Allow extern "C"

riscv-rt/CHANGELOG.md

@@ -44,6 +44,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
   `a2` is preserved in `a5`, as there are only two callee-saved registers.
   New documentation of startup functions (`_mp_hook` and `__pre_init`) now provide
   additional implementation guidelines to ensure a correct behavior of the runtime.
+- Allow `extern "C"` functions for exceptions, core-interrupts and external-interrupts.
 
 ### Removed
 

riscv-rt/macros/src/lib.rs

@@ -688,8 +688,8 @@ impl RiscvPacItem {
 
     fn valid_signature(&self) -> &str {
         match self {
-            Self::Exception => "`[unsafe] fn([&[mut] riscv_rt::TrapFrame]) [-> !]`",
-            _ => "`[unsafe] fn() [-> !]`",
+            Self::Exception => "`[unsafe] [extern \"C\"] fn([&[mut] riscv_rt::TrapFrame]) [-> !]`",
+            _ => "`[unsafe] [extern \"C\"] fn() [-> !]`",
         }
     }
 
@@ -719,7 +719,14 @@ impl RiscvPacItem {
             && f.sig.constness.is_none()
             && f.sig.asyncness.is_none()
             && f.vis == Visibility::Inherited
-            && f.sig.abi.is_none()
+            && match &f.sig.abi {
+                None => true,
+                Some(syn::Abi {
+                    extern_token: _,
+                    name: Some(name),
+                }) if name.value() == "C" => true,
+                _ => false,
+            }
             && f.sig.generics.params.is_empty()
             && f.sig.generics.where_clause.is_none()
             && f.sig.variadic.is_none()
@@ -741,7 +748,7 @@ impl RiscvPacItem {
 #[proc_macro_attribute]
 /// Attribute to declare an exception handler.
 ///
-/// The function must have the signature `[unsafe] fn([&[mut] riscv_rt::TrapFrame]) [-> !]`.
+/// The function must have the signature `[unsafe] [extern "C"] fn([&[mut] riscv_rt::TrapFrame]) [-> !]`.
 ///
 /// The argument of the macro must be a path to a variant of an enum that implements the `riscv_rt::ExceptionNumber` trait.
 ///
@@ -760,7 +767,7 @@ pub fn exception(args: TokenStream, input: TokenStream) -> TokenStream {
 #[proc_macro_attribute]
 /// Attribute to declare a core interrupt handler.
 ///
-/// The function must have the signature `[unsafe] fn() [-> !]`.
+/// The function must have the signature `[unsafe] [extern "C"] fn() [-> !]`.
 ///
 /// The argument of the macro must be a path to a variant of an enum that implements the `riscv_rt::CoreInterruptNumber` trait.
 ///
@@ -787,7 +794,7 @@ pub fn core_interrupt(args: TokenStream, input: TokenStream) -> TokenStream {
 #[proc_macro_attribute]
 /// Attribute to declare an external interrupt handler.
 ///
-/// The function must have the signature `[unsafe] fn() [-> !]`.
+/// The function must have the signature `[unsafe] [extern "C"] fn() [-> !]`.
 ///
 /// The argument of the macro must be a path to a variant of an enum that implements the `riscv_rt::ExternalInterruptNumber` trait.
 ///

tests-trybuild/tests/riscv-rt/core_interrupt/fail_signatures.stderr

@@ -1,16 +1,16 @@
-error: `#[core_interrupt]` function must have signature `[unsafe] fn() [-> !]`
+error: `#[core_interrupt]` function must have signature `[unsafe] [extern "C"] fn() [-> !]`
  --> tests/riscv-rt/core_interrupt/fail_signatures.rs:2:1
   |
 2 | fn my_interrupt(code: usize) {}
   | ^^
 
-error: `#[core_interrupt]` function must have signature `[unsafe] fn() [-> !]`
+error: `#[core_interrupt]` function must have signature `[unsafe] [extern "C"] fn() [-> !]`
  --> tests/riscv-rt/core_interrupt/fail_signatures.rs:5:1
   |
 5 | fn my_other_interrupt() -> usize {}
   | ^^
 
-error: `#[core_interrupt]` function must have signature `[unsafe] fn() [-> !]`
+error: `#[core_interrupt]` function must have signature `[unsafe] [extern "C"] fn() [-> !]`
  --> tests/riscv-rt/core_interrupt/fail_signatures.rs:8:1
   |
 8 | async fn my_async_interrupt() {}

tests-trybuild/tests/riscv-rt/exception/fail_signatures.stderr

@@ -1,16 +1,16 @@
-error: `#[exception]` function must have signature `[unsafe] fn([&[mut] riscv_rt::TrapFrame]) [-> !]`
+error: `#[exception]` function must have signature `[unsafe] [extern "C"] fn([&[mut] riscv_rt::TrapFrame]) [-> !]`
  --> tests/riscv-rt/exception/fail_signatures.rs:2:1
   |
 2 | fn my_exception(code: usize) {}
   | ^^
 
-error: `#[exception]` function must have signature `[unsafe] fn([&[mut] riscv_rt::TrapFrame]) [-> !]`
+error: `#[exception]` function must have signature `[unsafe] [extern "C"] fn([&[mut] riscv_rt::TrapFrame]) [-> !]`
  --> tests/riscv-rt/exception/fail_signatures.rs:5:1
   |
 5 | fn my_other_exception(trap_frame: &riscv_rt::TrapFrame, code: usize) {}
   | ^^
 
-error: `#[exception]` function must have signature `[unsafe] fn([&[mut] riscv_rt::TrapFrame]) [-> !]`
+error: `#[exception]` function must have signature `[unsafe] [extern "C"] fn([&[mut] riscv_rt::TrapFrame]) [-> !]`
  --> tests/riscv-rt/exception/fail_signatures.rs:8:1
   |
 8 | async fn my_async_exception(trap_frame: &riscv_rt::TrapFrame, code: usize) {}

tests-trybuild/tests/riscv-rt/external_interrupt/fail_signatures.stderr

@@ -1,16 +1,16 @@
-error: `#[external_interrupt]` function must have signature `[unsafe] fn() [-> !]`
+error: `#[external_interrupt]` function must have signature `[unsafe] [extern "C"] fn() [-> !]`
   --> tests/riscv-rt/external_interrupt/fail_signatures.rs:31:1
    |
 31 | fn my_interrupt() -> usize {}
    | ^^
 
-error: `#[external_interrupt]` function must have signature `[unsafe] fn() [-> !]`
+error: `#[external_interrupt]` function must have signature `[unsafe] [extern "C"] fn() [-> !]`
   --> tests/riscv-rt/external_interrupt/fail_signatures.rs:34:1
    |
 34 | fn my_other_interrupt(code: usize) -> usize {}
    | ^^
 
-error: `#[external_interrupt]` function must have signature `[unsafe] fn() [-> !]`
+error: `#[external_interrupt]` function must have signature `[unsafe] [extern "C"] fn() [-> !]`
   --> tests/riscv-rt/external_interrupt/fail_signatures.rs:37:1
    |
 37 | async fn my_async_interrupt(code: usize) -> usize {}