Support "never" return type

src/bindgen/config.rs

@@ -317,6 +317,8 @@ pub struct FunctionConfig {
     pub swift_name_macro: Option<String>,
     /// Sort key for function names
     pub sort_by: SortKey,
+    /// Optional text to output after functions which return `!`.
+    pub no_return: Option<String>,
 }
 
 impl Default for FunctionConfig {
@@ -329,6 +331,7 @@ impl Default for FunctionConfig {
             rename_args: None,
             swift_name_macro: None,
             sort_by: SortKey::Name,
+            no_return: None,
         }
     }
 }

src/bindgen/ir/function.rs

@@ -33,6 +33,7 @@ pub struct Function {
     pub cfg: Option<Cfg>,
     pub annotations: AnnotationSet,
     pub documentation: Documentation,
+    pub never_return: bool,
 }
 
 impl Function {
@@ -46,10 +47,16 @@ impl Function {
     ) -> Result<Function, String> {
         let mut args = sig.inputs.iter().try_skip_map(|x| x.as_ident_and_type())?;
 
+        let mut never_return = false;
         let mut ret = match sig.output {
             syn::ReturnType::Default => Type::Primitive(PrimitiveType::Void),
             syn::ReturnType::Type(_, ref ty) => {
-                Type::load(ty)?.unwrap_or_else(|| Type::Primitive(PrimitiveType::Void))
+                if let syn::Type::Never(_) = ty.as_ref() {
+                    never_return = true;
+                    Type::Primitive(PrimitiveType::Void)
+                } else {
+                    Type::load(ty)?.unwrap_or_else(|| Type::Primitive(PrimitiveType::Void))
+                }
             }
         };
 
@@ -69,6 +76,7 @@ impl Function {
             cfg: Cfg::append(mod_cfg, Cfg::load(attrs)),
             annotations: AnnotationSet::load(attrs)?,
             documentation: Documentation::load(attrs),
+            never_return,
         })
     }
 
@@ -205,6 +213,12 @@ impl Source for Function {
                 write!(out, " {}({})", swift_name_macro, func.swift_name());
             }
 
+            if func.never_return {
+                if let Some(ref no_return_attr) = config.function.no_return {
+                    out.write_fmt(format_args!(" {}", no_return_attr));
+                }
+            }
+
             out.write(";");
 
             condition.write_after(config, out);
@@ -246,6 +260,12 @@ impl Source for Function {
                 write!(out, " {}({})", swift_name_macro, func.swift_name());
             }
 
+            if func.never_return {
+                if let Some(ref no_return_attr) = config.function.no_return {
+                    out.write_fmt(format_args!(" {}", no_return_attr));
+                }
+            }
+
             out.write(";");
 
             condition.write_after(config, out);

tests/expectations/both/fns.c

@@ -11,4 +11,6 @@ typedef struct Fns {
   int8_t (*namedArgsWildcards)(int32_t _, int16_t named, int64_t _1);
 } Fns;
 
+void no_return(void);
+
 void root(Fns _fns);

tests/expectations/both/fns.compat.c

@@ -15,6 +15,8 @@ typedef struct Fns {
 extern "C" {
 #endif // __cplusplus
 
+void no_return(void);
+
 void root(Fns _fns);
 
 #ifdef __cplusplus

tests/expectations/both/function_noreturn.c

@@ -0,0 +1,16 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+#ifndef NO_RETURN_ATTR
+  #ifdef __GNUC__
+    #define NO_RETURN_ATTR __attribute__ ((noreturn))
+  #else // __GNUC__
+    #define NO_RETURN_ATTR
+  #endif // __GNUC__
+#endif // NO_RETURN_ATTR
+
+
+void loop_forever(void) NO_RETURN_ATTR;
+
+uint8_t normal_return(void);

tests/expectations/both/function_noreturn.compat.c

@@ -0,0 +1,24 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+#ifndef NO_RETURN_ATTR
+  #ifdef __GNUC__
+    #define NO_RETURN_ATTR __attribute__ ((noreturn))
+  #else // __GNUC__
+    #define NO_RETURN_ATTR
+  #endif // __GNUC__
+#endif // NO_RETURN_ATTR
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void loop_forever(void) NO_RETURN_ATTR;
+
+uint8_t normal_return(void);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus

tests/expectations/fns.c

@@ -11,4 +11,6 @@ typedef struct {
   int8_t (*namedArgsWildcards)(int32_t _, int16_t named, int64_t _1);
 } Fns;
 
+void no_return(void);
+
 void root(Fns _fns);

tests/expectations/fns.compat.c

@@ -15,6 +15,8 @@ typedef struct {
 extern "C" {
 #endif // __cplusplus
 
+void no_return(void);
+
 void root(Fns _fns);
 
