"one declaration" rule broken with USE_DEDICATED_SPI=0

[samy]

Hi In my project I tried to use the USE_DEDICATED_SPI=0 setting to reduce memory usage (and I have other SPI devices in the project) But each time I compile I have errors about C++ "One Declaration" rule broken (about SdSpiCard class) Do you have any idea ?

I can post the full project source code if needed

Thanks

[greiman]

I can' do anything without the code. Also I need a description of your hardware.

Try running this program. It compiles and runs on my hardware. Be sure to edit SdfatConfig.h and set ENABLE_DEDICATED_SPI zero like this.

#ifndef ENABLE_DEDICATED_SPI
#if defined(__AVR__) && FLASHEND < 0X8000
// 32K AVR boards.
#define ENABLE_DEDICATED_SPI 0  // <------- Edit Here
#else  // defined(__AVR__) && FLASHEND < 0X8000
// All other boards.
#define ENABLE_DEDICATED_SPI 0  //<--------- Edit Here
#endif  // defined(__AVR__) && FLASHEND < 0X8000
#endif  // ENABLE_DEDICATED_SPI

Edit SD_CS_PIN for your hardware.

#include "SdFat.h"

#if ENABLE_DEDICATED_SPI
#error "Edit SdFatConfig.h and set ENABLE_DEDICATED_SPI zero"
#endif

SdFat sd;
#define SD_CS_PIN 10  // use your Chip Select pin
#define SD_CONFIG SdSpiConfig(SD_CS_PIN, SHARED_SPI, SD_SCK_MHZ(8))

void setup() {
  Serial.begin(9600);
  while(!Serial) {}
  Serial.println("Type any character to begin");
  while (!Serial.available()) {}
  if (!sd.begin(SD_CONFIG)) {
    sd.initErrorHalt(&Serial);
  }
  Serial.println("Success");
}

void loop() {}

[stripwax]

Rather than editing SdFatConfig.h , would it not work correctly to define ENABLE_DEDICATED_SPI? In other words:

#define ENABLE_DEDICATED_SPI 0  // <-- this line
#include "SdFat.h"

#if ENABLE_DEDICATED_SPI
#error "Edit SdFatConfig.h and set ENABLE_DEDICATED_SPI zero"
#endif

SdFat sd;
#define SD_CS_PIN 10  // use your Chip Select pin
#define SD_CONFIG SdSpiConfig(SD_CS_PIN, SHARED_SPI, SD_SCK_MHZ(8))

void setup() {
  Serial.begin(9600);
  while(!Serial) {}
  Serial.println("Type any character to begin");
  while (!Serial.available()) {}
  if (!sd.begin(SD_CONFIG)) {
    sd.initErrorHalt(&Serial);
  }
  Serial.println("Success");
}

void loop() {}

Assuming this is a valid way to evaluate the ENABLE_DEDICATED_SPI flag, I can confirm I have the same problem as the original post:

c:\users\slowd\documents\arduino\libraries\sdfat\src\common\fscache.h:37:7: warning: type 'struct FsCache' violates the C++ One Definition Rule [-Wodr]
 class FsCache {
       ^
c:\users\slowd\documents\arduino\libraries\sdfat\src\common\fscache.h:37:7: note: a different type is defined in another translation unit
 class FsCache {
       ^
c:\users\slowd\documents\arduino\libraries\sdfat\src\common\fscache.h:179:18: note: the first difference of corresponding definitions is field 'm_blockDev'
   FsBlockDevice* m_blockDev;
                  ^
c:\users\slowd\documents\arduino\libraries\sdfat\src\common\fscache.h:179:18: note: a field of same name but different type is defined in another translation unit
   FsBlockDevice* m_blockDev;
                  ^
c:\users\slowd\documents\arduino\libraries\sdfat\src\common\fsblockdevice.h:31:16: note: type 'struct FsBlockDevice' should match type 'struct FsBlockDevice'
 typedef SdCard FsBlockDevice;
                ^
C:\Users\slowd\Documents\Arduino\libraries\SdFat\src/FatLib/FatPartition.h:51:7: warning: type 'struct FatPartition' violates the C++ One Definition Rule [-Wodr]
 class FatPartition {
       ^
C:\Users\slowd\Documents\Arduino\libraries\SdFat\src\FatLib\FatPartition.h:51:7: note: a different type is defined in another translation unit
 class FatPartition {
       ^

However, I can confirm, that setting ENABLE_DEDICATED_SPI via editing the SdFatConfig.h , does work correctly . This doesn't explain to me why this should work. Isn't the purpose of the #ifndef logic in SdFatConfig.h supposed to let us define a value for ENABLE_DEDICATED_SPI before #including sdfat.h ? If so, why doesn't that work here?

#ifndef ENABLE_DEDICATED_SPI
#if defined(__AVR__) && FLASHEND < 0X8000
// 32K AVR boards.
.....

[stripwax]

(update - apologies, I now understand the cause of what I described, which is coming from the limitation/misunderstanding of the Arduino IDE compilation process, rather than a problem in this library)

[greiman]

Yes, Adruino has way too many limitation. You can define symbols in other IDEs like PlatformIO. The #ifndef sections in SdFatConfig.h then work and you don't need to edit the file.

Community use of PlatformIO is free.

The PlatformIO for Arduino is here.