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Diffstat (limited to 'gnu')
| -rw-r--r-- | gnu/egcs/FAQ | 704 | ||||
| -rw-r--r-- | gnu/egcs/faq.html | 134 |
2 files changed, 318 insertions, 520 deletions
diff --git a/gnu/egcs/FAQ b/gnu/egcs/FAQ index d29e31fd9a4..1c43cac7624 100644 --- a/gnu/egcs/FAQ +++ b/gnu/egcs/FAQ @@ -1,71 +1,69 @@ GCC Frequently Asked Questions - + The latest version of this document is always available at [1]http://www.gnu.org/software/gcc/faq.html. - + This FAQ tries to answer specific questions concerning GCC. For - general information regarding C, C++, resp. Fortran please check the - [2]comp.lang.c FAQ, [3]comp.lang.c++ FAQ, [4]comp.std.c++ FAQ, and the - [5]Fortran Information page. + general information regarding C resp. C++, please check the + [2]comp.lang.c FAQ, [3]comp.lang.c++ FAQ, and the [4]comp.std.c++ FAQ. _________________________________________________________________ - + Questions - - 1. [6]General information - 1. [7]What is the relationship between GCC and EGCS - 2. [8]What is the relationship between GCC and Cygnus - 3. [9]What is an open development model? - 4. [10]How to report bugs - 5. [11]How do I get a bug fixed or a feature added? - 2. [12]Installation - 1. [13]Problems building the Fortran compiler - 2. [14]How to install multiple versions of GCC - 3. [15]Dynamic linker is unable to find GCC libraries - 4. [16]libstdc++/libio tests fail badly with --enable-shared - 5. [17]GCC can not find GNU as/GNU ld - 6. [18]cpp: Usage:... Error - 3. [19]Testsuite problems - 1. [20]Why is there no testsuite in GCC 2.95 - 2. [21]Unable to run the testsuite - 3. [22]How do I pass flags like -fnew-abi to the testsuite? - 4. [23]How can I run the test suite with multiple options? - 4. [24]Platform-specific issues - 1. [25]Problems with exception handling on x86 platforms - 2. [26]Problems with Invalid `asm' statements - 3. [27]Building Linux kernels - 4. [28]How do I compile X11 headers with g++ - 5. [29]How to build a cross compiler + + 1. [5]General information + 1. [6]What is the relationship between GCC and EGCS + 2. [7]What is the relationship between GCC and Cygnus + 3. [8]What is an open development model? + 4. [9]How to report bugs + 5. [10]How do I get a bug fixed or a feature added? + 2. [11]Installation + 1. [12]Problems building the Fortran compiler + 2. [13]How to install multiple versions of GCC + 3. [14]Dynamic linker is unable to find GCC libraries + 4. [15]libstdc++/libio tests fail badly with --enable-shared + 5. [16]GCC can not find GNU as/GNU ld + 6. [17]cpp: Usage:... Error + 3. [18]Testsuite problems + 1. [19]Why is there no testsuite in GCC 2.95 + 2. [20]Unable to run the testsuite + 3. [21]How do I pass flags like -fnew-abi to the testsuite? + 4. [22]How can I run the test suite with multiple options? + 4. [23]Platform-specific issues + 1. [24]Problems with exception handling on x86 platforms + 2. [25]Problems with Invalid `asm' statements + 3. [26]Building Linux kernels + 4. [27]How do I compile X11 headers with g++ + 5. [28]Signal 11 on GNU/Linux + 6. [29]How to build a cross compiler 5. [30]Bugs and Non-Bugs 1. [31]FD_ZERO macro 2. [32]Octave 2.0.13 does not compile - 3. [33]Why can't I initialize a static variable with stdin? - 4. [34]Why can't I use #if here? - 6. [35]Miscellaneous - 1. [36]Virtual memory exhausted - 2. [37]Snapshots, how, when, why - 3. [38]Friend Templates - 4. [39]Where to find libg++ - 5. [40]Why do I need autoconf, bison, xgettext, automake, etc - 6. [41]Problems debugging GCC code - 7. [42]Conflicts when using cvs update - 8. [43]Using GCC with GNAT/Ada - 9. [44]Using GCC with GNU Pascal - 10. [45]Using CVS to download snapshots - 11. [46]Why can't I build a shared library? - 12. [47]Dealing with spam on the lists - 13. [48]How to work around too long C++ symbol names? + 6. [33]Miscellaneous + 1. [34]Virtual memory exhausted + 2. [35]Snapshots, how, when, why + 3. [36]Friend Templates + 4. [37]Where to find libg++ + 5. [38]Why do I need autoconf, bison, xgettext, automake, etc + 6. [39]Problems debugging GCC code + 7. [40]Conflicts when using cvs update + 8. [41]Using GCC with GNAT/Ada + 9. [42]Using GCC with GNU Pascal + 10. [43]Using CVS to download snapshots + 11. [44]Why can't I build a shared library? + 12. [45]Dealing with spam on the lists + 13. [46]How to work around too long C++ symbol names? (-fsquangle) - 14. [49]When building from CVS sources, I see 'gperf: invalid + 14. [47]When building from CVS sources, I see 'gperf: invalid option -- F', even with the most current version of gperf. - 15. [50]When building C++, the linker says my constructors, + 15. [48]When building C++, the linker says my constructors, destructors or virtual tables are undefined, but I defined them - 16. [51]What is libstdc++-v3 and how can I use it with g++? + 16. [49]What is libstdc++-v3 and how can I use it with g++? _________________________________________________________________ - + General information - + What is the relationship between GCC and EGCS In 1990/1991 gcc version 1 had reached a point of stability. For the @@ -73,131 +71,130 @@ What is the relationship between GCC and EGCS in its design that would be difficult to resolve, so a major effort was made to resolve those limitiations 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 wanted to make with the EGCS project when it was formed in 1997. - + In April 1999 the Free Software Foundation officially halted development on the gcc2 compiler and appointed the EGCS project as the official GCC maintainers. - + We are in the process of merging GCC and EGCS, which will take some time. The net result will be a single project which will carry forward - GCC development under the ultimate control of the [52]GCC Steering + GCC development under the ultimate control of the [50]GCC Steering Committee. _________________________________________________________________ - + What is the relationship between GCC and Cygnus It is