This is Info file ../g77-0.5.23/f/g77.info, produced by Makeinfo version 1.68 from the input file ../g77-0.5.23/f/g77.texi. This file explains how to use the GNU Fortran system. Published by the Free Software Foundation 59 Temple Place - Suite 330 Boston, MA 02111-1307 USA Copyright (C) 1995-1997 Free Software Foundation, Inc. Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the sections entitled "GNU General Public License," "Funding for Free Software," and "Protect Your Freedom--Fight `Look And Feel'" are included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the sections entitled "GNU General Public License," "Funding for Free Software," and "Protect Your Freedom--Fight `Look And Feel'", and this permission notice, may be included in translations approved by the Free Software Foundation instead of in the original English. Contributed by James Craig Burley (). Inspired by a first pass at translating `g77-0.5.16/f/DOC' that was contributed to Craig by David Ronis (). INFO-DIR-SECTION Programming START-INFO-DIR-ENTRY * g77: (g77). The GNU Fortran compiler. END-INFO-DIR-ENTRY  File: g77.info, Node: Prerequisites, Next: Problems Installing, Up: Installation Prerequisites ============= The procedures described to unpack, configure, build, and install `g77' assume your system has certain programs already installed. The following prerequisites should be met by your system before you follow the `g77' installation instructions: `gzip' and `tar' To unpack the `gcc' and `g77' distributions, you'll need the `gunzip' utility in the `gzip' distribution. Most UNIX systems already have `gzip' installed. If yours doesn't, you can get it from the FSF. Note that you'll need `tar' and other utilities as well, but all UNIX systems have these. There are GNU versions of all these available--in fact, a complete GNU UNIX system can be put together on most systems, if desired. The version of GNU `gzip' used to package this release is 1.2.4. (The version of GNU `tar' used to package this release is 1.12.) `gcc-2.8.1.tar.gz' You need to have this, or some other applicable, version of `gcc' on your system. The version should be an exact copy of a distribution from the FSF. Its size is approximately 8.4MB. If you've already unpacked `gcc-2.8.1.tar.gz' into a directory (named `gcc-2.8.1') called the "source tree" for `gcc', you can delete the distribution itself, but you'll need to remember to skip any instructions to unpack this distribution. Without an applicable `gcc' source tree, you cannot build `g77'. You can obtain an FSF distribution of `gcc' from the FSF. `g77-0.5.23.tar.gz' You probably have already unpacked this package, or you are reading an advance copy of these installation instructions, which are contained in this distribution. The size of this package is approximately 1.4MB. You can obtain an FSF distribution of `g77' from the FSF, the same way you obtained `gcc'. Enough disk space The amount of disk space needed to unpack, build, install, and use `g77' depends on the type of system you're using, how you build `g77', and how much of it you install (primarily, which languages you install). The sizes shown below assume all languages distributed in `gcc-2.8.1', plus `g77', will be built and installed. These sizes are indicative of GNU/Linux systems on Intel x86 running COFF and on Digital Alpha (AXP) systems running ELF. These should be fairly representative of 32-bit and 64-bit systems, respectively. Note that all sizes are approximate and subject to change without notice! They are based on preliminary releases of g77 made shortly before the public beta release. -- `gcc' and `g77' distributions occupy 10MB packed, 40MB unpacked. These consist of the source code and documentation, plus some derived files (mostly documentation), for `gcc' and `g77'. Any deviations from these numbers for different kinds of systems are likely to be very minor. -- A "bootstrap" build requires an additional 91MB for a total of 132MB on an ix86, and an additional 136MB for a total of 177MB on an Alpha. -- Removing `gcc/stage1' after the build recovers 13MB for a total of 119MB on an ix86, and recovers 21MB for a total of 155MB on an Alpha. After doing this, the integrity of the build can still be verified via `make compare', and the `gcc' compiler modified and used to build itself for testing fairly quickly, using the copy of the compiler kept in `gcc/stage2'. -- Removing `gcc/stage2' after the build further recovers 39MB for a total of 80MB, and recovers 57MB for a total of 98MB on an Alpha. After doing this, the compiler can still be installed, especially if GNU `make' is used to avoid gratuitous rebuilds (or, the installation can be done by hand). -- Installing `gcc' and `g77' copies 23MB onto the `--prefix' disk for a total of 103MB on an ix86, and copies 31MB onto the `--prefix' disk for a total of 130MB on an Alpha. After installation, if no further modifications and builds of `gcc' or `g77' are planned, the source and build directory may be removed, leaving the total impact on a system's disk storage as that of the amount copied during installation. Systems with the appropriate version of `gcc' installed don't require the complete bootstrap build. Doing a "straight build" requires about as much space as does a bootstrap build followed by removing both the `gcc/stage1' and `gcc/stage2' directories. Installing `gcc' and `g77' over existing versions might require less *new* disk space, but note that, unlike many products, `gcc' installs itself in a way that avoids overwriting other installed versions of itself, so that other versions may easily be invoked (via `gcc -V VERSION'). So, the amount of space saved as a result of having an existing version of `gcc' and `g77' already installed is not much--typically only the command drivers (`gcc', `g77', `g++', and so on, which are small) and the documentation is overwritten by