Add a flag harmony_trailing_commas_in_parameters that allows trailing
commas in function parameter declaration lists and function call
parameter lists. Trailing commas are allowed in parenthetical lists like
`(a, b, c,)` only if the next token is `=>`, thereby making it an arrow
function declaration. Only 1 trailing comma is allowed, not `(a,,)`. A
trailing comma must follow a non-rest parameter, so `(,)` and `(...a,)`
are still SyntaxErrors. However, a trailing comma is allowed after a
spread parameter, e.g. `a(...b,);`.
Add parser tests for all of the above.
BUG=v8:5051
LOG=y
Review-Url: https://codereview.chromium.org/2094463002
Cr-Commit-Position: refs/heads/master@{#37355}
Previously, an async arrow function would be parsed if any valid
ConditionalExpression began with the identifier "async", and its following token
was on the same line.
So for example, `async.bar foo => 1` was parsed as a valid async arrow function.
This patch corrects this behaviour by asserting that the following token is a
valid arrow parameters start.
BUG=v8:4483
R=littledan@chromium.org, henrique.ferreiro@gmail.com
Review-Url: https://codereview.chromium.org/2089733002
Cr-Commit-Position: refs/heads/master@{#37154}
Reporting use counts by invoking a callback once per occurrence has
a large overhead cost in certain situations, for example when it needs
to be dispatched to a different thread (which is the case for Web Workers).
Parsing large scripts can produce a lot of occurrences (strict/sloppy mode
once per function).
Chromium (the only known user of UseCounters so far) does not actually care
about number of occurrences, but simply whether they happened at least once.
This commit changes behavior to report features at most once, which dramatically
improves performance for impacted use cases, and should not affect the only
known real world usage.
R=littledan@chromium.org
BUG=chromium:614775
Review-Url: https://codereview.chromium.org/2062203002
Cr-Commit-Position: refs/heads/master@{#36979}
Annex B 3.3 applies only for ordinary FunctionDeclarations, not
GeneratorDeclarations or AsyncFunctionDeclarations. This patch
- Skips applying Annex B 3.3 to async functions
- Adds a flag to refrain from applying it to generators
- UseCounter for how often duplicate function in block occurs
with generators (unclear how to measure need for hoisting from block)
BUG=v8:4806
Review-Url: https://codereview.chromium.org/1995863002
Cr-Commit-Position: refs/heads/master@{#36557}
Some IdentifierNames are only included in the set of FutureReservedWords
for strict mode code. Outside of strict mode, these IdentifierNames may
be used as Identifiers. Notably, this includes their use as
BindingIdentifiers in LexicalBindings.
From ES2015 12.1.1 Static Semantics: Early Errors (Identifiers):
> It is a Syntax Error if this phrase is contained in strict mode code
> and the StringValue of IdentifierName is: "implements", "interface",
> "let", "package", "private", "protected", "public", "static", or
> "yield".
http://www.ecma-international.org/ecma-262/6.0/#sec-identifiers-static-semantics-early-errors
Due to a error in its heuristic for disambiguating the `let` token, V8
does not currently allow any of the strict-mode-only FutureReservedWords
to be used as a BindingIdentifier outside of strict mode.
Update V8's heuristic for disambiguating the `let` keyword to account
for strict mode, enabling these IdentifierNames to be used
BUG=v8:4918
LOG=N
R=adamk@chromium.org
Review-Url: https://codereview.chromium.org/1891453005
Cr-Commit-Position: refs/heads/master@{#36296}
Yield expressions are not allowed in formal parameter initializers of
generators, but we weren't properly catching the case where the yield
expression appeared in the 'extends' clause of a class expression.
They also aren't allowed in arrow functions, which we were failing to
catch due to not looking at the obscurely-named "FormalParameterInitializerError"
bit of ExpressionClassifier.
This patch passes along an ExpressionClassifier when parsing class
expressions and accumulates the proper error for that case.
For the arrow function case, the fix is simply to check for the
"formal parameter initializer" error once we know we've parsed
an arrow function. The error message used for this has also
been made specific to yield expressions.
Tests are added both for the error case and the non-error cases (where
yield is used in such a position inside the class body).
BUG=v8:4966, v8:4968, v8:4974
LOG=n
Review-Url: https://codereview.chromium.org/1941823003
Cr-Commit-Position: refs/heads/master@{#35957}
Restrict the use of the `await` token as an identifier when parsing
source text as module code.
