Uncaught exception Cannot call null (reproducible!)

[nadako]

So far I failed to reproduce this outside VSCode, but it is 100% reproducible inside it. Might have something to do with --cwd calls because of the weird changed directories: [] below.

Main.hx

class Main {
	static function main() {
		Macro.func(); 
	}
}

Macro.hx

class Macro {
    public static macro function func() {
        var t = haxe.macro.Context.getType("Int");
        trace(t);
        return macro 1;
    }
}

build.hxml

-main Main
-js main.js

.vscode/settings.json

{
    "haxe.displayServer": {"arguments": ["-v"]},
    "haxe.buildCompletionCache": false,
    "haxe.enableDiagnostics": false
}

(so the amount of uncontrolled server calls is minimal)

1. Open this project in VSCode
2. Compile with the build task (so cache server is used)
3. Comment line 3 in Macro.hx (var t = haxe.macro.Context.getType("Int");) and save the file
4. Compile with the build task again - get the proper error (Unknown identifier : t)
5. Uncomment line 3 in Macro.hx back and save the file
6. Compile with the build task - BAM: Macro.hx:3: characters 17-50 : Uncaught exception Cannot call null

Haxe server output

Haxe language server started
Using --server-connect
Haxe connected!
Processing Arguments [--display,{"jsonrpc":"2.0","id":0,"method":"initialize","params":{"supportsResolve":true,"exclude":["zpp_nape"],"maxCompletionItems":1000}}]
Completion Response =
{"jsonrpc":"2.0","id":0,"result":{"result":{"methods":["display/definition","server/contexts","server/moduleCreated","server/invalidate","server/module","server/files","initialize","display/completion","typer/compiledTypes","display/references","server/modules","server/memory/context","display/completionItem/resolve","display/typeDefinition","server/memory","display/implementation","display/hover","display/package","display/signatureHelp","server/memory/module","server/readClassPaths","server/configure"],"haxeVersion":{"major":4,"minor":1,"patch":0,"pre":"rc.1","build":"bc6eca1fd"},"protocolVersion":{"major":0,"minor":4,"patch":0}},"timestamp":1582399821.6802447}}
Stats = 0 files, 0 classes, 0 methods, 0 macros
Time spent : 0.000s
Listening on port 6000
Processing Arguments [--display,{"jsonrpc":"2.0","id":1,"method":"server/configure","params":{"noModuleChecks":true,"print":{"completion":false,"reusing":false},"legacyCompletion":false}}]
Stats = 0 files, 0 classes, 0 methods, 0 macros
Time spent : 0.000s
Client connected
Processing Arguments [--cwd,c:\Users\nadako\Code\playground,build.hxml]
Defines dce=std,haxe3=1,haxe4=1,haxe=4.1.0-rc.1,haxe_ver=4.100,js-es5=1,js=1,js_es5=1,js_es=5,source-header=Generated by Haxe 4.1.0-rc.1+bc6eca1fd,target.name=js,target.unicode=true,target.utf16=true,true=1,utf16=1
Using signature 84fef1af5de52a14c9c1eb15ad163b2e
Display position: ?: -1--1
 0, js: Cached 48 modules
Stats = 158 files, 171 classes, 862 methods, 1 macros
Time spent : 0.150s
Client disconnected
Processing Arguments [--display,{"jsonrpc":"2.0","id":2,"method":"server/invalidate","params":{"file":"c:/Users/nadako/Code/playground/Macro.hx"}}]
Stats = 0 files, 0 classes, 0 methods, 0 macros
Time spent : 0.000s
Client connected
Processing Arguments [--cwd,c:\Users\nadako\Code\playground,build.hxml]
Defines dce=std,haxe3=1,haxe4=1,haxe=4.1.0-rc.1,haxe_ver=4.100,js-es5=1,js=1,js_es5=1,js_es=5,source-header=Generated by Haxe 4.1.0-rc.1+bc6eca1fd,target.name=js,target.unicode=true,target.utf16=true,true=1,utf16=1
Using signature 84fef1af5de52a14c9c1eb15ad163b2e
Display position: ?: -1--1
 0, js: skipping Main(Macro)
 0, js: skipping Macro
 1,evl: skipping Macro
> Macro.hx:4: characters 15-16 : Unknown identifier : t
Macro.hx:4: characters 15-16 : For function argument 'v'
 1,evl: found 35 directories
 0, js: found 41 directories
Stats = 2 files, 3 classes, 2 methods, 1 macros
Time spent : 0.030s
Client disconnected
Processing Arguments [--display,{"jsonrpc":"2.0","id":3,"method":"server/invalidate","params":{"file":"c:/Users/nadako/Code/playground/Macro.hx"}}]
Stats = 0 files, 0 classes, 0 methods, 0 macros
Time spent : 0.000s
Client connected
Processing Arguments [--cwd,c:\Users\nadako\Code\playground,build.hxml]
Defines dce=std,haxe3=1,haxe4=1,haxe=4.1.0-rc.1,haxe_ver=4.100,js-es5=1,js=1,js_es5=1,js_es=5,source-header=Generated by Haxe 4.1.0-rc.1+bc6eca1fd,target.name=js,target.unicode=true,target.utf16=true,true=1,utf16=1
Using signature 84fef1af5de52a14c9c1eb15ad163b2e
Display position: ?: -1--1
 0, js: changed directories: []
 0, js: skipping Main(Macro)
 0, js: skipping Macro
 1,evl: changed directories: []
 1,evl: skipping Macro
> Macro.hx:3: characters 17-50 : Uncaught exception Cannot call null
Main.hx:3: characters 3-15 : Called from here
> Main.hx:1: lines 1-5 : Defined in this class
Stats = 2 files, 3 classes, 2 methods, 1 macros
Client disconnected
Time spent : 0.005s

As mentioned, these changed directories: [] look suspicious and if it is the cause, it might explain why it's so hard to reproduce as it might be related to current working directories.

[Gama11]

This only seems to happen with --server-connect, which explains why simn bisected this to 1528b81b0990779b15ecee41227b19e6d29066dc - haxe-language-server only enables that if the haxe version is >= 4.1.

[RealyUniqueName]

Yeah, I can't reproduce this with --wait even repeating exact same commands and file modifications vshaxe does.

[RealyUniqueName]

Btw, that cannot call null comes from haxe.macro.Context static prototype being used without its fields populated.

[Simn]

Yes, I already investigated that a bit and found that the cf_expr values were all None. This suggests some problem in the compilation server, not something eval-specific.

[RealyUniqueName]

Provided sample works fine now.

[nadako]

FYI I still get this when working on macros sometimes, but it's much rarer after the fix! I'll try to provide an example next time I get it.

[zommerfelds]

Had the same issue today in vscode when working on macros. Restarting the language server fixed the issue, so can't repro anymore.