the new installation. The rest of the new installation is done without replacing existing installed versions (assuming they have different version numbers). `make' Your system must have `make', and you will probably save yourself a lot of trouble if it is GNU `make' (sometimes referred to as `gmake'). In particular, you probably need GNU `make' to build outside the source directory (with `configure''s `--srcdir' option.) The version of GNU `make' used to develop this release is 3.76.1. `cc' Your system must have a working C compiler. If it doesn't, you might be able to obtain a prebuilt binary of some version of `gcc' from the network or on CD-ROM, perhaps from the FSF. The best source of information about binaries is probably a system-specific Usenet news group, initially via its FAQ. *Note Installing GNU CC: (gcc)Installation, for more information on prerequisites for installing `gcc'. `sed' All UNIX systems have `sed', but some have a broken version that cannot handle configuring, building, or installing `gcc' or `g77'. The version of GNU `sed' used to develop this release is 2.05. (Note that GNU `sed' version 3.0 was withdrawn by the FSF--if you happen to have this version installed, replace it with version 2.05 immediately. See a GNU distribution site for further explanation.) `root' access or equivalent To perform the complete installation procedures on a system, you need to have `root' access to that system, or equivalent access to the `--prefix' directory tree specified on the `configure' command line. Portions of the procedure (such as configuring and building `g77') can be performed by any user with enough disk space and virtual memory. However, these instructions are oriented towards less-experienced users who want to install `g77' on their own personal systems. System administrators with more experience will want to determine for themselves how they want to modify the procedures described below to suit the needs of their installation. `autoconf' The version of GNU `autoconf' used to develop this release is 2.12. `autoconf' is not needed in the typical case of installing `gcc' and `g77'. *Note Missing tools?::, for information on when it might be needed and how to work around not having it. `bison' The version of GNU `bison' used to develop this release is 1.25. `bison' is not needed in the typical case of installing `gcc' and `g77'. *Note Missing tools?::, for information on when it might be needed and how to work around not having it. `gperf' The version of GNU `gperf' used to develop this release is 2.5. `gperf' is not needed in the typical case of installing `gcc' and `g77'. *Note Missing tools?::, for information on when it might be needed and how to work around not having it. `makeinfo' The version of GNU `makeinfo' used to develop this release is 1.68. `makeinfo' is part of the GNU `texinfo' package; `makeinfo' version 1.68 is distributed as part of GNU `texinfo' version 3.11. `makeinfo' is not needed in the typical case of installing `gcc' and `g77'. *Note Missing tools?::, for information on when it might be needed and how to work around not having it. An up-to-date version of GNU `makeinfo' is still convenient when obtaining a new version of a GNU distribution such as `gcc' or `g77', as it allows you to obtain the `.diff.gz' file instead of the entire `.tar.gz' distribution (assuming you have installed `patch'). `patch' The version of GNU `patch' used to develop this release is 2.5. Beginning with `g77' version 0.5.23, it is no longer necessary to patch the `gcc' back end to build `g77'. An up-to-date version of GNU `patch' is still convenient when obtaining a new version of a GNU distribution such as `gcc' or `g77', as it allows you to obtain the `.diff.gz' file instead of the entire `.tar.gz' distribution (assuming you have installed the tools needed to rebuild derived files, such as `makeinfo').  File: g77.info, Node: Problems Installing, Next: Settings, Prev: Prerequisites, Up: Installation Problems Installing =================== This is a list of problems (and some apparent problems which don't really mean anything is wrong) that show up when configuring, building, installing, or porting GNU Fortran. *Note Installation Problems: (gcc)Installation Problems, for more information on installation problems that can afflict either `gcc' or `g77'. * Menu: * General Problems:: Problems afflicting most or all systems. * System-specific Problems:: Problems afflicting particular systems. * Cross-compiler Problems:: Problems afflicting cross-compilation setups.  File: g77.info, Node: General Problems, Next: System-specific Problems, Up: Problems Installing General Problems ---------------- These problems can occur on most or all systems. * Menu: * GNU C Required:: Why even ANSI C is not enough. * Patching GNU CC:: Why `gcc' needn't be patched. * Building GNU CC Necessary:: Why you can't build *just* Fortran. * Missing strtoul or bsearch:: When linking `f771' fails. * Cleanup Kills Stage Directories:: For `g77' developers. * LANGUAGES Macro Ignored:: Sometimes `LANGUAGES' is ignored.  File: g77.info, Node: GNU C Required, Next: Patching GNU CC, Up: General Problems GNU C Required .............. Compiling `g77' requires GNU C, not just ANSI C. Fixing this wouldn't be very hard (just tedious), but the code using GNU extensions to the C language is expected to be rewritten for 0.6 anyway, so there are no plans for an interim fix. This requirement does not mean you must already have `gcc' installed to build `g77'. As long as you have a working C compiler, you can use a bootstrap build to automate the process of first building `gcc' using the working C compiler you have, then building `g77' and rebuilding `gcc' using that just-built `gcc', and so on.  