nac3core: exception type check and codegen

nac3ast/src/location.rs

@@ -3,7 +3,7 @@ use crate::ast_gen::StrRef;
 use std::fmt;
 
 #[derive(Clone, Copy, Debug, PartialEq)]
-pub struct FileName(StrRef);
+pub struct FileName(pub StrRef);
 impl Default for FileName {
     fn default() -> Self {
         FileName("unknown".into())
@@ -19,9 +19,9 @@ impl From<String> for FileName {
 /// A location somewhere in the sourcecode.
 #[derive(Clone, Copy, Debug, Default, PartialEq)]
 pub struct Location {
-    row: usize,
+    pub row: usize,
-    column: usize,
+    pub column: usize,
-    file: FileName
+    pub file: FileName
 }
 
 impl fmt::Display for Location {

nac3core/src/codegen/stmt.rs

@@ -394,6 +394,48 @@ pub fn gen_if<'ctx, 'a, G: CodeGenerator>(
     }
 }
 
+pub fn final_proxy<'ctx, 'a>(
+    ctx: &mut CodeGenContext<'ctx, 'a>,
+    target: BasicBlock<'ctx>,
+    block: BasicBlock<'ctx>,
+) {
+    let (final_state, final_targets, final_paths) = ctx.outer_final.as_mut().unwrap();
+    let prev = ctx.builder.get_insert_block().unwrap();
+    ctx.builder.position_at_end(block);
+    unsafe {
+        ctx.builder.build_store(*final_state, target.get_address().unwrap());
+    }
+    ctx.builder.position_at_end(prev);
+    final_targets.push(target);
+    final_paths.push(block);
+}
+
+pub fn get_builtins<'ctx, 'a, G: CodeGenerator>(
+    generator: &mut G,
+    ctx: &mut CodeGenContext<'ctx, 'a>,
+    symbol: &str,
+) -> FunctionValue<'ctx> {
+    ctx.module.get_function(symbol).unwrap_or_else(|| {
+        let ty = match symbol {
+            "__artiq_raise" => ctx.ctx.void_type().fn_type(
+                &[ctx.get_llvm_type(generator, ctx.primitives.exception).into()],
+                false,
+            ),
+            "__artiq_resume" => ctx.ctx.void_type().fn_type(&[], false),
+            "__artiq_end_catch" => ctx.ctx.void_type().fn_type(&[], false),
+            _ => unimplemented!(),
+        };
+        let fun = ctx.module.add_function(symbol, ty, None);
+        if symbol == "__artiq_raise" || symbol == "__artiq_resume" {
+            fun.add_attribute(
+                AttributeLoc::Function,
+                ctx.ctx.create_enum_attribute(Attribute::get_named_enum_kind_id("noreturn"), 1),
+            );
+        }
+        fun
+    })
+}
+
 pub fn exn_constructor<'ctx, 'a>(
     ctx: &mut CodeGenContext<'ctx, 'a>,
     obj: Option<(Type, ValueEnum<'ctx>)>,
@@ -459,6 +501,352 @@ pub fn exn_constructor<'ctx, 'a>(
     Some(zelf.into())
 }
 
