Added c++ linker command to allow to include libstdc++ when linking.

[helmut64]

This is needed otherwise the template C++ container support
are missing. The "compiler.c.elf.cmd" specifies the linker,
the C linker was wrong here and does not work for true C++ apps.

This change does not hurt because when no libstdc++ features are
being used there is no change.

Changed the Arduino function map() into Arduino_map(). This is needed
otherwise it clashes with the C++ template class. e.g.: #include

PS: I also added the same changes into the 32-bit Arduino ESP32 release.

[helmut64]

The other map is the regular C++ libstdc++ map which is being used in all C++ books, C++ projects, etc.. C++ is now here with this for more than 20 years. It is a fault by Arduino to use this name. It is also little being used compared to the C++ map.

[helmut64]

PS: I also checked the memory size of apps for the D21 SAMD platform, there is absolutely no difference with this patch.

[helmut64]

I believe now it should work.

[helmut64]

Why does it take several months to review and integrate my enhancement.

[helmut64]

@facchinm please help to integrate the pull requests, my one is sitting here for almost 8 month now, it takes only 5 minutes to review and commit it.
Regards Helmut

[PaulStoffregen]

Changed the Arduino function map() into Arduino_map().

How does this work? Looking at the files changed tab, I see a define, but nothing else which would allow the huge number of programs people have written with map() to compile and actually work. Did I miss something?

Hopefully you can understand how a change that breaks (or likely breaks) one of Arduino's very widely used features would never be accepted?

[helmut64]

@PaulStoffregen Hi Paul, the map problem is resolved by using the complete C++ namespace name std::map for C++. The remaining issue is the wrong linker statement. It can be fixed via

< compiler.c.elf.cmd=arm-none-eabi-gcc

compiler.c.elf.cmd=arm-none-eabi-g++

With the ESP32 this is no problem, for the the D21/SAMD platform switching to the g++ for linking will resolve the STL C++ libraries when used.

Do you have merge rights?

It is just disappointing that I do a fix, for the ESP32 it took a few days to get it merged/resolved, for the SAMD nothing happens for 7 month.

Regards Helmut

[cmaglie]

I tried this with the example:

void setup() {
  int x = map(1,2,3,4,5);
}
void loop() { }

and it fails with:

/tmp/arduino_modified_sketch_608153/sketch_jun27a.ino: In function 'void setup()':
sketch_jun27a:3:24: error: 'Arduino_map' was not declared in this scope
   int x = map(1,2,3,4,5);
                        ^
/tmp/arduino_modified_sketch_608153/sketch_jun27a.ino:3:7: warning: unused variable 'x' [-Wunused-variable]
   int x = map(1,2,3,4,5);
       ^
exit status 1
'Arduino_map' was not declared in this scope

are you sure that the PR is complete?
I see that there are a bunch of tentative commits that are undone later, maybe you want to clean up the history?

[cmaglie]

Oh I see, I guess this is a leftover:

https://github.com/arduino/ArduinoCore-samd/pull/276/files#diff-9ad272c11f2032a6e0231ebda4438a04R31

so just changing gcc with g++ for linking should be enough?

[helmut64]

Yes, just changing the linker to use g++
Regards Helmut