File: g77.info, Node: Patching GNU CC, Next: Building GNU CC Necessary, Prev: GNU C Required, Up: General Problems Patching GNU CC ............... `g77' no longer requires application of a patch file to the `gcc' compiler tree. In fact, no such patch file is distributed with `g77'. This is as of version 0.5.23.  File: g77.info, Node: Building GNU CC Necessary, Next: Missing strtoul or bsearch, Prev: Patching GNU CC, Up: General Problems Building GNU CC Necessary ......................... It should be possible to build the runtime without building `cc1' and other non-Fortran items, but, for now, an easy way to do that is not yet established.  File: g77.info, Node: Missing strtoul or bsearch, Next: Cleanup Kills Stage Directories, Prev: Building GNU CC Necessary, Up: General Problems Missing strtoul or bsearch .......................... On SunOS4 systems, linking the `f771' program used to produce an error message concerning an undefined symbol named `_strtoul', because the `strtoul' library function is not provided on that system. Other systems have, in the past, been reported to not provide their own `strtoul' or `bsearch' function. Some versions `g77' tried to default to providing bare-bones versions of `bsearch' and `strtoul' automatically, but every attempt at this has failed for at least one kind of system. To limit the failures to those few systems actually missing the required routines, the bare-bones versions are still provided, in `gcc/f/proj.c', if the appropriate macros are defined. These are `NEED_BSEARCH' for `bsearch' and `NEED_STRTOUL' for `NEED_STRTOUL'. Therefore, if you are sure your system is missing `bsearch' or `strtoul' in its library, define the relevant macro(s) before building `g77'. This can be done by editing `gcc/f/proj.c' and inserting either or both of the following `#define' statements before the comment shown: /* Insert #define statements here. */ #define NEED_BSEARCH #define NEED_STRTOUL Then, continue configuring and building `g77' as usual. Or, you can define these on the `make' command line. To build with the bundled `cc' on SunOS4, for example, try: make bootstrap BOOT_CFLAGS='-O2 -g -DNEED_STRTOUL' If you then encounter problems compiling `gcc/f/proj.c', it might be due to a discrepancy between how `bsearch' or `strtoul' are defined by that file and how they're declared by your system's header files. In that case, you'll have to use some basic knowledge of C to work around the problem, perhaps by editing `gcc/f/proj.c' somewhat.  File: g77.info, Node: Cleanup Kills Stage Directories, Next: LANGUAGES Macro Ignored, Prev: Missing strtoul or bsearch, Up: General Problems Cleanup Kills Stage Directories ............................... It'd be helpful if `g77''s `Makefile.in' or `Make-lang.in' would create the various `stageN' directories and their subdirectories, so developers and expert installers wouldn't have to reconfigure after cleaning up. That help has arrived as of version 0.5.23 of `g77'. Configuration itself no longer creates any particular directories that are unique to `g77'. The build procedures in `Make-lang.in' take care of that, on demand.  File: g77.info, Node: LANGUAGES Macro Ignored, Prev: Cleanup Kills Stage Directories, Up: General Problems LANGUAGES Macro Ignored ....................... Prior to version 0.5.23, `g77' would sometimes ignore the absence of `f77' and `F77' in the `LANGUAGES' macro definition used for the `make' command being processed. As of version 0.5.23, `g77' now obeys this macro in all relevant situations. However, in versions of `gcc' through 2.8.1, non-`g77' portions of `gcc', such as `g++', are known to go ahead and perform various language-specific activities when their respective language strings do not appear in the `LANGUAGES' macro in effect during that invocation of `make'. It is expected that these remaining problems will be fixed in a future version of `gcc'.  File: g77.info, Node: System-specific Problems, Next: Cross-compiler Problems, Prev: General Problems, Up: Problems Installing System-specific Problems ------------------------ A linker bug on some versions of AIX 4.1 might prevent building. *Note LINKFAIL::.  File: g77.info, Node: Cross-compiler Problems, Prev: System-specific Problems, Up: Problems Installing Cross-compiler Problems ----------------------- `g77' has been in alpha testing since September of 1992, and in public beta testing since February of 1995. Alpha testing was done by a small number of people worldwide on a fairly wide variety of machines, involving self-compilation in most or all cases. Beta testing has been done primarily via self-compilation, but in more and more cases, cross-compilation (and "criss-cross compilation", where a version of a compiler is built on one machine to run on a second and generate code that runs on a third) has been tried and has succeeded, to varying extents. Generally, `g77' can be ported to any configuration to which `gcc', `f2c', and `libf2c' can be ported and made to work together, aside from the known problems described in this manual. If you want to port `g77' to a particular configuration, you should first make sure `gcc' and `libf2c' can be ported to that configuration before focusing on `g77', because `g77' is so dependent on them. Even for cases where `gcc' and `libf2c' work, you might run into problems with cross-compilation on certain machines, for several reasons. * There is one known bug (a design bug to be fixed in 0.6) that prevents configuration of `g77' as a cross-compiler in some cases, though there are assumptions made during configuration that probably make doing non-self-hosting builds a hassle, requiring manual intervention. * `gcc' might still have some trouble being configured for certain combinations of machines. For example, it might not know how to handle floating-point constants. * Improvements to the way `libg2c' is built could make building `g77' as a cross-compiler easier--for example, passing and using `$(LD)' and `$(AR)' in the appropriate ways. * There are still some challenges putting together the right run-time libraries (needed by `libg2c') for a target system, depending on the systems involved in the configuration. (This is a general problem with cross-compilation, and with `gcc' in particular.)  