+pub fn gen_raise<'ctx, 'a, G: CodeGenerator>(
+    generator: &mut G,
+    ctx: &mut CodeGenContext<'ctx, 'a>,
+    exception: Option<&BasicValueEnum<'ctx>>,
+    loc: Location,
+) {
+    if let Some(exception) = exception {
+        unsafe {
+            let int32 = ctx.ctx.i32_type();
+            let zero = int32.const_zero();
+            let exception = exception.into_pointer_value();
+            let file_ptr = ctx.builder.build_in_bounds_gep(exception, &[zero, int32.const_int(1, false)], "file_ptr");
+            let filename = ctx.gen_string(generator, loc.file.0);
+            ctx.builder.build_store(file_ptr, filename);
+            let row_ptr = ctx.builder.build_in_bounds_gep(exception, &[zero, int32.const_int(2, false)], "row_ptr");
+            ctx.builder.build_store(row_ptr, int32.const_int(loc.row as u64, false));
+            let col_ptr = ctx.builder.build_in_bounds_gep(exception, &[zero, int32.const_int(3, false)], "col_ptr");
+            ctx.builder.build_store(col_ptr, int32.const_int(loc.column as u64, false));
+
+            let current_fun = ctx.builder.get_insert_block().unwrap().get_parent().unwrap();
+            let fun_name = ctx.gen_string(generator, current_fun.get_name().to_str().unwrap());
+            let name_ptr = ctx.builder.build_in_bounds_gep(exception, &[zero, int32.const_int(4, false)], "name_ptr");
+            ctx.builder.build_store(name_ptr, fun_name);
+        }
+
+        let raise = get_builtins(generator, ctx, "__artiq_raise");
+        let exception = *exception;
+        ctx.build_call_or_invoke(raise, &[exception], "raise");
+    } else {
+        let resume = get_builtins(generator, ctx, "__artiq_resume");
+        ctx.build_call_or_invoke(resume, &[], "resume");
+    }
+    ctx.builder.build_unreachable();
+}
+
+pub fn gen_try<'ctx, 'a, G: CodeGenerator>(
+    generator: &mut G,
+    ctx: &mut CodeGenContext<'ctx, 'a>,
+    target: &Stmt<Option<Type>>,
+) {
+    if let StmtKind::Try { body, handlers, orelse, finalbody, .. } = &target.node {
+        // if we need to generate anything related to exception, we must have personality defined
+        let personality_symbol = ctx.top_level.personality_symbol.as_ref().unwrap();
+        let personality = ctx.module.get_function(personality_symbol).unwrap_or_else(|| {
+            let ty = ctx.ctx.i32_type().fn_type(&[], true);
+            ctx.module.add_function(personality_symbol, ty, None)
+        });
+        let exception_type = ctx.get_llvm_type(generator, ctx.primitives.exception);
+        let ptr_type = ctx.ctx.i8_type().ptr_type(inkwell::AddressSpace::Generic);
+        let current_block = ctx.builder.get_insert_block().unwrap();
+        let current_fun = current_block.get_parent().unwrap();
+        let landingpad = ctx.ctx.append_basic_block(current_fun, "try.landingpad");
+        let dispatcher = ctx.ctx.append_basic_block(current_fun, "try.dispatch");
+        let mut dispatcher_end = dispatcher;
+        ctx.builder.position_at_end(dispatcher);
+        let exn = ctx.builder.build_phi(exception_type, "exn");
+        ctx.builder.position_at_end(current_block);
+
+        let mut cleanup = None;
+        let mut old_loop_target = None;
+        let mut old_return = None;
+        let mut old_outer_final = None;
+        let has_cleanup = if !finalbody.is_empty() {
+            let final_state = generator.gen_var_alloc(ctx, ptr_type.into());
+            old_outer_final = ctx.outer_final.replace((final_state, Vec::new(), Vec::new()));
+            if let Some((continue_target, break_target)) = ctx.loop_target {
+                let break_proxy = ctx.ctx.append_basic_block(current_fun, "try.break");
+                let continue_proxy = ctx.ctx.append_basic_block(current_fun, "try.continue");
+                final_proxy(ctx, break_target, break_proxy);
+                final_proxy(ctx, continue_target, continue_proxy);
+                old_loop_target = ctx.loop_target.replace((continue_proxy, break_proxy));
+            }
+            let return_proxy = ctx.ctx.append_basic_block(current_fun, "try.return");
+            if let Some(return_target) = ctx.return_target {
+                final_proxy(ctx, return_target, return_proxy);
+            } else {
+                let return_target = ctx.ctx.append_basic_block(current_fun, "try.return_target");
+                ctx.builder.position_at_end(return_target);
+                let return_value = ctx.return_buffer.map(|v| ctx.builder.build_load(v, "$ret"));
+                ctx.builder.build_return(return_value.as_ref().map(|v| v as &dyn BasicValue));
+                ctx.builder.position_at_end(current_block);
+                final_proxy(ctx, return_target, return_proxy);
+            }
+            old_return = ctx.return_target.replace(return_proxy);
+            cleanup = Some(ctx.ctx.append_basic_block(current_fun, "try.cleanup"));
+            true
+        } else {
+            ctx.outer_final.is_some()
+        };
+
+        let mut clauses = Vec::new();
+        let mut found_catch_all = false;
+        for handler_node in handlers.iter() {
+            let ExcepthandlerKind::ExceptHandler { type_, .. } = &handler_node.node;
+            // none or Exception
+            if type_.is_none() || ctx.unifier.unioned(type_.as_ref().unwrap().custom.unwrap(), ctx.primitives.exception) {
+                clauses.push(None);
+                found_catch_all = true;
+                break;
+            } else {
+                let type_ = type_.as_ref().unwrap();
+                let exn_name = ctx.resolver.get_type_name(
+                    &ctx.top_level.definitions.read(),
+                    &mut ctx.unifier,
+                    type_.custom.unwrap(),
+                );
+                let exn_id = ctx.resolver.get_string_id(&format!("0:{}", exn_name));
+                let exn_id_global =
+                    ctx.module.add_global(ctx.ctx.i32_type(), None, &format!("exn.{}", exn_id));
+                exn_id_global.set_initializer(&ctx.ctx.i32_type().const_int(exn_id as u64, false));
