* Remove "Invariant Violation" from dev errors
When I made the change to compile `invariant` to throw expressions, I
left a small runtime to set the error's `name` property to "Invariant
Violation" to maintain the existing behavior.
I think we can remove it. The argument for keeping it is to preserve
continuity in error logs, but this only affects development errors,
anyway: production error messages are replaced with error codes.
* Pass prod error messages directly to constructor
Updates the `invariant` transform to pass an error message string
directly to the Error constructor, instead of mutating the
message property.
Turns this code:
```js
invariant(condition, 'A %s message that contains %s', adj, noun);
```
into this:
```js
if (!condition) {
throw Error(
__DEV__
? `A ${adj} message that contains ${noun}`
: formatProdErrorMessage(ERR_CODE, adj, noun)
);
}
```
The error transform works by replacing calls to `invariant` with
an `if` statement.
Since we're replacing a call expression with a statement, Babel wraps
the new statement in an immediately-invoked function expression (IIFE).
This wrapper is unnecessary in practice because our `invariant` calls
are always part of their own expression statement.
In the production bundle, the function wrappers are removed by Closure.
But they remain in the development bundles.
This commit updates the transform to confirm that an `invariant` call
expression's parent node is an expression statement. (If not, it throws
a transform error.)
Then, it replaces the expression statement instead of the expression
itself, effectively removing the extraneous IIFE wrapper.
Upgraded from Babel 6 to Babel 7.
The only significant change seems to be the way `@babel/plugin-transform-classes` handles classes differently from `babel-plugin-transform-es2015-classes`. In regular mode, the former injects a `_createClass` function that increases the bundle size, and in the latter it removes the safeguard checks. However, this is okay because we don't all classes in new features, and we want to deprecate class usage in the future in the react repo.
Co-authored-by: Luna Ruan <luna@fb.com>
Co-authored-by: Abdul Rauf <abdulraufmujahid@gmail.com>
Co-authored-by: Maksim Markelov <maks-markel@mail.ru>
Removes `--extract-errors` argument from CI build script command.
Instead, the author is expected to run `yarn extract-errors` locally
or manually edit the error code map.
The lint rule should be sufficient to catch unminified errors, but
as an extra precaution, I added a post-build step that greps the
production bundles. The post-build step works even if someone disables
the lint rule for a specific line or file.
The React Native build does not minify error messages in production,
but it still needs to run the error messages transform to compile
`invariant` calls to `ReactError`. To do this, I added a `noMinify`
option to the Babel plugin. I also renamed it from
`minify-error-messages` to the more generic `transform-error-messages`.
* Transform invariant to custom error type
This transforms calls to the invariant module:
```js
invariant(condition, 'A %s message that contains %s', adj, noun);
```
Into throw statements:
```js
if (!condition) {
if (__DEV__) {
throw ReactError(`A ${adj} message that contains ${noun}`);
} else {
throw ReactErrorProd(ERR_CODE, adj, noun);
}
}
```
The only thing ReactError does is return an error whose name is set
to "Invariant Violation" to match the existing behavior.
ReactErrorProd is a special version used in production that throws
a minified error code, with a link to see to expanded form. This
replaces the reactProdInvariant module.
As a next step, I would like to replace our use of the invariant module
for user facing errors by transforming normal Error constructors to
ReactError and ReactErrorProd. (We can continue using invariant for
internal React errors that are meant to be unreachable, which was the
original purpose of invariant.)
* Use numbers instead of strings for error codes
* Use arguments instead of an array
I wasn't sure about this part so I asked Sebastian, and his rationale
was that using arguments will make ReactErrorProd slightly slower, but
using an array will likely make all the functions that throw slightly
slower to compile, so it's hard to say which way is better. But since
ReactErrorProd is in an error path, and fewer bytes is generally better,
no array is good.
* Casing nit
