[njs] Fixed catching of the exception thrown from an awaited function.

[Dmitry Volyntsev]

details:   https://hg.nginx.org/njs/rev/2774fed7b864
branches:  
changeset: 1871:2774fed7b864
user:      Dmitry Volyntsev <xeioex at nginx.com>
date:      Tue May 31 21:48:46 2022 -0700
description:
Fixed catching of the exception thrown from an awaited function.

This closes #500 issue on Github.

diffstat:

 src/njs_async.c                         |   6 +++---
 test/js/async_try_catch_call.t.js       |  29 +++++++++++++++++++++++++++++
 test/js/async_try_catch_expression.t.js |  28 ++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+), 3 deletions(-)

diffs (95 lines):

diff -r bd520efc0df1 -r 2774fed7b864 src/njs_async.c
--- a/src/njs_async.c	Tue May 31 21:48:26 2022 -0700
+++ b/src/njs_async.c	Tue May 31 21:48:46 2022 -0700
@@ -67,9 +67,6 @@ njs_await_fulfilled(njs_vm_t *vm, njs_va
     ctx = vm->top_frame->function->context;
 
     value = njs_arg(args, nargs, 1);
-    if (njs_is_error(value)) {
-        goto failed;
-    }
 
     async_frame = ctx->await;
     async = &async_frame->native;
@@ -143,6 +140,7 @@ njs_await_rejected(njs_vm_t *vm, njs_val
     value = njs_arg(args, nargs, 1);
 
     if (ctx->await->native.pc == ctx->pc) {
+        /* No catch block was set before await. */
         (void) njs_function_call(vm, njs_function(&ctx->capability->reject),
                                  &njs_value_undefined, value, 1, &vm->retval);
 
@@ -151,6 +149,8 @@ njs_await_rejected(njs_vm_t *vm, njs_val
         return NJS_ERROR;
     }
 
+    /* ctx->await->native.pc points to a catch block here. */
+
     ctx->pc = ctx->await->native.pc;
 
     return njs_await_fulfilled(vm, args, nargs, unused);
diff -r bd520efc0df1 -r 2774fed7b864 test/js/async_try_catch_call.t.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/js/async_try_catch_call.t.js	Tue May 31 21:48:46 2022 -0700
@@ -0,0 +1,29 @@
+/*---
+includes: [compareArray.js]
+flags: [async]
+---*/
+
+let stages = [];
+const fn = async () => { throw new Error('Oops') };
+
+async function af() {
+    try {
+        await fn();
+
+        $DONOTEVALUATE();
+    }
+    catch (v) {
+        stages.push(`catch:${v}`);
+    }
+    finally {
+        stages.push('finally');
+    }
+
+    return "end";
+};
+
+af().then(v => {
+    stages.push(v);
+    assert.compareArray(stages, ['catch:Error: Oops', 'finally', 'end']);
+})
+.then($DONE, $DONE)
diff -r bd520efc0df1 -r 2774fed7b864 test/js/async_try_catch_expression.t.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/js/async_try_catch_expression.t.js	Tue May 31 21:48:46 2022 -0700
@@ -0,0 +1,28 @@
+/*---
+includes: [compareArray.js]
+flags: [async]
+---*/
+
+let stages = [];
+
+async function af() {
+    try {
+        await ({}).a.a();
+
+        $DONOTEVALUATE();
+    }
+    catch (v) {
+        stages.push('catch');
+    }
+    finally {
+        stages.push('finally');
+    }
+
+    return "end";
+};
+
+af().then(v => {
+    stages.push(v);
+    assert.compareArray(stages, ['catch', 'finally', 'end']);
+})
+.then($DONE, $DONE)