Fix basic picolibc support

src/rp2040/boot_stage2/CMakeLists.txt

@@ -49,6 +49,7 @@ function(pico_define_boot_stage2 NAME SOURCES)
     if (PICO_C_COMPILER_IS_CLANG)
         target_link_options(${NAME} PRIVATE "-nostdlib")
     elseif (PICO_C_COMPILER_IS_GNU)
+        # this disables newlib's implementation of syscalls such as _read
         target_link_options(${NAME} PRIVATE "--specs=nosys.specs")
         target_link_options(${NAME} PRIVATE "-nostartfiles")
     endif ()

src/rp2350/boot_stage2/CMakeLists.txt

@@ -49,6 +49,7 @@ function(pico_define_boot_stage2 NAME SOURCES)
     if (PICO_C_COMPILER_IS_CLANG)
         target_link_options(${NAME} PRIVATE "-nostdlib")
     elseif (PICO_C_COMPILER_IS_GNU)
+        # this disables newlib's implementation of syscalls such as _read
         target_link_options(${NAME} PRIVATE "--specs=nosys.specs")
         target_link_options(${NAME} PRIVATE "-nostartfiles")
     endif ()

src/rp2_common/pico_clib_interface/picolibc_interface.c

@@ -58,6 +58,12 @@ static FILE __stdio = FDEV_SETUP_STREAM(picolibc_putc,
                                         picolibc_flush,
                                         _FDEV_SETUP_RW);
 
+#ifdef __GNUCLIKE_PRAGMA_DIAGNOSTIC
+#pragma GCC diagnostic ignored "-Wpragmas"
+#pragma GCC diagnostic ignored "-Wunknown-warning-option"
+#pragma GCC diagnostic ignored "-Wredundant-decls"
+#endif
+
 FILE *const stdin = &__stdio; __strong_reference(stdin, stdout); __strong_reference(stdin, stderr);
 
 void __weak __assert_func(const char *file, int line, const char *func, const char *failedexpr) {

src/rp2_common/pico_cxx_options/new_delete.cpp

@@ -8,6 +8,7 @@
 // Override the standard allocators to use regular malloc/free
 
 #if !PICO_CXX_DISABLE_ALLOCATION_OVERRIDES // Let user override
+#include <stdlib.h> // weird looking but it is required if dropping picolibc on top of GCC+newlib (reent issue)
 #include <cstdlib>
 #include "pico.h"
 

src/rp2_common/pico_platform_compiler/include/pico/platform/compiler.h

@@ -21,6 +21,9 @@
 
 #if defined __GNUC__
 #include <sys/cdefs.h>
+#if !defined(__printflike) && defined(__picolibc_format)
+#define __printflike(a,b) __picolibc_format(printf,a,b)
+#endif
 // note LLVM defines __GNUC__
 #ifdef __clang__
 #define PICO_C_COMPILER_IS_CLANG 1

src/rp2_common/pico_runtime/CMakeLists.txt

@@ -46,7 +46,10 @@ endforeach()
 
 # todo is this correct/needed?
 if (PICO_C_COMPILER_IS_GNU)
-    target_link_options(pico_runtime INTERFACE "--specs=nosys.specs")
+    if (PICO_LIBC STREQUAL "newlib")
+        # this disables newlib's implementation of syscalls such as _read
+        target_link_options(pico_runtime INTERFACE "--specs=nosys.specs")
+    endif()
 elseif (PICO_C_COMPILER_IS_CLANG)
    # target_link_options(pico_runtime INTERFACE "-nostdlib")
 endif()

src/rp2_common/pico_standard_link/CMakeLists.txt

@@ -178,7 +178,8 @@ if (NOT TARGET pico_standard_link)
     # if PICO_TARGET_BINARY_TYPE is set to foo on the target, otherwise ${CMAKE_CURRENT_LIST_DIR}/memmap_${PICO_DEFAULT_BINARY_TYPE).ld
     set(_LINKER_SCRIPT_EXPRESSION "$<IF:$<BOOL:$<TARGET_PROPERTY:PICO_TARGET_LINKER_SCRIPT>>,$<TARGET_PROPERTY:PICO_TARGET_LINKER_SCRIPT>,${PICO_LINKER_SCRIPT_PATH}/memmap_$<IF:$<STREQUAL:$<TARGET_PROPERTY:PICO_TARGET_BINARY_TYPE>,>,${PICO_DEFAULT_BINARY_TYPE},$<TARGET_PROPERTY:PICO_TARGET_BINARY_TYPE>>.ld>")
     target_link_options(pico_standard_link INTERFACE
-        "LINKER:--script=${_LINKER_SCRIPT_EXPRESSION}"
+        # use T instead of --script here,as picolibc.specs looks for -T not --linker
+        "-T${_LINKER_SCRIPT_EXPRESSION}"
             )
     pico_add_link_depend(pico_standard_link ${_LINKER_SCRIPT_EXPRESSION})
     unset(_LINKER_SCRIPT_EXPRESSION)

src/rp2_common/pico_standard_link/script_include/section_copy_to_ram_data.incl

@@ -35,6 +35,7 @@ SECTIONS
 
         . = ALIGN(4);
         /* preinit data */
+        PROVIDE_HIDDEN (__bothinit_array_start = .);
         PROVIDE_HIDDEN (__preinit_array_start = .);
         KEEP(*(SORT(.preinit_array.*)))
         KEEP(*(.preinit_array))
@@ -46,6 +47,7 @@ SECTIONS
         KEEP(*(SORT(.init_array.*)))
         KEEP(*(.init_array))
         PROVIDE_HIDDEN (__init_array_end = .);
+        PROVIDE_HIDDEN (__bothinit_array_end = .);
 
         . = ALIGN(4);
         /* finit data */

src/rp2_common/pico_standard_link/script_include/section_default_text.incl

@@ -51,6 +51,7 @@ SECTIONS
 
         . = ALIGN(4);
         /* preinit data */
+        PROVIDE_HIDDEN (__bothinit_array_start = .);
         PROVIDE_HIDDEN (__preinit_array_start = .);
         KEEP(*(SORT(.preinit_array.*)))
         KEEP(*(.preinit_array))
@@ -62,6 +63,7 @@ SECTIONS
         KEEP(*(SORT(.init_array.*)))
         KEEP(*(.init_array))
         PROVIDE_HIDDEN (__init_array_end = .);
+        PROVIDE_HIDDEN (__bothinit_array_end = .);
 
         . = ALIGN(4);
         /* finit data */

src/rp2_common/pico_standard_link/script_include/section_no_flash_data.incl

@@ -30,6 +30,7 @@ SECTIONS
 
         . = ALIGN(4);
         /* preinit data */
+        PROVIDE_HIDDEN (__bothinit_array_start = .);
         PROVIDE_HIDDEN (__preinit_array_start = .);
         KEEP(*(SORT(.preinit_array.*)))
         KEEP(*(.preinit_array))
@@ -41,6 +42,7 @@ SECTIONS
         KEEP(*(SORT(.init_array.*)))
         KEEP(*(.init_array))
         PROVIDE_HIDDEN (__init_array_end = .);
+        PROVIDE_HIDDEN (__bothinit_array_end = .);
 
         . = ALIGN(4);
         /* finit data */