a common mis-conception that Cygnus controls either directly or indirectly GCC. - + While Cygnus does donate hardware, network connections, code and developer time to GCC development, Cygnus does not control GCC. - - Overall control of GCC is in the hands of the [53]GCC Steering + + Overall control of GCC is in the hands of the [51]GCC Steering Committee which includes people from a variety of different organizations and backgrounds. The purpose of the steering committee is to make decisions in the best interest of GCC and to help ensure that no individual or company has control over the project. - + To summarize, Cygnus contributes to GCCproject, but does not exert a controlling influence over GCC. _________________________________________________________________ - + What is an open development model? - With GCC, we are going to try a bazaar style[54][1] approach to its + With GCC, we are going to try a bazaar style[52][1] approach to its development: We make 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. - + In addition to weekly snapshots of the GCC development sources, we have the sources readable from a CVS server by anyone. Furthermore we are using remote CVS to allow remote maintainers write access to the sources. - + 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. - + GCC 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 GCC, 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 ``[55]The Cathedral and the Bazaar''. The paper is a useful + called ``[53]The Cathedral and the Bazaar''. The paper is a useful starting point for discussions. _________________________________________________________________ - + How to report bugs - There are complete instructions in the [56]gcc info manual, section + There are complete instructions in the [54]gcc info manual, section Bugs. The manual can also 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 [57]BUGS included with the GCC source + "(gcc)Bugs"'. Or see the file [55]BUGS included with the GCC source code. - + Before you report a bug for the _C++ compiler_, please check the - [58]list of well-known bugs. If you want to report a bug with _egcs - 1.0.x_ or _egcs 1.1.x_, we strongly recommend upgrading to the current - release first. - - In short, if GCC says Internal compiler error (or any other error that + [56]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 gcc 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 [59]gcc-bugs@gcc.gnu.org or [60]bug-gcc@gnu.org + bug report to [57]gcc-bugs@gcc.gnu.org or [58]bug-gcc@gnu.org including: * The GCC version * The system type * All options you passed to the compiler * Preprocessed output of the source file that caused the compiler error - + 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 (extension .i for C or .ii for C++) will be large, so please compress the resulting file with one of the popular compression programs such as bzip2, gzip, zip, pkzip or compress (in decreasing order of preference). Use maximum compression (-9) if available. Please include the compressed CPP output in your bug report. - + Since we're supposed to be able to re-create the assembly output (extension .s), you usually don't have to include it in the bug report, although you may want to post parts of it to point out assembly code you consider to be wrong. - + Whether to use MIME attachments or uuencode is up to you. In any case, make sure the compiler command line, version and error output are in plain text, so that we don't have to decode the bug report in order to tell who should take care of it. A meaningful subject indicating language and platform also helps. - + The gcc 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 @@ -209,7 +206,7 @@ How to report bugs output in multiple files (using split, for example) and post them in separate messages, but we prefer to have self-contained bug reports in single messages. - + If you fail to supply enough information for a bug report to be reproduced, someone will probably ask you to post additional information (or just ignore your bug report, if they're in a bad day, @@ -220,7 +217,7 @@ How to report bugs supplied in the incomplete bug report (including the preprocessor output), so that the new bug report is self-contained. _________________________________________________________________ - + How do I get a bug fixed or a feature added? There are lots of ways to get something fixed. The list below may be @@ -240,51 +237,51 @@ How do I get a bug fixed or a feature added? commercial support organization since the people who read gcc-bugs, if they choose to help you, will be volunteering their time. This alternative will work best if you follow the directions - on [61]submitting bugreports. + on [59]submitting bugreports. * Fix it yourself. This alternative will probably bring results, if you work hard enough, but will probably take a lot of time, and, depending on the quality of your work and the perceived benefits of your changes, your code may or may not ever make it into an official release of GCC. _________________________________________________________________ - + Installation - + Problems building the Fortran compiler 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 GCC, 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. _________________________________________________________________ - + How to install multiple versions of gcc It may be desirable to install multiple versions of the compiler 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 latest compiler and available in /usr/local/bin; also assume that you want "gcc2" to be the older gcc2 compiler and also available in /usr/local/bin. - + The easiest way to do this is to configure the new GCC with --prefix=/usr/local/gcc and the older gcc2 with --prefix=/usr/local/gcc2. Build and install both compilers. Then make a symlink from /usr/local/bin/gcc to /usr/local/gcc/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 @@ -303,46 +300,46 @@ How to install multiple versions of gcc /usr/local/gcc/bin with names prefixed by "new-". You can use --program-transform-name if you have multiple versions of GCC, and wish to be sure about which version you are invoking. - + If you use --prefix, GCC may have difficulty locating a GNU assembler - or linker on your system, [62]GCC can not find GNU as/GNU ld explains + or linker on your system, [60]GCC can not find GNU as/GNU ld explains how to deal with this. _________________________________________________________________ - + Dynamic linker is unable to find GCC libraries 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 GCC. - + 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. - + However, if you feel you really need such an option to be passed automatically to the linker, you may add it to the gcc specs file. This file can be found in the same directory that contains cc1 (run gcc -print-prog-name=cc1 to find it). You may add linker flags such as -R or -rpath, depending on platform and linker, to the *link or *lib specs. - + Another alterative is to install a wrapper script around gcc, g++ or ld that adds the appropriate directory to the environment variable LD_RUN_PATH or equivalent (again, it's platform-dependent). - + Yet another option, that works on a few platforms, is to hard-code the full pathname of the library into its soname. This can only be accomplished by modifying the appropriate .ml file within @@ -350,7 +347,7 @@ Dynamic linker is unable to find GCC libraries so that $(libdir)/ appears just before the library name in -soname or -h options. _________________________________________________________________ - + GCC can not find GNU as/GNU ld GCC searches the PATH for an assembler and a loader, but it only does @@ -359,19 +356,19 @@ GCC can not find GNU as/GNU ld which the system asembler and loader can be found, you may have to take one of the following actions to arrange that gcc uses the GNU versions of those programs. - + To ensure that GCC finds the GNU assembler (the GNU loader), which are - required by [63]some configurations, you should configure these with + required by [61]some configurations, you should configure these with the same --prefix option as you used for GCC. Then build & install GNU as (GNU ld) and proceed with building GCC. - + 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. If such links do not exist while you're compiling GCC, you may have to create them in the build directories too, within the gcc directory _and_ in all the gcc/stage* subdirectories. - + GCC 2.95 allows 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'. GCC will try to use these pathnames before @@ -382,7 +379,7 @@ GCC can not find GNU as/GNU ld you to override the search path for assembler and linker with command-line options -B/path/ if the specified filenames exist. _________________________________________________________________ - + cpp: Usage:... Error If you get an error like this when building GCC (particularly when @@ -396,36 +393,36 @@ cpp: Usage:... Error '.', 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. _________________________________________________________________ - + Testsuite problems - + Why is there no testsuite in GCC 2.95 The GCC testsuite is not included in the GCC 2.95 release due to the uncertain copyright status of some tests. - + The GCC team will be reviewing the entire testsuite to find and remove any tests with uncertain copyright status. Once those tests are removed from the testsuite, the testsuite as a whole will be copyrighted under the terms of the GPL and included in future GCC releases. - + It is believed that only a few tests have uncertain copyright status and thus only a few tests will need to be removed from the testsuite. _________________________________________________________________ - + Unable to run the testsuite If you get a message about unable to find "standard.exp" when trying to run the GCC testsuites, then your dejagnu is too old to run the GCC tests. You will need to get a newer version of dejagnu; we've made a - [64]dejagnu snapshot available until a new version of dejagnu can be + [62]dejagnu snapshot available until a new version of dejagnu can be released. _________________________________________________________________ - + How do I pass flags like -fnew-abi to the testsuite? If you invoke runtest directly, you can use the --tool_opts option, @@ -436,7 +433,7 @@ How do I pass flags like -fnew-abi to the testsuite? e.g: make RUNTESTFLAGS='--tool_opts "-fnew-abi -fno-honor-std"' check-g++ _________________________________________________________________ - + How can I run the test suite with multiple options? If you invoke runtest directly, you can use the --target_board option, @@ -449,41 +446,41 @@ How can I run the test suite with multiple options? 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. _________________________________________________________________ - + Platform-specific issues - - Please read the [65]host/target specific installation notes, too. - + + Please read the [63]host/target specific installation notes, too. + Problems with exception handling on x86 platforms 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 [66]ftp://tsx-11.mit.edu/pub/linux/packages/GCC/. The + available at [64]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. _________________________________________________________________ - + Problems with invalid `asm' statements Previous releases of GCC (for example, GCC 2.7.2 or EGCS 1.1.2) 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 [67]bug + manual (Using and Porting GCC, section Extended Asm, see the [65]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 @@ -494,16 +491,16 @@ Problems with invalid `asm' statements 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 [68]Linux + Unfortunately, a lot of existing software, for example the [66]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 @@ -528,7 +525,7 @@ __delay (int loops) 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 GCC 2.95 as well as for previous versions of GCC and EGCS: extern __inline__ void @@ -546,7 +543,7 @@ __delay (int loops) unused. Normally asm constructs with only unused output operands may be removed by gcc, unless marked volatile as above. _________________________________________________________________ - + Building Linux kernels The linux kernel violates certain aliasing rules specified in the @@ -555,16 +552,16 @@ Building Linux kernels will produce malfunctioning kernels. To work around this problem, the flag -fno-strict-aliasing must be added to the CFLAGS variable in the main kernel Makefile. - + If you try to build a 2.0.x kernel for Intel machines with any compiler other than GCC 2.7.2, 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 [69]patch which fixes some of the asm problems. - You will also want to change asm constructs to [70]avoid clobbering + be interested in this [67]patch which fixes some of the asm problems. + You will also want to change asm constructs to [68]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 @@ -573,7 +570,7 @@ Building Linux kernels 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 @@ -582,63 +579,63 @@ Building Linux kernels 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. _________________________________________________________________ - + How do I compile X11 headers with g++ When compiling X11 headers with a GCC 2.95 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. _________________________________________________________________ - + How to build a cross compiler 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 [71]crossgcc FAQ for information about + + We recommend reading the [69]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 GCC, 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; 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. _________________________________________________________________ - + Bugs and Non-Bugs - + 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 [72]list of well-known bugs describing known + + There is a separate [70]list of well-known bugs describing known deficiencies. Naturally we'd like that list to be of zero length. - - To report a bug, see [73]How to report bugs. + + To report a bug, see [71]How to report bugs. _________________________________________________________________ - + FD_ZERO macro The FD_ZERO macro in (e.g.) libc-5.4.46 is incorrect. It uses - [74]invalid asm clobbers. The following rewrite by Ulrich Drepper + [72]invalid asm clobbers. The following rewrite by Ulrich Drepper <drepper@cygnus.com> should fix this for glibc 2.0: # define __FD_ZERO(fdsetp) \ do { \ @@ -653,132 +650,44 @@ FD_ZERO macro : "memory"); \ } while (0) _________________________________________________________________ - + Octave 2.0.13 does not compile 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 - [75]patch to Octave should fix this. - + [73]patch to Octave should fix this. + Octave 2.0.13.96, a test release, has been compiled without patches by egcs 1.1.2. It is available at - [76]ftp://ftp.che.wisc.edu/pub/octave/test-releases/. - _________________________________________________________________ - -Why can't I initialize a static variable with stdin? - - This has nothing to do with gcc, but people ask us about it a lot. - Code like this: - #include <stdio.h> - - FILE *yyin = stdin; - - will not compile with GNU libc (Linux libc6), because stdin is not a - constant. This was done deliberately, in order for there to be no - limit on the number of open FILE objects. It is surprising for people - used to traditional Unix C libraries, but it is permitted by the C - standard. - - This construct commonly occurs in code generated by old versions of - lex or yacc. We suggest you try regenerating the parser with a current - version of flex or bison, respectively. In your own code, the - appropriate fix is to move the initialization to the beginning of - main. - - There is a common misconception that the GCC developers are - responsible for GNU libc. These are in fact two entirely separate - projects. The appropriate place to ask questions relating to GNU libc - is [77]libc-alpha@sourceware.cygnus.com. + [74]ftp://ftp.che.wisc.edu/pub/octave/test-releases/. _________________________________________________________________ - -Why can't I use #if here? - - Let me guess... you wrote code that looks something like this: - memcpy(dest, src, -#ifdef PLATFORM1 - 12 -#else - 24 -#endif - ); - - and you got a whole pile of error messages: -test.c:11: warning: preprocessing directive not recognized within macro arg -test.c:11: warning: preprocessing directive not recognized within macro arg -test.c:11: warning: preprocessing directive not recognized within macro arg -test.c: In function `foo': -test.c:6: undefined or invalid # directive -test.c:8: undefined or invalid # directive -test.c:9: parse error before `24' -test.c:10: undefined or invalid # directive -test.c:11: parse error before `#' - - The problem, simply put, is that GCC's preprocessor does not allow you - to put #ifdef (or any other directive) inside the arguments of a - macro. Your C library's string.h happens to define memcpy as a macro - - this is perfectly legitimate. The code therefore will not compile. - - We have two good reasons for not allowing directives inside macro - arguments. First, it is not portable. It is "undefined behavior" - according to the C standard; that means different compilers will do - different things with it. Some will give you errors. Some will dump - core. Some will silently mangle your code - you could get the - equivalent of - memcpy(dest, src, 1224); - - from the above example. A very few might do what you expected it to. - We therefore feel it is most useful for GCC to reject this construct - immediately so that it is found and fixed. - - Second, it is