Subversion Repositories openrisc_2011-10-31

                                   GCC Bugs

   The   latest   version   of  this  document  is  always  available  at

   [1]http://gcc.gnu.org/bugs.html.

     _________________________________________________________________

Table of Contents

     * [2]Reporting Bugs

          + [3]What we need

          + [4]What we DON'T want

          + [5]Where to post it

          + [6]Detailed bug reporting instructions

          + [7]Detailed bug reporting instructions for GNAT

          + [8]Detailed bug reporting instructions when using a precompiled

            header

     * [9]Frequently Reported Bugs in GCC

          + [10]C++

               o [11]Missing features

               o [12]Bugs fixed in the 3.4 series

          + [13]Fortran

     * [14]Non-bugs

          + [15]General

          + [16]C

          + [17]C++

               o [18]Common problems when upgrading the compiler

     _________________________________________________________________

                                Reporting Bugs

   The main purpose of a bug report is to enable us to fix the bug. The most

   important prerequisite for this is that the report must be complete and

   self-contained.

   Before you report a bug, please check the [19]list of well-known bugs and,

   if possible, try a current development snapshot. If you want to report a bug

   with versions of GCC before 3.4 we strongly recommend upgrading to the

   current release first.

   Before reporting that GCC compiles your code incorrectly, please compile it

   with gcc -Wall and see whether this shows anything wrong with your code that

   could be the cause instead of a bug in GCC.

Summarized bug reporting instructions

   After this summary, you'll find detailed bug reporting instructions, that

   explain how to obtain some of the information requested in this summary.

  What we need

   Please include in your bug report all of the following items, the first

   three of which can be obtained from the output of gcc -v:

     * the exact version of GCC;

     * the system type;

     * the options given when GCC was configured/built;

     * the complete command line that triggers the bug;

     * the compiler output (error messages, warnings, etc.); and

     * the preprocessed file (*.i*) that triggers the bug, generated by adding

       -save-temps to the complete compilation command, or, in the case of a

       bug report for the GNAT front end, a complete set of source files (see

       below).

  What we do not want

     * A source file that #includes header files that are left out of the bug

       report (see above)

     * That source file and a collection of header files.

     * An attached archive (tar, zip, shar, whatever) containing all (or some

       :-) of the above.

     * A code snippet that won't cause the compiler to produce the exact output

       mentioned in the bug report (e.g., a snippet with just a few lines

       around  the one that apparently triggers the bug, with some pieces

       replaced with ellipses or comments for extra obfuscation :-)

     * The  location  (URL) of the package that failed to build (we won't

       download it, anyway, since you've already given us what we need to

       duplicate the bug, haven't you? :-)

     * An error that occurs only some of the times a certain file is compiled,

       such that retrying a sufficient number of times results in a successful

       compilation; this is a symptom of a hardware problem, not of a compiler

       bug (sorry)

     * Assembly files (*.s) produced by the compiler, or any binary files, such

       as object files, executables, core files, or precompiled header files

     * Duplicate  bug  reports,  or  reports of bugs already fixed in the

       development tree, especially those that have already been reported as

       fixed last week :-)

     * Bugs in the assembler, the linker or the C library. These are separate

       projects,  with separate mailing lists and different bug reporting

       procedures

     * Bugs in releases or snapshots of GCC not issued by the GNU Project.

       Report them to whoever provided you with the release

     * Questions about the correctness or the expected behavior of certain

       constructs that are not GCC extensions. Ask them in forums dedicated to

       the discussion of the programming language

  Where to post it

   Please  submit  your  bug report directly to the [20]GCC bug database.

   Alternatively, you can use the gccbug script that mails your bug report to

   the bug database.

   Only  if  all  this  is absolutely impossible, mail all information to

   [21]gcc-bugs@gcc.gnu.org.

Detailed bug reporting instructions

   Please refer to the [22]next section when reporting bugs in GNAT, the Ada

   compiler, or to the [23]one after that when reporting bugs that appear when

   using a precompiled header.

