From: Matt Corallo <git@bluematt.me>
Date: Wed, 22 Sep 2021 23:13:34 +0000 (+0000)
Subject: Map core::convert::Infallible to a similar manually-defined struct
X-Git-Tag: v0.0.101.1~1^2~9
X-Git-Url: http://git.bitcoin.ninja/?a=commitdiff_plain;h=2bdcba6c2297ca3cabc45c484e35c058ee7d4739;p=ldk-c-bindings

Map core::convert::Infallible to a similar manually-defined struct
---

diff --git a/c-bindings-gen/src/main.rs b/c-bindings-gen/src/main.rs
index 1572b31..38704b2 100644
--- a/c-bindings-gen/src/main.rs
+++ b/c-bindings-gen/src/main.rs
@@ -33,7 +33,7 @@ mod blocks;
 use types::*;
 use blocks::*;
 
-const DEFAULT_IMPORTS: &'static str = "\nuse std::str::FromStr;\nuse std::ffi::c_void;\nuse bitcoin::hashes::Hash;\nuse crate::c_types::*;\n";
+const DEFAULT_IMPORTS: &'static str = "\nuse std::str::FromStr;\nuse std::ffi::c_void;\nuse core::convert::Infallible;\nuse bitcoin::hashes::Hash;\nuse crate::c_types::*;\n";
 
 // *************************************
 // *** Manually-expanded conversions ***
diff --git a/c-bindings-gen/src/types.rs b/c-bindings-gen/src/types.rs
index b1224a9..d15cec2 100644
--- a/c-bindings-gen/src/types.rs
+++ b/c-bindings-gen/src/types.rs
@@ -889,6 +889,8 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 			"std::time::SystemTime" => Some("u64"),
 			"std::io::Error" => Some("crate::c_types::IOError"),
 
+			"core::convert::Infallible" => Some("crate::c_types::NotConstructable"),
+
 			"bech32::u5" => Some("crate::c_types::u5"),
 			"core::num::NonZeroU8" => Some("u8"),
 
@@ -967,6 +969,8 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 			// Note that we'll panic for String if is_ref, as we only have non-owned memory, we
 			// cannot create a &String.
 
+			"core::convert::Infallible" => Some("panic!(\"You must never construct a NotConstructable! : "),
+
 			"std::time::Duration"|"core::time::Duration" => Some("std::time::Duration::from_secs("),
 			"std::time::SystemTime" => Some("(::std::time::SystemTime::UNIX_EPOCH + std::time::Duration::from_secs("),
 
@@ -1045,6 +1049,8 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 			"alloc::string::String"|"String" => Some(".into_string()"),
 			"std::io::Error" if !is_ref => Some(".to_rust()"),
 
+			"core::convert::Infallible" => Some("\")"),
+
 			"std::time::Duration"|"core::time::Duration" => Some(")"),
 			"std::time::SystemTime" => Some("))"),
 
@@ -1136,6 +1142,8 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 			"std::time::SystemTime" => Some(""),
 			"std::io::Error" if !is_ref => Some("crate::c_types::IOError::from_rust("),
 
+			"core::convert::Infallible" => Some("panic!(\"Cannot construct an Infallible: "),
+
 			"bech32::u5" => Some(""),
 
 			"bitcoin::secp256k1::key::PublicKey"|"bitcoin::secp256k1::PublicKey"|"secp256k1::key::PublicKey"
@@ -1208,6 +1216,8 @@ impl<'a, 'c: 'a> TypeResolver<'a, 'c> {
 			"std::time::SystemTime" => Some(".duration_since(::std::time::SystemTime::UNIX_EPOCH).expect(\"Times must be post-1970\").as_secs()"),
 			"std::io::Error" if !is_ref => Some(")"),
 
+			"core::convert::Infallible" => Some("\")"),
+
 			"bech32::u5" => Some(".into()"),
 
 			"bitcoin::secp256k1::key::PublicKey"|"bitcoin::secp256k1::PublicKey"|"secp256k1::key::PublicKey"
diff --git a/lightning-c-bindings/src/c_types/mod.rs b/lightning-c-bindings/src/c_types/mod.rs
index 5db6dda..18d8a08 100644
--- a/lightning-c-bindings/src/c_types/mod.rs
+++ b/lightning-c-bindings/src/c_types/mod.rs
@@ -17,6 +17,16 @@ use std::convert::TryInto; // Bindings need at least rustc 1.34
 
 use std::io::{Cursor, Read}; // TODO: We should use core2 here when we support no_std
 
+#[repr(C)]
+/// A dummy struct of which an instance must never exist.
+/// This corresponds to the Rust type `Infallible`, or, in unstable rust, `!`
+pub struct NotConstructable {
+	_priv_thing: core::convert::Infallible,
+}
+impl From<core::convert::Infallible> for NotConstructable {
+	fn from(_: core::convert::Infallible) -> Self { unreachable!(); }
+}
+
 /// Integer in the range `0..32`
 #[derive(PartialEq, Eq, Copy, Clone)]
 #[allow(non_camel_case_types)]