+                clauses.push(Some(exn_id_global.as_pointer_value().as_basic_value_enum()));
+            }
+        }
+        let mut all_clauses = clauses.clone();
+        if let Some(old_clauses) = &ctx.outer_catch_clauses {
+            if !found_catch_all {
+                all_clauses.extend_from_slice(&old_clauses.0)
+            }
+        }
+        let old_clauses = ctx.outer_catch_clauses.replace((all_clauses, dispatcher, exn));
+        let old_unwind = ctx.unwind_target.replace(landingpad);
+        gen_block(generator, ctx, body.iter());
+        if ctx.builder.get_insert_block().unwrap().get_terminator().is_none() {
+            gen_block(generator, ctx, orelse.iter());
+        }
+        let body = ctx.builder.get_insert_block().unwrap();
+        // reset old_clauses and old_unwind
+        let (all_clauses, _, _) = ctx.outer_catch_clauses.take().unwrap();
+        ctx.outer_catch_clauses = old_clauses;
+        ctx.unwind_target = old_unwind;
+        ctx.return_target = old_return;
+        ctx.loop_target = old_loop_target;
+        old_loop_target = None;
+
+        let old_unwind = if !finalbody.is_empty() {
+            let final_landingpad = ctx.ctx.append_basic_block(current_fun, "try.catch.final");
+            ctx.builder.position_at_end(final_landingpad);
+            ctx.builder.build_landing_pad(
+                ctx.ctx.struct_type(&[ptr_type.into(), exception_type], false),
+                personality,
+                &[],
+                true,
+                "try.catch.final",
+            );
+            ctx.builder.build_unconditional_branch(cleanup.unwrap());
+            ctx.builder.position_at_end(body);
+            ctx.unwind_target.replace(final_landingpad)
+        } else {
+            None
+        };
+
+        // run end_catch before continue/break/return
+        let mut final_proxy_lambda =
+            |ctx: &mut CodeGenContext<'ctx, 'a>,
+             target: BasicBlock<'ctx>,
+             block: BasicBlock<'ctx>| final_proxy(ctx, target, block);
+        let mut redirect_lambda = |ctx: &mut CodeGenContext<'ctx, 'a>,
+                                   target: BasicBlock<'ctx>,
+                                   block: BasicBlock<'ctx>| {
+            ctx.builder.position_at_end(block);
+            ctx.builder.build_unconditional_branch(target);
+            ctx.builder.position_at_end(body);
+        };
+        let redirect = if ctx.outer_final.is_some() {
+            &mut final_proxy_lambda
+                as &mut dyn FnMut(&mut CodeGenContext<'ctx, 'a>, BasicBlock<'ctx>, BasicBlock<'ctx>)
+        } else {
+            &mut redirect_lambda
+                as &mut dyn FnMut(&mut CodeGenContext<'ctx, 'a>, BasicBlock<'ctx>, BasicBlock<'ctx>)
+        };
+        let resume = get_builtins(generator, ctx, "__artiq_resume");
+        let end_catch = get_builtins(generator, ctx, "__artiq_end_catch");
+        if let Some((continue_target, break_target)) = ctx.loop_target.take() {
+            let break_proxy = ctx.ctx.append_basic_block(current_fun, "try.break");
+            let continue_proxy = ctx.ctx.append_basic_block(current_fun, "try.continue");
+            ctx.builder.position_at_end(break_proxy);
+            ctx.builder.build_call(end_catch, &[], "end_catch");
+            ctx.builder.position_at_end(continue_proxy);
+            ctx.builder.build_call(end_catch, &[], "end_catch");
+            ctx.builder.position_at_end(body);
+            redirect(ctx, break_target, break_proxy);
+            redirect(ctx, continue_target, continue_proxy);
+            ctx.loop_target = Some((continue_proxy, break_proxy));
+            old_loop_target = Some((continue_target, break_target));
+        }
+        let return_proxy = ctx.ctx.append_basic_block(current_fun, "try.return");
+        ctx.builder.position_at_end(return_proxy);
+        ctx.builder.build_call(end_catch, &[], "end_catch");
+        let return_target = ctx.return_target.take().unwrap_or_else(|| {
+            let doreturn = ctx.ctx.append_basic_block(current_fun, "try.doreturn");
+            ctx.builder.position_at_end(doreturn);
+            let return_value = ctx.return_buffer.map(|v| ctx.builder.build_load(v, "$ret"));
+            ctx.builder.build_return(return_value.as_ref().map(|v| v as &dyn BasicValue));
+            doreturn
+        });
+        redirect(ctx, return_target, return_proxy);
+        ctx.return_target = Some(return_proxy);
+        old_return = Some(return_target);
+
+        let mut post_handlers = Vec::new();
+
+        let exnid = if !handlers.is_empty() {
+            ctx.builder.position_at_end(dispatcher);
+            unsafe {
+                let zero = ctx.ctx.i32_type().const_zero();
+                let exnid_ptr = ctx.builder.build_gep(
+                    exn.as_basic_value().into_pointer_value(),
+                    &[zero, zero],
+                    "exnidptr",
+                );
+                Some(ctx.builder.build_load(exnid_ptr, "exnid"))
+            }
+        } else {
+            None
+        };
+
+        for (handler_node, exn_type) in handlers.iter().zip(clauses.iter()) {
+            let ExcepthandlerKind::ExceptHandler { type_, name, body } = &handler_node.node;
+            let handler_bb = ctx.ctx.append_basic_block(current_fun, "try.handler");
+            ctx.builder.position_at_end(handler_bb);
+            if let Some(name) = name {
+                let exn_ty = ctx.get_llvm_type(generator, type_.as_ref().unwrap().custom.unwrap());
+                let exn_store = generator.gen_var_alloc(ctx, exn_ty);
+                ctx.var_assignment.insert(*name, (exn_store, None, 0));
+                ctx.builder.build_store(exn_store, exn.as_basic_value());
+            }
+            gen_block(generator, ctx, body.iter());
+            let current = ctx.builder.get_insert_block().unwrap();
+            // only need to call end catch if not terminated
+            // otherwise, we already handled in return/break/continue/raise
+            if current.get_terminator().is_none() {
