We use the compilation entry point as a caching scope for deserializing
lookups, to avoid redundantly iterating over parent scopes when
accessing the same variable multiple times.
However, this caching scope messes with lookups that are looking for
lexical name conflicts, as opposed to just resolving variables. In
particular, it messes with name conflict lookups and sloppy block
function hoisting checks, when there are other scopes in the way, e.g.
function f() {
let x;
try {
throw 0;
}
catch (x) {
// This catch is the entry scope
// Naive use of caches will find the catch-bound x (which is
// a VAR), and declare 'no conflict'.
eval("var x;");
// Naive use of caches will find the catch-bound x (which is
// a VAR), and determine that this function can be hoisted.
eval("{ function x() {} }");
}
}
Previously, we worked around this by avoiding cache uses for these
lookups, but this had the issue of instead caching the same variable
multiple times, on different scopes. In particular, we saw:
function f() {
with ({}) {
// This with is the entry scope, any other scope would do
// though.
// The conflict check on `var f` caches the function name
// variable on the function scope, the subsequent 'real'
// lookup of `f` caches the function name variable on the
// entry i.e. with scope.
eval("var f; f;");
}
}
With this patch, we change the caching behaviour to cache on the first
non-eval declaration scope above the eval -- in the above examples, this
becomes the parent function "f". For compilations with no intermediate
non-decl scopes (no with or catch scopes between the function and eval)
this becomes equivalent to the existing entry-point-based caching.
This means that normal lookups do have to (sometimes) iterate more scopes,
and we do have to be careful when using the cache to not use it for
lookups in these intermediate scopes (a new IsOuterScope DCHECK guards
against this), but we can now safely ignore the cache scope when doing
the name-collision lookups, as they only iterate up to the outer
non-eval declaration scope anyway.
Bug: chromium:1026603
Bug: chromium:1029461
Change-Id: I9e7a96ce4b8adbc7ed47a49fba6fba58b526235b
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1955731
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65391}
That makes the declaration in sync with how dynamic references are resolved,
avoiding duplicate variable creation in the likely case that the variable is
also referenced within the eval.
Bug: v8:5112, v8:5135, v8:8693
Change-Id: I0c55495f573fe8b5076b1627c139ff72d1adda74
Also-by: leszeks@chromium.org
Reviewed-on: https://chromium-review.googlesource.com/c/1408890
Commit-Queue: Toon Verwaest <verwaest@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#58850}
In edge cases such as the following, sloppy-mode block-scoped function
hoisting is expected to occur:
eval(`
with({a: 1}) {
function a() {}
}
`)
In this case, there should be the equivalent of a var declaration
outside of the eval, which gets set to the value of the local function
a when the body of the with is executed.
Previously, the way that var declarations are hoisted out of eval
meant that the assignment to that var was an ordinary DYNAMIC_GLOBAL
assignment. However, such a lookup mode meant that the object in the
with scope received the assignment!
This patch fixes that error by marking the assignments produced by
the sloppy mode block scoped function hoisting desugaring so as to
generate a different runtime call which skips with scopes.
Bug: chromium:720247, v8:5135
Change-Id: Ie36322ddc9ca848bf680163e8c016f50d4597748
Reviewed-on: https://chromium-review.googlesource.com/529230
Commit-Queue: Daniel Ehrenberg <littledan@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46116}
This moves scope-related logic (such as looking up variables) to Scope
where it belongs, and enables PreParser to do more Scope-related
operations in the future.
BUG=
Review-Url: https://codereview.chromium.org/2301183003
Cr-Commit-Position: refs/heads/master@{#39233}
Annex B.3.3 of the spec requires that sloppy-mode block-scoped functions
declared by "eval" are hoisted unless doing so would cause an early
error (which is to say, conflict with a lexical declaration). This patch
amends the check for conflicting declarations to include those outside
of the eval itself.
BUG=v8:4468, v8:4479
Review-Url: https://codereview.chromium.org/2112163002
Cr-Commit-Position: refs/heads/master@{#37783}
Reason for revert:
Correcting issue.
