster, so you may want
    148 to build it with them. Just do this in step 1:
    149 
    150   ./configure --with-gmp-build=GMPBUILD
    151 
    152 where GMPBUILD is the GMP build directory. The needed header files are:
    153 gmp-impl.h, longlong.h and all the necessary headers to use them, which
    154 may be located either in the GMP source directory or in the GMP build
    155 directory, in case they are different (MPFR takes care of that, as of
    156 MPFR 3.1.0).
    157 
    158 Warning: the library obtained in this way may use some internal GMP
    159 symbols, and thus dynamically linking your software with a different
    160 version of GMP might fail, even though it is declared as compatible
    161 by Libtool's versioning system.
    162 
    163 
    164 Tuning MPFR
    165 ===========
    166 
    167 [For the current GMP version (6.1.0), a Unix-like OS is required.]
    168 
    169 For this, you need to build MPFR with a GMP build directory (see above).
    170 In the GMP build directory, you also need to go into the "tune" subdirectory
    171 and type "make speed". This will build the GMP speed library, which is used
    172 by the MPFR tuning mechanism.
    173 
    174 Then go back to the MPFR build directory, go into the "tune" subdirectory and
    175 type "make tune". This will build an optimized file "mparam.h" for your
    176 specific architecture.
    177 
    178 
    179 ./configure options
    180 ===================
    181 
    182 --prefix=DIR            installs MPFR headers and library in DIR/include and
    183                         DIR/lib respectively (the default is "/usr/local").
    184 
    185 --with-gmp-include=DIR  assumes that DIR contains gmp.h
    186 --with-gmp-lib=DIR      assumes that DIR contains the GMP library
    187 --with-gmp=DIR          assumes that DIR is where you have installed GMP.
    188                         same as --with-gmp-lib=DIR/lib
    189                         and     --with-gmp-include=DIR/include
    190                         (use either --with-gmp alone or one or both of
    191                         --with-gmp-lib/--with-gmp-include)
    192                         Warning! Do not use these options if you have
    193                         CPPFLAGS and/or LDFLAGS containing a -I or -L
    194                         option with a directory that contains a GMP
    195                         header or library file, as these options just
    196                         add -I and -L options to CPPFLAGS and LDFLAGS
    197                         *after* the ones that are currently declared,
    198                         so that DIR will have a lower precedence. Also,
    199                         this may not work if DIR is a system directory
    200                         (typically /usr or /usr/local); see below.
    201 
    202 --with-gmp-build=DIR    assumes that DIR contains the GMP build directory,
    203                         and enables the use of GMP internals (see above).
    204                         Warning! This option and the group of options
    205                         --with-gmp are mutually exclusive.
    206 
    207 --enable-assert         build MPFR with assertions.
    208 
    209 --enable-thread-safe    build MPFR as thread safe, using compiler-level
    210                         Thread Local Storage (TLS). Note: TLS support is
    211                         roughly tested by configure. If configure detects
    212                         that TLS does not work (because of the compiler,
    213                         linker or system libraries), it will output an
    214                         error message, telling you to build MPFR without
    215                         thread safe. For instance, though Mac OS X uses
    216                         GCC, it may not currently support GCC's __thread
    217                         storage class.
    218 
    219 --disable-thread-safe   build MPFR without TLS. By default, TLS support
    220                         is detected automatically, and MPFR is built as
    221                         thread safe if supported. However this detection
    222                         is only a heuristic: TLS can be detected as
    223                         supported while its support is incomplete or
    224                         buggy (MPFR tests may fail). In such a case,
    225                         this option is useful.
    226 
    227 --enable-gmp-internals  allows the MPFR build to use GMP's undocumented
    228                         functions (not from the public API). Note that
    229                         library versioning is not guaranteed to work if
    230                         this option is used. Thus it must not be used in
    231                         binary distributions.
