This FAQ tries to answer specific questions concerning EGCS. For general information regarding C resp. C++, please check the comp.lang.c FAQ, comp.lang.c++ FAQ, and the comp.std.c++ FAQ.
Six years ago, gcc version 1 had reached a point of stability. For the targets it could support, it worked well. It had limitations inherent in its design that would be difficult to resolve, so a major effort was made and gcc version 2 was the result. When we had gcc2 in a useful state, development efforts on gcc1 stopped and we all concentrated on making gcc2 better than gcc1 could ever be. This is the kind of step forward we want to make with EGCS.
In brief, the three biggest differences between EGCS and gcc2 are:
These three differences will work together to result in a more useful compiler, a more stable compiler, a central compiler that works for more people, a compiler that generates better code.
There are a lot of exciting compiler optimizations that have come out. We want them in gcc. There are a lot of front ends out there for gcc for languages like Fortran or Pascal. We want them easily installable by users. After six years of working on gcc2, we've come to see problems and limitations in the way gcc is architected; it is time to address these again.
With EGCS, we are going to try a bazaar style[1] approach to its development: We're going to be making snapshots publicly available to anyone who wants to try them; we're going to welcome anyone to join the development mailing list. All of the discussions on the development mailing list are available via the web. We're going to be making releases with a much higher frequency than they have been made in the past: We're shooting for three by the end of 1997.
In addition to weekly snapshots of the EGCS development sources, we are going to look at making the sources readable from a CVS server by anyone. We want to make it so external maintainers of parts of EGCS are able to commit changes to their part of EGCS directly into the sources without going through an intermediary.
There have been many potential gcc developers who were not able to participate in gcc development in the past. We want these people to help in any way they can; we ultimately want gcc to be the best compiler in the world.
A compiler is a complicated piece of software, there will still be strong central maintainers who will reject patches, who will demand documentation of implementations, and who will keep the level of quality as high as it is today. Code that could use wider testing may be integrated--code that is simply ill-conceived won't be.
EGCS is not the first piece of software to use this open development process; FreeBSD, the Emacs lisp repository, and the Linux kernel are a few examples of the bazaar style of development.
With EGCS, we will be adding new features and optimizations at a rate that has not been done since the creation of gcc2; these additions will inevitably have a temporarily destabilizing effect. With the help of developers working together with this bazaar style development, the resulting stability and quality levels will be better than we've had before.
[1] We've been discussing different development models a lot over the past few months. The paper which started all of this introduced two terms: A cathedral development model versus a bazaar development model. The paper is written by Eric S. Raymond, it is called ``The Cathedral and the Bazaar''. The paper is a useful starting point for discussions.
Some folks have questioned whether or not making releases is consistent with the goals of the EGCS project and whether or not making releases is a fork from gcc2.
The EGCS project has several goals, including: * Experimenting with a new development model, release process and release packaging, * Using the new development model to accelerate development of new features, optimizations, etc for future inclusion in gcc, * Providing high quality releases to the public. An EGCS release is a copy of the EGCS sources that the developers have tested and are believed to be suitable for wider scale use and testing. Making releases of stable, tested sources is both a goal and a means by which we hope to achieve other goals of the EGCS project. The existence of a stable tested release allows EGCS to be more thoroughly used and tested by a wider audience than is capable of testing snapshots. The expanded audience provides developers with critical feedback in a timely manner, which is beneficial to GCC as a whole and is consistent with the stated goals of EGCS. The gcc maintainers are encouraged to migrate tested fixes and new features from EGCS into gcc at their discretion. EGCS maintainers are willing to assist the gcc maintainers as time permits. EGCS periodically merges in changes from gcc into the EGCS sources. What will keep EGCS from becoming a fork is cooperation between the developers of gcc and EGCS. We don't see this situation as significantly different than other projects that make releases based on some version of the gcc sources (Cygnus, g77, etc). All the code is still available for inclusion in gcc at the discretion of the gcc maintainers.
There are complete instructions in the egcs info manual, section Bugs. The manual can be read using `M-x info' in Emacs, or if the GNU info program is installed on your system by `info --node "(gcc)Bugs"'. Or see the file BUGS included with the egcs source code.
Before you report a bug for the C++ compiler, please check the list of well-known bugs. If you want to report a bug with egcs 1.0.x, we recommend upgrading to the current release first.