+                ctx.builder.build_call(end_catch, &[], "end_catch");
+            }
+            post_handlers.push(current);
+            ctx.builder.position_at_end(dispatcher_end);
+            if let Some(exn_type) = exn_type {
+                let dispatcher_cont =
+                    ctx.ctx.append_basic_block(current_fun, "try.dispatcher_cont");
+                let actual_id = exnid.unwrap().into_int_value();
+                let expected_id = ctx
+                    .builder
+                    .build_load(exn_type.into_pointer_value(), "expected_id")
+                    .into_int_value();
+                let result = ctx.builder.build_int_compare(EQ, actual_id, expected_id, "exncheck");
+                ctx.builder.build_conditional_branch(result, handler_bb, dispatcher_cont);
+                dispatcher_end = dispatcher_cont;
+            } else {
+                ctx.builder.build_unconditional_branch(handler_bb);
+                break;
+            }
+        }
+
+        ctx.unwind_target = old_unwind;
+        ctx.loop_target = old_loop_target;
+        ctx.return_target = old_return;
+
+        ctx.builder.position_at_end(landingpad);
+        let clauses: Vec<_> = if finalbody.is_empty() { &all_clauses } else { &clauses }
+            .iter()
+            .map(|v| v.unwrap_or(ptr_type.const_zero().into()))
+            .collect();
+        let landingpad_value = ctx
+            .builder
+            .build_landing_pad(
+                ctx.ctx.struct_type(&[ptr_type.into(), exception_type], false),
+                personality,
+                &clauses,
+                has_cleanup,
+                "try.landingpad",
+            )
+            .into_struct_value();
+        let exn_val = ctx.builder.build_extract_value(landingpad_value, 1, "exn").unwrap();
+        ctx.builder.build_unconditional_branch(dispatcher);
+        exn.add_incoming(&[(&exn_val, landingpad)]);
+
+        if dispatcher_end.get_terminator().is_none() {
+            ctx.builder.position_at_end(dispatcher_end);
+            if let Some(cleanup) = cleanup {
+                ctx.builder.build_unconditional_branch(cleanup);
+            } else if let Some((_, outer_dispatcher, phi)) = ctx.outer_catch_clauses {
+                phi.add_incoming(&[(&exn_val, dispatcher_end)]);
+                ctx.builder.build_unconditional_branch(outer_dispatcher);
+            } else {
+                ctx.build_call_or_invoke(resume, &[], "resume");
+                ctx.builder.build_unreachable();
+            }
+        }
+
+        if finalbody.is_empty() {
+            let tail = ctx.ctx.append_basic_block(current_fun, "try.tail");
+            if body.get_terminator().is_none() {
+                ctx.builder.position_at_end(body);
+                ctx.builder.build_unconditional_branch(tail);
+            }
+            if matches!(cleanup, Some(cleanup) if cleanup.get_terminator().is_none()) {
+                ctx.builder.position_at_end(cleanup.unwrap());
+                ctx.builder.build_unconditional_branch(tail);
+            }
+            for post_handler in post_handlers {
+                if post_handler.get_terminator().is_none() {
+                    ctx.builder.position_at_end(post_handler);
+                    ctx.builder.build_unconditional_branch(tail);
+                }
+            }
+            ctx.builder.position_at_end(tail);
+        } else {
+            let final_branches = ctx.outer_final.take().unwrap();
+            ctx.outer_final = old_outer_final;
+
+            // exception path
+            let cleanup = cleanup.unwrap();
+            ctx.builder.position_at_end(cleanup);
+            gen_block(generator, ctx, finalbody.iter());
+            if !ctx.is_terminated() {
+                ctx.build_call_or_invoke(resume, &[], "resume");
+                ctx.builder.build_unreachable();
+            }
+
+            // normal path
+            let (final_state, mut final_targets, final_paths) = final_branches;
+            let tail = ctx.ctx.append_basic_block(current_fun, "try.tail");
+            final_targets.push(tail);
+            let finalizer = ctx.ctx.append_basic_block(current_fun, "try.finally");
+            ctx.builder.position_at_end(finalizer);
+            gen_block(generator, ctx, finalbody.iter());
+            if !ctx.is_terminated() {
+                let dest = ctx.builder.build_load(final_state, "final_dest");
+                ctx.builder.build_indirect_branch(dest, &final_targets);
+            }
+            for block in final_paths.iter() {
+                if block.get_terminator().is_none() {
+                    ctx.builder.position_at_end(*block);
+                    ctx.builder.build_unconditional_branch(finalizer);
+                }
+            }
+            for block in [body].iter().chain(post_handlers.iter()) {
+                if block.get_terminator().is_none() {
+                    ctx.builder.position_at_end(*block);
+                    unsafe {
+                        ctx.builder.build_store(final_state, tail.get_address().unwrap());
+                    }
+                    ctx.builder.build_unconditional_branch(finalizer);
+                }
+            }
+            ctx.builder.position_at_end(tail);
+        }
     } else {
         unreachable!()
     }
@@ -531,9 +919,15 @@ pub fn gen_stmt<'ctx, 'a, G: CodeGenerator>(
             let value = gen_binop_expr(generator, ctx, target, op, value);
             generator.gen_assign(ctx, target, value);
         }
+        StmtKind::Try { .. } => gen_try(generator, ctx, stmt),
+        StmtKind::Raise { exc, .. } => {
+            let exc = exc.as_ref().map(|exc| generator.gen_expr(ctx, exc).unwrap().to_basic_value_enum(ctx, generator));
+            gen_raise(generator, ctx, exc.as_ref(), stmt.location)
+        }
         _ => unimplemented!(),
     };
-    false
+}
+
 pub fn gen_block<'ctx, 'a, 'b, G: CodeGenerator, I: Iterator<Item = &'b Stmt<Option<Type>>>>(
     generator: &mut G,
     ctx: &mut CodeGenContext<'ctx, 'a>,

