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Simon Zünd e417b339ee [debug] Report variables in TDZ as 'value unavailable'
Consider the function:

function foo() {
  debugger;
  let y = 1;
}

V8 will elide the hole initialization for 'y'. When we pause at the
debugger statement, then 'y' evaluates to 'undefined'.

This CL fixes this in the ScopeIterator. When we encounter local
variables with an `undefined` value we check the static scope
information if we are stopped *before* the variable's initializer.
If yes, then we are in the variable's TDZ and report
"value unavailable".

Drive-by: Mark `GetSourcePosition()` as `const` to make it available
in the visitor method.

R=bmeurer@chromium.org

Bug: chromium:1328681
Change-Id: I8b966eaa2af64a35a58095a744440851760921a0
Fixed: chromium:1303493
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3829539
Commit-Queue: Simon Zünd <szuend@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/main@{#82483}
2022-08-16 09:59:57 +00:00
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bazel [bazel] Silent zlib warning '-Wdeprecated-non-prototype' 2022-08-04 10:12:05 +00:00
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gni [infra] Change all Python shebangs to Python3 2022-08-05 14:55:00 +00:00
include [api] Advance API deprecation 2022-08-16 08:11:57 +00:00
infra Reland "Reland "[infra] Enable sandbox for x64 and arm64 builders and add a set of builders with Sandbox off"" 2022-08-16 09:22:10 +00:00
samples [sandbox] Initialize sandbox during V8::Initialize 2022-07-15 09:29:32 +00:00
src [debug] Report variables in TDZ as 'value unavailable' 2022-08-16 09:59:57 +00:00
test [debug] Report variables in TDZ as 'value unavailable' 2022-08-16 09:59:57 +00:00
testing [test] Migrate cctest/test-api-accessors.cc to unittests/ 2022-05-17 08:27:55 +00:00
third_party [infra] Change all Python shebangs to Python3 2022-08-05 14:55:00 +00:00
tools [wasm] Add --no-wasm-lazy-compilation to stress 2022-08-16 06:03:57 +00:00
.bazelrc [bazel] Use v8_enable_handle_zapping only in debug builds. 2022-01-11 11:32:39 +00:00
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V8 JavaScript Engine

V8 is Google's open source JavaScript engine.

V8 implements ECMAScript as specified in ECMA-262.

V8 is written in C++ and is used in Google Chrome, the open source browser from Google.

V8 can run standalone, or can be embedded into any C++ application.

V8 Project page: https://v8.dev/docs

Getting the Code

Checkout depot tools, and run

    fetch v8

This will checkout V8 into the directory v8 and fetch all of its dependencies. To stay up to date, run

    git pull origin
    gclient sync

For fetching all branches, add the following into your remote configuration in .git/config:

    fetch = +refs/branch-heads/*:refs/remotes/branch-heads/*
    fetch = +refs/tags/*:refs/tags/*

Contributing

Please follow the instructions mentioned at v8.dev/docs/contribute.