Unable to build C stubs on macOS

[reykjalin]

When I try to build the C stubs I see errors that look like this:

./c_stubs/SFTime_cstub.c:89:5: error: use of GNU old-style field designator extension [-Werror,-Wgnu-designator]
    identifier:  "sfTime struct",
    ^~~~~~~~~~~
    .identifier =

It seems that Apple Clang is complaining about using older versions of struct field initialization, and fixing the problem should be as simple as adding a . in front of each field.

Full output during build

/Applications/Xcode.app/Contents/Developer/usr/bin/make -C src c_all
ocamldep SF*.ml SF*.mli oo_*.ml oo_*.mli > ml_depend.mk
ocamlopt -g -w A -ccopt "-Wall -Werror -Wno-deprecated-declarations" -c -ccopt "-I/usr/include/" ./c_stubs/sf_caml_conv_c.c
ocamlopt -g -w A -ccopt "-Wall -Werror -Wno-deprecated-declarations" -c -ccopt "-I/usr/include/" ./c_stubs/sf_conv_vectors_c.c
ocamlopt -g -w A -ccopt "-Wall -Werror -Wno-deprecated-declarations" -c -ccopt "-I/usr/include/" ./c_stubs/SFConfig_cstub.c
ocamlopt -g -w A -ccopt "-Wall -Werror -Wno-deprecated-declarations" -c -ccopt "-I/usr/include/" ./c_stubs/SFTime_cstub.c
./c_stubs/SFTime_cstub.c:89:5: error: use of GNU old-style field designator extension [-Werror,-Wgnu-designator]
    identifier:  "sfTime struct",
    ^~~~~~~~~~~
    .identifier =
./c_stubs/SFTime_cstub.c:90:5: error: use of GNU old-style field designator extension [-Werror,-Wgnu-designator]
    finalize:    custom_finalize_default,
    ^~~~~~~~~
    .finalize =
./c_stubs/SFTime_cstub.c:91:5: error: use of GNU old-style field designator extension [-Werror,-Wgnu-designator]
    compare:     custom_compare_default,
    ^~~~~~~~
    .compare =
./c_stubs/SFTime_cstub.c:92:5: error: use of GNU old-style field designator extension [-Werror,-Wgnu-designator]
    hash:        custom_hash_default,
    ^~~~~
    .hash =
./c_stubs/SFTime_cstub.c:93:5: error: use of GNU old-style field designator extension [-Werror,-Wgnu-designator]
    serialize:   custom_serialize_default,
    ^~~~~~~~~~
    .serialize =
./c_stubs/SFTime_cstub.c:94:5: error: use of GNU old-style field designator extension [-Werror,-Wgnu-designator]
    deserialize: custom_deserialize_default
    ^~~~~~~~~~~~
    .deserialize =
6 errors generated.
make[1]: *** [SFTime_cstub.o] Error 2
make: *** [c_all] Error 2

I'm using Apple Clang version 12.0.0. Full version output:

Apple clang version 12.0.0 (clang-1200.0.32.2)
Target: x86_64-apple-darwin19.6.0
Thread model: posix
InstalledDir: /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin

[reykjalin]

Turns out there are more issues that surface once this has been fixed. I'm trying to come up with a patch right now, but might take a bit.

[reykjalin]

I get stuck here:

ocamlopt -g -w A -ccopt "-Wall -Werror -Wno-deprecated-declarations" -c -ccopt "-I/usr/include/" ./c_stubs/SFBlendMode_cstub.c
./c_stubs/SFBlendMode_cstub.c:47:5: error: statement requires expression of integer type ('sfBlendMode' invalid)
    switch (blendMode)
    ^       ~~~~~~~~~
1 error generated.