   In general, all the information we need can be obtained by collecting the

   command line below, as well as its output and the preprocessed file it

   generates.

     gcc -v -save-temps all-your-options source-file

   The only excuses to not send us the preprocessed sources are (i) if you've

   found a bug in the preprocessor, (ii) if you've reduced the testcase to a

   small file that doesn't include any other file or (iii) if the bug appears

   only when using precompiled headers. If you can't post the preprocessed

   sources because they're proprietary code, then try to create a small file

   that triggers the same problem.

   Since we're supposed to be able to re-create the assembly output (extension

   .s), you usually should not 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.

   Please avoid posting an archive (.tar, .shar or .zip); we generally need

   just a single file to reproduce the bug (the .i/.ii/.f preprocessed file),

   and, by storing it in an archive, you're just making our volunteers' jobs

   harder. Only when your bug report requires multiple source files to be

   reproduced should you use an archive. This is, for example, the case if you

   are using INCLUDE directives in Fortran code, which are not processed by the

   preprocessor, but the compiler. In that case, we need the main file and all

   INCLUDEd files. In any case, make sure the compiler version, error message,

   etc, are included in the body of your bug report as plain text, even if

   needlessly duplicated as part of an archive.

Detailed bug reporting instructions for GNAT

   See the [24]previous section for bug reporting instructions for GCC language

   implementations other than Ada.

   Bug reports have to contain at least the following information in order to

   be useful:

     * the exact version of GCC, as shown by "gcc -v";

     * the system type;

     * the options when GCC was configured/built;

     * the exact command line passed to the gcc program triggering the bug (not

       just the flags passed to gnatmake, but gnatmake prints the parameters it

       passed to gcc)

     * a collection of source files for reproducing the bug, preferably a

       minimal set (see below);

     * a description of the expected behavior;

     * a description of actual behavior.

   If  your  code  depends  on  additional  source files (usually package

   specifications), submit the source code for these compilation units in a

   single file that is acceptable input to gnatchop, i.e. contains no non-Ada

   text. If the compilation terminated normally, you can usually obtain a list

   of dependencies using the "gnatls -d main_unit" command, where main_unit is

   the file name of the main compilation unit (which is also passed to gcc).

   If you report a bug which causes the compiler to print a bug box, include

   that bug box in your report, and do not forget to send all the source files

   listed after the bug box along with your report.

   If you use gnatprep, be sure to send in preprocessed sources (unless you

   have to report a bug in gnatprep).

   When you have checked that your report meets these criteria, please submit

   it according to our [25]generic instructions. (If you use a mailing list for

   reporting, please include an "[Ada]" tag in the subject.)

Detailed bug reporting instructions when using a precompiled header

   If you're encountering a bug when using a precompiled header, the first

   thing to do is to delete the precompiled header, and try running the same

   GCC command again. If the bug happens again, the bug doesn't really involve

   precompiled headers, please report it without using them by following the

   instructions [26]above.

   If you've found a bug while building a precompiled header (for instance, the

   compiler crashes), follow the usual instructions [27]above.

   If you've found a real precompiled header bug, what we'll need to reproduce

   it is the sources to build the precompiled header (as a single .i file), the

   source file that uses the precompiled header, any other headers that source

   file includes, and the command lines that you used to build the precompiled

   header and to use it.

   Please don't send us the actual precompiled header. It is likely to be very

   large and we can't use it to reproduce the problem.

     _________________________________________________________________

                        Frequently Reported Bugs in GCC

   This is a list of bugs in GCC that are reported very often, but not yet

   fixed. While it is certainly better to fix bugs instead of documenting them,

   this document might save people the effort of writing a bug report when the

   bug is already well-known.

   There are many reasons why a reported bug doesn't get fixed. It might be

   difficult to fix, or fixing it might break compatibility. Often, reports get

   a low priority when there is a simple work-around. In particular, bugs

   caused by invalid code have a simple work-around: fix the code.

     _________________________________________________________________

C++

  Missing features

   The export keyword is not implemented.

          Most C++ compilers (G++ included) do not yet implement export, which

          is necessary for separate compilation of template declarations and

          definitions. Without export, a template definition must be in scope

          to be used. The obvious workaround is simply to place all definitions

          in the header itself. Alternatively, the compilation unit containing

          template definitions may be included from the header.

  Bugs fixed in the 3.4 series

   The following bugs are present up to (and including) GCC 3.3.x. They have

   been fixed in 3.4.0.

