zig cc --target=wasm32-freestanding-musl cannot use musl

[antocuni]

Zig Version

0.11.0-dev.4406+d370005d3

Steps to Reproduce and Observed Behavior

I tried to compile this simple C program with zig cc:

#include <stdlib.h>
int main(){
    void *buf = malloc(1024);
}

This is the output I get:

$ zig cc --target=wasm32-freestanding-musl -g main.c
main.c:3:10: fatal error: 'stdlib.h' file not found
#include <stdlib.h>
         ^~~~~~~~~~
1 error generated.

Expected Behavior

This is a good question, I admit I didn't know what to expect and I was mostly experimenting.
My gut feeling is that some of the libc functions are impossible to provide in a wasm32-freestanding environment, because they need imports, e.g. for I/O.

But other functions such as malloc, free, strcpy, etc., they should probably work?

I have the impression that wasm32-freestanding-musl is a valid target for zig but not for zig cc?

$ zig cc --target=wasm32-freestanding-musl -g x.c -lc
LLD Link... wasm-ld: error: entry symbol not defined (pass --no-entry to suppress): _start

You need to explicitly pass -lc to link with libc.

[antocuni]

Thank you, -lc helps a bit but still not completely.

I tried with this file and I slightly different command line, to build a shared lib instead of an executable:

#include <stdlib.h>
void __attribute__((export_name("foo")))
foo(void){
    void *buf = malloc(1024);
}

$ zig version
0.11.0-dev.4406+d370005d3
$ zig cc --target=wasm32-freestanding-musl -g main.c -lc -shared
LLD Link... wasm-ld: error: /home/antocuni/.cache/zig/o/40b945db78c815c99730bdbe0de139e2/main.o: undefined symbol: malloc

The interesting thing is that with zig 0.10.1 I have a different behavior: in this case, the compilation works fine, but malloc ends up as an WASM import instead of being linked from MUSL:

$ zig version
0.10.1
$ zig cc --target=wasm32-freestanding-musl -g main.c -lc -shared
$ ls a.out
a.out
$ wasm2wat a.out
(module
  (type (;0;) (func (param i32) (result i32)))
  (type (;1;) (func))
  (import "env" "malloc" (func $malloc (type 0)))
  (func $foo (type 1)
    (local i32 i32 i32 i32 i32 i32 i32)
    global.get $__stack_pointer
    local.set 0
    i32.const 16
    local.set 1
    local.get 0
    local.get 1
    i32.sub
    local.set 2
    local.get 2
    global.set $__stack_pointer
    i32.const 1024
    local.set 3
    local.get 3
    call $malloc
    local.set 4
    local.get 2
    local.get 4
    i32.store offset=12
    i32.const 16
    local.set 5
    local.get 2
    local.get 5
    i32.add
    local.set 6
    local.get 6
    global.set $__stack_pointer
    return)
  (table (;0;) 1 1 funcref)
  (memory (;0;) 16)
  (global $__stack_pointer (mut i32) (i32.const 1048576))
  (export "memory" (memory 0))
  (export "foo" (func $foo)))

[alexrp]

#22240