File: g77.info, Node: Settings, Next: Quick Start, Prev: Problems Installing, Up: Installation Changing Settings Before Building ================================= Here are some internal `g77' settings that can be changed by editing source files in `gcc/f/' before building. This information, and perhaps even these settings, represent stop-gap solutions to problems people doing various ports of `g77' have encountered. As such, none of the following information is expected to be pertinent in future versions of `g77'. * Menu: * Larger File Unit Numbers:: Raising `MXUNIT'. * Always Flush Output:: Synchronizing write errors. * Maximum Stackable Size:: Large arrays forced off the stack. * Floating-point Bit Patterns:: Possible programs building `g77' as a cross-compiler. * Large Initialization:: Large arrays with `DATA' initialization. * Alpha Problems Fixed:: Problems with 64-bit systems like Alphas now fixed?  File: g77.info, Node: Larger File Unit Numbers, Next: Always Flush Output, Up: Settings Larger File Unit Numbers ------------------------ As distributed, whether as part of `f2c' or `g77', `libf2c' accepts file unit numbers only in the range 0 through 99. For example, a statement such as `WRITE (UNIT=100)' causes a run-time crash in `libf2c', because the unit number, 100, is out of range. If you know that Fortran programs at your installation require the use of unit numbers higher than 99, you can change the value of the `MXUNIT' macro, which represents the maximum unit number, to an appropriately higher value. To do this, edit the file `f/runtime/libI77/fio.h' in your `g77' source tree, changing the following line: #define MXUNIT 100 Change the line so that the value of `MXUNIT' is defined to be at least one *greater* than the maximum unit number used by the Fortran programs on your system. (For example, a program that does `WRITE (UNIT=255)' would require `MXUNIT' set to at least 256 to avoid crashing.) Then build or rebuild `g77' as appropriate. *Note:* Changing this macro has *no* effect on other limits your system might place on the number of files open at the same time. That is, the macro might allow a program to do `WRITE (UNIT=100)', but the library and operating system underlying `libf2c' might disallow it if many other files have already been opened (via `OPEN' or implicitly via `READ', `WRITE', and so on). Information on how to increase these other limits should be found in your system's documentation.  File: g77.info, Node: Always Flush Output, Next: Maximum Stackable Size, Prev: Larger File Unit Numbers, Up: Settings Always Flush Output ------------------- Some Fortran programs require output (writes) to be flushed to the operating system (under UNIX, via the `fflush()' library call) so that errors, such as disk full, are immediately flagged via the relevant `ERR=' and `IOSTAT=' mechanism, instead of such errors being flagged later as subsequent writes occur, forcing the previously written data to disk, or when the file is closed. Essentially, the difference can be viewed as synchronous error reporting (immediate flagging of errors during writes) versus asynchronous, or, more precisely, buffered error reporting (detection of errors might be delayed). `libg2c' supports flagging write errors immediately when it is built with the `ALWAYS_FLUSH' macro defined. This results in a `libg2c' that runs slower, sometimes quite a bit slower, under certain circumstances--for example, accessing files via the networked file system NFS--but the effect can be more reliable, robust file I/O. If you know that Fortran programs requiring this level of precision of error reporting are to be compiled using the version of `g77' you are building, you might wish to modify the `g77' source tree so that the version of `libg2c' is built with the `ALWAYS_FLUSH' macro defined, enabling this behavior. To do this, find this line in `f/runtime/f2c.h' in your `g77' source tree: /* #define ALWAYS_FLUSH */ Remove the leading `/* ', so the line begins with `#define', and the trailing ` */'. Then build or rebuild `g77' as appropriate.  File: g77.info, Node: Maximum Stackable Size, Next: Floating-point Bit Patterns, Prev: Always Flush Output, Up: Settings Maximum Stackable Size ---------------------- `g77', on most machines, puts many variables and arrays on the stack where possible, and can be configured (by changing `FFECOM_sizeMAXSTACKITEM' in `gcc/f/com.c') to force smaller-sized entities into static storage (saving on stack space) or permit larger-sized entities to be put on the stack (which can improve run-time performance, as it presents more opportunities for the GBE to optimize the generated code). *Note:* Putting more variables and arrays on the stack might cause problems due to system-dependent limits on stack size. Also, the value of `FFECOM_sizeMAXSTACKITEM' has no effect on automatic variables and arrays. *Note But-bugs::, for more information.  File: g77.info, Node: Floating-point Bit Patterns, Next: Large Initialization, Prev: Maximum Stackable Size, Up: Settings Floating-point Bit Patterns --------------------------- The `g77' build will crash if an attempt is made to build it as a cross-compiler for a target when `g77' cannot reliably determine the bit pattern of floating-point constants for the target. Planned improvements for version 0.6 of `g77' will give it the capabilities it needs to not have to crash the build but rather generate correct code for the target. (Currently, `g77' would generate bad code under such circumstances if it didn't crash during the build, e.g. when compiling a source file that does something like `EQUIVALENCE (I,R)' and `DATA R/9.43578/'.)  