In short, if egcs says Internal compiler error (or any other error that you'd like us to be able to reproduce, for that matter), please mail a bug report to egcs-bugs@egcs.cygnus.com including:
All this can normally be accomplished by mailing the command line, the output of the command, and the resulting `your-file.i' for C, or `your-file.ii' for C++, corresponding to:
gcc -v --save-temps all-your-options your-file.c
Typically the CPP output will be large, so please compress the resulting file with one of the popular compression programs such as gzip, bzip2, compress or pkzip, then include the compressed CPP output as an attachment to your message.
The egcs lists have message size limits (100 kbytes) and bug reports over those limits will currently be bounced. We're trying to find a way to allow larger bug reports to be posted, but this is currently impossible. So, although we prefer to have complete bug reports archived, if you cannot reduce the bug report below the limit, please make it available for ftp or http and post the URL.
If you get this error, it means either EGCS incorrectly guessed what version of libc is installed on your GNU/Linux system, or you incorrectly specified a version of glibc when configuring EGCS.
If you did not provide a target name when configuring EGCS, then you've found a bug which needs to be reported. If you did provide a target name at configure time, then you should reconfigure without specifying a target name.
The Fortran front end can not be built with most vendor compilers; it must be built with gcc. As a result, you may get an error if you do not follow the install instructions carefully.
In particular, instead of using "make" to build EGCS, you should use "make bootstrap" if you are building a native compiler or "make cross" if you are building a cross compiler.
It has also been reported that the Fortran compiler can not be built on Red Hat 4.X GNU/Linux for the Alpha. Fixing this may require upgrading binutils or to Red Hat 5.0; we'll provide more information as it becomes available.
It may be desirable to install both EGCS and gcc2 on the same system. This can be done by using different prefix paths at configure time and a few symlinks.
Basically, configure the two compilers with different --prefix options, then build and install each compiler. Assume you want "gcc" to be the EGCS compiler and available in /usr/local/bin; also assume that you want "gcc2" to be the gcc2 compiler and also available in /usr/local/bin.
The easiest way to do this is to configure EGCS with --prefix=/usr/local/egcs and gcc2 with --prefix=/usr/local/gcc2. Build and install both compilers. Then make a symlink from /usr/local/bin/gcc to /usr/local/egcs/bin/gcc and from /usr/local/bin/gcc2 to /usr/local/gcc2/bin/gcc. Create similar links for the "g++", "c++" and "g77" compiler drivers.
An alternative to using symlinks is to configure with a --program-transform-name option. This option specifies a sed command to process installed program names with. Using it you can, for instance, have all the EGCS programs installed as "egcs-gcc" and the like. You will still have to specify different --prefix options for EGCS and gcc2, because it is only the executable program names that are transformed. The difference is that you (as administrator) do not have to set up symlinks, but must specify additional directories in your (as a user) PATH. A complication with --program-transform-name is that the sed command invariably contains characters significant to the shell, and these have to be escaped correctly, also it is not possible to use "^" or "$" in the command. Here is the option to prefix "egcs-" to the egcs installed programs "--program-transform-name='s,\\\\(.*\\\\),egcs-\\\\1,'". With the above --prefix option, that will install the EGCS programs into /usr/local/egcs/bin with names prefixed by "egcs-". You can use --program-transform-name if you have multiple versions of EGCS, and wish to be sure about which version you are invoking.
If you use --prefix, EGCS may have difficulty locating a GNU assembler or linker on your system, GCC can not find GNU as/GNU ld explains how to deal with this.
This problem manifests itself by programs not finding shared libraries they depend on when the programs are started. Note this problem often manifests itself with failures in the libio/libstdc++ tests after configuring with --enable-shared and building EGCS.
GCC does not specify a runpath so that the dynamic linker can find dynamic libraries at runtime.
The short explanation is that if you always pass a -R option to the linker, then your programs become dependent on directories which may be NFS mounted, and programs may hang unnecessarily when an NFS server goes down.
The problem is not programs that do require the directories; those programs are going to hang no matter what you do. The problem is programs that do not require the directories.
SunOS effectively always passed a -R option for every -L option; this was a bad idea, and so it was removed for Solaris. We should not recreate it.
To ensure that EGCS finds the GNU assembler (the GNU loader), which are required by some configurations, you should configure these with the same --prefix option as you used for EGCS. Then build & install GNU as (GNU ld) and proceed with building EGCS.
Another alternative is to create links to GNU as and ld in any of the directories printed by the command `gcc -print-search-dirs | grep '^programs:''. The link to `ld' should be named `real-ld' if `ld' already exists.