    232 
    233 --with-sysroot=DIR      Search for dependent libraries within DIR (which
    234                         may be useful in cross-compilation). If you use
    235                         this option, you need to have Libtool 2.4+ on
    236                         the target system. See Libtool 2.4+'s NEWS file.
    237                         Technical information can be found at [1].
    238 
    239 [1] http://permalink.gmane.org/gmane.comp.gnu.libtool.patches/10111
    240 
    241 Note: By default, the configure script tries to set CC/CFLAGS to GMP's
    242 ones (this feature needs GMP 4.3.0 or later, or the --with-gmp-build
    243 option). However this is not guaranteed to work as the configure script
    244 does some compiler tests earlier, and the change may be too late. Also,
    245 the values obtained from GMP may be incorrect if GMP has been built
    246 on a different machine. In such a case, the user may need to specify
    247 CC/CFLAGS as explained below.
    248 
    249 Moreover, even without --with-gmp-build and --enable-gmp-internals,
    250 MPFR might use some GMP internals by mistake. This would be a bug,
    251 which should be reported to the MPFR developers.
    252 
    253 Run "./configure --help" to see the other options (default options
    254 from Autoconf and Automake).
    255 
    256 
    257 If 'gmp.h' and 'libgmp' do not match
    258 ====================================
    259 
    260 Under some circumstances, the configure script may output a message
    261 saying:
    262 
    263   'gmp.h' and 'libgmp' seem to have different versions or
    264   we cannot run a program linked with GMP (if you cannot
    265   see the version numbers above). [...]
    266 
    267 Even though the configure script does not fail in such a case, this
    268 message most often indicates a real error, which needs to be avoided.
    269 Possible causes are:
    270 
    271 * The wanted GMP library does not have the same ABI as the one chosen
    272   to build MPFR. The consequences may be:
    273 
    274     - A different GMP library (with the correct ABI) has been found,
    275       but does not have the same version as 'gmp.h'.
    276 
    277     - No other GMP libraries have been found (in this case, no version
    278       numbers should be printed above the warning message).
    279 
    280   This is incorrect and one of the following steps (make, make check)
    281   will probably fail. GMP (actually gmp.h) now provides CC and CFLAGS
    282   information to select the correct ABI, so that this problem should
    283   no longer occur; but if GMP was provided by a binary package, such
    284   information may not be valid. See the
    285 
    286     checking for CC and CFLAGS in gmp.h...
    287 
    288   line in the configure output (about the 11th line) and the following
    289   few ones for more information. You may need to reinstall GMP or to
    290   provide your own CC and/or CFLAGS. See also the remaining of this
    291   INSTALL file.
    292 
    293 * A configure option like --with-gmp or --with-gmp-include was used
    294   with a system include directory, e.g. one of the following:
    295 
    296     --with-gmp=/usr
    297     --with-gmp=/usr/local
    298     --with-gmp-include=/usr/include
    299     --with-gmp-include=/usr/local/include
    300 
    301   GCC (and possibly other compilers) will ignore such a directive for
    302   include directories (but this rule is not applied for the library
    303   itself!). This means that the library search paths will be reordered
    304   as declared, but the specified include directory will still be near
    305   the end of the include search paths (thus with a low precedence).
    306   This is not a problem if only one GMP version is installed, but
    307   otherwise, a wrong gmp.h may be chosen, so that the versions of
    308   gmp.h and libgmp may not match. The suggestions are the following:
    309 
    310     - If you want to use the GMP version under /usr, then you should
    311       uninstall all the other GMP versions (header and library files)
    312       that may be seen in the search paths, in particular those under
    313       /usr/local.
    314 
    315     - If you want to use the GMP version under /usr/local, then you
    316       should uninstall all the other GMP versions (header and library
    317       files) that may be seen in the search paths, but *NOT* the one
    318       under /usr (the version under /usr is provided by the OS vendor,
    319       and changing/removing anything related to it may break your
    320       system, and /usr should have a lower precedence than /usr/local
    321       anyway).
