[bindings] Pass GenericTypes through to write_template_generic

[rust-lightning] / c-bindings-gen / src / main.rs

diff --git a/c-bindings-gen/src/main.rs b/c-bindings-gen/src/main.rs
index 6c1c8a246b30096df058814bb5965caa38ce0b4c..7917c36d841256cc2c4cec5f5dba74cdc5fa1d4c 100644 (file)
--- a/c-bindings-gen/src/main.rs
+++ b/c-bindings-gen/src/main.rs
@@ -600,6 +600,21 @@ fn writeln_impl<W: std::io::Write>(w: &mut W, i: &syn::ItemImpl, types: &mut Typ
                                                        ExportStatus::Export => {},
                                                        ExportStatus::NoExport|ExportStatus::TestOnly => return,
                                                }
+
+                                               // For cases where we have a concrete native object which implements a
+                                               // trait and need to return the C-mapped version of the trait, provide a
+                                               // From<> implementation which does all the work to ensure free is handled
+                                               // properly. This way we can call this method from deep in the
+                                               // type-conversion logic without actually knowing the concrete native type.
+                                               writeln!(w, "impl From<native{}> for crate::{} {{", ident, full_trait_path).unwrap();
+                                               writeln!(w, "\tfn from(obj: native{}) -> Self {{", ident).unwrap();
+                                               writeln!(w, "\t\tlet mut rust_obj = {} {{ inner: Box::into_raw(Box::new(obj)), is_owned: true }};", ident).unwrap();
+                                               writeln!(w, "\t\tlet mut ret = {}_as_{}(&rust_obj);", ident, trait_obj.ident).unwrap();
+                                               writeln!(w, "\t\t// We want to free rust_obj when ret gets drop()'d, not rust_obj, so wipe rust_obj's pointer and set ret's free() fn").unwrap();
+                                               writeln!(w, "\t\trust_obj.inner = std::ptr::null_mut();").unwrap();
+                                               writeln!(w, "\t\tret.free = Some({}_free_void);", ident).unwrap();
+                                               writeln!(w, "\t\tret\n\t}}\n}}").unwrap();
+
                                                write!(w, "#[no_mangle]\npub extern \"C\" fn {}_as_{}(this_arg: *const {}) -> crate::{} {{\n", ident, trait_obj.ident, ident, full_trait_path).unwrap();
                                                writeln!(w, "\tcrate::{} {{", full_trait_path).unwrap();
                                                writeln!(w, "\t\tthis_arg: unsafe {{ (*this_arg).inner as *mut c_void }},").unwrap();