Pre-1.2 snapshots of egcs allow you to specify the full pathname of the assembler and the linker to use. The configure flags are `--with-as=/path/to/as' and `--with-ld=/path/to/ld'. EGCS will try to use these pathnames before looking for `as' or `(real-)ld' in the standard search dirs. If, at configure-time, the specified programs are found to be GNU utilities, `--with-gnu-as' and `--with-gnu-ld' need not be used; these flags will be auto-detected.
If you get an error like this when building EGCS (particularly when building __mulsi3), then you likely have a problem with your environment variables.
cpp: Usage: /usr/lib/gcc-lib/i586-unknown-linux-gnulibc1/2.7.2.3/cpp [switches] input output
First look for an explicit '.' in either LIBRARY_PATH or GCC_EXEC_PREFIX from your environment. If you do not find an explicit '.', look for an empty pathname in those variables. Note that ':' at either the start or end of these variables is an implicit '.' and will cause problems.
Also note '::' in these paths will also cause similar problems.
If you get a message about unable to find "standard.exp" when trying to run the EGCS testsuites, then your dejagnu is too old to run the EGCS tests. You will need to get a newer version of dejagnu; we've made a dejagnu snapshot available until a new version of dejagnu can be released.
-fnew-abi to the testsuite?If you invoke runtest directly, you can use the
--tool_opts option, e.g:
runtest --tool_opts "-fnew-abi -fno-honor-std" <other options>Or, if you use
make check you can use the
make variable RUNTESTFLAGS, e.g:
make RUNTESTFLAGS='--tool_opts "-fnew-abi -fno-honor-std"' check-g++
If you invoke runtest directly, you can use the
--target_board option, e.g:
runtest --target_board "unix{-fPIC,-fpic,}" <other options>
Or, if you use make check you can use the
make variable RUNTESTFLAGS, e.g:
make RUNTESTFLAGS='--target_board "unix{-fPIC,-fpic,}"' check-gcc
Either of these examples will run the tests three times. Once
with -fPIC, once with -fpic, and once with
no additional flags.
This technique is particularly useful on multilibbed targets.
EGCS requires the use of GAS on all versions of IRIX, except IRIX 6, due to limitations in older IRIX assemblers.
Either of these messages indicates that you are using the MIPS assembler when instead you should be using GAS.
as0: Error: ./libgcc2.c, line 1:Badly delimited numeric literal
.4byte $LECIE1-$LSCIE1
as0: Error: ./libgcc2.c, line 1:malformed statement
as0: Error: /home/law/egcs_release/gcc/libgcc2.c, line 1:undefined symbol in expression
.word $LECIE1-$LSCIE1
For IRIX 6, you should use the native assembler as GAS is not yet supported on this platform.
If you are using the GNU assembler (aka gas) on an x86 platform and exception handling is not working correctly, then odds are you're using a buggy assembler. Releases of binutils prior to 2.9 are known to assemble exception handling code incorrectly.
We recommend binutils-2.9.1 or newer. Some post-2.9.1 snapshots of binutils fix some subtle bugs, particularly on x86 and alpha. They are available at ftp://tsx-11.mit.edu/pub/linux/packages/GCC/. The 2.9.1.0.15 snapshot is known to work fine on those platforms; other than that, be aware that snapshots are in general untested and may not work (or even build). Use them at your own risk.
Previous releases of gcc (for example, gcc-2.7.2.X) did not detect as invalid a clobber specifier that clobbered an operand. Instead, it could spuriously and silently generate incorrect code for certain non-obvious cases of source code. Even more unfortunately, the manual (Using and Porting GCC, section Extended Asm, see the bug report entry) did not explicitly say that it was invalid to specify clobber registers that were destined to overlap operands; it could arguably be interpreted that it was correct to clobber an input operand to mark it as not holding a usable value after the asm.
For the general case, there is no way to tell whether a specified clobber is intended to overlap with a specific (input) operand or is a program error, where the choice of actual register for operands failed to avoid the clobbered register. Such unavoidable overlap is detected by versions egcs-2.92.18 19981104 and above, and flagged as an error rather than accepted. An error message is given, such as:
foo.c: In function `foo': foo.c:7: Invalid `asm' statement: foo.c:7: fixed or forbidden register 0 (ax) was spilled for class AREG.Unfortunately, a lot of existing software, for example the Linux kernel version 2.0.35 for the Intel x86, has constructs where input operands are marked as clobbered.
