Bug 737449

Here is a new package which includes these fix. Does it work now ?
I have issues in the doc generation at the moment so it is not in the package.
F14: http://koji.fedoraproject.org/koji/taskinfo?taskID=3347108
F15: 
http://koji.fedoraproject.org/koji/taskinfo?taskID=3347110

package from koji works fine

Doesn't help on Fedora 15, x86_64

Here the result:

SdFile.cpp: In static member function 'static uint8_t SdFile::make83Name(const char*, uint8_t*)':
SdFile.cpp:259:17: error: variable '__c' must be const in order to be put into read-only section by means of '__attribute__((progmem))'
make: *** [SdFile.o] Error 1


rpm -qa | grep avr

avr-gcc-c++-4.6.1-2.fc15.x86_64
avr-binutils-2.21-2.fc15.x86_64
avr-libc-1.7.1-1.fc15.noarch
avr-gcc-4.6.1-2.fc15.x86_64
avrdude-5.10-3.fc15.x86_64

uname -a

Linux jhwx200.home.lan 2.6.40.4-5.fc15.x86_64 #1 SMP Tue Aug 30 14:38:32 UTC 2011 x86_64 x86_64 x86_64 GNU/Linux

Trying to compile Sprinter (reprap 3D printer firmware)

(In reply to comment #3)
> Doesn't help on Fedora 15, x86_64

that's exactly where I tested it. Does my reproducer work for you?

Just curious, could you paste that broken code here?

Btw, this bug was in PSTR definition that did not use const in it's internal type definition. I guess that there is some code out there, that uses it's own types just declared as PROGMEM, but not 'const'. This will break with updated avr-gcc, but it needs to be fixed in the code affected or avr-gcc must be silenced, afaik there's not too much that can be done in avr-libc without breaking old (proper) code.

Updated test case (it's expected to fail with updated avr-gcc):
==================================
#include <avr/pgmspace.h>

int main(void)
{
  const void *x=PSTR("hello");
  static const char y[] PROGMEM ="foo";
  static char z[] PROGMEM ="bar";

  for(;x!=y && y[0] && z[0];); /* nothing, just make x,y,z used from gcc's point of view */

  return 0;
}
==================================

$ avr-gcc -c -mmcu=atmega16 -Os -Wall main.c

main.c:7:16: error: variable 'z' must be const in order to be put into read-only section by means of '__attribute__((progmem))'

Created attachment 522908 [details]
SDfile.cpp that causes the problem on my machine

I have added the SDfile.cpp which is the original Arduino SdFat Library AFAICS.

The problem is caused in line 259:

     // illegal FAT characters
      PGM_P p = PSTR("|<>^+=?/[];,*\"\\");

So I will now hunt for the definition of PSTR used in this context.

I need to recompile the SDfat library as my target board is a Samnguino, which uses the ATMega 644p and the precompiled libraries of the arduino IDE are not available for Sanguino.

I've added that line to reproducer and it works fine. Also both PGM_P and PSTR definitions in pgmspace.h are correct.

#include <avr/pgmspace.h>

int main(void)
{
  const void *x=PSTR("hello");
  static const char y[] PROGMEM ="foo";
  static char z[] PROGMEM ="bar";
  PGM_P p = PSTR("|<>^+=?/[];,*\"\\");

/* preprocessed as:

 const prog_char * p = (__extension__({static const char __c[] __attribute__((__progmem__)) = ("|<>^+=?/[];,*\"\\"); &__c[0];}));

*/

  for(;x!=y && y[0] && z[0] && p!=x;); /* nothing, just make x,y,z used from gcc's point of view */

  return 0;
}

So you should verify you have correct version installed and that your sources do not bundle own copy of pgmspace.h 
check /usr/avr/include/avr/pgmspace.h line 255 for 'const'
and check preprocessed output of SDfile.cpp (just add -E to compiler) and you should know, where the problem is.

Hm. My preprocessed file looks OK. I did:

# /usr/bin/avr-g++ -c -mmcu=atmega644p  -I. -DF_CPU=16000000 -I/usr/share/arduino/hardware/arduino/cores/arduino -Os -Wall  -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -w -ffunction-sections -fdata-sections -DARDUINO=22 -E SdFile.cpp -o SdFile.o

The generated SdFile.o has:

      const prog_char * p = (__extension__({static const char __c[] __attribute__((__progmem__)) = ("|<>^+=?/[];,*\"\\"); &__c[0];}));

But without the -E I still get:

# /usr/bin/avr-g++ -c -mmcu=atmega644p  -I. -DF_CPU=16000000 -I/usr/share/arduino/hardware/arduino/cores/arduino -Os -Wall  -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -w -ffunction-sections -fdata-sections -DARDUINO=22 SdFile.cpp -o SdFile.o
SdFile.cpp: In static member function 'static uint8_t SdFile::make83Name(const char*, uint8_t*)':
SdFile.cpp:259:17: error: variable '__c' must be const in order to be put into read-only section by means of '__attribute__((progmem))'

I have checked that I have the correct /usr/avr/include/avr/pgmspace.h and line 255 has the const.

I am a bit lost now. There is no other pgmspace.h on my box.

(In reply to comment #9)
> I am a bit lost now. There is no other pgmspace.h on my box.

I've tried it with pre-processed output:
======================
typedef char prog_char __attribute__((__progmem__));

int main(void)
{
 const void *x=(__extension__({static const char __c[] __attribute__((__progmem__)) = ("hello"); &__c[0];}));
 static const char y[] __attribute__((__progmem__)) ="foo";
 const prog_char * p = (__extension__({static const char __c[] __attribute__((__progmem__)) = ("|<>^+=?/[];,*\"\\"); &__c[0];}));

 for(;x!=y && y[0] && p!=x;);

 return 0;
}
======================
avr-gcc ... works
avr-g++ ... complains

Seems it's bug in gcc-4.6.x, so I've googled a little and found:
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49764
so file a new bug against avr-gcc

Thank you, Michael - seems you have hit the problem on the head!

That bug report is exactly the problem I am seeing here.

Will file BZ against avr-gcc :-)

Added BZ #737950 with a reproducer snippet

Closing, as BZ #737950 was closed.