And implement addons as necessary.
There are many more makers to be moved, and I'm not completely satisfied with this (due to the ease of making a mistake in the AST structure, and slightly less but also because of the need to remember whitespaces), but this is already enough to see how this will look like.
The diagnostic implemented is a simple one (E0109). It serves as a test for the new foundation.
This commit only implements diagnostics for type in bodies and body-carrying signatures; the next commit will include diagnostics in the rest of the things.
Also fix one weird bug that was detected when implementing this that caused `Fn::(A, B) -> C` (which is a valid, if bizarre, alternative syntax to `Fn(A, B) -> C` to lower incorrectly.
And also fix a maybe-bug where parentheses were sneaked into a code string needlessly; this was not detected until now because the parentheses were removed (by the make-AST family API), but with a change in this commit they are now inserted. So fix that too.
Instead of lowering them to `<expr> = <expr>`, then hacking on-demand to resolve them, we lower them to `<pat> = <expr>`, and use the pattern infrastructure to handle them. It turns out, destructuring assignments are surprisingly similar to pattern bindings, and so only minor modifications are needed.
This fixes few bugs that arose because of the non-uniform handling (for example, MIR lowering not handling slice and record patterns, and closure capture calculation not handling destructuring assignments at all), and furthermore, guarantees we won't have such bugs in the future, since the programmer will always have to explicitly handle `Expr::Assignment`.
Tests don't pass yet; that's because the generated patterns do not exist in the source map. The next commit will fix that.
fix: Remove check that text of `parse_expr_from_str()` matches the produced parsed tree
This check is incorrect when we have comments and whitespace in the text.
We can strip comments, but then we still have whitespace, which we cannot strip without changing meaning for the parser. So instead I opt to remove the check, and wrap the expression in parentheses (asserting what produced is a parenthesized expression) to strengthen verification.
Fixes#18144.
This check is incorrect when we have comments and whitespace in the text.
We can strip comments, but then we still have whitespace, which we cannot strip without changing meaning for the parser. So instead I opt to remove the check, and wrap the expression in parentheses (asserting what produced is a parenthesized expression) to strengthen verification.
