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Some areas of the generated JS files are not covered by source maps. #943

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nevkontakte opened this issue Sep 24, 2019 · 1 comment
Open

Some areas of the generated JS files are not covered by source maps. #943

nevkontakte opened this issue Sep 24, 2019 · 1 comment

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@nevkontakte
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@nevkontakte nevkontakte commented Sep 24, 2019

Hi folks, I was trying to see if I can help with Go 1.13 support, but I can't get source-map-support to work properly and deciphering stack traces is becoming difficult :/

My steps:

$ nvm use 10  # Activate node 10.x
$ npm install --global source-map-support
$ export NODE_PATH="$(npm root --global)"  # Without this node doesn't seem to find the package.
$ node --require source-map-support/register --eval ""  # Completes with no errors.
$ gopherjs test -v fmt

/home/aleks/go/src/github.com/gopherjs/gopherjs/test.784702578:4210
                _r = reflectlite.TypeOf((ptrType.nil)).Elem(); /* */ $s = 2; case 2: if($c) { $c = false; _r = _r.$blk(); } if (_r && _r.$blk !== undefined) { break s; }
                                        ^
TypeError: Cannot read property 'Elem' of undefined
    at Object.$init (/home/aleks/go/src/github.com/gopherjs/gopherjs/test.784702578:4210:41)
    at Object.$init (/home/aleks/go/src/github.com/gopherjs/gopherjs/test.784702578:7350:15)
    at Object.$init (/home/aleks/go/src/github.com/gopherjs/gopherjs/test.784702578:8306:14)
    at Object.$init (/home/aleks/go/src/github.com/gopherjs/gopherjs/test.784702578:45090:14)
    at $init (/home/aleks/go/src/github.com/gopherjs/gopherjs/test.784702578:45567:17)
    at $goroutine (/home/aleks/go/src/github.com/gopherjs/gopherjs/test.784702578:1478:19)
    at $runScheduled (/home/aleks/go/src/github.com/gopherjs/gopherjs/test.784702578:1518:7)
    at $schedule (/home/aleks/go/src/github.com/gopherjs/gopherjs/test.784702578:1534:5)
    at $go (/home/aleks/go/src/github.com/gopherjs/gopherjs/test.784702578:1510:3)
    at Object.<anonymous> (/home/aleks/go/src/github.com/gopherjs/gopherjs/test.784702578:45588:1)
    at Object.<anonymous> (/home/aleks/go/src/github.com/gopherjs/gopherjs/test.784702578:45591:4)
    at Module._compile (internal/modules/cjs/loader.js:654:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:665:10)
    at Module.load (internal/modules/cjs/loader.js:566:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:506:12)
    at Function.Module._load (internal/modules/cjs/loader.js:498:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:695:10)
    at startup (internal/bootstrap/node.js:201:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:516:3)
FAIL    fmt     0.620s

Note there isn't a warning about missing source-map-support module. It would be there if I didn't do the export NODE_PATH=... thing.

I also tried this:

$ gopherjs test -v -c fmt
$ ls fmt_test.js*
fmt_test.js  fmt_test.js.map
$ node --require source-map-support/register fmt_test.js