nac3core/src/symbol_resolver.rs

@@ -109,6 +109,7 @@ pub trait SymbolResolver {
 
     fn get_symbol_location(&self, str: StrRef) -> Option<Location>;
     fn get_default_param_value(&self, expr: &nac3parser::ast::Expr) -> Option<SymbolValue>;
+    fn get_string_id(&self, s: &str) -> i32;
     // handle function call etc.
 }
 
@@ -297,6 +298,25 @@ impl dyn SymbolResolver + Send + Sync {
     ) -> Result<Type, String> {
         parse_type_annotation(self, top_level_defs, unifier, primitives, expr)
     }
+
+    pub fn get_type_name(
+        &self,
+        top_level_defs: &[Arc<RwLock<TopLevelDef>>],
+        unifier: &mut Unifier,
+        ty: Type,
+    ) -> String {
+        unifier.stringify(
+            ty,
+            &mut |id| {
+                if let TopLevelDef::Class { name, .. } = &*top_level_defs[id].read() {
+                    name.to_string()
+                } else {
+                    unreachable!("expected class definition")
+                }
+            },
+            &mut |id| format!("var{}", id),
+        )
+    }
 }
 
 impl Debug for dyn SymbolResolver + Send + Sync {

nac3core/src/toplevel/composer.rs

@@ -148,7 +148,7 @@ impl TopLevelComposer {
                 self.unifier.get_shared_unifier(),
                 self.primitives_ty,
             )])),
-            personality_symbol: None,
+            personality_symbol: Some("__artiq_personality".into()),
         }
     }
 
