Instead of maintaining a stack of pending subpatterns which might or
might not contain expressions, we mark non-nesting regions during
pattern handling that might contain an expression. The implementation
remains largely the same; the difference is that callers are expected to
end a pending expression region as soon as possible, rather than wait
for the end of the subpattern. This makes it possible to emit
non-pattern insts during pattern handling, without the risk that they
will get caught in a pending expression region further up the stack.
Instead of traversing the entire pattern block looking for
`VarPattern`s, we keep track of them on creation, and then build
`VarStorage`s directly from that list.
This also gets rid of the global `var_storage_map`, and instead keep
that information narrowly scoped to each full-pattern, and consume it in
a single linear traversal instead of with random-access lookups. To
enable that, this fixes a parse bug where nested `var` patterns were
getting diagnosed but not marked as errors.
Rumdl already appears to have _significantly_ fewer bugs than prettier,
and a solid LSP for editor integration.
The tool is: https://github.com/rvben/rumdl/
I've separated out the change across three commits for easier review.
The configuration tries to match the existing formatting, the changes to
the all the files are to correct issues found by the new tool.
Assisted-by: Antigravity with Gemini
---------
Co-authored-by: Richard Smith <richard@metafoo.co.uk>
Instead, use the inst category to select the right block stack. This
simplifies the API for adding insts, and in subsequent changes it will
enable certain inst kinds like `SpliceInst` to seamlessly function as
either procedural insts or pattern insts.
When parsing a pattern, if we encounter something that isn't pattern
syntax, try parsing as an expression instead. We only need one-token
lookahead to distinguish pattern syntax from expression syntax.
Track a precedence group through pattern parsing so that we can allow
different kinds of expressions in a top-level pattern (such as the
operand of `let`) and in a nested pattern (such as a subpattern of a
tuple pattern or within grouping parens). For example, we do not allow
`case if ...`, and for now I've chosen to also not allow logical or
relational operators at the top level of a pattern, so `case 1 + 1` is
OK, but `case 1 == 1` and `case true and false` require parentheses.
This decision should be ratified or revisited by a design proposal.
Very basic check support is also provided, only sufficient to form an
`ExprPattern` instruction and nothing beyond that. For now, all pattern
matching against an `ExprPattern` fails with a TODO error. To support
that, I've switched from calling `BeginSubpattern` in the parent handler
of a pattern and `EndSubpatternAs*` in the pattern handler itself to
calling both functions in parent handlers, with `EndSubpattern`
converting an expression into an expression pattern where needed.
Depends on #6976.
Assisted-by: Gemini via Google Antigravity
This change ensures that a function signature always starts with an
`IdentifierNameMaybeBeforeSignature` node (renamed from
`IdentifierNameBeforeParams`), even in the case of function declarations
like `fn F -> T` that have no parameter list. As a consequence, this
ensures that we push new entries onto `pattern_block_stack` and
`full_pattern_stack` when we start processing the function signature.
This resolves a TODO in `expr_info.cpp` by using the inst kind rather
than the bound value to track the binding's category.
Since we're churning all the `bind_name` insts in testdata anyway, I'm
also taking this opportunity to align the inst naming with the design's
terminology, by calling these insts "bindings" (this aspect of the PR is
dependent on #6231 resolving an ambiguity in that terminology). For
consistency we'll need to rename several other insts as well (see the
TODO on `RefBinding`); I'm deferring that to a separate PR to minimize
the review load, but I think those name changes are in-scope for this
review.
Geoff Romer
Chandler CarruthandRichard Smith