    322 
    323   To find where GMP versions have been installed:
    324 
    325     $ locate libgmp  (if you have a locate database)
    326 
    327   and if the compiler is GCC:
    328 
    329     $ gcc -print-file-name=libgmp.so     (under most systems)
    330     $ gcc -print-file-name=libgmp.dylib  (under Mac OS X)
    331 
    332   and if this does not work, you may try:
    333 
    334     $ gcc -print-search-dirs
    335 
    336 * An official GCC version was used under Debian GNU/Linux. Problems
    337   may come from the fact that Debian chose a different convention
    338   for library search paths concerning 32-bit and 64-bit libraries.
    339   A possible problem can be, for instance:
    340 
    341   [Debian's GCC, correct library path]
    342   $ gcc -print-file-name=libgmp.so
    343   /home/vlefevre/gmp/athlon64/lib/../lib/libgmp.so
    344 
    345   [Official GCC, incorrect library path]
    346   $ gcc-4.3.1 -print-file-name=libgmp.so
    347   /usr/lib/../lib64/libgmp.so
    348 
    349   The solution: use a GCC provided by Debian or add symbolic links
    350   such as lib64 -> lib (on 64-bit machines) for your library paths.
    351 
    352 * The problem may also be temporary and only due to the fact that
    353   libtool could not be used at this time. This is unlikely, though.
    354 
    355 
    356 In case of problem
    357 ==================
    358 
    359 First, look for any warning message in the configure output.
    360 
    361 Several documents may help you to solve the problem:
    362   * this INSTALL file, in particular information given below;
    363   * the FAQ (either the FAQ.html file distributed with MPFR, or the
    364     on-line version <http://www.mpfr.org/faq.html>, which may be more
    365     up-to-date);
    366   * the MPFR web page for this version <http://www.mpfr.org/mpfr-4.0.1/>,
    367     which lists bugs found in this version and provides some patches.
    368 
    369 If the "configure" fails, please check that the C compiler and its
    370 options are the same as those for the GMP build (specially the ABI).
    371 You can see the latter with the following command:
    372 
    373   grep "^CC\|^CFLAGS" GMPBUILD/Makefile
    374 
    375 if the GMP build directory is available. Then type:
    376 
    377   ./configure <configure options> CC=<C compiler> CFLAGS="<compiler options>"
    378 
    379 (quotes are needed when there are spaces or other special characters
    380 in the CC/CFLAGS value) and continue the install. On some platforms,
    381 you should provide further options to match those used by GMP, or set
    382 some environment variables. For instance, see the "Notes on AIX/PowerPC"
    383 section below.
    384 
    385 Warning! Do NOT use optimization options that can change the semantics
    386 of math operations, such as GCC's -ffast-math or Sun CC's -fast.
    387 Otherwise conversions from/to double's may be incorrect on infinities,
    388 NaN's and signed zeros. Since native FP arithmetic is used in a few
    389 places only, such options would not make MPFR faster anyway.
    390 
    391 If some "make check" tests fail, you can try the --disable-thread-safe
    392 configure option (see the configure options above): it has been reported
    393 that some platforms have buggy TLS support. Before trying this option,
    394 you may want to check in the configure output whether MPFR was built
    395 with TLS support; if yes, you will have a line:
    396   checking for TLS support... yes
    397 Alternatively "grep MPFR_USE_THREAD_SAFE config.log" will show that
    398 MPFR_USE_THREAD_SAFE is defined to 1. If it is "no" (or the variable
    399 is not defined), the --disable-thread-safe option would be useless.
