Add support for the `"C-unwind"` ABI (#2334)

* Add support for the `"C-unwind"` ABI

This allows using `"C-unwind"` as an ABI override if the rust target is
nightly.

7 files changed, 49 insertions, 2 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index baa5cb20..5f559a3f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -150,6 +150,8 @@
 ## Added
  * new feature: `--override-abi` flag to override the ABI used by functions
    matching a regular expression.
+ * new feature: allow using the `C-unwind` ABI in `--override-abi` on nightly
+   rust.
 
 ## Changed
 
diff --git a/bindgen-cli/options.rs b/bindgen-cli/options.rs
index c186cfd9..90f38cb2 100644
--- a/bindgen-cli/options.rs
+++ b/bindgen-cli/options.rs
@@ -570,7 +570,7 @@ where
                 .help("Deduplicates extern blocks."),
             Arg::new("override-abi")
                 .long("override-abi")
-                .help("Overrides the ABI of functions matching <regex>. The <override> value must be of the shape <abi>:<regex> where <abi> can be one of C, stdcall, fastcall, thiscall, aapcs or win64.")
+                .help("Overrides the ABI of functions matching <regex>. The <override> value must be of the shape <regex>=<abi> where <abi> can be one of C, stdcall, fastcall, thiscall, aapcs, win64 or C-unwind.")
                 .value_name("override")
                 .multiple_occurrences(true)
                 .number_of_values(1),
diff --git a/bindgen-tests/tests/expectations/tests/c-unwind-abi-override-nightly.rs b/bindgen-tests/tests/expectations/tests/c-unwind-abi-override-nightly.rs
new file mode 100644
index 00000000..6b34192f
--- /dev/null
+++ b/bindgen-tests/tests/expectations/tests/c-unwind-abi-override-nightly.rs
@@ -0,0 +1,18 @@
+#![allow(
+    dead_code,
+    non_snake_case,
+    non_camel_case_types,
+    non_upper_case_globals
+)]
+#![cfg(feature = "nightly")]
+#![feature(abi_thiscall)]
+
+extern "C-unwind" {
+    pub fn foo();
+}
+extern "C-unwind" {
+    pub fn bar();
+}
+extern "C" {
+    pub fn baz();
+}
diff --git a/bindgen-tests/tests/headers/c-unwind-abi-override-nightly.h b/bindgen-tests/tests/headers/c-unwind-abi-override-nightly.h
new file mode 100644
index 00000000..ac79a420
--- /dev/null
+++ b/bindgen-tests/tests/headers/c-unwind-abi-override-nightly.h
@@ -0,0 +1,5 @@
+// bindgen-flags: --override-abi="foo|bar=C-unwind" --rust-target=nightly --raw-line '#![cfg(feature = "nightly")]' --raw-line '#![feature(abi_thiscall)]'
+
+void foo();
+void bar();
+void baz();
diff --git a/bindgen/codegen/mod.rs b/bindgen/codegen/mod.rs
index 4e90102d..d0c19136 100644
--- a/bindgen/codegen/mod.rs
+++ b/bindgen/codegen/mod.rs
@@ -2483,6 +2483,9 @@ impl MethodCodegen for Method {
             ClangAbi::Known(Abi::Vectorcall) => {
                 ctx.options().rust_features().vectorcall_abi
             }
+            ClangAbi::Known(Abi::CUnwind) => {
+                ctx.options().rust_features().c_unwind_abi
+            }
             _ => true,
         };
 
@@ -4009,6 +4012,12 @@ impl TryToRustTy for FunctionSig {
                 warn!("Skipping function with vectorcall ABI that isn't supported by the configured Rust target");
                 Ok(proc_macro2::TokenStream::new())
             }
+            ClangAbi::Known(Abi::CUnwind)
+                if !ctx.options().rust_features().c_unwind_abi =>
+            {
+                warn!("Skipping function with C-unwind ABI that isn't supported by the configured Rust target");
+                Ok(proc_macro2::TokenStream::new())
+            }
             _ => Ok(quote! {
                 unsafe extern #abi fn ( #( #arguments ),* ) #ret
             }),
@@ -4120,6 +4129,12 @@ impl CodeGenerator for Function {
                 warn!("Skipping function with vectorcall ABI that isn't supported by the configured Rust target");
                 return None;
             }
+            ClangAbi::Known(Abi::CUnwind)
+                if !ctx.options().rust_features().c_unwind_abi =>
+            {
+                warn!("Skipping function with C-unwind ABI that isn't supported by the configured Rust target");
+                return None;
+            }
             ClangAbi::Known(Abi::Win64) if signature.is_variadic() => {
                 warn!("Skipping variadic function with Win64 ABI that isn't supported");
                 return None;
diff --git a/bindgen/features.rs b/bindgen/features.rs
index 4f05b9eb..9f6535aa 100644
--- a/bindgen/features.rs
+++ b/bindgen/features.rs
@@ -133,6 +133,7 @@ macro_rules! rust_target_base {
             /// Nightly rust
             ///  * `thiscall` calling convention ([Tracking issue](https://github.com/rust-lang/rust/issues/42202))
             ///  * `vectorcall` calling convention (no tracking issue)
+            ///  * `c_unwind` calling convention ([Tracking issue](https://github.com/rust-lang/rust/issues/74990))
             => Nightly => nightly;
         );
     }
@@ -242,6 +243,7 @@ rust_feature_def!(
     Nightly {
         => thiscall_abi;
         => vectorcall_abi;
+        => c_unwind_abi;
     }
 );
 
@@ -291,7 +293,8 @@ mod test {
                 f_nightly.maybe_uninit &&
                 f_nightly.repr_align &&
                 f_nightly.thiscall_abi &&
-                f_nightly.vectorcall_abi
+                f_nightly.vectorcall_abi &&
+                f_nightly.c_unwind_abi
         );
     }
 
diff --git a/bindgen/ir/function.rs b/bindgen/ir/function.rs
index 8a70d60a..52346f6c 100644
--- a/bindgen/ir/function.rs
+++ b/bindgen/ir/function.rs
@@ -188,6 +188,8 @@ pub enum Abi {
     Aapcs,
     /// The "win64" ABI.
     Win64,
+    /// The "C-unwind" ABI.
+    CUnwind,
 }
 
 impl FromStr for Abi {
@@ -202,6 +204,7 @@ impl FromStr for Abi {
             "vectorcall" => Ok(Self::Vectorcall),
             "aapcs" => Ok(Self::Aapcs),
             "win64" => Ok(Self::Win64),
+            "C-unwind" => Ok(Self::CUnwind),
             _ => Err(format!("Invalid or unknown ABI {:?}", s)),
         }
     }
@@ -217,6 +220,7 @@ impl std::fmt::Display for Abi {
             Self::Vectorcall => "vectorcall",
             Self::Aapcs => "aapcs",
             Self::Win64 => "win64",
+            Self::CUnwind => "C-unwind",
         };
 
         s.fmt(f)