From
http://www.ecma-international.org/ecma-262/6.0/#sec-future-reserved-words:
> 11.6.2.2 Future Reserved Words
>
> The following tokens are reserved for used as keywords in future
> language extensions.
>
> Syntax
>
> FutureReservedWord ::
> enum
> await
>
> await is only treated as a FutureReservedWord when Module is the goal
> symbol of the syntactic grammar.
BUG=v8:4767
LOG=N
R=adamk@chromium.org
Review-Url: https://codereview.chromium.org/1723313002
Cr-Commit-Position: refs/heads/master@{#35914}
The legacy function declaration locations from Annex B 3.2 and 3.4 do not
apply for generator declarations. This patch cracks down on those usages,
which is tested for by new incoming test262 tests.
BUG=v8:4824
LOG=Y
R=adamk
Review-Url: https://codereview.chromium.org/1900033003
Cr-Commit-Position: refs/heads/master@{#35835}
The first version of --harmony-for-in avoided throwing PreParser
errors in order to retain use counting. This patch threads
use_counts_ through to the PreParser to allow use counting in
the PreParser while also throwing errors for this case.
Also slightly refactored the Parser code to do a little less
code duplication.
BUG=v8:4942
LOG=y
Review URL: https://codereview.chromium.org/1913203002
Cr-Commit-Position: refs/heads/master@{#35780}
Refactor the Scope object to automatically enable strict mode when
initialized as a "module" scope, relieving the caller of this
responsibility.
BUG=v8:4941
LOG=N
R=adamk@chromium.org
Review URL: https://codereview.chromium.org/1906923002
Cr-Commit-Position: refs/heads/master@{#35730}
[15.2.1.11 Static Semantics:
LexicallyDeclaredNames](https://tc39.github.io/ecma262/#sec-module-semantics-static-semantics-lexicallydeclarednames)
(in contrast with its definition for StatementListItem) makes no
explicit provision for HoistableDeclarations. This means that function
declarations are treated as lexically scoped in module code, as
described in section 15.2.1.11's informative note:
> At the top level of a function, or script, function declarations are
> treated like var declarations rather than like lexical declarations.
BUG=v8:4884
LOG=N
R=adamk@chromium.org
Review URL: https://codereview.chromium.org/1851673007
Cr-Commit-Position: refs/heads/master@{#35633}
The parser should never need to look at the underlying closure object,
hence the field can be moved from ParseInfo into CompilationInfo.
R=rossberg@chromium.org
Review URL: https://codereview.chromium.org/1863083002
Cr-Commit-Position: refs/heads/master@{#35358}
We expect that the majority of malloc'd memory held by V8 is allocated
in Zone objects. Introduce an Allocator class that is used by Zones to
manage memory, and allows for querying the current usage.
BUG=none
R=titzer@chromium.org,bmeurer@chromium.org,jarin@chromium.org
LOG=n
TBR=rossberg@chromium.org
Review URL: https://codereview.chromium.org/1847543002
Cr-Commit-Position: refs/heads/master@{#35196}
Makes --ignition cause eager compilation if we aren't building the startup
snapshot.
BUG=v8:4280
LOG=N
Review URL: https://codereview.chromium.org/1811553003
Cr-Commit-Position: refs/heads/master@{#35066}
ES#sec-islabelledfunction specifies that labelled function declarations
may not occur as the body of a control flow construct such as an if
statement. This patch implements those restrictions, which also
eliminates a previous case resulting in a DCHECK failure which is now
a SyntaxError.
BUG=chromium:595309
R=adamk
LOG=Y
Review URL: https://codereview.chromium.org/1808373003
Cr-Commit-Position: refs/heads/master@{#35049}
Now that ES2015 const has shipped, in Chrome 49, legacy const declarations
are no more. This lets us remove a bunch of code from many parts of the
codebase.
In this patch, I remove parser support for generating legacy const variables
from const declarations. This also removes the special "illegal declaration"
bit from Scope, which has ripples into all compiler backends.
Also gone are any tests which relied on legacy const declarations.