   Two-stage name-lookup.

          GCC did not implement two-stage name-lookup (also see [28]below).

   Covariant return types.

          GCC did not implement non-trivial covariant returns.

   Parse errors for "simple" code.

          GCC gave parse errors for seemingly simple code, such as

struct A

{

  A();

  A(int);

};

struct B

{

  B(A);

  B(A,A);

  void foo();

};

A bar()

{

  B b(A(),A(1));  // Variable b, initialized with two temporaries

  B(A(2)).foo();  // B temporary, initialized with A temporary

  return (A());   // return A temporary

}

          Although being valid code, each of the three lines with a comment was

          rejected  by  GCC. The work-arounds for older compiler versions

          proposed below do not change the semantics of the programs at all.

          The problem in the first case was that GCC started to parse the

          declaration  of  b as a function called b returning B, taking a

          function returning A as an argument. When it encountered the 1, it

          was too late. To show the compiler that this should be really an

          expression, a comma operator with a dummy argument could be used:

B b((0,A()),A(1));

          The work-around for simpler cases like the second one was to add

          additional parentheses around the expressions that were mistaken as

          declarations:

(B(A(2))).foo();

          In the third case, however, additional parentheses were causing the

          problems: The compiler interpreted A() as a function (taking no

          arguments, returning A), and (A()) as a cast lacking an expression to

          be casted, hence the parse error. The work-around was to omit the

          parentheses:

return A();

          This problem occurred in a number of variants; in throw statements,

          people also frequently put the object in parentheses.

     _________________________________________________________________

Fortran

   G77 bugs are documented in the G77 manual rather than explicitly listed

   here. Please see [29]Known Causes of Trouble with GNU Fortran in the G77

   manual.

     _________________________________________________________________

                                   Non-bugs

   The  following are not actually bugs, but are reported often enough to

   warrant a mention here.

   It is not always a bug in the compiler, if code which "worked" in a previous

   version, is now rejected. Earlier versions of GCC sometimes were less picky

   about standard conformance and accepted invalid source code. In addition,

   programming languages themselves change, rendering code invalid that used to

   be conforming (this holds especially for C++). In either case, you should

   update your code to match recent language standards.

     _________________________________________________________________

General

   Problems with floating point numbers - the [30]most often reported non-bug.

          In  a  number  of  cases, GCC appears to perform floating point

          computations incorrectly. For example, the C++ program

#include 

int main()

{

  double a = 0.5;

  double b = 0.01;

  std::cout << (int)(a / b) << std::endl;

  return 0;

}

          might print 50 on some systems and optimization levels, and 49 on

          others.

          This is the result of rounding: The computer cannot represent all

          real numbers exactly, so it has to use approximations. When computing

          with  approximation, the computer needs to round to the nearest

          representable number.

          This is not a bug in the compiler, but an inherent limitation of the

          floating  point  types.  Please  study  [31]this paper for more

          information.

     _________________________________________________________________

C

   Increment/decrement operator (++/--) not working as expected - a [32]problem

          with many variations.

          The following expressions have unpredictable results:

x[i]=++i

foo(i,++i)

i*(++i)                 /* special case with foo=="operator*" */

std::cout << i << ++i   /* foo(foo(std::cout,i),++i)          */

          since the i without increment can be evaluated before or after ++i.

          The  C  and C++ standards have the notion of "sequence points".

          Everything that happens between two sequence points happens in an

          unspecified order, but it has to happen after the first and before

          the second sequence point. The end of a statement and a function call

          are examples for sequence points, whereas assignments and the comma

          between function arguments are not.

          Modifying a value twice between two sequence points as shown in the

          following examples is even worse:

i=++i

foo(++i,++i)

(++i)*(++i)               /* special case with foo=="operator*" */

std::cout << ++i << ++i   /* foo(foo(std::cout,++i),++i)        */

          This leads to undefined behavior (i.e. the compiler can do anything).

   Casting does not work as expected when optimization is turned on.