Original issue's description:
> Revert of Add errors for declarations which conflict with catch parameters. (patchset #6 id:100001 of https://codereview.chromium.org/2109733003/ )
>
> Reason for revert:
> Fuzzer claims `try { \"\" ; } catch(x) { let x1 = [1,,], x = x; }` causes a crash.
>
> Original issue's description:
> > Add errors for declarations which conflict with catch parameters.
> >
> > Catch parameters are largely treated as lexical declarations in the
> > block which contains their body for the purposes of early syntax errors,
> > with some exceptions outlined in B.3.5. This patch introduces most of
> > those errors, except those from `eval('for (var e of ...);')` inside of
> > a catch with a simple parameter named 'e'.
> >
> > Note that annex B.3.5 allows var declarations to conflict with simple
> > catch parameters, except when the variable declaration is the init of a
> > for-of statement.
> >
> > BUG=v8:5112,v8:4231
> >
> > Committed: https://crrev.com/2907c726b2bb5cf20b2bec639ca9e6a521585406
> > Cr-Commit-Position: refs/heads/master@{#37462}
>
> TBR=littledan@chromium.org
> # Skipping CQ checks because original CL landed less than 1 days ago.
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
> BUG=v8:5112,v8:4231
>
> Committed: https://crrev.com/8834d5ecb559001c87c42322969471da60574a8c
> Cr-Commit-Position: refs/heads/master@{#37464}
R=littledan@chromium.org
BUG=v8:5112,v8:4231
Review-Url: https://codereview.chromium.org/2119933002
Cr-Commit-Position: refs/heads/master@{#37728}
Reason for revert:
Fuzzer claims `try { \"\" ; } catch(x) { let x1 = [1,,], x = x; }` causes a crash.
Original issue's description:
> Add errors for declarations which conflict with catch parameters.
>
> Catch parameters are largely treated as lexical declarations in the
> block which contains their body for the purposes of early syntax errors,
> with some exceptions outlined in B.3.5. This patch introduces most of
> those errors, except those from `eval('for (var e of ...);')` inside of
> a catch with a simple parameter named 'e'.
>
> Note that annex B.3.5 allows var declarations to conflict with simple
> catch parameters, except when the variable declaration is the init of a
> for-of statement.
>
> BUG=v8:5112,v8:4231
>
> Committed: https://crrev.com/2907c726b2bb5cf20b2bec639ca9e6a521585406
> Cr-Commit-Position: refs/heads/master@{#37462}
TBR=littledan@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:5112,v8:4231
Review-Url: https://codereview.chromium.org/2112223002
Cr-Commit-Position: refs/heads/master@{#37464}
Catch parameters are largely treated as lexical declarations in the
block which contains their body for the purposes of early syntax errors,
with some exceptions outlined in B.3.5. This patch introduces most of
those errors, except those from `eval('for (var e of ...);')` inside of
a catch with a simple parameter named 'e'.
Note that annex B.3.5 allows var declarations to conflict with simple
catch parameters, except when the variable declaration is the init of a
for-of statement.
BUG=v8:5112,v8:4231
Review-Url: https://codereview.chromium.org/2109733003
Cr-Commit-Position: refs/heads/master@{#37462}
In ES2016, function declarations nested in blocks are formally allowed. This was
never a part of ECMAScript, but was a common extension. Unfortunately
implementations differed in the exact semantics. Annex B.3.3 in the spec tries
to standardize the parts which are common to different implementations, but does
so with some fairly complicated semantics.
This CL addresses three issues related to annex B.3.3:
* When the outer function had a complex parameter list, no hoisting whatsoever was
being performed.
* Hoisting was not blocked by parameters of the same name.
* Hoisting was not blocked by nested lexical declarations of the same name.
We had tests which checked for the second, but they were incorrectly passing due to
the first. This CL adds more complete tests.
BUG=v8:5151, v8:5111
Review-Url: https://codereview.chromium.org/2099623003
Cr-Commit-Position: refs/heads/master@{#37405}
