"restart" for request type "launch" does a re-run instead of a re-attach

[weinand]

while testing the MERN tour #22277:

A "restart" in a launch config of request type "launch" does not only "re-attach" to node but runs the program again. This doesn't make much sense if the "program" is still running, like e.g. "nodemon".

So on every edit of "test.js" VS Code launches the program "nodemon" again:

nodemon --debug=5858 test.js
nodemon --debug=5858 test.js
nodemon --debug=5858 test.js
nodemon --debug=5858 test.js
...

What should happen is the following:

nodemon --debug=5858 test.js
attach 5858
attach 5858
attach 5858
...

[weinand]

Since VS Code knows nothing about the "restart" attribute of a node launch-config I had to fix this problem in node-debug:

• when VS Code receives a "restart" flag in the terminate event, it will "restart" the session by sending a "launchRequest" to the DAP (this is the existing behaviour). To let the DAP know that this is the result of a "restart", an additional attribute "__restart" is added to the launchRequest argument (this experimental attribute has been added for this milestone).
• whenever "node-debug" receives a "__restart" attribute with value "true" it does not launch the program again but attaches to the debug port specified in the launchRequest argument.

/cc @roblourens

[weinand]

To verify, just create a program "app.js" with this contents:

var i = 0;
setInterval(() => {
	console.log('hello world:' + i++);
}, 1000);

Create a launch config from the Intellisense snippet "Nodemon Setup".

Whenever you edit app.js VS Code should re-attach to the new node process but no longer launch "nodemon" again.

Please note: this has been only fixed for "protocol": "legacy".