File: g77.info, Node: Large Initialization, Next: Alpha Problems Fixed, Prev: Floating-point Bit Patterns, Up: Settings Initialization of Large Aggregate Areas --------------------------------------- A warning message is issued when `g77' sees code that provides initial values (e.g. via `DATA') to an aggregate area (`COMMON' or `EQUIVALENCE', or even a large enough array or `CHARACTER' variable) that is large enough to increase `g77''s compile time by roughly a factor of 10. This size currently is quite small, since `g77' currently has a known bug requiring too much memory and time to handle such cases. In `gcc/f/data.c', the macro `FFEDATA_sizeTOO_BIG_INIT_' is defined to the minimum size for the warning to appear. The size is specified in storage units, which can be bytes, words, or whatever, on a case-by-case basis. After changing this macro definition, you must (of course) rebuild and reinstall `g77' for the change to take effect. Note that, as of version 0.5.18, improvements have reduced the scope of the problem for *sparse* initialization of large arrays, especially those with large, contiguous uninitialized areas. However, the warning is issued at a point prior to when `g77' knows whether the initialization is sparse, and delaying the warning could mean it is produced too late to be helpful. Therefore, the macro definition should not be adjusted to reflect sparse cases. Instead, adjust it to generate the warning when densely initialized arrays begin to cause responses noticeably slower than linear performance would suggest.  File: g77.info, Node: Alpha Problems Fixed, Prev: Large Initialization, Up: Settings Alpha Problems Fixed -------------------- `g77' used to warn when it was used to compile Fortran code for a target configuration that is not basically a 32-bit machine (such as an Alpha, which is a 64-bit machine, especially if it has a 64-bit operating system running on it). That was because `g77' was known to not work properly on such configurations. As of version 0.5.20, `g77' is believed to work well enough on such systems. So, the warning is no longer needed or provided. However, support for 64-bit systems, especially in areas such as cross-compilation and handling of intrinsics, is still incomplete. The symptoms are believed to be compile-time diagnostics rather than the generation of bad code. It is hoped that version 0.6 will completely support 64-bit systems.  File: g77.info, Node: Quick Start, Next: Complete Installation, Prev: Settings, Up: Installation Quick Start =========== This procedure configures, builds, and installs `g77' "out of the box" and works on most UNIX systems. Each command is identified by a unique number, used in the explanatory text that follows. For the most part, the output of each command is not shown, though indications of the types of responses are given in a few cases. To perform this procedure, the installer must be logged in as user `root'. Much of it can be done while not logged in as `root', and users experienced with UNIX administration should be able to modify the procedure properly to do so. Following traditional UNIX conventions, it is assumed that the source trees for `g77' and `gcc' will be placed in `/usr/src'. It also is assumed that the source distributions themselves already reside in `/usr/FSF', a naming convention used by the author of `g77' on his own system: /usr/FSF/gcc-2.8.1.tar.gz /usr/FSF/g77-0.5.23.tar.gz If you vary *any* of the steps below, you might run into trouble, including possibly breaking existing programs for other users of your system. Before doing so, it is wise to review the explanations of some of the steps. These explanations follow this list of steps. sh[ 1]# cd /usr/src sh[ 2]# gunzip -c < /usr/FSF/gcc-2.8.1.tar.gz | tar xf - [Might say "Broken pipe"...that is normal on some systems.] sh[ 3]# gunzip -c < /usr/FSF/g77-0.5.23.tar.gz | tar xf - ["Broken pipe" again possible.] sh[ 4]# ln -s gcc-2.8.1 gcc sh[ 5]# ln -s g77-0.5.23 g77 sh[ 6]# mv -i g77/* gcc [No questions should be asked by mv here; or, you made a mistake.] sh[ 7]# cd gcc sh[ 8]# ./configure --prefix=/usr [Do not do the above if gcc is not installed in /usr/bin. You might need a different --prefix=..., as described below.] sh[ 9]# make bootstrap [This takes a long time, and is where most problems occur.] sh[10]# make compare [This verifies that the compiler is `sane'. If any files are printed, you have likely found a g77 bug.] sh[11]# rm -fr stage1 sh[12]# make -k install [The actual installation.] sh[13]# g77 -v [Verify that g77 is installed, obtain version info.] sh[14]# *Note Updating Your Info Directory: Updating Documentation, for information on how to update your system's top-level `info' directory to contain a reference to this manual, so that users of `g77' can easily find documentation instead of having to ask you for it. Elaborations of many of the above steps follows: Step 1: `cd /usr/src' You can build `g77' pretty much anyplace. By convention, this manual assumes `/usr/src'. It might be helpful if other users on your system knew where to look for the source code for the installed version of `g77' and `gcc' in any case. Step 3: `gunzip -d < /usr/FSF/g77-0.5.23.tar.gz | tar xf -' It is not always necessary to obtain the latest version of `g77' as a complete `.tar.gz' file if you have a complete, earlier distribution of `g77'. If appropriate, you can unpack that earlier version of `g77', and then apply the appropriate patches to achieve the same result--a source tree containing version 0.5.23 of `g77'. Step 4: `ln -s gcc-2.8.1 gcc' Step 5: `ln -s g77-0.5.23 g77' These commands mainly help reduce typing, and help reduce visual clutter in examples in this manual showing what to type to install `g77'. *Note Unpacking::, for information on using distributions of `g77' made by organizations other than the FSF. Step 6: `mv -i g77/* gcc' After