          This is often caused by a violation of aliasing rules, which are part

          of the ISO C standard. These rules say that a program is invalid if

          you try to access a variable through a pointer of an incompatible

          type. This is happening in the following example where a short is

          accessed through a pointer to integer (the code assumes 16-bit shorts

          and 32-bit ints):

#include 

int main()

{

  short a[2];

  a[0]=0x1111;

  a[1]=0x1111;

  *(int *)a = 0x22222222; /* violation of aliasing rules */

  printf("%x %x\n", a[0], a[1]);

  return 0;

}

          The aliasing rules were designed to allow compilers more aggressive

          optimization. Basically, a compiler can assume that all changes to

          variables happen through pointers or references to variables of a

          type compatible to the accessed variable. Dereferencing a pointer

          that violates the aliasing rules results in undefined behavior.

          In the case above, the compiler may assume that no access through an

          integer pointer can change the array a, consisting of shorts. Thus,

          printf may be called with the original values of a[0] and a[1]. What

          really happens is up to the compiler and may change with architecture

          and optimization level.

          Recent versions of GCC turn on the option -fstrict-aliasing (which

          allows alias-based optimizations) by default with -O2. And some

          architectures  then really print "1111 1111" as result. Without

          optimization the executable will generate the "expected" output "2222

          2222".

          To disable optimizations based on alias-analysis for faulty legacy

          code, the option -fno-strict-aliasing can be used as a work-around.

          The option -Wstrict-aliasing (which is included in -Wall) warns about

          some  - but not all - cases of violation of aliasing rules when

          -fstrict-aliasing is active.

          To fix the code above, you can use a union instead of a cast (note

          that  this  is  a GCC extension which might not work with other

          compilers):

#include 

int main()

{

  union

  {

    short a[2];

    int i;

  } u;

  u.a[0]=0x1111;

  u.a[1]=0x1111;

  u.i = 0x22222222;

  printf("%x %x\n", u.a[0], u.a[1]);

  return 0;

}

          Now the result will always be "2222 2222".

          For  some  more insight into the subject, please have a look at

          [33]this article.

   Cannot use preprocessor directive in macro arguments.

          Let me guess... you used an older version of GCC to compile 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

          This is because your C library's  happens to define memcpy

          as a macro - which is perfectly legitimate. In recent versions of

          glibc,  for  example, printf is among those functions which are

          implemented as macros.

          Versions of GCC prior to 3.3 did not allow you to put #ifdef (or any

          other preprocessor directive) inside the arguments of a macro. The

          code therefore would not compile.

          As of GCC 3.3 this kind of construct is always accepted and the

          preprocessor will probably do what you expect, but see the manual for

          detailed semantics.

          However,  this  kind  of code is not portable. It is "undefined

          behavior" according to the C standard; that means different compilers

          may do different things with it. 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.

   Cannot 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 

FILE *yyin = stdin;

          will not compile with GNU libc, because stdin is not a constant. This

          was  done  deliberately,  to  make it easier to maintain binary

          compatibility  when  the  type  FILE needs to be changed. 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; please check the [34]GNU libc web pages for details.

     _________________________________________________________________

C++

   Nested classes can access private members and types of the containing class.

          Defect report 45 clarifies that nested classes are members of the

          class  they are nested in, and so are granted access to private

          members of that class.

   G++ emits two copies of constructors and destructors.

          In general there are three types of constructors (and destructors).

         1. The complete object constructor/destructor.

         2. The base object constructor/destructor.

         3. The allocating constructor/deallocating destructor.

          The first two are different, when virtual base classes are involved.

   Global destructors are not run in the correct order.

          Global  destructors should be run in the reverse order of their

          constructors  completing. In most cases this is the same as the

          reverse  order  of  constructors  starting, but sometimes it is

          different, and that is important. You need to compile and link your

          programs with --use-cxa-atexit. We have not turned this switch on by

          default, as it requires a cxa aware runtime library (libc, glibc, or

          equivalent).

   Classes in exception specifiers must be complete types.

          [15.4]/1  tells you that you cannot have an incomplete type, or

          pointer  to  incomplete  (other than cv void *) in an exception

          specification.

   Exceptions don't work in multithreaded applications.

          You  need  to  rebuild g++ and libstdc++ with --enable-threads.

          Remember, C++ exceptions are not like hardware interrupts. You cannot

          throw an exception in one thread and catch it in another. You cannot

          throw an exception from a signal handler and catch it in the main

          thread.