    400 
    401 Some tests failure may be due to other compiler bugs, in particular
    402 in optimization code. You can try to build MPFR without compiler
    403 optimizations by giving -O0 (letter O, digit 0) in CFLAGS. If the
    404 MPFR tests no longer fail, this was probably due to a compiler bug,
    405 though we cannot exclude a bug in MPFR. You may want to contact us
    406 (see below), possibly after looking at:
    407   https://members.loria.fr/PZimmermann/software/compilerbugs.html
    408 
    409 On some platforms, try with "gmake" (GNU make) instead of "make".
    410 Problems have been reported with the Tru64 make.
    411 
    412 If the configure script reports that gmp.h version and libgmp version
    413 are different, or if the build was OK, but the tests failed to link
    414 with GMP or gave an error like
    415 
    416   undefined reference to `__gmp_get_memory_functions'
    417 
    418 meaning that the GMP library was not found or a wrong GMP library was
    419 selected by the linker, then your library search paths are probably
    420 not correctly set (some paths are missing or they are specified in an
    421 incorrect order).
    422 
    423 Such problems commonly occur under some GNU/Linux machines, where the
    424 default header and library search paths may be inconsistent: GCC is
    425 configured to search /usr/local/include and /usr/local/lib by default,
    426 while the dynamic linker ignores /usr/local/lib. If you have a GMP
    427 version installed in /usr (provided by the OS vendor) and a new one
    428 installed in /usr/local, then the header of the new GMP version and
    429 the library of the old GMP version will be used! The best solution
    430 is to make sure that the dynamic linker configuration is consistent
    431 with GCC's behavior, for instance by having /usr/local/lib in
    432 /etc/ld.so.conf or in some file from /etc/ld.so.conf.d (as Debian
    433 did: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=395177). See
    434 also https://gcc.gnu.org/ml/gcc-help/2010-01/msg00171.html for more
    435 information. Alternatively you can use:
    436   * environment variables. This may sometimes be necessary. If DIR
    437     is the installation directory of GMP, add DIR/include to your
    438     CPATH or C_INCLUDE_PATH (for compilers other than GCC, please
    439     check the manual of your compiler), and add DIR/lib to your
    440     LIBRARY_PATH and LD_LIBRARY_PATH (and/or LD_RUN_PATH);
    441   * --with-gmp* configure options (described above), e.g.
    442     --with-gmp=/opt/local (to use /opt/local/include for headers and
    443     /opt/local/lib for libraries), but other software that uses GMP
    444     and/or MPFR will need correct paths too, and environment variables
    445     allow one to set such search paths in a global way.
    446     Note about "--with-gmp=/usr/local". This option may appear to
    447     solve the above inconsistency problem, but does not work as you
    448     expect. Indeed it affects the library search path, in particular,
    449     the one used by the dynamic linker (thus adding the missing
    450     /usr/local/lib directory as wanted), but since /usr/local/include
    451     is a "standard system include directory" for GCC, the include
    452     search patch is not changed; this is often not a problem in this
    453     particular case because usually, /usr/local/include is already
    454     last in the include search patch, but this may fail under some
    455     occasions and may trigger obscure errors.
    456 
    457 For instance, under Unix, where paths are separated by a colon:
    458 
    459   * With POSIX sh-compatible shells (e.g. sh, ksh, bash, zsh):
    460     export C_INCLUDE_PATH="/usr/local/include:/other/path/include"
    461     export LIBRARY_PATH="/usr/local/lib:/other/path/lib"
    462     export LD_LIBRARY_PATH="$LIBRARY_PATH"
    463 
    464   * With csh or tcsh:
    465     setenv C_INCLUDE_PATH "/usr/local/include:/other/path/include"
    466     setenv LIBRARY_PATH "/usr/local/lib:/other/path/lib"
    467     setenv LD_LIBRARY_PATH "$LIBRARY_PATH"
    468 
    469 If almost all the tests fail and the messages in the test-suite.log file
    470 (or in the output, when running individual tests from the command line)
    471 start with a line of the form:
    472 
    473   Incorrect MPFR version! (xxx header vs yyy library)
    474 
    475 then this means that an installed MPFR version is tested instead of the
    476 one that has just been built. This is probably not a bug in MPFR, but a
    477 problem caused by the user or system configuration (particular options,
    478 environment variables, etc.) or a bug in the toolchain. In particular,
    479 if LD_LIBRARY_PATH overrides the run path (set up by libtool) and an
    480 installed ABI-compatible version of MPFR is in a directory listed in
    481 the LD_LIBRARY_PATH search path, then this will break. An example with
    482 GNU ld:
    483 
    484   https://sourceware.org/bugzilla/show_bug.cgi?id=21476
    485 
    486 If you can't solve your problem, you should contact us via the MPFR
    487 mailing-list <mpfr (a] inria.fr>, indicating the machine and operating system
    488 used (uname -a), the compiler and version used (gcc -v if you use gcc),
    489 the configure options used if any (including variables such as CC and
    490 CFLAGS), the version of GMP and MPFR used, and a description of the
    491 problem encountered, in particular the tests/test-suite.log file if
    492 "make check" failed. Please send us also the log of the "configure"
    493 (config.log).