Note that we do still generate a Variable in mode CONST_LEGACY in one case:
function name bindings in sloppy mode. The likely fix there is to add a new
Variable::Kind for this case and handle it appropriately for stores in each
backend, but I leave that for a later patch to make this one completely
subtractive.
Review URL: https://codereview.chromium.org/1819123002
Cr-Commit-Position: refs/heads/master@{#35002}
Reason for revert:
Violates ES6 spec (crbug.com/4850), and implementation was over-eager. Will revert for now.
Original issue's description:
> Parser: Make skipping HTML comments optional.
>
> API change: This adds a new flag skip_html_comments to v8::ScriptOriginOptions. This flag controls whether V8 will attempt to honour HTML-style comments in JS sources.
>
> (That is: Gracefully ignore <!-- ... ---> in JS sources, which was a popular technique in the early days of JavaScript, to prevent non-JS-enabled browsers from displaying script sources to uses.)
>
> The flag defaults to 'true' when using v8::ScriptOrigin constructor, which preserves the existing behaviour. Embedders which are happy with the existing behaviour will thus not need any changes.
>
> BUG=chromium:573887
> LOG=Y
>
> Committed: https://crrev.com/91d344288aa51ed03eaaa1cb3e368ac1e82f0173
> Cr-Commit-Position: refs/heads/master@{#34904}
TBR=jochen@chromium.org,rossberg@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=chromium:573887, v8:4850
LOG=Y
Review URL: https://codereview.chromium.org/1817163003
Cr-Commit-Position: refs/heads/master@{#34958}
API change: This adds a new flag skip_html_comments to v8::ScriptOriginOptions. This flag controls whether V8 will attempt to honour HTML-style comments in JS sources.
(That is: Gracefully ignore <!-- ... ---> in JS sources, which was a popular technique in the early days of JavaScript, to prevent non-JS-enabled browsers from displaying script sources to uses.)
The flag defaults to 'true' when using v8::ScriptOrigin constructor, which preserves the existing behaviour. Embedders which are happy with the existing behaviour will thus not need any changes.
BUG=chromium:573887
LOG=Y
Review URL: https://codereview.chromium.org/1801203002
Cr-Commit-Position: refs/heads/master@{#34904}
Modules already have a separate entrypoint into the engine (at the moment,
this is v8::ScriptCompiler::CompileModule, though that will change to
something like ParseModule). This meant that requiring a commandline flag
simply added an extra complexity burden on embedders. By removing the v8
flag, this lets embedders use their own flagging mechanism (such as d8's
"--module", or Blink's RuntimeEnabledFeatures) to control whether
modules are to be used.
Also remove old modules tests that were being skipped (since they test
very old, pre-ES2015 modules syntax).
R=littledan@chromium.org
BUG=v8:1569, chromium:594639
LOG=y
Review URL: https://codereview.chromium.org/1804693002
Cr-Commit-Position: refs/heads/master@{#34764}
These flags have been on by default since version 4.9, which has been
in stable Chrome for over a week now, demonstrating that they're
here to stay.
Also moved the tests out of harmony/ and into es6/.
Review URL: https://codereview.chromium.org/1776683003
Cr-Commit-Position: refs/heads/master@{#34692}
ES2015 generally bans FunctionDeclarations in positions which expect a Statement,
as opposed to a StatementListItem, such as a FunctionDeclaration which constitutes
the body of a for loop. However, Annex B 3.2 and 3.4 make exceptions for labeled
function declarations and function declarations as the body of an if statement in
sloppy mode, in the latter case specifying that the semantics are as if the
function declaration occurred in a block. Chrome has historically permitted
further extensions, for the body of any flow control construct.
This patch addresses both the syntactic and semantic mismatches between V8 and
the spec. For the semantic mismatch, function declarations as the body of if
statements change from unconditionally hoisting in certain cases to acquiring
the sloppy mode function in block semantics (based on Annex B 3.3). For the
extra syntax permitted, this patch adds a flag,
--harmony-restrictive-declarations, which excludes disallowed function declaration
cases. A new UseCounter, LegacyFunctionDeclaration, is added to count how often
function declarations occur as the body of other constructs in sloppy mode. With
this patch, the code generally follows the form of the specification with respect
to parsing FunctionDeclarations, rather than allowing them in arbitrary Statement
positions, and makes it more clear where our extensions occur.