   Templates, scoping, and digraphs.

          If you have a class in the global namespace, say named X, and want to

          give it as a template argument to some other class, say std::vector,

          then std::vector<::X> fails with a parser error.

          The reason is that the standard mandates that the sequence <: is

          treated  as  if  it  were  the token [. (There are several such

          combinations of characters - they are called digraphs.) Depending on

          the version, the compiler then reports a parse error before the

          character : (the colon before X) or a missing closing bracket ].

          The simplest way to avoid this is to write std::vector< ::X>, i.e.

          place  a  space between the opening angle bracket and the scope

          operator.

   Copy constructor access check while initializing a reference.

          Consider this code:

class A

{

public:

  A();

private:

  A(const A&);   // private copy ctor

};

A makeA(void);

void foo(const A&);

void bar(void)

{

  foo(A());       // error, copy ctor is not accessible

  foo(makeA());   // error, copy ctor is not accessible

  A a1;

  foo(a1);        // OK, a1 is a lvalue

}

          Starting with GCC 3.4.0, binding an rvalue to a const reference

          requires an accessible copy constructor. This might be surprising at

          first sight, especially since most popular compilers do not correctly

          implement this rule.

          The C++ Standard says that a temporary object should be created in

          this context and its contents filled with a copy of the object we are

          trying to bind to the reference; it also says that the temporary copy

          can be elided, but the semantic constraints (eg. accessibility) of

          the copy constructor still have to be checked.

          For further information, you can consult the following paragraphs of

          the C++ standard: [dcl.init.ref]/5, bullet 2, sub-bullet 1, and

          [class.temporary]/2.

  Common problems when upgrading the compiler

    ABI changes

   The C++ application binary interface (ABI) consists of two components: the

   first defines how the elements of classes are laid out, how functions are

   called, how function names are mangled, etc; the second part deals with the

   internals of the objects in libstdc++. Although we strive for a non-changing

   ABI, so far we have had to modify it with each major release. If you change

   your compiler to a different major release you must recompile all libraries

   that contain C++ code. If you fail to do so you risk getting linker errors

   or malfunctioning programs. Some of our Java support libraries also contain

   C++ code, so you might want to recompile all libraries to be safe. It should

   not be necessary to recompile if you have changed to a bug-fix release of

   the same version of the compiler; bug-fix releases are careful to avoid ABI

   changes. See also the [35]compatibility section of the GCC manual.

   Remark: A major release is designated by a change to the first or second

   component  of the two- or three-part version number. A minor (bug-fix)

   release is designated by a change to the third component only. Thus GCC 3.2

   and 3.3 are major releases, while 3.3.1 and 3.3.2 are bug-fix releases for

   GCC 3.3. With the 3.4 series we are introducing a new naming scheme; the

   first release of this series is 3.4.0 instead of just 3.4.

    Standard conformance

   With each release, we try to make G++ conform closer to the ISO C++ standard

   (available  at  [36]http://www.ncits.org/cplusplus.htm).  We have also

   implemented  some of the core and library defect reports (available at

   [37]http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html     &

   [38]http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html

   respectively).

   Non-conforming legacy code that worked with older versions of GCC may be

   rejected by more recent compilers. There is no command-line switch to ensure

   compatibility in general, because trying to parse standard-conforming and

   old-style  code  at  the  same  time  would  render  the  C++ frontend

   unmaintainable. However, some non-conforming constructs are allowed when the

   command-line option -fpermissive is used.

   Two  milestones in standard conformance are GCC 3.0 (including a major

   overhaul of the standard library) and the 3.4.0 version (with its new C++

   parser).

    New in GCC 3.0

     * The  standard  library is much more conformant, and uses the std::

       namespace (which is now a real namespace, not an alias for ::).

     * The standard header files for the c library don't end with .h, but begin

       with c (i.e.  rather than ). The .h names are still

       available, but are deprecated.

     *  is deprecated, use  instead.

     * streambuf::seekoff  &  streambuf::seekpos are private, instead use

       streambuf::pubseekoff & streambuf::pubseekpos respectively.

     * If std::operator << (std::ostream &, long long) doesn't exist, you need

       to recompile libstdc++ with --enable-long-long.

