Line 1 breakpoint locations may no longer be accurate after 10.16+

[kjin]

A failing test (testing setting line-1 breakpoints) that is the cause of #729 highlights a potentially breaking change for us in Node 10.16: scripts are now parsed slightly differently. Consider the following code:

module.exports = function foo(n) { return n; }

In Node 10.15 and below, getting the above script via Inspector's Debugger.getScriptSource yields:

(function (exports, require, module, __filename, __dirname) { module.exports = function foo(n) { return n; }
});

In Node 10.16+, it yields the original source:

module.exports = function foo(n) { return n; }

This almost certainly affects line-1 breakpoints.

[kjin]

This issue should not be closed until the test skipped in #738 is re-enabled.

[bcoe]

@kjin interesting, I remember when this was introduced, compileFunction is now used:

https://github.com/nodejs/node/blob/master/lib/internal/modules/cjs/loader.js#L856

rather than source being pre-wrapped with a wrapper, this should ultimately help ensure slightly more accurate information, but it does mean that prior to Node.10.16 the wrapper exists afterwords it does not.

[kjin]

@bcoe Thanks, I found the PR that caused this change: nodejs/node#21573