I'm not sure how to properly fix this since the blendMode variable is a struct, and switch statements only work on integer types (according to the error at least). When I changed this to an if-else statement (using if (sfBlendAlpha == blendMode) etc.) I got a different error:

ocamlopt -g -w A -ccopt "-Wall -Werror -Wno-deprecated-declarations" -c -ccopt "-I/usr/include/" ./c_stubs/SFBlendMode_cstub.c
./c_stubs/SFBlendMode_cstub.c:47:19: error: invalid operands to binary expression ('const sfBlendMode' and 'sfBlendMode')
        if (sfBlendAlpha == blendMode) {
            ~~~~~~~~~~~~ ^  ~~~~~~~~~
./c_stubs/SFBlendMode_cstub.c:49:24: error: invalid operands to binary expression ('const sfBlendMode' and 'sfBlendMode')
        } else if (sfBlendAdd == blendMode) {
                   ~~~~~~~~~~ ^  ~~~~~~~~~
./c_stubs/SFBlendMode_cstub.c:51:29: error: invalid operands to binary expression ('const sfBlendMode' and 'sfBlendMode')
        } else if (sfBlendMultiply == blendMode) {
                   ~~~~~~~~~~~~~~~ ^  ~~~~~~~~~
./c_stubs/SFBlendMode_cstub.c:53:25: error: invalid operands to binary expression ('const sfBlendMode' and 'sfBlendMode')
        } else if (sfBlendNone == blendMode) {
                   ~~~~~~~~~~~ ^  ~~~~~~~~~
4 errors generated.

This is the patch I've applied so far.

diff --git a/src/c_stubs/SFTime_cstub.c b/src/c_stubs/SFTime_cstub.c
index ff17994..cb3eadb 100644
--- a/src/c_stubs/SFTime_cstub.c
+++ b/src/c_stubs/SFTime_cstub.c
@@ -86,12 +86,12 @@ sfTime_div(sfTime a, double b)
 }

 static struct custom_operations sfTime_custom_ops = {
-    identifier:  "sfTime struct",
-    finalize:    custom_finalize_default,
-    compare:     custom_compare_default,
-    hash:        custom_hash_default,
-    serialize:   custom_serialize_default,
-    deserialize: custom_deserialize_default
+    .identifier =  "sfTime struct",
+    .finalize =    custom_finalize_default,
+    .compare =     custom_compare_default,
+    .hash =        custom_hash_default,
+    .serialize =   custom_serialize_default,
+    .deserialize = custom_deserialize_default
 };

 value Val_sfTime(sfTime *time)
diff --git a/src/c_stubs/SFWindow_cstub.c b/src/c_stubs/SFWindow_cstub.c
index f10b670..66b98b7 100644
--- a/src/c_stubs/SFWindow_cstub.c
+++ b/src/c_stubs/SFWindow_cstub.c
@@ -85,7 +85,7 @@ caml_sfWindow_createFromHandle(value ml_handle, value ml_settings)

     SfContextSettings_val(&settings, ml_settings);

-    win = sfWindow_createFromHandle(Nativeint_val(ml_handle), &settings);
+    win = sfWindow_createFromHandle((void *) Nativeint_val(ml_handle), &settings);
     if (!win) caml_failwith("SFWindow.createFromHandle");

     return Val_sfWindow(win);

I think we'd need some sort of comparison function that compares each of the fields in the structs to properly address the error. I don't use the C API though, so I don't think I'll dig into this any deeper. Sorry 😕.

[fccm]

The C stubs are not maintained anymore since a while.
Sorry for not explain it in the REAMDE file.
I just added an explanation about it in the README file now.

I was thinking to remove it from the sources, but didn't had time to.

Also I'm not sure if it can interest someone to resurrect it.
(Maybe it's easier to debug C than C++, or for any other reason.)

[reykjalin]

The C stubs are not maintained anymore since a while.
Sorry for not explain it in the REAMDE file.

Don't worry about it! I did see in the README that the C stubs are deprecated. And like I said; I'm not using the C stubs, so this isn't hindering me in any way. The only reason I started looking into it is because of the changes I made in #4 🙂.

Since they're no longer maintained I guess it's no big deal then 😄.

And thank you, by the way, for maintaining these bindings!

I was thinking to remove it from the sources, but didn't had time to.

No rush! The readme already says they're deprecated, so I think it's fine to keep them. Like you said; someone might come along that's interested in maintaining them 🙂