njs: block scoped function definitions support.

@drsm @xeioex

Updated. https://gist.github.com/hongzhidao/4f4e902bfec4a44834f93aa77dbfb19d

@hongzhidao

BTW, how do you get the result like below? the percentage of pass, for example 25.2%.

you need --summary option.

@xeioex

The code above inserts a variable into multiple scopes (into function and block scopes)

I thought about it. Essentially we need two different things to store the added variable information: scope->declared_vars and scope->variables. scope-> declared_vars is required in each scope and will be used to check duplicated declarations as needed, scope->variables is kept the current way. Now we combine them together.

BTW, how do you get the result like below? the percentage of pass, for example 25.2%.

- - Passed 6785 tests (25.0%)
- - Failed 20334 tests (75.0%)
+ - Passed 6831 tests (25.2%)
+ - Failed 20288 tests (74.8%)

@hongzhidao

declaration_exception.js is missing

Problem with lexically declared name:

;{ function f() {} { var f }}

I updated it again, spliting it into separate patches 😃 https://gist.github.com/hongzhidao/4f4e902bfec4a44834f93aa77dbfb19d

Problem with lexically declared name:

;{ function f() {} { var f }}

Is it a problem? Get it, yes.

I follow the instruction, but I don’t know how to filter out the right information.

1. use --command='<full path to njs cli binary> -q' to disable filenames in output of exceptions (randoms filenames are used by tests)
2. you need to run test262 2 times before and after the test, to see the diff diff -u test262_njs_orig.log test262_njs_after.log

There are four cases:

1. function definition at top level of module.
2. function definition at top level of another function.
3. function definition inside a block.
4. function definition at top level of script.

// 1. or 4. depends on vm->options.module
function f() {}
function a() {
    // 2.
    function f() {}
}
function b() {
    {
        // 3.
        function f() {}
    }
}

Cases 1. and 3. are identical. I use block in tests because node’s REPL doesn’t support evaluation as a module.

• the definition behave like lexically declared variable (let f)

root@node:~# node --use-strict
> ;{ function f() {} function f() {} }
SyntaxError: Identifier 'f' has already been declared
> ;{ function f() { return 1; } { function f() { return 2; } } f(); }
1
> ;{ { function f() { return 1; } f(); } function f() { return 2; } }
1
> ;{ var f; function f() {} }
SyntaxError: Identifier 'f' has already been declared
> ;{ let f; function f() {} }
SyntaxError: Identifier 'f' has already been declared
> ;{ function f() {} f = 1; f}
1

• the definition is hoisted to the top of the block and initialized there. so there is no TDZ.

> ;{ typeof f; function f() {} }
'function'

The cases 2. and 4. are identical.

• the definition behave like var declared variable.

> (() => { function f() { return 1; } function f() { return 2; } return f(); })()
2
> (() => { function f() { return 1; } f = 1; return f; })()
1

• the definition is hoisted to the top of the surrounding function. and initialized before any other var declared stuff.

> (() => { var x = typeof f; function f() { return 1; } return x; })()
'function'
> (() => { var f; var x = typeof f; function f() { return 1; } return x; })()
'function'
> (() => { var f = 1; var x = typeof f; function f() { return 1; } return x; })()
'number'
> (() => { var x = typeof f; function f() { return 1; } var f = 1; return x; })()
'function'

We have to change our module wrapper from

function() {
/* module code */
}

to

() => {
    if (true) {
        /* module code */
    }
}

to support the feature.

@drsm

My understand.

1. functions can only be declared at top level or inside a block.
2. functions scope is at where it declared.
3. with if (1) x, there is no scope inside if.

Right?