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@JLHwung Why not set 'this.scope.inStaticBlock' when you enter a static block, and unset this again every time you enter function body, arrow or block statement, and then for await check if this is set and if so, throw.

@KFlash Besides function body, arrow, we should also take care of the class field initializers. A plain block statement { expr } inherit the await production, so we should not reset for plain block. Essentially it should be maintained in whatever production that does not inherit [Await], which is easily overlooked when new language feature is introduced. A boolean state has fastest access time, however such state inStaticBlock will only be accessed when we see a binding identifier named await, which is rare.

I think the current approach is easier to maintain because we already have to push a lexical scope for static block, so an extra mark on the scope, compacted to bit arrays, does not introduce extra recording tasks. The worst scenario of current approach is an await nested in N block statements within a static block, while the boolean approach certainly performs better in this scenario.

@JLHwung An easy solution for this is to "copy" what the author of this proposal did. Look at the open PR for implementation of static block in the Typescript repo.