BUG=v8:4647
R=adamk
LOG=Y
Review URL: https://codereview.chromium.org/1757543003
Cr-Commit-Position: refs/heads/master@{#34470}
The preparser should ignore "use strong" if the --strong_mode flag
is not turned on, but this should not stop processing subsequent
directives.
R=rossberg@chromium.org
BUG=
LOG=N
Review URL: https://codereview.chromium.org/1752753002
Cr-Commit-Position: refs/heads/master@{#34392}
This frees up one bit in FunctionKind, which I plan to make slightly
more syntactic info about functions available in SharedFunctionInfo
(needed for ES2015 Function.name support).
BUG=v8:3956, v8:4760
LOG=n
Review URL: https://codereview.chromium.org/1704223002
Cr-Commit-Position: refs/heads/master@{#34125}
This is hopefully the last in a series of cleanup patches around
destructuring assignment. It simplifies the ParseAssignmentExpression
API, making the callers call CheckDestructuringElement() where appropriate.
CheckDestructuringElement has been further simplified to only emit the
errors that the parser depends on it emitting.
I've also beefed up the test coverage in test-parsing.cc to
handling all the destructuring flags being on, which caught an oddity
in how we disallow initializers in spreads in patterns (we need to treat
RewritableAssignmentExpressions as Assignments for the purpose of
error checking).
Finally, I added a few helper methods to ParserBase to handle a few
classes of expressions (assignments and literals-as-patterns).
Review URL: https://codereview.chromium.org/1696603002
Cr-Commit-Position: refs/heads/master@{#33961}
They were already treated as a BindingPattern error; this patch simply
replaces that call with one marking them as both a binding and assignment
error, and adds parsing tests for both cases.
BUG=v8:4707
LOG=n
Review URL: https://codereview.chromium.org/1632303002
Cr-Commit-Position: refs/heads/master@{#33528}
Although the `for..in` statement allows Expressions to define the
iterator, only an AssignmentExpression may occupy this position in the
`for..of` statement.
BUG=v8:4692
LOG=N
R=adamk@chromium.org
Review URL: https://codereview.chromium.org/1602823003
Cr-Commit-Position: refs/heads/master@{#33420}
The old handling of escaped keywords erroneously treated escaped versions
of "let" and "static" as ESCAPED_KEYWORD, leading to erroneous errors in
sloppy mode. Moreover, though the class literal parsing code attempted
to fix up the parsing of escaped versions of "static" to allow it in the
right places, that code wasn't complete.
Fixing the scanner to mark escaped "static" as ESCAPED_STRICT_RESERVED_WORD
allows simplifying the class literal parsing code. A little extra code
was needed to properly handle the new treatment of escaped "let".
Note that "yield" is still broken (that is, we're overly restrictive of
escaped "yield" in sloppy mode).
Review URL: https://codereview.chromium.org/1602013007
Cr-Commit-Position: refs/heads/master@{#33396}
This includes anonymous Function, Generator, and Class declarations when
preceded by 'export default'. Parsing only at the moment, nothing useful is
done with the parsed Function/ClassLiteral.
BUG=v8:1569
LOG=n
Review URL: https://codereview.chromium.org/1589173002
Cr-Commit-Position: refs/heads/master@{#33344}
This patch moves the semantics of 'const' in sloppy mode to match those
in strict mode, that is, const makes lexical (let-like) bindings, must
have an initializer, and does not create properties of the global object.
R=adamk
LOG=Y
BUG=v8:3305
CQ_INCLUDE_TRYBOTS=tryserver.chromium.linux:linux_chromium_rel_ng;tryserver.blink:linux_blink_rel
Review URL: https://codereview.chromium.org/1571873004
Cr-Commit-Position: refs/heads/master@{#33218}
The sloppy block-scoped function declaration placeholder statements
are held in parser_zone_-allocated hashtables. These hashtables are
not updated when local_zone_s are removed. Therefore, the
NewSloppyBlockFunctionStatement method should allocate
SloppyBlockScopeFunctionStatements in the parser_zone_ to avoid a
use-after-free. Scope fixup code may end up updating something which
is thrown away, but this is a small cost and much simpler than
removing dead hashtable entries later.
R=adamk
LOG=Y
BUG=chromium:537816
Review URL: https://codereview.chromium.org/1564923007
Cr-Commit-Position: refs/heads/master@{#33185}