   If you get lots of errors about things like cout not being found, you've

   most likely forgotten to tell the compiler to look in the std:: namespace.

   There are several ways to do this:

     * Say std::cout at the call. This is the most explicit way of saying what

       you mean.

     * Say using std::cout; somewhere before the call. You will need to do this

       for each function or type you wish to use from the standard library.

     * Say  using  namespace  std; somewhere before the call. This is the

       quick-but-dirty fix. This brings the whole of the std:: namespace into

       scope. Never do this in a header file, as every user of your header file

       will be affected by this decision.

    New in GCC 3.4.0

   The  new  parser  brings  a lot of improvements, especially concerning

   name-lookup.

     * The "implicit typename" extension got removed (it was already deprecated

       since GCC 3.1), so that the following code is now rejected, see [14.6]:

template  struct A

{

    typedef int X;

};

template  struct B

{

    A::X          x;  // error

    typename A::X y;  // OK

};

B b;

     * For  similar reasons, the following code now requires the template

       keyword, see [14.2]:

template  struct A

{

    template  struct X {};

};

template  struct B

{

    typename A::X<0>          x;  // error

    typename A::template X<0> y;  // OK

};

B b;

     * We  now  have two-stage name-lookup, so that the following code is

       rejected, see [14.6]/9:

template  int foo()

{

    return i;  // error

}

     * This also affects members of base classes, see [14.6.2]:

template  struct A

{

    int i, j;

};

template  struct B : A

{

    int foo1() { return i; }       // error

    int foo2() { return this->i; } // OK

    int foo3() { return B::i; } // OK

    int foo4() { return A::i; } // OK

    using A::j;

    int foo5() { return j; }       // OK

};

   In addition to the problems listed above, the manual contains a section on

   [39]Common Misunderstandings with GNU C++.

References

   1. http://gcc.gnu.org/bugs.html

   2. http://gcc.gnu.org/bugs.html#report

   3. http://gcc.gnu.org/bugs.html#need

   4. http://gcc.gnu.org/bugs.html#dontwant

   5. http://gcc.gnu.org/bugs.html#where

   6. http://gcc.gnu.org/bugs.html#detailed

   7. http://gcc.gnu.org/bugs.html#gnat

   8. http://gcc.gnu.org/bugs.html#pch

   9. http://gcc.gnu.org/bugs.html#known

  10. http://gcc.gnu.org/bugs.html#cxx

  11. http://gcc.gnu.org/bugs.html#missing

  12. http://gcc.gnu.org/bugs.html#fixed34

  13. http://gcc.gnu.org/bugs.html#fortran

  14. http://gcc.gnu.org/bugs.html#nonbugs

  15. http://gcc.gnu.org/bugs.html#nonbugs_general

  16. http://gcc.gnu.org/bugs.html#nonbugs_c

  17. http://gcc.gnu.org/bugs.html#nonbugs_cxx

  18. http://gcc.gnu.org/bugs.html#upgrading

  19. http://gcc.gnu.org/bugs.html#known

  20. http://gcc.gnu.org/bugzilla/

  21. mailto:gcc-bugs@gcc.gnu.org

  22. http://gcc.gnu.org/bugs.html#gnat

  23. http://gcc.gnu.org/bugs.html#pch

  24. http://gcc.gnu.org/bugs.html#detailed

  25. http://gcc.gnu.org/bugs.html#where

  26. http://gcc.gnu.org/bugs.html#detailed

  27. http://gcc.gnu.org/bugs.html#detailed

  28. http://gcc.gnu.org/bugs.html#new34

  29. http://gcc.gnu.org/onlinedocs/gcc-3.4.6/g77/Trouble.html

  30. http://gcc.gnu.org/PR323

  31. http://www.validlab.com/goldberg/paper.ps

  32. http://gcc.gnu.org/PR11751

  33. http://mail-index.NetBSD.org/tech-kern/2003/08/11/0001.html

  34. http://www.gnu.org/software/libc/

  35. http://gcc.gnu.org/onlinedocs/gcc/Compatibility.html

  36. http://www.ncits.org/cplusplus.htm

  37. http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_defects.html

  38. http://www.open-std.org/jtc1/sc22/wg21/docs/lwg-defects.html

  39. http://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Misunderstandings.html