'native' import statements in @parser:header are dropped

[ericvergnaud]

Consider the following grammar:

grammar G;

@parser:header {
// import X from './X';
import X from './X';
class Y extends X {}
}

a: 'a' EOF;

The generated code will look as follows:

.../...
// import X from './X';
class Y extends X {}
class GParser extends Parser { .../... }

notice that the native statement "import X from './X';" has been dropped.
it doesn't happen with preceding comment or the succeeding declaration.
I suspect it is because the tool sees the 'import...' line as an antlr import statement...

[ericvergnaud]

mmm... this only happens during testing, so I should be able to fix it without side effects

[ericvergnaud]

The issue title is misleading.
It happened in TypeScript testing only, as a side effect of having the @parser::header text inserted in not only the parser but also the listener and the visitor, which makes no sense.
As a result, because some of the inserted code would not resolve in the listener/visitor), tsc (the Typescript compiler) would mess up silently and drop the imports in the transpired js files (not in the ts files).
@parrt this is fixed by removing the named action "header" after generating the parser, which needs your blessing.

[KvanTTT]

I'm afraid I can't bless such a fix. It's unclear why CodeGenPipilne removes name action and method removeParserHeader in Grammar looks irrelevant. Is it possible just not to add header named action?

[ericvergnaud]

@Kvantt, thanks for your comments, some of them are useful, but at mentioned originally, this is not a time for review yet. Blessing is only required from Ter.

…

Le 7 sept. 2022 à 13:40, Ivan Kochurkin ***@***.***> a écrit : I'm afraid I can't bless such a fix. It's unclear why CodeGenPipilne removes name action and method removeParserHeader in Grammar looks irrelevant. Is it possible just not to add header named action? — Reply to this email directly, view it on GitHub <#3868 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAZNQJCGTC6LAOTTDOZRNPTV5B5MDANCNFSM6AAAAAAQFXAEGI>. You are receiving this because you authored the thread.

[ericvergnaud]

Closed in favor of #3877