[Bug c/30380] New: bug in cppdefault.c

[Bug c/30380] New: bug in cppdefault.c

[hartmann at physik dot uni-kl dot de]

hello!

there is a nasty little bug in cppdefault.c in gcc 4.0.3:
wrong:
  const char cpp_GCC_INCLUDE_DIR[] = GCC_INCLUDE_DIR;
  const size_t cpp_GCC_INCLUDE_DIR_len = sizeof GCC_INCLUDE_DIR - 8;
correct:
  const char cpp_GCC_INCLUDE_DIR[] = GCC_INCLUDE_DIR;
  const size_t cpp_GCC_INCLUDE_DIR_len = sizeof GCC_INCLUDE_DIR - 1;

it is also persistent in gcc-4.1.1

effects of this bug:
  add_standard_paths in c-incpath.c is defeated. therefore standard include
headers
  are not accessed relatively to the executable-path. instead there are
accessed
  with the paths which are build in during configuration. this does not matter
if
  you want to use gcc only in /usr. but if the prefix-dir and the installdir
differ 
  you get a problem. this is common on mingw.
  When GCC_INCLUDE_DIR is shorter than 8 chars you get an even bigger problem
because
  size_t wraps around...

in case anybody is interested:
  i stumbled over this bug by trying to build a position-independent gcc for
mingw.
  to do this, i must hack cppdefault.c:
      #define GCC_INCLUDE_DIR       "/usr/lib/gcc/mingw32/4.0.3/"
      #define GPLUSPLUS_INCLUDE_DIR
"/usr/lib/gcc/mingw32/4.0.3/../../../../include/c++/4.0.3"
      #define GPLUSPLUS_TOOL_INCLUDE_DIR
"/usr/lib/gcc/mingw32/4.0.3/../../../../include/c++/4.0.3/mingw32"
      #define GPLUSPLUS_BACKWARD_INCLUDE_DIR
"/usr/lib/gcc/mingw32/4.0.3/../../../../include/c++/4.0.3/backward"
      #define LOCAL_INCLUDE_DIR     "/usr/lib/gcc/mingw32/4.0.3/include"
      #undef PREFIX_INCLUDE_DIR
      #undef CROSS_INCLUDE_DIR
      #undef TOOL_INCLUDE_DIR
      #undef SYSTEM_INCLUDE_DIR
      #define STANDARD_INCLUDE_DIR 
"/usr/lib/gcc/mingw32/4.0.3/../../../../include"
  here /usr/lib/gcc/mingw32/4.0.3/ is a dummy which could be anything... . it
is replaced
  later by add_standard_paths. perhaps there is a way to avoide this hack
(exec-prefix ??) but i have not tried this jet.

greetings, timo


-- 
           Summary: bug in cppdefault.c
           Product: gcc
           Version: 4.0.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: hartmann at physik dot uni-kl dot de


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30380

[Bug c/30380] bug in cppdefault.c

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2007-01-05 04:25 -------
"include" is 7 characters which is what the -8 is for as I understand it.

I think you mishacked the cppdefault.c.
What is passed to cppdefault always includes "include":
  -DGCC_INCLUDE_DIR=\"$(libsubdir)/include\" \

So I think you are incorrect in setting it not to include "include".

So we always compare against - the include too:
              if (!strncmp (p->fname, cpp_GCC_INCLUDE_DIR, len))


Also we need to have the include part for cpp_include_default:
#ifdef GCC_INCLUDE_DIR
    /* This is the dir for fixincludes and for gcc's private headers.  */
    { GCC_INCLUDE_DIR, "GCC", 0, 0, 0, 0 },
#endif


 so you mishacked the compiler.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30380

[Bug c/30380] bug in cppdefault.c

[hartmann at physik dot uni-kl dot de]

------- Comment #2 from hartmann at physik dot uni-kl dot de  2007-01-05 16:42 -------
ok.
the trick with the "include" which provides additional 7 chars confused me. but
the issue remains: I'm not able to produce an position independent gcc for
mingw without hacking cppdefaults.c. The reason for this is that the paths for
cppdefault.c which are passed on the commandline
(-DGCC_INCLUDE_DIR="/mingw/lib/gcc/mingw32/4.0.3/include"
-DGPLUSPLUS_INCLUDE_DIR="/mingw/lib/gcc/mingw32/4.0.3/../../../../include/c++/4.0.3"
-DGPLUSPLUS_TOOL_INCLUDE_DIR="/mingw/lib/gcc/mingw32/4.0.3/../../../../include/c++/4.0.3/mingw32"
....) are transformed into absolute paths in cppdefaults.o: 
  strings cppdefault.o 
   D:/Programme/timo/msys-new/mingw/lib/gcc/mingw32/4.0.3/include
   D:/Programme/timo/msys-new/mingw/include/c++/4.0.3
   D:/Programme/timo/msys-new/mingw/include/c++/4.0.3/mingw32
   D:/Programme/timo/msys-new/mingw/include/c++/4.0.3/backward
   ....

I am using msys. some part of msys is apparently translating paths from
mingw-style "/mingw/..." to absolute windows style "D:/...".

Till I figured out how to overcome this, I will use the hacked defines in
cppdefault.c (but I will use "const size_t cpp_GCC_INCLUDE_DIR_len = sizeof
GCC_INCLUDE_DIR - 8" now and append an include to GCC_INCLUDE_DIR).

Because this is apparently a bug in msys/mingw, I will ask there and not bother
the gcc-bug-list anymore.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=30380