/home/aleks/go/src/github.com/gopherjs/gopherjs/fmt_test.js:4210
                _r = reflectlite.TypeOf((ptrType.nil)).Elem(); /* */ $s = 2; case 2: if($c) { $c = false; _r = _r.$blk(); } if (_r && _r.$blk !== undefined) { break s; }
                                        ^
TypeError: Cannot read property 'Elem' of undefined
    at Object.$init (/home/aleks/go/src/github.com/gopherjs/gopherjs/fmt_test.js:4210:41)
    at Object.$init (/home/aleks/go/src/github.com/gopherjs/gopherjs/fmt_test.js:7350:15)
    at Object.$init (/home/aleks/go/src/github.com/gopherjs/gopherjs/fmt_test.js:8306:14)
    at Object.$init (/home/aleks/go/src/github.com/gopherjs/gopherjs/fmt_test.js:45090:14)
    at $init (/home/aleks/go/src/github.com/gopherjs/gopherjs/fmt_test.js:45567:17)
    at $goroutine (/home/aleks/go/src/github.com/gopherjs/gopherjs/fmt_test.js:1478:19)
    at $runScheduled (/home/aleks/go/src/github.com/gopherjs/gopherjs/fmt_test.js:1518:7)
    at $schedule (/home/aleks/go/src/github.com/gopherjs/gopherjs/fmt_test.js:1534:5)
    at $go (/home/aleks/go/src/github.com/gopherjs/gopherjs/fmt_test.js:1510:3)
    at Object.<anonymous> (/home/aleks/go/src/github.com/gopherjs/gopherjs/fmt_test.js:45588:1)
    at Object.<anonymous> (/home/aleks/go/src/github.com/gopherjs/gopherjs/fmt_test.js:45591:4)
    at Module._compile (internal/modules/cjs/loader.js:654:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:665:10)
    at Module.load (internal/modules/cjs/loader.js:566:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:506:12)
    at Function.Module._load (internal/modules/cjs/loader.js:498:3)
    at Function.Module.runMain (internal/modules/cjs/loader.js:695:10)
    at startup (internal/bootstrap/node.js:201:19)
    at bootstrapNodeJSCore (internal/bootstrap/node.js:516:3)

The result is exactly the same.

$ gopherjs version
GopherJS 1.13-wip
$ node --version
v10.0.0

For the reference, the compiled scripts: fmt_test.zip. Manual inspection doesn't seem to reveal any smoking gun.

Any suggestions? Thanks! :)
@nevkontakte nevkontakte changed the title Source maps have no effect Source maps have no effect in `gopherjs test` Sep 24, 2019
@nevkontakte
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@nevkontakte nevkontakte commented Oct 6, 2019

I dug into the isse a little bit today and it looks like the source map support is working, but I got lucky enough to get a stack trace which lands into areas of the compiled code which are not mapped onto any original Go code.

For example:

    at Object.$init (/home/aleks/go/src/github.com/gopherjs/gopherjs/fmt_test.js:45090:14)

I used https://pastcompute.github.io/ScriptMapper/ to decode the source map and this is where this line ends up pointing at:

/fmt/stringer_test.go,45018,0,60,2,null
null,45019,0,null,null,null
null,45090,0,null,null,null <----
null,45091,0,null,null,null
...
null,45193,0,null,null,null
/fmt/fmt_test.go,45196,0,1421,30,null

The generated script:

	$init = function() {
		$pkg.$init = function() {};
		/* */ var $f, $c = false, $s = 0, $r; if (this !== undefined && this.$blk !== undefined) { $f = this; $c = true; $s = $f.$s; $r = $f.$r; } s: while (true) { switch ($s) { case 0:
                // ↓ Line 45090
		$r = bufio.$init(); /* */ $s = 1; case 1: if($c) { $c = false; $r = $r.$blk(); } if ($r && $r.$blk !== undefined) { break s; }
		$r = bytes.$init(); /* */ $s = 2; case 2: if($c) { $c = false; $r = $r.$blk(); } if ($r && $r.$blk !== undefined) { break s; }
		$r = errors.$init(); /* */ $s = 3; case 3: if($c) { $c = false; $r = $r.$blk(); } if ($r && $r.$blk !== undefined) { break s; }
		$r = fmt.$init(); /* */ $s = 4; case 4: if($c) { $c = false; $r = $r.$blk(); } if ($r && $r.$blk !== undefined) { break s; }

This code looks like some sort of GopherJS-generated package preamble, which is probably why it isn't mapped directly on the original source code. It would be nice, however to have it mapped at least into the file it was generated for.
@nevkontakte nevkontakte changed the title Source maps have no effect in `gopherjs test` Some areas of the generated JS files are not covered by source maps. Oct 6, 2019
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