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Add detection of newlib vs picolibc if not specified #2935

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Merged
kilograham merged 2 commits into from
May 20, 2026
+37 −2
Merged

Add detection of newlib vs picolibc if not specified #2935

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5a6fcf6
Add detection of newlib vs picolibc if not specified
kilograham May 14, 2026
1d3d6fc
fix search order to be newlib then picolibc for autodetect
kilograham May 19, 2026
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39 changes: 37 additions & 2 deletions src/rp2_common/pico_clib_interface/CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -36,8 +36,43 @@ if (NOT TARGET pico_clib_interface)

if (NOT PICO_CLIB)
# PICO_CMAKE_CONFIG: PICO_CLIB, The C library to use e.g. newlib/picolibc/llvm_libc, type=string, default=based on PICO_COMPILER, group=build, docref=cmake-toolchain-config
set(PICO_CLIB newlib)
endif()
set(CLIB_DETECT_CODE "
#include <stdio.h>
#ifdef __PICOLIBC__
#define USING_PICOLIBC 1
#elif defined(__NEWLIB__)
#define USING_NEWLIB 1
#endif

#if (picolibc && !USING_PICOLIBC) || (newlib && !USING_NEWLIB)
#error not using wanted c library
#endif
")

# Create a temporary file for the source
set(CLIB_DETECT_SOURCE "${CMAKE_CURRENT_BINARY_DIR}/clib_check.c")
file(WRITE "${CLIB_DETECT_SOURCE}" "${CLIB_DETECT_CODE}")

set(CMAKE_TRY_COMPILE_TARGET_TYPE STATIC_LIBRARY)
foreach(CLIB picolibc newlib)
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@rgrr rgrr May 17, 2026

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I think order should be "newlib picolibc", because newlib was default before

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# Attempt to compile the source file
try_compile(CLIB_MATCHED
"${CMAKE_CURRENT_BINARY_DIR}" # Directory for temporary build files
"${CLIB_DETECT_SOURCE}" # Source file to compile
COMPILE_DEFINITIONS "-D${CLIB}=1"
)
if (CLIB_MATCHED)
set(PICO_CLIB ${CLIB})
break()
endif()
endforeach ()
if (NOT PICO_CLIB)
message("C library not detected; defaulting to newlib")
set(PICO_CLIB newlib)
endif()
file(REMOVE "${CLIB_DETECT_SOURCE}")
set(PICO_CLIB "${PICO_CLIB}" CACHE INTERNAL "")
endif()
message("C library type is ${PICO_CLIB}")
target_link_libraries(pico_clib_interface INTERFACE pico_${PICO_CLIB}_interface)
endif()
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