Fails to compile when using strdup function

[Urjasvi Suthar]

Hello,

I am trying to compile for wasm with emscripten but there seems to be no 'strdup' C standard function.

```

src/token.c:169:10: error: use of undeclared identifier 'strdup'; did you mean 'strupr'?
  169 |                 .str = strdup(str),
      |                        ^~~~~~
      |                        strupr
/Users/x/emsdk/upstream/emscripten/cache/sysroot/include/compat/string.h:9:14: note: 'strupr' declared here
    9 | extern char* strupr(char *);
      |              ^
1 error generated.
emcc: error: '/Users/x/emsdk/upstream/bin/clang -target wasm64-unknown-emscripten -fignore-exceptions -mno-bulk-memory -mno-bulk-memory-opt -mno-nontrapping-fptoint -mllvm -combiner-global-alias-analysis=false -mllvm -enable-emscripten-sjlj -mllvm -disable-lsr --sysroot=/Users/x/emsdk/upstream/emscripten/cache/sysroot -DEMSCRIPTEN -Werror=implicit-function-declaration -Xclang -iwithsysroot/include/fakesdl -Xclang -iwithsysroot/include/compat -Iexternal/lz4/lib -std=c23 -Wall -Wextra src/token.c -c -o /var/folders/7x/khcwdw3d39g8c3k03mcrcw3r0000gn/T/emscripten_temp_u3yctg1o/token_1.o' failed (returned 1)

```

Is this C23 standard not supported yet or am I missing something?

I know I can implement it myself easily (that what I am currently doing as workaround), but less code and #ifdefs the better :)

Regards,

Urjasvi Suthar

[Sam Clegg]

`strdup` is available in emscripten.  Its part of the musl libc: https://github.com/emscripten-core/emscripten/blob/ebfeaf7a17f53ad322ea322efa8dfca5c752679b/system/lib/libc/musl/include/string.h#L70

It looks like using `-std=c23` is somehow suppressing that definition.   Could you open a bug about that?

cheers,

sam

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[Sam Clegg]

After a little investigation it seems like the problem is that when you use `-std=c23` or `-std=c11` clang will define `__STRICT_ANSI__`.  `strdup` was not available in this mode, at least not prior to C23.  So musl does not declare it in that mode.

You can work around this by using `-std=gnu23` or by adding `-D_BSD_SOURCE`.

cheers,
sam

[Urjasvi Suthar]

Thank you for your response. The work-around worked, should I still open a bug report?

Regards,

Urjasvi Suthar

[Sam Clegg]

Yes, I think it is probably worth having a bug to track this.  Thank you.

To view this discussion visit https://groups.google.com/d/msgid/emscripten-discuss/416bf0c0-9ed8-4e3d-8cc0-fd5faba9bf5dn%40googlegroups.com.

[Urjasvi Suthar]

Here, https://github.com/emscripten-core/emscripten/issues/23398

Thanks and regards,

Urjasvi Suthar