Add support for c_void as an opaque C++ type

Author: dpaoliello

.vscode/settings.json

@@ -1,5 +1,8 @@
 {
     "search.exclude": {
         "**/target": true
-    }
+    },
+    "vscode-nmake-tools.workspaceBuildDirectories": [
+        "."
+    ]
 }

gen/src/write.rs

@@ -211,7 +211,7 @@ fn pick_includes_and_builtins(out: &mut OutFile, apis: &[Api]) {
                 Some(Isize) => out.builtin.rust_isize = true,
                 Some(CxxString) => out.include.string = true,
                 Some(RustString) => out.builtin.rust_string = true,
-                Some(Bool) | Some(Char) | Some(F32) | Some(F64) | None => {}
+                Some(Bool) | Some(Char) | Some(F32) | Some(F64) | Some(Cvoid) | None => {}
             },
             Type::RustBox(_) => out.builtin.rust_box = true,
             Type::RustVec(_) => out.builtin.rust_vec = true,
@@ -1323,6 +1323,7 @@ fn write_atom(out: &mut OutFile, atom: Atom) {
         F64 => write!(out, "double"),
         CxxString => write!(out, "::std::string"),
         RustString => write!(out, "::rust::String"),
+        Cvoid => write!(out, "void"),
     }
 }
 

src/extern_type.rs

@@ -2,6 +2,7 @@ use self::kind::{Kind, Opaque, Trivial};
 use crate::CxxString;
 #[cfg(feature = "alloc")]
 use alloc::string::String;
+use core::ffi::c_void;
 
 /// A type for which the layout is determined by its C++ definition.
 ///
@@ -222,4 +223,5 @@ impl_extern_type! {
 
     [Opaque]
     CxxString = "std::string"
+    c_void = "void"
 }

syntax/atom.rs

@@ -20,6 +20,7 @@ pub enum Atom {
     F64,
     CxxString,
     RustString,
+    Cvoid,
 }
 
 impl Atom {
@@ -46,6 +47,7 @@ impl Atom {
             "f64" => Some(F64),
             "CxxString" => Some(CxxString),
             "String" => Some(RustString),
+            "c_void" => Some(Cvoid),
             _ => None,
         }
     }
@@ -77,6 +79,7 @@ impl AsRef<str> for Atom {
             F64 => "f64",
             CxxString => "CxxString",
             RustString => "String",
+            Cvoid => "c_void",
         }
     }
 }

syntax/check.rs

@@ -126,7 +126,7 @@ fn check_type_rust_vec(cx: &mut Check, ty: &Ty1) {
                 None | Some(Bool) | Some(Char) | Some(U8) | Some(U16) | Some(U32) | Some(U64)
                 | Some(Usize) | Some(I8) | Some(I16) | Some(I32) | Some(I64) | Some(Isize)
                 | Some(F32) | Some(F64) | Some(RustString) => return,
-                Some(CxxString) => {}
+                Some(CxxString) | Some(Cvoid) => {}
             }
         }
         Type::Str(_) => return,
@@ -165,7 +165,7 @@ fn check_type_shared_ptr(cx: &mut Check, ptr: &Ty1) {
             None | Some(Bool) | Some(U8) | Some(U16) | Some(U32) | Some(U64) | Some(Usize)
             | Some(I8) | Some(I16) | Some(I32) | Some(I64) | Some(Isize) | Some(F32)
             | Some(F64) | Some(CxxString) => return,
-            Some(Char) | Some(RustString) => {}
+            Some(Char) | Some(RustString) | Some(Cvoid) => {}
         }
     } else if let Type::CxxVector(_) = &ptr.inner {
         cx.error(ptr, "std::shared_ptr<std::vector> is not supported yet");
@@ -186,7 +186,7 @@ fn check_type_weak_ptr(cx: &mut Check, ptr: &Ty1) {
             None | Some(Bool) | Some(U8) | Some(U16) | Some(U32) | Some(U64) | Some(Usize)
             | Some(I8) | Some(I16) | Some(I32) | Some(I64) | Some(Isize) | Some(F32)
             | Some(F64) | Some(CxxString) => return,
-            Some(Char) | Some(RustString) => {}
+            Some(Char) | Some(RustString) | Some(Cvoid) => {}
         }
     } else if let Type::CxxVector(_) = &ptr.inner {
         cx.error(ptr, "std::weak_ptr<std::vector> is not supported yet");
@@ -211,7 +211,7 @@ fn check_type_cxx_vector(cx: &mut Check, ptr: &Ty1) {
             | Some(I16) | Some(I32) | Some(I64) | Some(Isize) | Some(F32) | Some(F64)
             | Some(CxxString) => return,
             Some(Char) => { /* todo */ }
-            Some(Bool) | Some(RustString) => {}
+            Some(Bool) | Some(RustString) | Some(Cvoid) => {}
         }
     }
 

syntax/pod.rs

@@ -10,7 +10,7 @@ impl<'a> Types<'a> {
                     match atom {
                         Bool | Char | U8 | U16 | U32 | U64 | Usize | I8 | I16 | I32 | I64
                         | Isize | F32 | F64 => true,
-                        CxxString | RustString => false,
+                        CxxString | RustString | Cvoid => false,
                     }
                 } else if let Some(strct) = self.structs.get(ident) {
                     derive::contains(&strct.derives, Trait::Copy)

syntax/tokens.rs

@@ -20,6 +20,9 @@ impl ToTokens for Type {
                 } else if ident.rust == RustString {
                     let span = ident.rust.span();
                     tokens.extend(quote_spanned!(span=> ::cxx::alloc::string::));
+                } else if ident.rust == Cvoid {
+                    let span = ident.rust.span();
+                    tokens.extend(quote_spanned!(span=> ::core::ffi::));
                 }
                 ident.to_tokens(tokens);
             }

tests/ffi/lib.rs

@@ -205,6 +205,8 @@ pub mod ffi {
 
         fn c_get_use_count(weak: &WeakPtr<C>) -> usize;
 
+        unsafe fn c_takes_void_star(value: *const c_void);
+
         #[rust_name = "i32_overloaded_method"]
         fn cOverloadedMethod(&self, x: i32) -> String;
         #[rust_name = "str_overloaded_method"]

tests/ffi/tests.cc

@@ -598,6 +598,12 @@ size_t c_get_use_count(const std::weak_ptr<C> &weak) noexcept {
   return weak.use_count();
 }
 
+void c_takes_void_star(const void *value) noexcept {
+  if (value == nullptr) {
+    cxx_test_suite_set_correct();
+  }
+}
+
 extern "C" C *cxx_test_suite_get_unique_ptr() noexcept {
   return std::unique_ptr<C>(new C{2020}).release();
 }

tests/ffi/tests.h

@@ -190,6 +190,8 @@ const rust::Vec<uint8_t> &c_try_return_ref_rust_vec(const C &c);
 
 size_t c_get_use_count(const std::weak_ptr<C> &weak) noexcept;
 
+void c_takes_void_star(const void *value) noexcept;
+
 void c_take_trivial_ptr(std::unique_ptr<D> d);
 void c_take_trivial_ref(const D &d);
 void c_take_trivial_mut_ref(D &d);

tests/test.rs

@@ -361,6 +361,8 @@ fn test_extern_opaque() {
     let f = ffi2::c_return_ns_opaque_ptr();
     check!(ffi2::c_take_opaque_ns_ref(f.as_ref().unwrap()));
     check!(ffi2::c_take_opaque_ns_ptr(f));
+
+    check!(unsafe { ffi::c_takes_void_star(core::ptr::null()) });
 }
 
 #[test]