The problem I'm trying to solve is: `var x: i32 = x;`. This change makes it so that name lookup fails, by removing `x` from name lookup between the `=` and `;`.
`var x: i32` still adds to name lookup to handle future situations like `var (x: i32, x: i32);` which is still a redefinition of `x`; if we don't add `x` to name lookup, it gets harder to catch that example.
The VariableDeclaration/VariableInitializer refactor in ParseTree supports this by given a bracketing-like structure for semantics to cue that it's entering an initialization expression. With this, VariableInitializer can remove the name lookup and queue it to be restored. VariableDeclaration doesn't need to change too much since it's still bracketed by VariableIntroducer, and so we just traverse slightly differently.
Note this also incidentally changes a little about NameReference, that it's returning the storage consistently instead of the name. You can see this e.g. in global_lookup.carbon, `Assign(node8, node4): node2;` using node4 (VarStorage) instead of Node5 (BindName). Really either _could_ work, since from a BindName we can get to the VarStorage, and that may be reason to switch later if we find it preferable to have the BindName for whatever reason.
But the *actual* value in NameLookup is a BindName so that errors can associate with the _name_ instead of the "storage" parse node, which is currently the `:`. This is mainly for fail_duplicate_decl.carbon, which has a "Previous definition" note that points at the storage's parse node.
Doing some sorting of functions / enums (generally speaking, I've been trying to keep these loosely lexically sorted for lack of a better ordering).
Also removes some code that seems to be dead, and a minor TODO comment fix.
This works on multiple statements to make them better for the bracketing model. Stub nodes are added in more cases of invalid syntax, simply so that the semantics has reliably structured input. Comments in parse_node_kind.def now try to show the expected parse tree structure in postorder form.
This labels If, While, and For a little differently in parse nodes so that at the start of the postorder traversal, it'll already be available to semantics which structure is being processed. I need to do a little more with If in particular, but this felt like a reasonable stopping point.
While this makes significant parser changes, the changes to parser_state.def are minimal, mostly naming-related. The actual flow isn't substantively changed, just a couple minor names and the new As(If|While) state which allows distinguishing IfCondition and WhileCondition.
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
First change towards re-implementing interfaces using the new parser. I kept it small to make sure we are on the same page regarding stack states and how the parse tree should look like.
Co-authored-by: ergawy <kareem.ergawy@guardsquare.com>
While the Parser has similar divergent states, lists of Expressions tend to be handled more like this. I'm keeping the divergent start state in order to continue support of a distinct error, but I think this organization of FunctionParameter/FunctionParameterFinish will be less surprising.
Adds remaining expression support, and switches the default to Parser2.
Note, this doesn't delete the current Parser yet. I'll just do that in its own PR.
Adds `while` and most of the expression support. Splits apart the fixity test to demonstrate more closely which bits are still failing.
```
//toolchain/parser/testdata:basics/fail_paren_match_regression.carbon.test FAILED in 0.8s
//toolchain/parser/testdata:basics/function_call.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:basics/package.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:basics/structs.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:basics/tuples.carbon.test FAILED in 0.6s
//toolchain/parser/testdata:basics/var.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:for/fail_colon_instead_of_in.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:for/fail_missing_in.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:for/fail_missing_var.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:for/nested.carbon.test FAILED in 0.6s
//toolchain/parser/testdata:for/simple.carbon.test FAILED in 0.8s
//toolchain/parser/testdata:function/definition/with_params.carbon.test FAILED in 0.8s
//toolchain/parser/testdata:operators/fixity_in_call.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:operators/fixity_in_var.carbon.test FAILED in 0.8s
```
Co-authored-by: Chandler Carruth <chandlerc@gmail.com>
Also does `if` support, discussed refactorings, like PopState/PushState instead of edits.
With these changes, I'm to where I can start talking about what's still missing:
```
//toolchain/parser/testdata:basics/fail_invalid_designators.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:basics/fail_paren_match_regression.carbon.test FAILED in 0.6s
//toolchain/parser/testdata:basics/function_call.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:basics/package.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:basics/structs.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:basics/tuples.carbon.test FAILED in 0.6s
//toolchain/parser/testdata:basics/var.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:for/fail_colon_instead_of_in.carbon.test FAILED in 0.6s
//toolchain/parser/testdata:for/fail_missing_in.carbon.test FAILED in 0.6s
//toolchain/parser/testdata:for/fail_missing_var.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:for/nested.carbon.test FAILED in 0.6s
//toolchain/parser/testdata:for/simple.carbon.test FAILED in 0.6s
//toolchain/parser/testdata:function/definition/with_params.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:operators/associative.carbon.test FAILED in 0.6s
//toolchain/parser/testdata:operators/fail_missing_precedence_and_or.carbon.test FAILED in 0.6s
//toolchain/parser/testdata:operators/fail_missing_precedence_or_and.carbon.test FAILED in 0.6s
//toolchain/parser/testdata:operators/fail_variety.carbon.test FAILED in 0.6s
//toolchain/parser/testdata:operators/fixity.carbon.test FAILED in 0.9s
//toolchain/parser/testdata:operators/missing_precedence_not.carbon.test FAILED in 0.6s
//toolchain/parser/testdata:operators/postfix_unary.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:operators/prefix_unary.carbon.test FAILED in 0.7s
//toolchain/parser/testdata:while/basic.carbon.test FAILED in 0.6s
//toolchain/parser/testdata:while/fail_unbraced.carbon.test FAILED in 0.6s
```
This does modify a couple `if` tests to not test so much expression syntax -- that just seems like unrelated syntax.
The intent of this approach is to eliminate recursion limits as a barrier for the parser. While it may not be urgent to address, I want to avoid pouring effort into a parser approach that we don't think will be usable long-term.
Right now this is passing a minor set of tests. It's intended to be enough to show how I'm thinking about flow control for the parser. I'm manually switching back and forth because it seemed like the easiest approach that avoids duplicating tests.
Jon Ross-Perkins
Kareem Ergawy