doing this, you can, if you like, type `rm g77' and `rmdir g77-0.5.23' to remove the empty directory and the symbol link to it. But, it might be helpful to leave them around as quick reminders of which version(s) of `g77' are installed on your system. *Note Unpacking::, for information on the contents of the `g77' directory (as merged into the `gcc' directory). Step 8: `./configure --prefix=/usr' This is where you specify that the `g77' and `gcc' executables are to be installed in `/usr/bin/', the `g77' and `gcc' documentation is to be installed in `/usr/info/' and `/usr/man/', and so on. You should ensure that any existing installation of the `gcc' executable is in `/usr/bin/'. However, if that existing version of `gcc' is not 2.8.1, or if you simply wish to avoid risking overwriting it with a newly built copy of the same version, you can specify `--prefix=/usr/local' (which is the default) or some other path, and invoke the newly installed version directly from that path's `bin' directory. *Note Where in the World Does Fortran (and GNU CC) Go?: Where to Install, for more information on determining where to install `g77'. *Note Configuring gcc::, for more information on the configuration process triggered by invoking the `./configure' script. Step 9: `make bootstrap' *Note Installing GNU CC: (gcc)Installation, for information on the kinds of diagnostics you should expect during this procedure. *Note Building gcc::, for complete `g77'-specific information on this step. Step 10: `make compare' *Note Where to Port Bugs: Bug Lists, for information on where to report that you observed files having different contents during this phase. *Note How to Report Bugs: Bug Reporting, for information on *how* to report bugs like this. Step 11: `rm -fr stage1' You don't need to do this, but it frees up disk space. Step 12: `make -k install' If this doesn't seem to work, try: make -k install install-libf77 Or, make sure you're using GNU `make'. *Note Installation of Binaries::, for more information. *Note Updating Your Info Directory: Updating Documentation, for information on entering this manual into your system's list of texinfo manuals. Step 13: `g77 -v' If this command prints approximately 25 lines of output, including the GNU Fortran Front End version number (which should be the same as the version number for the version of `g77' you just built and installed) and the version numbers for the three parts of the `libf2c' library (`libF77', `libI77', `libU77'), and those version numbers are all in agreement, then there is a high likelihood that the installation has been successfully completed. You might consider doing further testing. For example, log in as a non-privileged user, then create a small Fortran program, such as: PROGRAM SMTEST DO 10 I=1, 10 PRINT *, 'Hello World #', I 10 CONTINUE END Compile, link, and run the above program, and, assuming you named the source file `smtest.f', the session should look like this: sh# g77 -o smtest smtest.f sh# ./smtest Hello World # 1 Hello World # 2 Hello World # 3 Hello World # 4 Hello World # 5 Hello World # 6 Hello World # 7 Hello World # 8 Hello World # 9 Hello World # 10 sh# If invoking `g77' doesn't seem to work, the problem might be that you've installed it in a location that is not in your shell's search path. For example, if you specified `--prefix=/gnu', and `/gnu/bin' is not in your `PATH' environment variable, you must explicitly specify the location of the compiler via `/gnu/bin/g77 -o smtest smtest.f'. After proper installation, you don't need to keep your gcc and g77 source and build directories around anymore. Removing them can free up a lot of disk space.  File: g77.info, Node: Complete Installation, Next: Distributing Binaries, Prev: Quick Start, Up: Installation Complete Installation ===================== Here is the complete `g77'-specific information on how to configure, build, and install `g77'. * Menu: * Unpacking:: * Merging Distributions:: * Where to Install:: * Configuring gcc:: * Building gcc:: * Pre-installation Checks:: * Installation of Binaries:: * Updating Documentation:: * Missing tools?::  File: g77.info, Node: Unpacking, Next: Merging Distributions, Up: Complete Installation Unpacking --------- The `gcc' source distribution is a stand-alone distribution. It is designed to be unpacked (producing the `gcc' source tree) and built as is, assuming certain prerequisites are met (including the availability of compatible UNIX programs such as `make', `cc', and so on). However, before building `gcc', you will want to unpack and merge the `g77' distribution in with it, so that you build a Fortran-capable version of `gcc', which includes the `g77' command, the necessary run-time libraries, and this manual. Unlike `gcc', the `g77' source distribution is *not* a stand-alone distribution. It is designed to be unpacked and, afterwards, immediately merged into an applicable `gcc' source tree. That is, the `g77' distribution *augments* a `gcc' distribution--without `gcc', generally only the documentation is immediately usable. A sequence of commands typically used to unpack `gcc' and `g77' is: sh# cd /usr/src sh# gunzip -c /usr/FSF/gcc-2.8.1.tar.gz | tar xf - sh# gunzip -c /usr/FSF/g77-0.5.23.tar.gz | tar xf - sh# ln -s gcc-2.8.1 gcc sh# ln -s g77-0.5.23 g77 sh# mv -i g77/* gcc *Notes:* The commands beginning with `gunzip...' might print `Broken pipe...' as they complete. That is nothing to worry about, unless you actually *hear* a pipe breaking. The `ln' commands are helpful in reducing typing and clutter in installation examples in this manual. Hereafter, the top level of `gcc' source tree is referred to as `gcc', and the top level of just the `g77' source tree (prior to issuing the `mv' command, above) is referred to as `g77'. There are three top-level names in a `g77' distribution: g77/COPYING.g77 g77/README.g77 g77/f All three entries