 #ifdef __cplusplus

tests/expectations/fns.cpp

@@ -13,6 +13,8 @@ struct Fns {
 
 extern "C" {
 
+void no_return();
+
 void root(Fns _fns);
 
 } // extern "C"

tests/expectations/function_noreturn.c

@@ -0,0 +1,16 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+#ifndef NO_RETURN_ATTR
+  #ifdef __GNUC__
+    #define NO_RETURN_ATTR __attribute__ ((noreturn))
+  #else // __GNUC__
+    #define NO_RETURN_ATTR
+  #endif // __GNUC__
+#endif // NO_RETURN_ATTR
+
+
+void loop_forever(void) NO_RETURN_ATTR;
+
+uint8_t normal_return(void);

tests/expectations/function_noreturn.compat.c

@@ -0,0 +1,24 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+#ifndef NO_RETURN_ATTR
+  #ifdef __GNUC__
+    #define NO_RETURN_ATTR __attribute__ ((noreturn))
+  #else // __GNUC__
+    #define NO_RETURN_ATTR
+  #endif // __GNUC__
+#endif // NO_RETURN_ATTR
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void loop_forever(void) NO_RETURN_ATTR;
+
+uint8_t normal_return(void);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus

tests/expectations/function_noreturn.cpp

@@ -0,0 +1,20 @@
+#include <cstdarg>
+#include <cstdint>
+#include <cstdlib>
+#include <new>
+#ifndef NO_RETURN_ATTR
+  #ifdef __GNUC__
+    #define NO_RETURN_ATTR __attribute__ ((noreturn))
+  #else // __GNUC__
+    #define NO_RETURN_ATTR
+  #endif // __GNUC__
+#endif // NO_RETURN_ATTR
+
+
+extern "C" {
+
+void loop_forever() NO_RETURN_ATTR;
+
+uint8_t normal_return();
+
+} // extern "C"

tests/expectations/tag/fns.c

@@ -11,4 +11,6 @@ struct Fns {
   int8_t (*namedArgsWildcards)(int32_t _, int16_t named, int64_t _1);
 };
 
+void no_return(void);
+
 void root(struct Fns _fns);

tests/expectations/tag/fns.compat.c

@@ -15,6 +15,8 @@ struct Fns {
 extern "C" {
 #endif // __cplusplus
 
+void no_return(void);
+
 void root(struct Fns _fns);
 
 #ifdef __cplusplus

tests/expectations/tag/function_noreturn.c

@@ -0,0 +1,16 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+#ifndef NO_RETURN_ATTR
+  #ifdef __GNUC__
+    #define NO_RETURN_ATTR __attribute__ ((noreturn))
+  #else // __GNUC__
+    #define NO_RETURN_ATTR
+  #endif // __GNUC__
+#endif // NO_RETURN_ATTR
+
+
+void loop_forever(void) NO_RETURN_ATTR;
+
+uint8_t normal_return(void);

tests/expectations/tag/function_noreturn.compat.c

@@ -0,0 +1,24 @@
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+#ifndef NO_RETURN_ATTR
+  #ifdef __GNUC__
+    #define NO_RETURN_ATTR __attribute__ ((noreturn))
+  #else // __GNUC__
+    #define NO_RETURN_ATTR
+  #endif // __GNUC__
+#endif // NO_RETURN_ATTR
+
+
+#ifdef __cplusplus
+extern "C" {
+#endif // __cplusplus
+
+void loop_forever(void) NO_RETURN_ATTR;
+
+uint8_t normal_return(void);
+
+#ifdef __cplusplus
+} // extern "C"
+#endif // __cplusplus

tests/rust/fns.rs

@@ -9,3 +9,8 @@ pub struct Fns {
 
 #[no_mangle]
 pub extern "C" fn root(_fns: Fns) {}
+
+#[no_mangle]
+pub extern "C" fn no_return() -> ! {
+    loop {}
+}

tests/rust/function_noreturn.rs

@@ -0,0 +1,9 @@
+#[no_mangle]
+pub extern fn loop_forever() -> ! {
+    loop {}
+}
+
+#[no_mangle]
+pub extern fn normal_return() -> u8 {
+    0
+}

tests/rust/function_noreturn.toml

@@ -0,0 +1,12 @@
+after_includes = """
+#ifndef NO_RETURN_ATTR
+  #ifdef __GNUC__
+    #define NO_RETURN_ATTR __attribute__ ((noreturn))
+  #else // __GNUC__
+    #define NO_RETURN_ATTR
+  #endif // __GNUC__
+#endif // NO_RETURN_ATTR
+"""
+
+[fn]
+no_return = "NO_RETURN_ATTR"