@@ -166,7 +166,7 @@ impl TopLevelComposer {
     ) -> Result<(StrRef, DefinitionId, Option<Type>), String> {
         let defined_names = &mut self.defined_names;
         match &ast.node {
-            ast::StmtKind::ClassDef { name: class_name, body, .. } => {
+            ast::StmtKind::ClassDef { name: class_name, bases, body, .. } => {
                 if self.keyword_list.contains(class_name) {
                     return Err(format!(
                         "cannot use keyword `{}` as a class name (at {})",
@@ -174,11 +174,12 @@ impl TopLevelComposer {
                         ast.location
                     ));
                 }
-                if !defined_names.insert({
+                let fully_qualified_class_name = if mod_path.is_empty() {
-                    let mut n = mod_path.clone();
+                    *class_name
-                    n.push_str(&class_name.to_string());
+                } else {
-                    n
+                    format!("{}.{}", &mod_path, class_name).into()
-                }) {
+                };
+                if !defined_names.insert(fully_qualified_class_name.into()) {
                     return Err(format!(
                         "duplicate definition of class `{}` (at {})",
                         class_name,
@@ -196,7 +197,7 @@ impl TopLevelComposer {
                     Arc::new(RwLock::new(Self::make_top_level_class_def(
                         class_def_id,
                         resolver.clone(),
-                        class_name,
+                        fully_qualified_class_name,
                         Some(constructor_ty),
                     ))),
                     None,
@@ -218,8 +219,13 @@ impl TopLevelComposer {
                 // we do not push anything to the def list, so we keep track of the index
                 // and then push in the correct order after the for loop
                 let mut class_method_index_offset = 0;
-                let mut contains_constructor = false;
                 let init_id = "__init__".into();
+                let exception_id = "Exception".into();
+                // TODO: Fix this hack. We will generate constructor for classes that inherit
+                // from Exception class (directly or indirectly), but this code cannot handle
+                // subclass of other exception classes.
+                let mut contains_constructor = bases
+                    .iter().any(|base| matches!(base.node, ast::ExprKind::Name { id, .. } if id == exception_id));
                 for b in body {
                     if let ast::StmtKind::FunctionDef { name: method_name, .. } = &b.node {
                         if method_name == &init_id {
@@ -232,21 +238,14 @@ impl TopLevelComposer {
                                 b.location
                             ));
                         }
-                        let global_class_method_name = {
+                        let global_class_method_name = Self::make_class_method_name(
-                            let mut n = mod_path.clone();
+                            fully_qualified_class_name.into(),
-                            n.push_str(
+                            &method_name.to_string(),
-                                Self::make_class_method_name(
+                        );
-                                    class_name.into(),
-                                    &method_name.to_string(),
-                                )
-                                .as_str(),
-                            );
-                            n
-                        };
                         if !defined_names.insert(global_class_method_name.clone()) {
                             return Err(format!(
                                 "class method `{}` defined twice (at {})",
-                                &global_class_method_name[mod_path.len()..],
+                                global_class_method_name,
                                 b.location
                             ));
                         }
@@ -304,15 +303,15 @@ impl TopLevelComposer {
                 // if self.keyword_list.contains(name) {
                 //     return Err("cannot use keyword as a top level function name".into());
                 // }
-                let global_fun_name = {
+                let global_fun_name = if mod_path.is_empty() {
-                    let mut n = mod_path.clone();
+                    name.to_string()
-                    n.push_str(&name.to_string());
+                } else {
-                    n
+                    format!("{}.{}", mod_path, name)
                 };
                 if !defined_names.insert(global_fun_name.clone()) {
                     return Err(format!(
                         "top level function `{}` defined twice (at {})",
-                        &global_fun_name[mod_path.len()..],
+                        global_fun_name,
                         ast.location
                     ));
                 }
@@ -1582,6 +1581,7 @@ impl TopLevelComposer {
                             primitives: &self.primitives_ty,
                             virtual_checks: &mut Vec::new(),
                             calls: &mut calls,
+                            in_handler: false
                         };
 
                         let fun_body =
@@ -1595,6 +1595,13 @@ impl TopLevelComposer {
                                     instance_to_symbol.insert("".into(), simple_name.to_string());
                                     continue;
                                 }
+                                if !decorator_list.is_empty()
+                                    && matches!(&decorator_list[0].node,
+                                        ast::ExprKind::Name{ id, .. } if id == &"rpc".into())
+                                {
+                                    instance_to_symbol.insert("".into(), simple_name.to_string());
+                                    continue;
+                                }
                                 body
                             } else {
                                 unreachable!("must be function def ast")
@@ -1605,7 +1612,42 @@ impl TopLevelComposer {
 
