I have a Raspberry Pi (3) with a Pico SDK freshly installed via the recommended script.
I've added the pico-project-generator and created a project as follows:
./pico-project-generator/pico_project.py myProject
That empty project builds fine:
cd myProject/build
cmake ..
build
I then make the following changes, in anticipation of writing + using some C++ classes as the project expands:
cd $projectRoot
mv myProject.c myProject.cpp
<also edit CMakeLists.txt to reflect that file rename>
The previous cmake .. ; make now produces the following errors:
In file included from /usr/include/newlib/stdio.h:35:0,
from /home/pi/pico/myProject/myProject.cpp:1:
/home/pi/pico/pico-sdk/src/rp2_common/pico_platform/include/pico/platform.h:237:31: error: duplicate 'inline'
#define __force_inline inline __always_inline
^
/home/pi/pico/pico-sdk/src/rp2_common/pico_platform/include/pico/platform.h:282:1: note: in expansion of macro '__force_inline'
__force_inline static void __compiler_memory_barrier(void) {
^~~~~~~~~~~~~~
<repeats a total of 8 times>
make[2]: *** [CMakeFiles/myProject.dir/build.make:63: CMakeFiles/myProject.dir/myProject.cpp.obj] Error 1
make[1]: *** [CMakeFiles/Makefile2:1559: CMakeFiles/myProject.dir/all] Error 2
make: *** [Makefile:84: all] Error 2
From the official pi-pico-sdk PDF:
The SDK has a C style API, however the SDK headers may be safely included from C++ code, and the functions called (they are declared with C linkage).
C++ files are integrated into SDK projects in the same way as C files: listing them in your CMakeLists file under either the add_executable() entry, or a separate target_sources() entry to append them to your target.
... which suggests to me that there should be nothing extra/different that I need to do.
The fact that /usr/include/newlib/stdio.h appears in the output is sounding alarm bells, but I don't know how to identify how/why that version of stdio.h is being used.
This first came to light when a project I wrote months ago would no longer build on this just-re-imaged Pi. The steps above describe the minimal way of triggering the error.
The only code in the project right now is that generated by the pico-project-generator template:
myProject.cpp
#include <stdio.h>
#include "pico/stdlib.h"
int main()
{
stdio_init_all();
puts("Hello, world!");
return 0;
}
cMakelists.txt
# Generated Cmake Pico project file
cmake_minimum_required(VERSION 3.13)
set(CMAKE_C_STANDARD 11)
set(CMAKE_CXX_STANDARD 17)
# initalize pico_sdk from installed location
# (note this can come from environment, CMake cache etc)
set(PICO_SDK_PATH "/home/pi/pico/pico-sdk")
# Pull in Raspberry Pi Pico SDK (must be before project)
include(pico_sdk_import.cmake)
project(myProject C CXX ASM)
# Initialise the Raspberry Pi Pico SDK
pico_sdk_init()
# Add executable. Default name is the project name, version 0.1
add_executable(myProject myProject.cpp )
pico_set_program_name(myProject "myProject")
pico_set_program_version(myProject "0.1")
pico_enable_stdio_uart(myProject 1)
pico_enable_stdio_usb(myProject 0)
# Add the standard library to the build
target_link_libraries(myProject pico_stdlib)
pico_add_extra_outputs(myProject)
Update
I had kept a .tgz of my entire /home/pi from before re-imaging the Pi. Restoring the older pico SDK from that alongside the new one and switching between them via PICO_SDK_PATH etc. confirms that a CMakeLists.txt + C++ source file that won't build with the latest SDK does indeed build just fine with the old SDK.
I've attempted to compare the two build/Makefile versions and they are very different.
Further update
A GitHub issue has already been raised regarding this error. I've added a minimal example demonstrating the problem there.