extraordinarily difficult to implement the preprocessor - such that it does what you would expect for every possible directive - found inside a macro argument. The best example is perhaps -#define foo(arg) ... arg ... -foo(blah -#undef foo -blah) - - which is impossible to implement in portable C without leaking memory. - Allowing only a subset of directives would be confusing. - - It is always possible to rewrite code which uses conditionals inside - macros so that it doesn't. You could write the above example -#ifdef PLATFORM1 - memcpy(dest, src, 12); -#else - memcpy(dest, src, 24); -#endif - - This is a bit more typing, but I personally think it's better style in - addition to being more portable. - _________________________________________________________________ - + Miscellaneous - + Virtual memory exhausted error 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. _________________________________________________________________ - + Snapshots, how, when, why We make snapshots of the GCC 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 GCC mailing lists. See [78]mailing lists on the + you subscribe to the GCC mailing lists. See [75]mailing lists on the main GCC 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 @@ -787,7 +696,7 @@ Snapshots, how, when, why various other programs if you use diff files to update from one snapshot to the next. _________________________________________________________________ - + Friend Templates In order to make a specialization of a template function a friend of a @@ -830,161 +739,159 @@ void bar(foo<T>) { /* ... */ } 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. _________________________________________________________________ - + Where to find libg++ Many folks have been asking where to find libg++ for GCC. First we should point out that few programs actually need libg++; most only need libstdc++/libio which are included in the GCC distribution. - + If you do need libg++ you can get a libg++ release that works with GCC - from [79]ftp://egcs.cygnus.com/pub/egcs/infrastructure/. Note that the + from [76]ftp://egcs.cygnus.com/pub/egcs/infrastructure/. Note that the 2.8.2 snapshot pre-dates the 2.8.1.2 release. _________________________________________________________________ - + autoconf, bison, xgettext, automake, etc 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 GCC. - + 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 gcc_update - script in the contrib subdirectory of GCC, which handles this + + 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. - (Note: Up to and including GCC 2.95 this script was called egcs_update - .) - + 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 GCC. - - Autoconf is available from [80]http://sourceware.cygnus.com/autoconf/; - have a look at [81]ftp://egcs.cygnus.com/pub/egcs/infrastructure/ for + rebuild egcs. + + Autoconf is available from [77]http://sourceware.cygnus.com/autoconf/; + have a look at [78]ftp://egcs.cygnus.com/pub/egcs/infrastructure/ for the other packages. _________________________________________________________________ - + Conflicts when using cvs update 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. _________________________________________________________________ - + Problems debugging GCC code On some systems GCC 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. _________________________________________________________________ - + Using GCC with GNAT/Ada The GNU Ada front-end is not currently supported by GCC; 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. _________________________________________________________________ - + Using GCC with GNU Pascal - The [82]GNU Pascal front-end does work with EGCS 1.1 It does not work + The [79]GNU Pascal front-end does work with EGCS 1.1 It does not work with EGCS 1.0.x and the main branch of the CVS repository. A tarball can be found at - [83]ftp://agnes.dida.physik.uni-essen.de/gnu-pascal/beta/. + [80]ftp://agnes.dida.physik.uni-essen.de/gnu-pascal/beta/. _________________________________________________________________ - + Using CVS to download snapshots 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 "gcc_latest_snapshot". + always has the tag "egcs_latest_snapshot". _________________________________________________________________ - + Why can't I build a shared library? 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 _________________________________________________________________ - + How to work around too long C++ symbol names? (-fsquangle) 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. _________________________________________________________________ - + When building from CVS sources, I see 'gperf: invalid option -- F', even with the most current version of gperf. 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 - [84]ftp://egcs.cygnus.com/pub/egcs/infrastructure/ - + [81]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 [85]FAQ entry + if you're building from CVS sources. Please see the [82]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 @@ -992,7 +899,7 @@ the most current version of gperf. provide only the gperf input file. So gperf should only be necessary if you are building anything obtained from CVS. _________________________________________________________________ - + When building C++, the linker says my constructors, destructors or virtual tables are undefined, but I defined them @@ -1003,40 +910,40 @@ tables are undefined, but I defined them constructors, the assignment operator, the destructor and the virtual table of a class in the translation unit that defines its first such non-inline method. - + Therefore, if you fail to define this particular method, the linker may complain about the lack of definitions for apparently unrelated symbols. Unfortunately, in order to improve this error message, it might be necessary to change the linker, and this can't always be done. - + The solution is to ensure that all virtual