should be moved (or copied) into a `gcc' source tree (typically named after its version number and as it appears in the FSF distributions--e.g. `gcc-2.8.1'). `g77/f' is the subdirectory containing all of the code, documentation, and other information that is specific to `g77'. The other two files exist to provide information on `g77' to someone encountering a `gcc' source tree with `g77' already present, who has not yet read these installation instructions and thus needs help understanding that the source tree they are looking at does not come from a single FSF distribution. They also help people encountering an unmerged `g77' source tree for the first time. *Note:* Please use *only* `gcc' and `g77' source trees as distributed by the FSF. Use of modified versions is likely to result in problems that appear to be in the `g77' code but, in fact, are not. Do not use such modified versions unless you understand all the differences between them and the versions the FSF distributes--in which case you should be able to modify the `g77' (or `gcc') source trees appropriately so `g77' and `gcc' can coexist as they do in the stock FSF distributions.  File: g77.info, Node: Merging Distributions, Next: Where to Install, Prev: Unpacking, Up: Complete Installation Merging Distributions --------------------- After merging the `g77' source tree into the `gcc' source tree, you have put together a complete `g77' source tree. As of version 0.5.23, `g77' no longer modifies the version number of `gcc', nor does it patch `gcc' itself. `g77' still depends on being merged with an appropriate version of `gcc'. For version 0.5.23 of `g77', the specific version of `gcc' supported is 2.8.1. However, other versions of `gcc' might be suitable "hosts" for this version of `g77'. GNU version numbers make it easy to figure out whether a particular version of a distribution is newer or older than some other version of that distribution. The format is, generally, MAJOR.MINOR.PATCH, with each field being a decimal number. (You can safely ignore leading zeros; for example, 1.5.3 is the same as 1.5.03.) The MAJOR field only increases with time. The other two fields are reset to 0 when the field to their left is incremented; otherwise, they, too, only increase with time. So, version 2.6.2 is newer than version 2.5.8, and version 3.0 is newer than both. (Trailing `.0' fields often are omitted in announcements and in names for distributions and the directories they create.) If your version of `gcc' is older than the oldest version supported by `g77' (as casually determined by listing the contents of `gcc/f/INSTALL/', which contains these installation instructions in plain-text format), you should obtain a newer, supported version of `gcc'. (You could instead obtain an older version of `g77', or try and get your `g77' to work with the old `gcc', but neither approach is recommended, and you shouldn't bother reporting any bugs you find if you take either approach, because they're probably already fixed in the newer versions you're not using.) If your version of `gcc' is newer than the newest version supported by `g77', it is possible that your `g77' will work with it anyway. If the version number for `gcc' differs only in the PATCH field, you might as well try that version of `gcc'. Since it has the same MAJOR and MINOR fields, the resulting combination is likely to work. So, for example, if a particular version of `g77' has support for `gcc' versions 2.8.0 and 2.8.1, it is likely that `gcc-2.8.2' would work well with `g77'. However, `gcc-2.9.0' would almost certainly not work with that version of `g77' without appropriate modifications, so a new version of `g77' would be needed (and you should wait for it rather than bothering the maintainers--*note User-Visible Changes: Changes.). This complexity is the result of `gcc' and `g77' being separate distributions. By keeping them separate, each product is able to be independently improved and distributed to its user base more frequently. However, the GBE interface defined by `gcc' typically undergoes some incompatible changes at least every time the MINOR field of the version number is incremented, and such changes require corresponding changes to the `g77' front end (FFE).  File: g77.info, Node: Where to Install, Next: Configuring gcc, Prev: Merging Distributions, Up: Complete Installation Where in the World Does Fortran (and GNU CC) Go? ------------------------------------------------ Before configuring, you should make sure you know where you want the `g77' and `gcc' binaries to be installed after they're built, because this information is given to the configuration tool and used during the build itself. A `g77' installation normally includes installation of a Fortran-aware version of `gcc', so that the `gcc' command recognizes Fortran source files and knows how to compile them. For this to work, the version of `gcc' that you will be building as part of `g77' *must* be installed as the "active" version of `gcc' on the system. Sometimes people make the mistake of installing `gcc' as `/usr/local/bin/gcc', leaving an older, non-Fortran-aware version in `/usr/bin/gcc'. (Or, the opposite happens.) This can result in `gcc' being unable to compile Fortran source files, because when the older version of `gcc' is invoked, it complains that it does not recognize the language, or the file name suffix. So, determine whether `gcc' already is installed on your system, and, if so, *where* it is installed, and prepare to configure the new version of `gcc' you'll be building so that it installs over the existing version of `gcc'. You might want to back up your existing copy of `/usr/bin/gcc', and the entire `/usr/lib' directory, before you perform the actual installation (as described in this manual). Existing `gcc' installations typically are found in `/usr' or `/usr/local'. (This means the commands are