                         let returned =
                             inferencer.check_block(fun_body.as_slice(), &mut identifiers)?;
-
+                        {
+                            // check virtuals
+                            let defs = ctx.definitions.read();
+                            for (subtype, base, loc) in inferencer.virtual_checks.iter() {
+                                let base_id = {
+                                    let base = inferencer.unifier.get_ty(*base);
+                                    if let TypeEnum::TObj { obj_id, .. } = &*base {
+                                        *obj_id
+                                    } else {
+                                        return Err(format!("Base type should be a class (at {})", loc))
+                                    }
+                                };
+                                let subtype_id = {
+                                    let ty = inferencer.unifier.get_ty(*subtype);
+                                    if let TypeEnum::TObj { obj_id, .. } = &*ty {
+                                        *obj_id
+                                    } else {
+                                        let base_repr = inferencer.unifier.default_stringify(*base);
+                                        let subtype_repr = inferencer.unifier.default_stringify(*subtype);
+                                        return Err(format!("Expected a subtype of {}, but got {} (at {})", base_repr, subtype_repr, loc))
+                                    }
+                                };
+                                let subtype_entry = defs[subtype_id.0].read();
+                                if let TopLevelDef::Class { ancestors, .. } = &*subtype_entry {
+                                    let m = ancestors.iter()
+                                        .find(|kind| matches!(kind, TypeAnnotation::CustomClass { id, .. } if *id == base_id));
+                                    if m.is_none() {
+                                        let base_repr = inferencer.unifier.default_stringify(*base);
+                                        let subtype_repr = inferencer.unifier.default_stringify(*subtype);
+                                        return Err(format!("Expected a subtype of {}, but got {} (at {})", base_repr, subtype_repr, loc))
+                                    }
+                                } else {
+                                    unreachable!();
+                                }
+                            }
+                        }
                         if !self.unifier.unioned(inst_ret, self.primitives_ty.none) && !returned {
                             let def_ast_list = &self.definition_ast_list;
                             let ret_str = self.unifier.stringify(

nac3core/src/typecheck/function_check.rs

@@ -227,6 +227,20 @@ impl<'a> Inferencer<'a> {
                 self.check_block(body, &mut new_defined_identifiers)?;
                 Ok(false)
             }
+            StmtKind::Try { body, handlers, orelse, finalbody, .. } => {
+                self.check_block(body, &mut defined_identifiers.clone())?;
+                self.check_block(orelse, &mut defined_identifiers.clone())?;
+                for handler in handlers.iter() {
+                    let mut defined_identifiers = defined_identifiers.clone();
+                    let ast::ExcepthandlerKind::ExceptHandler { name, body, .. } = &handler.node;
+                    if let Some(name) = name {
+                        defined_identifiers.insert(*name);
+                    }
+                    self.check_block(body, &mut defined_identifiers)?;
+                }
+                self.check_block(finalbody, defined_identifiers)?;
+                Ok(false)
+            }
             StmtKind::Expr { value, .. } => {
                 self.check_expr(value, defined_identifiers)?;
                 Ok(false)

nac3core/src/typecheck/type_inferencer/mod.rs

@@ -52,9 +52,10 @@ pub struct Inferencer<'a> {
     pub function_data: &'a mut FunctionData,
     pub unifier: &'a mut Unifier,
     pub primitives: &'a PrimitiveStore,
-    pub virtual_checks: &'a mut Vec<(Type, Type)>,
+    pub virtual_checks: &'a mut Vec<(Type, Type, Location)>,
     pub variable_mapping: HashMap<StrRef, Type>,
     pub calls: &'a mut HashMap<CodeLocation, CallId>,
+    pub in_handler: bool,
 }
 