methods that are not pure are defined. Note that a destructor must be defined even if it is declared pure-virtual [class.dtor]/7. _________________________________________________________________ - + What is libstdc++-v3 and how can I use it with g++? - From the [86]libstdc++-FAQ: "The EGCS Standard C++ Library v3, or + From the [83]libstdc++-FAQ: "The EGCS Standard C++ Library v3, or libstdc++-2.90.x, is an ongoing project to implement the ISO 14882 Standard C++ library as described in chapters 17 through 27 and annex D." - + At the moment the libstdc++-v3 is no "drop in replacement" for GCC's libstdc++. The best way to use it is as follows: 1. Build and install GCC 2. Build and install libstdc++-v3 3. Use compiler flags to use the new libstdc++ - + Please note that the libstdc++-v3 is not yet complete and should only be used by experienced programmers. - - For more information please refer to the [87]libstdc++-v3 homepage + + For more information please refer to the [84]libstdc++-v3 homepage _________________________________________________________________ - - [88]Return to the GCC home page - - _Last modified: October 19, 1999_ + + [85]Return to the GCC home page + + _Last modified: August 15, 1999_ References @@ -1044,87 +951,84 @@ References 2. http://www.eskimo.com/~scs/C-faq/top.html 3. http://www.cerfnet.com/~mpcline/On-Line-C++-FAQs/ 4. http://reality.sgi.com/austern_mti/std-c++/faq.html - 5. http://www.fortran.com/fortran/info.html - 6. http://gcc.gnu.org/faq.html#general - 7. http://gcc.gnu.org/faq.html#gcc - 8. http://gcc.gnu.org/faq.html#cygnus - 9. http://gcc.gnu.org/faq.html#open-development - 10. http://gcc.gnu.org/faq.html#bugreport - 11. http://gcc.gnu.org/faq.html#support - 12. http://gcc.gnu.org/faq.html#installation - 13. http://gcc.gnu.org/faq.html#fortran - 14. http://gcc.gnu.org/faq.html#multiple - 15. http://gcc.gnu.org/faq.html#rpath - 16. http://gcc.gnu.org/faq.html#rpath - 17. http://gcc.gnu.org/faq.html#gas - 18. http://gcc.gnu.org/faq.html#environ - 19. http://gcc.gnu.org/faq.html#testsuite - 20. http://gcc.gnu.org/faq.html#testsuite - 21. http://gcc.gnu.org/faq.html#dejagnu - 22. http://gcc.gnu.org/faq.html#testoptions - 23. http://gcc.gnu.org/faq.html#multipletests - 24. http://gcc.gnu.org/faq.html#platform - 25. http://gcc.gnu.org/faq.html#x86eh - 26. http://gcc.gnu.org/faq.html#asmclobber - 27. http://gcc.gnu.org/faq.html#linuxkernel - 28. http://gcc.gnu.org/faq.html#X11R6 - 29. http://gcc.gnu.org/faq.html#cross - 30. http://gcc.gnu.org/faq.html#bugs - 31. http://gcc.gnu.org/faq.html#fdzero - 32. http://gcc.gnu.org/faq.html#octave - 33. http://gcc.gnu.org/faq.html#stdin - 34. http://gcc.gnu.org/faq.html#macarg - 35. http://gcc.gnu.org/faq.html#misc - 36. http://gcc.gnu.org/faq.html#memexhausted - 37. http://gcc.gnu.org/faq.html#snapshot - 38. http://gcc.gnu.org/faq.html#friend - 39. http://gcc.gnu.org/faq.html#libg++ - 40. http://gcc.gnu.org/faq.html#generated_files - 41. http://gcc.gnu.org/faq.html#gdb - 42. http://gcc.gnu.org/faq.html#conflicts - 43. http://gcc.gnu.org/faq.html#gnat - 44. http://gcc.gnu.org/faq.html#gpc - 45. http://gcc.gnu.org/faq.html#cvssnapshots - 46. http://gcc.gnu.org/faq.html#picflag-needed - 47. http://gcc.gnu.org/spam.html - 48. http://gcc.gnu.org/faq.html#squangle - 49. http://gcc.gnu.org/faq.html#gperf - 50. http://gcc.gnu.org/faq.html#vtables - 51. http://gcc.gnu.org/faq.html#libstdc++ - 52. http://gcc.gnu.org/steering.html - 53. http://gcc.gnu.org/steering.html - 54. http://gcc.gnu.org/faq.html#cathedral-vs-bazaar - 55. http://locke.ccil.org/~esr/writings/cathedral.html - 56. http://gcc.gnu.org/onlinedocs/ - 57. http://egcs.cygnus.com/cgi-bin/cvsweb.cgi/~checkout~/egcs/gcc/BUGS?content-type=text/plain&only_with_tag=HEAD - 58. http://gcc.gnu.org/bugs.html - 59. mailto:gcc-bugs@gcc.gnu.org - 60. mailto:bug-gcc@gnu.org - 61. http://gcc.gnu.org/faq.html#bugreport - 62. http://gcc.gnu.org/faq.html#gas - 63. http://gcc.gnu.org/install/specific.html - 64. ftp://egcs.cygnus.com/pub/egcs/infrastructure/dejagnu-19981026.tar.gz - 65. http://gcc.gnu.org/install/specific.html - 66. ftp://tsx-11.mit.edu/pub/linux/packages/GCC/ - 67. http://gcc.gnu.org/faq.html#bugreport - 68. http://gcc.gnu.org/faq.html#linuxkernel - 69. http://www.suse.de/~florian/kernel+egcs.html - 70. http://gcc.gnu.org/faq.html#asmclobber - 71. http://www.objsw.com/CrossGCC/ - 72. http://gcc.gnu.org/bugs.html - 73. http://gcc.gnu.org/faq.html#bugreport - 74. http://gcc.gnu.org/faq.html#asmclobber - 75. http://www.che.wisc.edu/octave/mailing-lists/bug-octave/1998/270 - 76. ftp://ftp.che.wisc.edu/pub/octave/test-releases/ - 77. mailto:libc-alpha@sourceware.cygnus.com - 78. http://gcc.gnu.org/index.html#mailinglists - 79. ftp://egcs.cygnus.com/pub/egcs/infrastructure/ - 80. http://sourceware.cygnus.com/autoconf/ - 81. ftp://egcs.cygnus.com/pub/egcs/infrastructure/ - 82. http://home.pages.de/~GNU-Pascal/ - 83. ftp://agnes.dida.physik.uni-essen.de/gnu-pascal/beta/ - 84. ftp://egcs.cygnus.com/pub/egcs/infrastructure - 85. http://gcc.gnu.org/faq.html#generated_files - 86. http://sourceware.cygnus.com/libstdc++/faq/ - 87. http://sourceware.cygnus.com/libstdc++/ - 88. http://gcc.gnu.org/index.html + 5. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#general + 6. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#gcc + 7. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#cygnus + 8. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#open-development + 9. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#bugreport + 10. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#support + 11. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#installation + 12. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#fortran + 13. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#multiple + 14. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#rpath + 15. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#rpath + 16. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#gas + 17. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#environ + 18. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#testsuite + 19. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#testsuite + 20. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#dejagnu + 21. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#testoptions + 22. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#multipletests + 23. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#platform + 24. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#x86eh + 25. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#asmclobber + 26. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#linuxkernel + 27. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#X11R6 + 28. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#sig11 + 29. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#cross + 30. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#bugs + 31. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#fdzero + 32. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#octave + 33. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#misc + 34. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#memexhausted + 35. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#snapshot + 36. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#friend + 37. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#libg++ + 38. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#generated_files + 39. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#gdb + 40. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#conflicts + 41. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#gnat + 42. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#gpc + 43. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#cvssnapshots + 44. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#picflag-needed + 45. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/spam.html + 46. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#squangle + 47. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#gperf + 48. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#vtables + 49. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#libstdc++ + 50. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/steering.html + 51. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/steering.html + 52. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#cathedral-vs-bazaar + 53. http://locke.ccil.org/~esr/writings/cathedral.html + 54. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/onlinedocs/ + 55. http://egcs.cygnus.com/cgi-bin/cvsweb.cgi/~checkout~/egcs/gcc/BUGS?content-type=text/plain&only_with_tag=HEAD + 56. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/bugs.html + 57. mailto:gcc-bugs@gcc.gnu.org + 58. mailto:bug-gcc@gnu.org + 59. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#bugreport + 60. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#gas + 61. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/install/specific.html + 62. ftp://egcs.cygnus.com/pub/egcs/infrastructure/dejagnu-19981026.tar.gz + 63. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/install/specific.html + 64. ftp://tsx-11.mit.edu/pub/linux/packages/GCC/ + 65. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#bugreport + 66. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#linuxkernel + 67. http://www.suse.de/~florian/kernel+egcs.html + 68. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#asmclobber + 69. http://www.objsw.com/CrossGCC/ + 70. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/bugs.html + 71. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#bugreport + 72. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#asmclobber + 73. http://www.che.wisc.edu/octave/mailing-lists/bug-octave/1998/270 + 74. ftp://ftp.che.wisc.edu/pub/octave/test-releases/ + 75. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/index.html#mailinglists + 76. ftp://egcs.cygnus.com/pub/egcs/infrastructure/ + 77. http://sourceware.cygnus.com/autoconf/ + 78. ftp://egcs.cygnus.com/pub/egcs/infrastructure/ + 79. http://home.pages.de/~GNU-Pascal/ + 80. ftp://agnes.dida.physik.uni-essen.de/gnu-pascal/beta/ + 81. ftp://egcs.cygnus.com/pub/egcs/infrastructure + 82. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/faq.html#generated_files + 83. http://sourceware.cygnus.com/libstdc++/faq/ + 84. http://sourceware.cygnus.com/libstdc++/ + 85. file://localhost/egcs/omelette/tmp/12663/gcc-2.95.1/index.html diff --git a/gnu/egcs/faq.html b/gnu/egcs/faq.html index 8b5c857ba1c..61be1809567 100644 --- a/gnu/egcs/faq.html +++ b/gnu/egcs/faq.html @@ -10,14 +10,12 @@ http://www.gnu.org/software/gcc/faq.html">http://www.gnu.org/software/gcc/faq.html</a>.</p> <p>This FAQ tries to answer specific questions concerning GCC. For -general information regarding C, C++, resp. Fortran please check the +general information regarding C resp. C++, please check the <a href="http://www.eskimo.com/~scs/C-faq/top.html">comp.lang.c FAQ</a>, <a href="http://www.cerfnet.com/~mpcline/On-Line-C++-FAQs/"> -comp.lang.c++ FAQ</a>, +comp.lang.c++ FAQ</a>, and the <a href="http://reality.sgi.com/austern_mti/std-c++/faq.html"> -comp.std.c++ FAQ</a>, and the <a -href="http://www.fortran.com/fortran/info.html">Fortran Information -page</a>.</p> +comp.std.c++ FAQ</a>.</p> <hr> @@ -57,6 +55,7 @@ page</a>.</p> <li><a href="#asmclobber">Problems with <tt>Invalid `asm' statement</tt>s</a></li> <li><a href="#linuxkernel">Building Linux kernels</a> </li> <li><a href="#X11R6">How do I compile X11 headers with g++</a> </li> + <li><a href="#sig11">Signal 11 on GNU/Linux</a></li> <li><a href="#cross">How to build a cross compiler</a></li> </ol></li> @@ -64,8 +63,6 @@ page</a>.</p> <ol> <li><a href="#fdzero">FD_ZERO macro</a></li> <li><a href="#octave">Octave 2.0.13 does not compile</a></li> - <li><a href="#stdin">Why can't I initialize a static variable with <tt>stdin</tt>?