This change adds support for `const` redeclaration on REPL mode with
the semantincs recommended in the design doc:
1) REPL scripts should not be able to reassign bindings to `const`
variables.
2) Re-declaring `const` variables of page scripts is not allowed in
REPL scripts.
3) Re-declearing `const` variables is not allowed in the same REPL
script.
4) `const` re-declaration is allowed across separate REPL scripts.
5) Old references to previously declared variables get updated with the
new value, even those references from within optimized functions.
Design doc: https://goo.gle/devtools-const-repl
Bug: chromium:1076427
Change-Id: Ic73d2ae7fcfbfc1f5b58f61e0c3c69e9c4d85d77
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2865721
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Mythri Alle <mythria@chromium.org>
Commit-Queue: Luis Fernando Pardo Sixtos <lpardosixtos@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#74510}
This is a reland of 5bddc0e142
The original CL was speculatively reverted as it was suspected to
cause failures on the non-determinism bot. This was ultimately
confirmed to not be the case, so this CL is safe to reland as-is.
Original change's description:
> Implement top-level await for REPL mode
>
> Design doc: bit.ly/v8-repl-mode
>
> This CL allows the usage of 'await' without wrapping code in an async
> function when using REPL mode in global evaluate. REPL mode evaluate
> is changed to *always* return a Promise. The resolve value of the
> promise is the completion value of the REPL script.
>
> The implementation is based on two existing mechanisms:
> - Similar to async functions, the content of a REPL script is
> enclosed in a synthetic 'try' block. Any thrown error
> is used to reject the Promise of the REPL script.
>
> - The content of the synthetic 'try' block is also re-written the
> same way a normal script is. This is, artificial assignments to
> a ".result" variable are inserted to simulate a completion
> value. The difference for REPL scripts is, that ".result" is
> used to resolve the Promise of the REPL script.
>
> - ".result" is not returned directly but wrapped in an object
> literal: "{ .repl_result: .result}". This is done to prevent
> resolved promises from being chained and resolved prematurely:
>
> > Promse.resolve(42);
>
> should evaluate to a promise, not 42.
>
> Bug: chromium:1021921
> Change-Id: I00a5aafd9126ca7c97d09cd8787a3aec2821a67f
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1900464
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Commit-Queue: Simon Zünd <szuend@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#65273}
TBR: yangguo@chromium.org,verwaest@chromium.org
Bug: chromium:1021921
Change-Id: I95c5dc17593161009a533188f91b4cd67234c32f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1954388
Reviewed-by: Simon Zünd <szuend@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65360}
This reverts commit 5bddc0e142.
Reason for revert: Possible culprit for https://bugs.chromium.org/p/chromium/issues/detail?id=1029863
Original change's description:
> Implement top-level await for REPL mode
>
> Design doc: bit.ly/v8-repl-mode
>
> This CL allows the usage of 'await' without wrapping code in an async
> function when using REPL mode in global evaluate. REPL mode evaluate
> is changed to *always* return a Promise. The resolve value of the
> promise is the completion value of the REPL script.
>
> The implementation is based on two existing mechanisms:
> - Similar to async functions, the content of a REPL script is
> enclosed in a synthetic 'try' block. Any thrown error
> is used to reject the Promise of the REPL script.
>
> - The content of the synthetic 'try' block is also re-written the
> same way a normal script is. This is, artificial assignments to
> a ".result" variable are inserted to simulate a completion
> value. The difference for REPL scripts is, that ".result" is
> used to resolve the Promise of the REPL script.
>
> - ".result" is not returned directly but wrapped in an object
> literal: "{ .repl_result: .result}". This is done to prevent
> resolved promises from being chained and resolved prematurely:
>
> > Promse.resolve(42);
>
> should evaluate to a promise, not 42.
>
> Bug: chromium:1021921
> Change-Id: I00a5aafd9126ca7c97d09cd8787a3aec2821a67f
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1900464
> Reviewed-by: Yang Guo <yangguo@chromium.org>
> Reviewed-by: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Commit-Queue: Simon Zünd <szuend@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#65273}
TBR=yangguo@chromium.org,leszeks@chromium.org,verwaest@chromium.org,szuend@chromium.org
# Not skipping CQ checks because original CL landed > 1 day ago.
Bug: chromium:1021921
Change-Id: I9eaea584e2e09f3dffcbbca3d75a3c9bcb0a1adf
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1948719
Reviewed-by: Maya Lekova <mslekova@chromium.org>
Commit-Queue: Maya Lekova <mslekova@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65333}
Design doc: bit.ly/v8-repl-mode
This CL allows the usage of 'await' without wrapping code in an async
function when using REPL mode in global evaluate. REPL mode evaluate
is changed to *always* return a Promise. The resolve value of the
promise is the completion value of the REPL script.
The implementation is based on two existing mechanisms:
- Similar to async functions, the content of a REPL script is
enclosed in a synthetic 'try' block. Any thrown error
is used to reject the Promise of the REPL script.
- The content of the synthetic 'try' block is also re-written the
same way a normal script is. This is, artificial assignments to
a ".result" variable are inserted to simulate a completion
value. The difference for REPL scripts is, that ".result" is
used to resolve the Promise of the REPL script.
- ".result" is not returned directly but wrapped in an object
literal: "{ .repl_result: .result}". This is done to prevent
resolved promises from being chained and resolved prematurely:
> Promse.resolve(42);
should evaluate to a promise, not 42.
Bug: chromium:1021921
Change-Id: I00a5aafd9126ca7c97d09cd8787a3aec2821a67f
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1900464
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Commit-Queue: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65273}
Design doc: bit.ly/v8-repl-mode
This CL adds a new REPL mode that can be used via
DebugEvaluate::GlobalREPL. REPL mode only implements re-declaration
of 'let' bindings at the moment. Example:
REPL Input 1: let x = 21;
REPL Input 2: let x = 42;
This would normally throw a SyntaxError, but works in REPL mode.
The implementation is done by:
- Setting a 'repl mode' bit on {Script}, {ScopeInfo}, {ParseInfo}
and script {Scope}.
- Each global let declaration still gets a slot reserved in the
respective {ScriptContext}.
- When a new REPL mode {ScriptContext} is created, name clashes
for let bindings are not reported as errors.
- Declarations, loads and stores for global let in REPL mode are
now "load/store global" instead of accessing their respective
context slot directly. This causes a lookup in the ScriptContextTable
where the found slot for each name is guaranteed to be the same
(the first one).
Bug: chromium:1004193, chromium:1018158
Change-Id: Ia6ab526b9f696400dbb8bfb611a4d43606119a47
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1876061
Commit-Queue: Simon Zünd <szuend@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64793}