The manual now describes how to write constructs with operands that are modified by the construct, but not actually used. To write an asm which modifies an input operand but does not output anything usable, specify that operand as an output operand outputting to an unused dummy variable.
In the following example for the x86 architecture (taken from the Linux 2.0.35 kernel -- include/asm-i386/delay.h), the register-class constraint "a" denotes a register class containing the single register "ax" (aka. "eax"). It is therefore invalid to clobber "ax"; this operand has to be specified as an output as well as an input. The following code is therefore invalid:
extern __inline__ void
__delay (int loops)
{
__asm__ __volatile__
(".align 2,0x90\n1:\tdecl %0\n\tjns 1b"
: /* no outputs */
: "a" (loops)
: "ax");
}
It could be argued that since the register class for "a" contains
only a single register, this could be detected as an "obvious" intended
clobber of the input operand. While that is feasible, it opens up for
further "obvious" cases, where the level of obviousness changes from
person to person. As there is a correct way to write such asm constructs,
this obviousness-detection is not needed other than for reasons of
compatibility with an existing code-base, and that code base can be
corrected.
This corrected and clobber-less version, is valid for egcs of current CVS, as well as for previous versions of gcc:
extern __inline__ void
__delay (int loops)
{
int dummy;
__asm__ __volatile__
(".align 2,0x90\n1:\tdecl %0\n\tjns 1b"
: "=a" (dummy)
: "0" (loops));
}
Note that the asm construct now has an output operand, but it is unused.
Normally asm constructs with only unused output operands may be removed by
gcc, unless marked volatile as above.
If you bootstrap the compiler on HP-UX 10.x using the HP assembler instead of gas, every file will fail the comparison test. Please see the section on HP-UX 10.x in the Host/Target specific installation notes for more information
When building EGCS, the build process loops rebuilding cc1 over and over again. This happens on mips-sgi-irix5.2, and possibly other platforms.
It has been reported that this is a known bug in the make shipped with IRIX 5.2. We recommend you use GNU make instead of the vendor supplied make program; however, you may have success with "smake" on IRIX 5.2 if you do not have GNU make available.
Linux 2.2.x kernels work with any version of egcs.
If you try to build a 2.0.x kernel for Intel machines with egcs,
then you are on your own. The 2.0.x kernels are to be built only with
gcc 2.7.2. They use certain asm constructs which are
incorrect, but (by accident) happen to work with gcc 2.7.2. If you
insist on building 2.0.x kernels with egcs, you may be interested in
this patch
which fixes some of the asm problems. You will also want to change
asm constructs to avoid clobbering their input
operands.
If you installed a recent binutils/gas snapshot on your GNU/Linux system, you may not be able to build the kernel because objdump does not understand the "-k" switch. The solution for this problem is to remove /usr/bin/encaps. (This is an obsolete program that was part of older binutils distributions; the Linux kernel's Makefile looks for this program to decide if you have an old or a new binutils. Problems occur if you installed a new binutils but haven't removed encaps, because the Makefile thinks you have the old one.)
Finally, you may get errors with the X driver of the form
_X11TransSocketUNIXConnect: Can't connect: errno = 111
This is a kernel bug. The function sys_iopl in arch/i386/kernel/ioport.c does an illegal hack which used to work but is now broken since GCC optimizes more aggressively . The newer 2.1.x kernels already have a fix which should also work in 2.0.32.
EGCS does not currently support windows, either natively or with the cygwin32 dll. However Mumit Khan has been working on supporting Windows with EGCS. You should check out his site if you're interested in Windows support. GNU Win32 related projects
EGCS does not currently support OS/2. However, Andrew Zabolotny has been working on a generic os/2 port with pgcc. The current code code can be found at http://www.goof.com/pcg/os2/.
When compiling X11 headers with a egcs 2.92.33 or newer, g++ will complain that types are missing. These headers assume that omitting the type means 'int'; this assumption is wrong for C++.
g++ accepts such (illegal) constructs with the option -fpermissive; it will assume that missing type is 'int' (as defined by the C89 standard).
Since the upcoming C99 standard also obsoletes the implicit type assumptions, the X11 headers have to get fixed eventually.
A bug in the SunOS4 linker will cause it to crash when linking -fPIC compiled objects.
To fix this problem you can either use the most recent version of binutils or get the latest SunOS4 linker patch (patch ID 100170-10) from Sun's patch site.