</a></li> - <li><a href="#macarg">Why can't I use #if here?</a></li> </ol></li> <li><a href="#misc">Miscellaneous</a> @@ -197,11 +194,11 @@ the GNU <tt>info</tt> program is installed on your system by `<tt>info --node included with the GCC source code.</p> <p>Before you report a bug for the <em>C++ compiler</em>, please check -the <a href="bugs.html">list of well-known bugs</a>. If you want to -report a bug with <em>egcs 1.0.x</em> or <em>egcs 1.1.x</em>, we -strongly recommend upgrading to the current release first.</p> +the <a href="bugs.html">list of well-known bugs</a>. If you +want to report a bug with <em>egcs 1.0.x</em>, we recommend upgrading +to the current release first.</p> -<p>In short, if GCC says <tt>Internal compiler error</tt> (or any +<p>In short, if gcc says <tt>Internal compiler error</tt> (or any other error that you'd like us to be able to reproduce, for that matter), please mail a bug report to <a href="mailto:gcc-bugs@gcc.gnu.org">gcc-bugs@gcc.gnu.org</a> or @@ -742,107 +739,6 @@ egcs 1.1.2. It is available at <a href="ftp://ftp.che.wisc.edu/pub/octave/test-releases/"> ftp://ftp.che.wisc.edu/pub/octave/test-releases/</a>.</p> -<hr> -<h2><a name="stdin">Why can't I initialize a static variable with <tt>stdin</tt>?</a></h2> - -<p>This has nothing to do with gcc, but people ask us about it a -lot. Code like this:</p> - -<pre> - #include <stdio.h> - - FILE *yyin = stdin; -</pre> - -<p>will not compile with GNU libc (Linux libc6), because -<tt>stdin</tt> is not a constant. This was done deliberately, in -order for there to be no limit on the number of open FILE objects. It -is surprising for people used to traditional Unix C libraries, but it -is permitted by the C standard.</p> - -<p>This construct commonly occurs in code generated by old versions of -lex or yacc. We suggest you try regenerating the parser with a -current version of flex or bison, respectively. In your own code, the -appropriate fix is to move the initialization to the beginning of -main.</p> - -<p>There is a common misconception that the GCC developers are -responsible for GNU libc. These are in fact two entirely separate -projects. The appropriate place to ask questions relating to GNU libc -is <a href="mailto:libc-alpha@sourceware.cygnus.com">libc-alpha@sourceware.cygnus.com</a>. -</p> - -<hr> -<h2><a name="macarg">Why can't I use #if here?</a></h2> - -<p>Let me guess... you wrote code that looks something like this:</p> -<pre> - memcpy(dest, src, -#ifdef PLATFORM1 - 12 -#else - 24 -#endif - ); -</pre> -<p>and you got a whole pile of error messages:</p> -<pre> -test.c:11: warning: preprocessing directive not recognized within macro arg -test.c:11: warning: preprocessing directive not recognized within macro arg -test.c:11: warning: preprocessing directive not recognized within macro arg -test.c: In function `foo': -test.c:6: undefined or invalid # directive -test.c:8: undefined or invalid # directive -test.c:9: parse error before `24' -test.c:10: undefined or invalid # directive -test.c:11: parse error before `#' -</pre> - -<p>The problem, simply put, is that GCC's preprocessor does not allow -you to put #ifdef (or any other directive) inside the arguments of a -macro. Your C library's <tt>string.h</tt> happens to define -<tt>memcpy</tt> as a macro - this is perfectly legitimate. The code -therefore will not compile.</p> - -<p>We have two good reasons for not allowing directives inside -macro arguments. First, it is not portable. It is "undefined -behavior" according to the C standard; that means different -compilers will do different things with it. Some will give you -errors. Some will dump core. Some will silently mangle your code - -you could get the equivalent of</p> -<pre> - memcpy(dest, src, 1224); -</pre> -<p>from the above example. A very few might do what you expected it -to. We therefore feel it is most useful for GCC to reject this -construct immediately so that it is found and fixed.</p> - -<p>Second, it is extraordinarily difficult to implement the -preprocessor such that it does what you would expect for every -possible directive found inside a macro argument. The best example is -perhaps</p> -<pre> -#define foo(arg) ... arg ... -foo(blah -#undef foo -blah) -</pre> -<p>which is <emph>impossible</emph> to implement in portable C without -leaking memory. Allowing only a subset of directives would be -confusing.</p> - -<p>It is always possible to rewrite code which uses conditionals -inside macros so that it doesn't. You could write the above -example</p> -<pre> -#ifdef PLATFORM1 - memcpy(dest, src, 12); -#else - memcpy(dest, src, 24); -#endif -</pre> -<p>This is a bit more typing, but I personally think it's better style -in addition to being more portable. <hr> <a name="misc"></a> @@ -959,17 +855,15 @@ bison, and xgettext.</p> correct. This causes problems for generated files as "make" may think those generated files are out of date and try to regenerate them.</p> -<p>An easy way to work around this problem is to use the <CODE>gcc_update -</CODE> script in the contrib subdirectory of GCC, which handles this -transparently without requiring installation of any additional tools. -(Note: Up to and including GCC 2.95 this script was called <CODE>egcs_update -</CODE>.)</p> +<p>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.</p> <p>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 GCC.</p> +to rebuild egcs.</p> <p>Autoconf is available from <a href="http://sourceware.cygnus.com/autoconf/"> @@ -1028,7 +922,7 @@ out the latest snapshot.</p> <p>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 "gcc_latest_snapshot".</p> +has the tag "egcs_latest_snapshot".</p> <hr> @@ -1139,7 +1033,7 @@ is declared pure-virtual [class.dtor]/7.</p> <hr> <p><a href="index.html">Return to the GCC home page</a></p> -<p><i>Last modified: October 19, 1999</i></p> +<p><i>Last modified: August 15, 1999</i></p> </body> </html> |