    494 
    495 
    496 Notes about ABI
    497 ===============
    498 
    499 On 64-bit computers, it may happen that the default ABI (Application Binary
    500 Interface) chosen by MPFR does not correspond to the default one chosen by
    501 the compiler.
    502 
    503 In particular, this kind of message may indicate the problem:
    504 /usr/bin/ld: skipping incompatible mpfr/src/.libs/libmpfr.a when searching for -lmpfr
    505 
    506 In fact, since MPFR relies on GMP, it uses the same ABI as GMP.
    507 To be sure that your program compiles and links correctly, use the same
    508 compiler flags as MPFR does (look for CFLAGS in config.log).
    509 
    510 You might also recompile GMP with a different ABI, with for example
    511 ./configure ABI=32.
    512 
    513 
    514 Notes on Mac OS X
    515 =================
    516 
    517 If you get an error of the form
    518 
    519   ld: pointer in read-only segment not allowed in slidable image...
    520 
    521 this can mean that the link is done against a static (GMP) library.
    522 In such a case, you should configure MPFR with --disable-shared to
    523 disable the build of the shared library.
    524 
    525 
    526 Notes on FreeBSD 4.3
    527 ====================
    528 
    529 FreeBSD 4.3 is provided with an incorrect <float.h> header file, and
    530 MPFR tests related to long double's may fail. If you cannot upgrade
    531 the system, you can still use MPFR with FreeBSD 4.3, but you should
    532 not use conversions with the long double type.
    533 
    534 
    535 Notes on AIX/PowerPC
    536 ====================
    537 
    538 The following has been tested on AIX 7.1.3 (gcc111.fsffrance.org)
    539 with gcc 4.8.1 and GMP 6.1.0.
    540 
    541 If GMP was built with the 64-bit ABI, before building and testing MPFR,
    542 you should set the OBJECT_MODE environment variable to 64, e.g., with:
    543 
    544   export OBJECT_MODE=64
    545 
    546 (in a sh-compatible shell). Alternatively add the following to the configure
    547 line: AR="ar -X64" NM="nm -B -X64".
    548 
    549 
    550 Notes on Solaris
    551 ================
    552 
    553 Do not put a -R<dir> option in the LD_OPTIONS environment variable, at least
    554 if the directory <dir> can contain an MPFR library. Otherwise this MPFR
    555 library may be chosen for the tests (make check) instead of the one that has
    556 just been built, in which case, either you will get errors due to unmatched
    557 versions or this problem may remain undetected. The reason is that this
    558 option will appear before the -R options added by libtool, such as the one
    559 to the src/.libs directory containing the MPFR library that has just been
    560 built, and will have the precedence.
    561 
    562 
    563 MPFR for use with Windows Applications
    564 ======================================
    565 
    566 There are several ways of building MPFR on Windows, the most appropriate
    567 approach depending on how you intend to use the resulting libraries.
    568 
    569 a. Using MinGW
    570 ==============
    571 
    572 1 - We advise to use MinGW (http://www.mingw.org/ for 32-bit, and
    573     https://sourceforge.net/projects/mingw-w64/ for 32- and 64-bit),
    574     which is simpler and less demanding than Cygwin. Contrary to Cygwin,
    575     it also provides native Windows code.