Error: Unknown pseudo-op: `.arch'
GNU/Linux Alpha EV56 or PCA56 hosts running Red Hat 4.2 or 5.0 may
see errors of this sort. This is a signal that a new assembler is needed
if you want to generate BWX insns for your machine.
The version shipped with Red Hat 4.2 (2.7.0.2) has a fault wherein it will silently generate incorrect code. The version shipped with Red Hat 5.0 (2.8.0.1) is not broken, but required an extra -m21164a argument on the command-line. In order to visibly trap 2.7.0.2, I now issue DEC's .arch pseudo into the assembly. Relieving the problem of mucking with command-line arguments for 2.8.0.1 is a pleasant side effect.
If you've got Red Hat 5.0 installed, you may grab binutils 2.9.1 and be happy. If you've got Red Hat 4.2, bugs make it much harder to upgrade pieces on your own, and you are better off upgrading the entire system.
In either case, your problem may be bypassed by not emitting BWX code by default. Do this by using
configure alphaev5-unknown-linux-gnulibc1if you have RH 4.2, or
configure alphaev5-unknown-linux-gnuif you have RH 5.0.
Error: macro requires $at register while noat in effect
This error also indicates that you should upgrade to a newer version of
the assembler, 2.9 or later. If you can not upgrade the assembler, the
compiler option "-Wa,-m21164a" may work around this problem.
If you receive Signal 11 errors when building on GNU/Linux, then it is possible you have a hardware problem. Further information on this can be found on www.bitwizard.nl.
Some versions of the AIX binder (linker) can fail with a relocation overflow severe error when the -bbigtoc option is used to link GCC-produced object files into an executable that overflows the TOC. A fix for APAR IX75823 (OVERFLOW DURING LINK WHEN USING GCC AND -BBIGTOC) is available from IBM Customer Support and from its service.boulder.ibm.com website as PTF U455193.
AIX 4.3 utilizes a new "large format" archive to support both 32-bit and 64-bit object modules. The routines provided in AIX 4.3.0 and AIX 4.3.1 to parse archive libraries did not handle the new format correctly. These routines are used by GCC and result in error messages during linking such as "not a COFF file". The version of the routines shipped with AIX 4.3.1 should work for a 32-bit environment. The -g option of the archive command may be used to create archives of 32-bit objects using the original "small format". A correct version of the routines is shipped with AIX 4.3.2.
The AIX 4.3.2.1 linker (bos.rte.bind_cmds Level 4.3.2.1) will dump core with a segmentation fault when invoked by any version of GCC. A fix for APAR IX87327 will be available from IBM Customer Support.
The initial assembler shipped with AIX 4.3.0 generates incorrect object files. A fix for APAR IX74254 (64BIT DISASSEMBLED OUPUT FROM COMPILER FAILS TO ASSEMBLE/BIND) is available from IBM Customer Support and from its service.boulder.ibm.com website as PTF U453956. This fix is incorporated in AIX 4.3.1 and above.
Gcc does not currently support generating O32 ABI binaries in the mips-sgi-irix6 configurations.
It used to be possible to create a gcc with O32 ABI only support by configuring it for the mips-sgi-irix5 target. See Links to other FAQs for GCC on IRIX platforms for details.
Gcc does not correctly pass/return structures which are smaller than 16 bytes and which are not 8 bytes. The problem is very involved and difficult to fix. It affects a number of other targets also, but IRIX 6 is affected the most, because it is a 64 bit target, and 4 byte structures are common. The exact problem is that structures are being padded at the wrong end, e.g. a 4 byte structure is loaded into the lower 4 bytes of the register when it should be loaded into the upper 4 bytes of the register.
Gcc is consistent with itself, but not consistent with the SGI C compiler [and the SGI supplied runtime libraries], so the only failures that can happen are when there are library functions that take/return such structures. There are very few such library functions. I can only recall seeing two of them: inet_ntoa, and semctl.
http://reality.sgi.com/ariel/freeware
On some versions of NEXTSTEP 3.x, compilation of EGCS will fail during stage1. More information can be found in the section on NEXTSTEP 3.x in the Host/Target specific installation notes.
Building cross compilers is a rather complex undertaking because they usually need additional software (cross assembler, cross linker, target libraries, target include files, etc).
We recommend reading the crossgcc FAQ for information about building cross compilers.