 struct NaiveFolder();
@@ -123,6 +124,56 @@ impl<'a> fold::Fold<()> for Inferencer<'a> {
                     },
                 }
             }
+            ast::StmtKind::Try { body, handlers, orelse, finalbody, config_comment } => {
+                let body = body.into_iter().map(|stmt| self.fold_stmt(stmt)).collect::<Result<Vec<_>, _>>()?;
+                let outer_in_handler = self.in_handler;
+                let mut exception_handlers = Vec::with_capacity(handlers.len());
+                self.in_handler = true;
+                {
+                    let top_level_defs = self.top_level.definitions.read();
+                    let mut naive_folder = NaiveFolder();
+                    for handler in handlers.into_iter() {
+                        let ast::ExcepthandlerKind::ExceptHandler { type_, name, body } = handler.node;
+                        let type_ = if let Some(type_) = type_ {
+                            let typ = self.function_data.resolver.parse_type_annotation(
+                                top_level_defs.as_slice(),
+                                self.unifier,
+                                self.primitives,
+                                &type_
+                            )?;
+                            self.virtual_checks.push((typ, self.primitives.exception, handler.location));
+                            if let Some(name) = name {
+                                if !self.defined_identifiers.contains(&name) {
+                                    self.defined_identifiers.insert(name);
+                                }
+                                if let Some(old_typ) = self.variable_mapping.insert(name, typ) {
+                                    self.unifier.unify(old_typ, typ)?;
+                                }
+                            }
+                            let mut type_ = naive_folder.fold_expr(*type_)?;
+                            type_.custom = Some(typ);
+                            Some(Box::new(type_))
+                        } else {
+                            None
+                        };
+                        let body = body.into_iter().map(|stmt| self.fold_stmt(stmt)).collect::<Result<Vec<_>, _>>()?;
+                        exception_handlers.push(Located {
+                            location: handler.location,
+                            node: ast::ExcepthandlerKind::ExceptHandler { type_, name, body },
+                            custom: None
+                        });
+                    }
+                }
+                self.in_handler = outer_in_handler;
+                let handlers = exception_handlers;
+                let orelse = orelse.into_iter().map(|stmt| self.fold_stmt(stmt)).collect::<Result<Vec<_>, _>>()?;
+                let finalbody = finalbody .into_iter().map(|stmt| self.fold_stmt(stmt)).collect::<Result<Vec<_>, _>>()?;
+                Located {
+                    location: node.location,
+                    node: ast::StmtKind::Try { body, handlers, orelse, finalbody, config_comment },
+                    custom: None
+                }
+            }
             ast::StmtKind::For { target, iter, body, orelse, config_comment, type_comment } => {
                 self.infer_pattern(&target)?;
                 let target = self.fold_expr(*target)?;
@@ -229,7 +280,8 @@ impl<'a> fold::Fold<()> for Inferencer<'a> {
             _ => fold::fold_stmt(self, node)?,
         };
         match &stmt.node {
-            ast::StmtKind::For { .. } => {}
+            ast::StmtKind::For { .. } => {},
+            ast::StmtKind::Try { .. } => {},
             ast::StmtKind::If { test, .. } | ast::StmtKind::While { test, .. } => {
                 self.unify(test.custom.unwrap(), self.primitives.bool, &test.location)?;
             }
@@ -242,6 +294,16 @@ impl<'a> fold::Fold<()> for Inferencer<'a> {
             ast::StmtKind::Break { .. }
             | ast::StmtKind::Continue { .. }
             | ast::StmtKind::Pass { .. } => {}
+            ast::StmtKind::Raise { exc, cause, .. } => {
+                if let Some(cause) = cause {
+                    return report_error("raise ... from cause is not supported", cause.location);
+                }
+                if let Some(exc) = exc {
+                    self.virtual_checks.push((exc.custom.unwrap(), self.primitives.exception, exc.location));
+                } else if !self.in_handler {
+                    return report_error("cannot reraise outside exception handlers", stmt.location);
+                }
+            }
             ast::StmtKind::With { items, .. } => {
                 for item in items.iter() {
                     let ty = item.context_expr.custom.unwrap();
@@ -537,6 +599,8 @@ impl<'a> Inferencer<'a> {
             top_level: self.top_level,
             defined_identifiers,
             variable_mapping,
+            // lambda should not be considered in exception handler
+            in_handler: false,
         };
         let fun = FunSignature {
             args: fn_args
@@ -583,6 +647,8 @@ impl<'a> Inferencer<'a> {
             primitives: self.primitives,
             calls: self.calls,
             defined_identifiers,
+            // listcomp expr should not be considered as inside an exception handler...
+            in_handler: false
         };
         let generator = generators.pop().unwrap();
         if generator.is_async {
@@ -661,7 +727,7 @@ impl<'a> Inferencer<'a> {
                     } else {
                         self.unifier.get_fresh_var().0
                     };
-                    self.virtual_checks.push((arg0.custom.unwrap(), ty));
+                    self.virtual_checks.push((arg0.custom.unwrap(), ty, func_location));
                     let custom = Some(self.unifier.add_ty(TypeEnum::TVirtual { ty }));
                     return Ok(Located {
                         location,