    576 
    577     If you also use MSYS, you should use "make" for MSYS instead of
    578     the "make" utility from MinGW-W64 or from GCC, which causes the
    579     following error:
    580 
    581       libtool: warning: libobj name 'extract.Tpo -c -o extract.lo extract.lo'
    582       may not contain shell special characters.
    583       rm: unknown option -- c
    584 
    585     References about this issue and solution:
    586       https://sourceforge.net/p/msys2/tickets/223/
    587       https://sympa.inria.fr/sympa/arc/mpfr/2016-07/msg00009.html
    588 
    589 2 - If you just want to make a binary with gcc, there is nothing to do:
    590     GMP, MPFR and the program compile exactly as under Linux. (It is
    591     recommended to pass --build=xxx-yyy-mingw64 to the GMP configure command,
    592     or --build=xxx with xxx containing mingw.)
    593 
    594 3 - To avoid using the Microsoft runtime (which might not be conform to ISO C),
    595     you can use the MinGW runtime package (which is an integral part of MinGW).
    596     For example, with MinGW versions 3.15 and later you can get an
    597     ISO-compliant printf() if you compile your application with either
    598     '-ansi', '-posix' or '-D__USE_MINGW_ANSI_STDIO'. In order to have the
    599     MPFR formatted output functions based on ISO-compliant printf(), you
    600     need to compile GMP (not MPFR) with CC="gcc -D__USE_MINGW_ANSI_STDIO"
    601     (since the standard printf modifiers %e, %Ld and %td are passed to GMP).
    602     Not doing so may result in failures of some of the printf-related tests.
    603     For instance, the following error on some Windows machine has been
    604     reported:
    605 
    606       https://sympa.inria.fr/sympa/arc/mpfr/2016-02/msg00053.html
    607 
    608       Error in mpfr_vsprintf (s, "%e", ...);
    609       expected: "-1.250000e+000"
    610       got:      "-1.250000e+00"
    611       FAIL tsprintf.exe (exit status: 1)
    612 
    613     The cause is that here the C functions vsnprintf and vsprintf used
    614     internally in GMP do not produce the same output:
    615 
    616       https://sympa.inria.fr/sympa/arc/mpfr/2016-03/msg00045.html
    617       https://sympa.inria.fr/sympa/arc/mpfr/2016-03/msg00051.html
    618       https://sympa.inria.fr/sympa/arc/mpfr/2016-03/msg00053.html
    619 
    620     Building MPFR with -D__USE_MINGW_ANSI_STDIO is currently useless except
    621     for some error messages in the test suite.
    622 
    623 b. Using Cygwin
    624 ===============
    625 
    626 This build should be similar to that for MinGW except that the resulting
    627 library depends on the Cygwin DLL and cannot therefore be used with
    628 Visual Studio as with MinGW. Indeed, the binaries compiled with Cygwin
    629 require a dynamic library (cygwin.dll) to work; there is a Cygwin option
    630 -mno-cygwin to build native code, but it may require some non-portable tricks.
    631 
    632 In case of failure, you may need to pass LDFLAGS='-shared-libgcc' at the
    633 end of the configure line due to a bug in GCC. Otherwise, if threading
    634 support is not needed, you can configure MPFR with --disable-thread-safe.
    635 
    636 c. Using Microsoft Visual C++ and Intel C++ Compilers
    637 =====================================================
    638 
    639 Static and dynamic MPFR libraries for the 32- and 64-bit versions of
    640 Windows can be built with Microsoft Visual Studio 2015 using the
    641 Microsoft Visual C++ compiler, see:
    642 
    643   https://www.visualstudio.com/
    644 
    645 The Intel C++ compiler provided as a part of Intel Parallel Studio XE
    646 can also be used:
    647 
    648   https://software.intel.com/en-us/intel-parallel-studio-xe
    649 
    650 The relevant build projects are available here:
    651 
    652   https://github.com/BrianGladman
    653