If you have all the pieces available, then `make cross' should build a cross compiler. `make LANGUAGES="c c++" install' will install the cross compiler.
Note that if you're trying to build a cross compiler in a tree which includes binutils-2.8 in addition to EGCS, then you're going to need to make a couple minor tweaks so that the cross assembler, linker and nm utilities will be found.
binutils-2.8 builds those files as gas.new, ld.new and nm.new; EGCS gcc looks for them using gas-new, ld-new and nm-new, so you may have to arrange for any symlinks which point to <file>.new to be changed to <file>-new.
Unfortunately, improvements in tools that are widely used are sooner or later bound to break something. Sometimes, the code that breaks was wrong, and then that code should be fixed, even if it works for earlier versions of gcc or other compilers. The following problems with some releases of widely used packages have been identified:
There is a separate list of well-known bugs describing known deficiencies. Naturally we'd like that list to be of zero length.
To report a bug, see How to report bugs.
The FD_ZERO macro in (e.g.) libc-5.4.46 is incorrect. It uses invalid asm clobbers. The following rewrite by Ulrich Drepper <drepper@cygnus.com> should fix this for glibc 2.0:
# define __FD_ZERO(fdsetp) \
do { \
int __d0, __d1; \
__asm__ __volatile__ ("cld; rep; stosl" \
: "=m" (((__fd_mask *) \
(fdsetp))[__FDELT (__FD_SETSIZE)]), \
"=&c" (__d0), "=&D" (__d1) \
: "a" (0), "1" (sizeof (__fd_set) \
/ sizeof (__fd_mask)), \
"2" ((__fd_mask *) (fdsetp)) \
: "memory"); \
} while (0)
Apparently Octave 2.0.13 uses some C++ features which have been obsoleted and thus fails to build with egcs-1.1 and later. This patch to Octave should fix this.
This error means your system ran out of memory; this can happen for large files, particularly when optimizing. If you're getting this error you should consider trying to simplify your files or reducing the optimization level.
Note that using -pedantic or -Wreturn-type can cause an explosion in the amount of memory needed for template-heavy C++ code, such as code that uses STL. Also note that -Wall includes -Wreturn-type, so if you use -Wall you will need to specify -Wno-return-type to turn it off.
We make snapshots of the EGCS sources about once a week; there is no predetermined schedule. These snapshots are intended to give everyone access to work in progress. Any given snapshot may generate incorrect code or even fail to build.
If you plan on downloading and using snapshots, we highly recommend you subscribe to the EGCS mailing lists. See mailing lists on the main EGCS page for instructions on how to subscribe.
When using the diff files to update from older snapshots to newer snapshots, make sure to use "-E" and "-p" arguments to patch so that empty files are deleted and full pathnames are provided to patch. If your version of patch does not support "-E", you'll need to get a newer version. Also note that you may need autoconf, autoheader and various other programs if you use diff files to update from one snapshot to the next.
In order to make a specialization of a template function a friend of a (possibly template) class, you must explicitly state that the friend function is a template, by appending angle brackets to its name, and this template function must have been declared already. Here's an example:
template <typename T> class foo {
friend void bar(foo<T>);
}
The above declaration declares a non-template function named bar, so it must be explicitly defined for each specialization of foo. A template definition of bar won't do, because it is unrelated with the non-template declaration above. So you'd have to end up writing:
void bar(foo<int>) { /* ... */ }
void bar(foo<void>) { /* ... */ }
If you meant bar to be a template function, you should have forward-declared it as follows. Note that, since the template function declaration refers to the template class, the template class must be forward-declared too:
template <typename T>
class foo;
template <typename T>
void bar(foo<T>);
template <typename T>
class foo {
friend void bar<>(foo<T>);
};
template <typename T>
void bar(foo<T>) { /* ... */ }
In this case, the template argument list could be left empty, because it can be implicitly deduced from the function arguments, but the angle brackets must be present, otherwise the declaration will be taken as a non-template function. Furthermore, in some cases, you may have to explicitly specify the template arguments, to remove ambiguity.
An error in the last public comment draft of the ANSI/ISO C++ Standard and the fact that previous releases of gcc would accept such friend declarations as template declarations has led people to believe that the forward declaration was not necessary, but, according to the final version of the Standard, it is.
Many folks have been asking where to find libg++ for EGCS. First we should point out that few programs actually need libg++; most only need libstdc++/libio which are included in the EGCS distribution.
