Build failed for a baremetal

Neither points to a Morello toolchain. There is nothing wrong with using Morello LLVM, as you currently are as I understand, otherwise there is also the Morello GNU toolchain:

developer.arm.com/.../arm-gnu-toolchain-for-morello-downloads

Many thanks for your reply. I'll try and update you. Can you please suggest from the list of 2 toolchains which one to use for building the project

https://developer.arm.com/downloads/-/arm-gnu-toolchain-downloads

https://developer.arm.com/Tools%20and%20Software/GNU%20Toolchain

I am assuming maybe I am not using the correct compiler version.

Dropping the cheri.h include and adding stdint.h (for uint32_t) that code compiles just fine with the latest Morello LLVM and CheriBSD: https://cheri-compiler-explorer.cl.cam.ac.uk/z/o9rcr6 (though I would recommend a typedef rather than a #define for defining a new type)

What's in your cheri.h?

Many thanks for your reply, however it is already defined in line highlighted with bold red as shown in the code below but still the build failed:

#include "cheri.h"
#include <stdio.h>
#include <stdlib.h>
#include <time.h>



#define seq_t uint32_t* __capability
// The __capability qualifier here is not necessary when compiling for "pure" mode
// (because all pointers have capabilities in "pure" mode), but might be needed
// if compiling for "hybrid" mode, so has been left in for convenience and clarity.

#define SEQ_LEN 15

void populate (seq_t __cheri_output sequence, int size);
void print (seq_t __cheri_input sequence, int size);
void sort (seq_t sequence, int size);
void swap (seq_t first, seq_t second);

int main (void) {
    printf("Morello bare-metal bubble sort example\n\n");

    seq_t sequence = (__cheri_tocap seq_t)malloc(sizeof(uint32_t) * SEQ_LEN);

    populate(sequence, SEQ_LEN);

    printf("Original sequence:\n  ");
    print(sequence, SEQ_LEN);

    sort(sequence, SEQ_LEN);

    printf("Sorted sequence:\n  ");
    print(sequence, SEQ_LEN);

    free((__cheri_fromcap void*)sequence);

    return 0;
}

void populate (seq_t __cheri_output sequence, int size) {
    srand(time(NULL));

    for (int i = 0; i < size; i++) {
        sequence[i] = rand() % (101);
    }
}

void print (seq_t __cheri_input sequence, int size) {
    for (int i = 0; i < size; i++) {
        if (i > 0) {
            printf(", ");
        }
        printf("%d", sequence[i]);
    }
    printf("\n");
}

void sort (seq_t sequence, int size) {
    for (int i = 0; i < (size - 1); i++) {
        for (int j = 0; j < (size - i - 1); j++) {
            if (sequence[j] > sequence[j+1]) {
                swap(&sequence[j], &sequence[j+1]);
            }
        }
    }
}

void swap (seq_t first, seq_t second) {
    uint32_t temp = *first;
    *first = *second;
    *second = temp;
}

`seq_t` looks to be defined as `typedef uint32_t *seq_t` which, in the hybrid ABI, is not a capability, and so __cheri_tocap/__cheri_fromcap are telling you that you aren't casting to/from a capability respectively. If you want to use a capability you need `typedef uint32_t * __capability seq_t`.