1620583 - [meta] Improve error reporting code

Status: NEW

(Core :: JavaScript Engine, task, P3)

Description

[Tom Schuster [:evilpie]]

Our current error reporting code is very old and quite complicated. Here is a first list of ideas on how to improve this:

• Remove "extra" warnings
• Remove "werror"
• Remove JSREPORT_* flags
• Separate error and warning reporting
• Simpler error reporting API like ThrowError(cx, JSMSG_UNDECLARED_VAR, "xyz");
• Make JSErrorReport type better with ownership and less manual memory management
• UTF8 vs Latin1

Comment 1

[Jeff Walden [:Waldo]]

Note that ThrowError ought be split up into ThrowError, ThrowTypeError, ThrowRangeError, and so on, making error numbers either not encode/dictate an error type or asserting at runtime if there's a mismatch. (We already do the latter in self-hosted code for its forms of these functions.)

And all these functions, and the error-reporting internals, need at some point to be adjusted to not use varargs but rather template varargs, that cons the trailing arguments up into a list structure of some sort. (This may or may not be slightly afield of this bug's purpose, unclear.)

Comment 2

[Tom Schuster [:evilpie]]

I like the idea. DOM code uses functions with the same name and uses a template parameter to statically assert the correct error type.
One annoying thing about SpiderMonkey is that we might need 4 variants: ASCII, Latin1, UTF-8 and Unicode/~UCS-2.