If you do need libg++ you can get a libg++ release that works with EGCS from ftp://egcs.cygnus.com/pub/egcs/infrastructure/. Note that the 2.8.2 snapshot pre-dates the 2.8.1.2 release.
If you're using diffs up dated from one snapshot to the next, or if you're using the CVS repository, you may need several additional programs to build EGCS.
These include, but are not necessarily limited to autoconf, automake, bison, and xgettext.
This is necessary because neither diff nor cvs keep timestamps correct. This causes problems for generated files as "make" may think those generated files are out of date and try to regenerate them.
An easy way to work around this problem is to use the egcs_update script in the contrib subdirectory of egcs, which handles this transparently without requiring installation of any additional tools.
When building from diffs or CVS or if you modified some sources, you may also need to obtain development versions of some GNU tools, as the production versions do not necessarily handle all features needed to rebuild egcs.
Autoconf is available from http://sourceware.cygnus.com/autoconf/; have a look at ftp://egcs.cygnus.com/pub/egcs/infrastructure/ for the other packages.
It is not uncommon to get CVS conflict messages for some generated files when updating your local sources from the CVS repository. Typically such conflicts occur with bison or autoconf generated files.
As long as you haven't been making modifications to the generated files or the generator files, it is safe to delete the offending file, then run cvs update again to get a new copy.
On some systems EGCS will produce dwarf debug records by default; however the gdb-4.16 release may not be able to read such debug records.
You can either use the argument "-gstabs" instead of "-g" or pick up a copy of gdb-4.17 to work around the problem.
The GNU Ada front-end is not currently supported by EGCS; however, it is possible to build the GNAT compiler with a little work.
First, retrieve the gnat-3.10p sources. The sources for the Ada front end and runtime all live in the "ada" subdirectory. Move that subdirectory to egcs/gcc/ada.
Second, apply the patch found in egcs/gcc/README.gnat.
Finally, rebuild per the GNAT build instructions.
The GNU Pascal front-end does work with egcs-1.1 It does not work with egcs-1.0.x and the main branch as of egcs-2.92.18. A tarball can be found at ftp://agnes.dida.physik.uni-essen.de/gnu-pascal/beta/.
It is possible to checkout specific snapshots with CVS or to check out the latest snapshot.
We use CVS tags to identify each snapshot we make. Snapshot tags have the form "egcs_ss_YYYYMMDD". In addition, the latest official snapshot always has the tag "egcs_latest_snapshot".
When building a shared library you may get an error message from the linker like `assert pure-text failed:' or `DP relative code in file'.
This kind of error occurs when you've failed to provide proper flags to gcc when linking the shared library.
You can get this error even if all the .o files for the shared library were compiled with the proper PIC option. When building a shared library, gcc will compile additional code to be included in the library. That additional code must also be compiled with the proper PIC option.
Adding the proper PIC option (-fpic or -fPIC) to the link line which creates the shared library will fix this problem on targets that support PIC in this manner. For example:
gcc -c -fPIC myfile.c gcc -shared -o libmyfile.so -fPIC myfile.o
If the standard assembler of your platform can't cope with the large symbol names that the default g++ name mangling mechanism produces, your best bet is to use GNU as, from the GNU binutils package.
Unfortunately, GNU as does not support all platforms supported by egcs, so you may have to use an experimental work-around: the -fsquangle option, that enables compression of symbol names.
Note that this option is still under development, and subject to change. Since it modifies the name mangling mechanism, you'll need to build libstdc++ and any other C++ libraries with this option enabled. Furthermore, if this option changes its behavior in the future, you'll have to rebuild them all again. :-(
This option can be enabled by default by initializing `flag_do_squangling' with `1' in `gcc/cp/decl2.c' (it is not initialized by default), then rebuilding egcs and any C++ libraries.
The current version of gperf (v2.7) does not support the -F flag which is used when building egcs from CVS sources. You will need to obtain a patch for gperf and rebuild the program; this patch is available at ftp://egcs.cygnus.com/pub/egcs/infrastructure/
Patches for other tools, particularly autoconf, may also be necessary if you're building from CVS sources. Please see the FAQ entry regarding these tools to determine if anything else is needed.
These patched utilities should only be required if you are building from CVS sources. For example, gperf is used to generate C code for a perfect hash function given an input file. Distributions of egcs already contain the generated C code, while the CVS sources will provide only the gperf input file. So gperf should only be necessary if you are building anything obtained from CVS.
Last modified: March 10, 1999