regenerator: allow nested finally block (#601)

Previously, 

```js
function *foo() {
    try {
    } finally {
        try {
        } finally {
             throw new Error('foo');
        }
    }
}

```

make swc panic

Closes #600.

.github/ISSUE_TEMPLATE/bug_report.md

@@ -1,6 +1,6 @@
 ---
 name: Bug report
-about: Create a report to help us improve
+about: Use this when swc breaks something
 title: ''
 labels: C-bug
 assignees: ''

.github/ISSUE_TEMPLATE/crash_report.md

@@ -1,6 +1,6 @@
 ---
 name: Crash report
-about: Create a report to help us improve
+about: Use this when swc panics
 title: 'panic: '
 labels: C-bug
 assignees: ''

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,15 @@
+---
+name: Feature request
+about: Use this when you want a new feature
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Describe the feature**
+
+**Babel plugin or link to the feature description**
+
+**Additional context**
+Add any other context about the problem here.

.github/ISSUE_TEMPLATE/question.md

@@ -0,0 +1,10 @@
+---
+name: Question
+about: Use this when you have a question
+title: ''
+labels: ''
+assignees: ''
+
+---
+
+**Question**

ecmascript/transforms/src/compat/es2015/regenerator/case.rs

@@ -74,9 +74,9 @@ impl<'a> CaseHandler<'a> {
 }
 
 impl CaseHandler<'_> {
-    fn with_entry<F, Ret>(&mut self, entry: Entry, op: F) -> Ret
+    fn with_entry<F>(&mut self, entry: Entry, op: F)
     where
-        F: FnOnce(&mut Self) -> Ret,
+        F: FnOnce(&mut Self),
     {
         self.leaps.push(entry);
         let ret = op(self);
@@ -92,15 +92,20 @@ impl CaseHandler<'_> {
             return None;
         }
 
-        let mut last_loc_value = 0;
+        //        let mut last_loc_value = 0;
         Some(ArrayLit {
             span: DUMMY_SP,
             elems: replace(&mut self.try_entries, Default::default())
                 .into_iter()
                 .map(|entry: TryEntry| {
-                    let this_loc_value = entry.first_loc;
+                    //                    let this_loc_value = entry.first_loc;
-                    assert!(this_loc_value.stmt_index >= last_loc_value);
+                    //                    assert!(
-                    last_loc_value = this_loc_value.stmt_index;
+                    //                        this_loc_value.stmt_index >= last_loc_value,
+                    //                        "this_loc_value = {:?}; last_loc_value = {};",
+                    //                        this_loc_value,
+                    //                        last_loc_value
+                    //                    );
+                    //                    last_loc_value = this_loc_value.stmt_index;
 
                     let ce = entry.catch_entry;
                     let fe = entry.finally_entry;
@@ -1091,7 +1096,7 @@ impl CaseHandler<'_> {
                 };
 
                 self.update_ctx_prev_loc(Some(&mut try_entry.first_loc));
-
+                // TODO: Track unmarked entries in a separate field,
                 self.with_entry(Entry::TryEntry(try_entry.clone()), |folder| {
                     //
                     folder.explode_stmts(block.stmts);
@@ -1343,7 +1348,12 @@ impl CaseHandler<'_> {
                 self.mark(after);
             }
 
-            Stmt::Decl(_) | Stmt::ForOf(_) => self.emit(s),
+            Stmt::ForOf(s) => unreachable!(
+                "for-of statement should be removed by es2015::for_of pass\n{:?}",
+                s
+            ),
+
+            Stmt::Decl(_) => self.emit(s),
         }
     }
 }

ecmascript/transforms/src/compat/es2015/regenerator/hoist.rs

@@ -79,11 +79,9 @@ impl Fold<VarDecl> for Hoister {
 
 impl Fold<VarDeclOrExpr> for Hoister {
     fn fold(&mut self, var: VarDeclOrExpr) -> VarDeclOrExpr {
-        let var = var.fold_children(self);
-
         match var {
             VarDeclOrExpr::VarDecl(var) => VarDeclOrExpr::Expr(box self.var_decl_to_expr(var)),
-            _ => var,
+            _ => var.fold_children(self),
         }
     }
 }

ecmascript/transforms/src/compat/es2015/regenerator/leap.rs

@@ -13,8 +13,8 @@ impl LeapManager {
     pub fn push(&mut self, entry: Entry) {
         self.stack.push(entry);
     }
-    pub fn pop(&mut self) {
+    pub fn pop(&mut self) -> Option<Entry> {
-        self.stack.pop();
+        self.stack.pop()
     }
 
     pub fn find_leap_loc<F>(&self, mut pred: F, label: Option<&JsWord>) -> Option<Loc>

ecmascript/transforms/tests/es2015_regenerator.rs

@@ -6,7 +6,10 @@
 use swc_common::chain;
 use swc_ecma_parser::Syntax;
 use swc_ecma_transforms::{
-    compat::es2015::regenerator, modules::common_js::common_js, pass::Pass, resolver,
+    compat::{es2015, es2015::regenerator, es2016, es2017, es2017::async_to_generator},
+    modules::common_js::common_js,
+    pass::Pass,
+    resolver,
 };
 
 #[macro_use]
@@ -965,3 +968,53 @@ expect(v.next()).toEqual({ value: 4, done: false });
 expect(v.next()).toEqual({ done: true });
 "
 );
+
+test_exec!(
+    syntax(),
+    |_| chain!(es2017(), es2016(), es2015(Default::default()),),
+    issue_600_full,
+    "async function foo(b) {
+	    for (let a of b) {
+	        await a
+	    }
+    }"
+);
+
+test_exec!(
+    syntax(),
+    |_| chain!(
+        async_to_generator(),
+        es2015::for_of(Default::default()),
+        es2015::regenerator(),
+    ),
+    issue_600_exact_passes,
+    "async function foo(b) {
+	    for (let a of b) {
+	        await a
+	    }
+    }"
+);
+
+test_exec!(
+    syntax(),
+    |_| es2015::regenerator(),
+    issue_600_min,
+    "function* foo() {
+        try {
+            yield 1;
+            throw new Error('1')
+        } finally{
+            try {
+                yield 2;
+            } finally{
+                throw new Error('2');
+            }
+        }
+    }
+    
+    var v = foo();
+    expect(v.next()).toEqual({ value: 1, done: false });
+    expect(v.next()).toEqual({ value: 2, done: false });
+    expect(() => v.next()).toThrow('2')
+    "
+);

ecmascript/transforms/tests/es2017_async_to_generator.rs

@@ -2105,3 +2105,26 @@ async function foo() {}
 
 "#
 );
+
+// async_to_generator_parameters
+test!(
+    syntax(),
+    |_| async_to_generator(),
+    issue_600,
+    r#"
+async function foo() {
+	for (let a of b) {
+	}
+}
+"#,
+    "function _foo() {
+    _foo = _asyncToGenerator(function*() {
+        for (let a of b){
+        }
+    });
+    return _foo.apply(this, arguments);
+}
+function foo() {
+    return _foo.apply(this, arguments);
+}"
+);