41844 2010-07-08 02:51:44 -0700 JavaScript parser violates ECMA automatic semicolon insertion rule 2010-07-08 16:24:04 -0700 1 1 1 Unclassified WebKit JavaScriptCore 528+ (Nightly build) PC All RESOLVED FIXED P2 Normal --- 1 kent.hansen webkit-unassigned oliver oldest_to_newest 248113 0 kent.hansen 2010-07-08 02:51:44 -0700 The following snippet: JSGlobalContextRef context = JSGlobalContextCreateInGroup(NULL, NULL); const char *script = "if (0)"; JSValueRef val = JSEvaluateScript(context, JSStringCreateWithUTF8CString(script), NULL, NULL, 1, NULL); JSStringRef str = JSValueToStringCopy(context, val, NULL); char buf[256]; JSStringGetUTF8CString(str, buf, 256); printf("%s\n", buf); prints "undefined". ECMA-262 5th ed, section 7.9.1 "Rules of automatic semicolon", states: "When, as the program is parsed from left to right, the end of the input stream of tokens is encountered and the parser is unable to parse the input token stream as a single complete ECMAScript Program, then a semicolon is automatically inserted at the end of the input stream." So far, so good. But then the above is followed by: "However, there is an additional overriding condition on the preceding rules: a semicolon is never inserted automatically if the semicolon would then be parsed as an empty statement [...]." When the program is "if (0)", as in the above snippet, per the above rule, a semicolon should _not_ automatically be inserted. Instead a SyntaxError should be thrown. 248583 1 oliver 2010-07-08 15:18:59 -0700 This isn't automatic semicolon insertion for the usual reasons eg. { if (0) } will fail to parse. The parse success is due to the lexer automatically inserting a semicolon to the end of a script if it has not seen a line terminator when it reaches the end. I'm no sure what the specific reason for it is. 248601 2 60976 oliver 2010-07-08 15:56:09 -0700 Created attachment 60976 Patch 248609 3 60976 darin 2010-07-08 16:10:02 -0700 Comment on attachment 60976 Patch What’s the chance that some real world WebKit-only content depends on the broken behavior? 248613 4 oliver 2010-07-08 16:14:55 -0700 (In reply to comment #3) > (From update of attachment 60976 [details]) > What’s the chance that some real world WebKit-only content depends on the broken behavior? Fairly low -- no other browser does this, and it depends on having the incorrect code as the very last thing in the file (eg. no trailing new lines or other syntax) 248620 5 oliver 2010-07-08 16:24:04 -0700 Committed r62862 60976 2010-07-08 15:56:09 -0700 2010-07-08 16:11:22 -0700 Patch bug-41844-20100708155608.patch text/plain 4328 oliver ZGlmZiAtLWdpdCBhL0phdmFTY3JpcHRDb3JlL0NoYW5nZUxvZyBiL0phdmFTY3JpcHRDb3JlL0No YW5nZUxvZwppbmRleCA2NWM5MjQyOTE4ZDE0YThlYzBhMmJiMjI5Mzk3MmQxZTZjM2IzOTA3Li4w OTMyYmUzYzRlODkzNGJmZjIwYzU2NTdiNmZmZTBhZmZhMmFmYzFkIDEwMDY0NAotLS0gYS9KYXZh U2NyaXB0Q29yZS9DaGFuZ2VMb2cKKysrIGIvSmF2YVNjcmlwdENvcmUvQ2hhbmdlTG9nCkBAIC0x LDUgKzEsMTggQEAKIDIwMTAtMDctMDggIE9saXZlciBIdW50ICA8b2xpdmVyQGFwcGxlLmNvbT4K IAorICAgICAgICBSZXZpZXdlZCBieSBOT0JPRFkgKE9PUFMhKS4KKworICAgICAgICBKYXZhU2Ny aXB0IHBhcnNlciB2aW9sYXRlcyBFQ01BIGF1dG9tYXRpYyBzZW1pY29sb24gaW5zZXJ0aW9uIHJ1 bGUKKyAgICAgICAgaHR0cHM6Ly9idWdzLndlYmtpdC5vcmcvc2hvd19idWcuY2dpP2lkPTQxODQ0 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