Auto merge of rust-lang#722 - emilio:mangling-panic, r=fitzgen

ir: Don't panic when finding an unknown calling convention until code generation

This unblocks stylo in windows until we get `__thiscall` support in syntex. see rust-lang#541.

Author: bors-servo

src/codegen/mod.rs

@@ -2869,7 +2869,7 @@ impl TryToRustTy for FunctionSig {
 
         let fnty = ast::TyKind::BareFn(P(ast::BareFnTy {
             unsafety: ast::Unsafety::Unsafe,
-            abi: self.abi().expect("Invalid abi for function!"),
+            abi: self.abi().expect("Invalid or unknown ABI for function!"),
             lifetimes: vec![],
             decl: decl,
         }));
@@ -2950,7 +2950,7 @@ impl CodeGenerator for Function {
         };
 
         let item = ForeignModBuilder::new(signature.abi()
-                .expect("Invalid abi for function!"))
+                .expect("Invalid or unknown ABI for function!"))
             .with_foreign_item(foreign_item)
             .build(ctx);
 

src/ir/function.rs

@@ -105,8 +105,7 @@ fn get_abi(cc: CXCallingConv) -> Option<abi::Abi> {
         CXCallingConv_X86FastCall => Some(abi::Abi::Fastcall),
         CXCallingConv_AAPCS => Some(abi::Abi::Aapcs),
         CXCallingConv_X86_64Win64 => Some(abi::Abi::Win64),
-        CXCallingConv_Invalid => None,
-        other => panic!("unsupported calling convention: {:?}", other),
+        _ => None,
     }
 }
 
@@ -297,12 +296,11 @@ impl FunctionSig {
             try!(ty.ret_type().ok_or(ParseError::Continue))
         };
         let ret = Item::from_ty_or_ref(ty_ret_type, cursor, None, ctx);
-        let abi = get_abi(ty.call_conv());
+        let call_conv = ty.call_conv();
+        let abi = get_abi(call_conv);
 
         if abi.is_none() {
-            assert!(cursor.kind() == CXCursor_ObjCInstanceMethodDecl ||
-                    cursor.kind() == CXCursor_ObjCClassMethodDecl,
-                       "Invalid ABI for function signature")
+            warn!("Unknown calling convention: {:?}", call_conv);
         }
 
         Ok(Self::new(ret, args, ty.is_variadic(), abi))