installed in `/usr/bin' or `/usr/local/bin', the libraries in `/usr/lib' or `/usr/local/lib', and so on.) If you aren't certain where the currently installed version of `gcc' and its related programs reside, look at the output of this command: gcc -v -o /tmp/delete-me -xc /dev/null -xnone All sorts of interesting information on the locations of various `gcc'-related programs and data files should be visible in the output of the above command. (The output also is likely to include a diagnostic from the linker, since there's no `main_()' function.) However, you do have to sift through it yourself; `gcc' currently provides no easy way to ask it where it is installed and where it looks for the various programs and data files it calls on to do its work. Just *building* `g77' should not overwrite any installed programs--but, usually, after you build `g77', you will want to install it, so backing up anything it might overwrite is a good idea. (This is true for any package, not just `g77', though in this case it is intentional that `g77' overwrites `gcc' if it is already installed--it is unusual that the installation process for one distribution intentionally overwrites a program or file installed by another distribution, although, in this case, `g77' is an augmentation of the `gcc' distribution.) Another reason to back up the existing version first, or make sure you can restore it easily, is that it might be an older version on which other users have come to depend for certain behaviors. However, even the new version of `gcc' you install will offer users the ability to specify an older version of the actual compilation programs if desired, and these older versions need not include any `g77' components. *Note Specifying Target Machine and Compiler Version: (gcc)Target Options, for information on the `-V' option of `gcc'.  File: g77.info, Node: Configuring gcc, Next: Building gcc, Prev: Where to Install, Up: Complete Installation Configuring GNU CC ------------------ `g77' is configured automatically when you configure `gcc'. There are two parts of `g77' that are configured in two different ways--`g77', which "camps on" to the `gcc' configuration mechanism, and `libg2c', which uses a variation of the GNU `autoconf' configuration system. Generally, you shouldn't have to be concerned with either `g77' or `libg2c' configuration, unless you're configuring `g77' as a cross-compiler. In this case, the `libg2c' configuration, and possibly the `g77' and `gcc' configurations as well, might need special attention. (This also might be the case if you're porting `gcc' to a whole new system--even if it is just a new operating system on an existing, supported CPU.) To configure the system, see *Note Installing GNU CC: (gcc)Installation, following the instructions for running `./configure'. Pay special attention to the `--prefix=' option, which you almost certainly will need to specify. (Note that `gcc' installation information is provided as a plain-text file in `gcc/INSTALL'.) The information printed by the invocation of `./configure' should show that the `f' directory (the Fortran language) has been configured. If it does not, there is a problem. *Note:* Configuring with the `--srcdir' argument, or by starting in an empty directory and typing a command such as `../gcc/configure' to build with separate build and source directories, is known to work with GNU `make', but it is known to not work with other variants of `make'. Irix5.2 and SunOS4.1 versions of `make' definitely won't work outside the source directory at present. `g77''s portion of the `configure' script used to issue a warning message about this when configuring for building binaries outside the source directory, but no longer does this as of version 0.5.23. Instead, `g77' simply rejects most common attempts to build it using a non-GNU `make' when the build directory is not the same as the source directory, issuing an explanatory diagnostic.  File: g77.info, Node: Building gcc, Next: Pre-installation Checks, Prev: Configuring gcc, Up: Complete Installation Building GNU CC --------------- Building `g77' requires building enough of `gcc' that these instructions assume you're going to build all of `gcc', including `g++', `protoize', and so on. You can save a little time and disk space by changes the `LANGUAGES' macro definition in `gcc/Makefile.in' or `gcc/Makefile', but if you do that, you're on your own. One change is almost *certainly* going to cause failures: removing `c' or `f77' from the definition of the `LANGUAGES' macro. After configuring `gcc', which configures `g77' and `libg2c' automatically, you're ready to start the actual build by invoking `make'. *Note:* You *must* have run the `configure' script in `gcc' before you run `make', even if you're using an already existing `gcc' development directory, because `./configure' does the work to recognize that you've added `g77' to the configuration. There are two general approaches to building GNU CC from scratch: "bootstrap" This method uses minimal native system facilities to build a barebones, unoptimized `gcc', that is then used to compile ("bootstrap") the entire system. "straight" This method assumes a more complete native system exists, and uses that just once to build the entire system. On all systems without a recent version of `gcc' already installed, the bootstrap method must be used. In particular, `g77' uses extensions to the C language offered, apparently, only by `gcc'. On most systems with a recent version of `gcc' already installed, the straight method can be used. This is an advantage, because it takes less CPU time and disk space for the build. However, it does require that the system have fairly recent versions of many GNU programs and other programs, which are not enumerated here. * Menu: * Bootstrap Build:: For all systems. * Straight Build:: For systems with a recent version of `gcc'.