zig

commit 35c6fe665c7f3f8ba14aaee97c832000cbf5ddc2 (tree)
parent 332020f3103366d54c518be2e8a57cf440a254de
Author: Manlio Perillo <manlio.perillo@gmail.com>
Date:   Mon, 12 Dec 2022 11:32:48 +0100

langref: document extern variadic functions

Add a new subsection within the C section, documenting extern variadic
functions.

Diffstat:
M
doc/langref.html.in
 | 
27
+++++++++++++++++++++++++++

1 file changed, 27 insertions(+), 0 deletions(-)
diff --git a/doc/langref.html.in b/doc/langref.html.in
@@ -10802,6 +10802,33 @@ pub const MAKELOCAL = @compileError("unable to translate C expr: unexpected toke
         <p>{#syntax#}ptr_to_struct_array[index].struct_member{#endsyntax#}</p>
       {#header_close#}
 
+      {#header_open|C Variadic Functions#}
+      <p>Zig supports extern variadic functions.</p>
+      {#code_begin|test|variadic_function#}
+      {#link_libc#}
+      {#code_verbose_cimport#}
+const std = @import("std");
+const testing = std.testing;
+
+pub extern "c" fn printf(format: [*:0]const u8, ...) c_int;
+
+test "variadic function" {
+    try testing.expect(printf("Hello, world!\n") == 14);
+    try testing.expect(@typeInfo(@TypeOf(printf)).Fn.is_var_args);
+}
+      {#code_end#}
+      <p>
+        Non extern variadic functions are currently not implemented, but there
+        is an accepted proposal. See <a href="https://github.com/ziglang/zig/issues/515">#515</a>.
+      </p>
+      {#code_begin|obj_err|non-extern function is variadic#}
+export fn printf(format: [*:0]const u8, ...) c_int {
+    _ = format;
+
+    return 0;
+}
+      {#code_end#}
+      {#header_close#}
       {#header_open|Exporting a C Library#}
       <p>
       One of the primary use cases for Zig is exporting a library with the C ABI for other programming languages