[JsLIGO] Removal of automatic insertion of vertical bars in type expressions
Motivation and Context
Description
In order to avoid a shift/reduce in the parser of JsLIGO, a heuristic was used (as a self-pass on the tokens) to inject vertical bars in front of what looks like a variant type expression. Unfortunately, the heuristic is not complete and the pretty-printer does not output leading vertical bars and the result sometimes fail to parse (as the heuristic is incomplete and fails to insert a bar).
The heart of the LR conflict is this. A string is allowed as a type to guide the compilation to Michelson, for instance, with sapling or layout. The case ["C"]
creates a shift/reduce conflict because the LR algorithm cannot distinguish a variant type with a constant constructor C
from a type tuple (that is, an array of type expressions) containing the special type "C"
.
In this MR, we propose to remove the heuristic and forbid the first component of a type tuple to be a string. While this is in theory a breaking change, the uses of those types (sapling, layout) rely on a string as a type after another component type, therefore not as the first component in a tuple (array).
Component
-
compiler -
website -
webide -
vscode-plugin -
debugger
Types of changes
-
Bug fix (non-breaking change which fixes an issue) -
New feature (non-breaking change which adds functionality) -
Breaking change (fix or feature that would cause existing functionality to not work as expected) -
Performance improvement (non-breaking change that improves performance) -
None (change with no changelog)
Changelog
Checklist:
-
Changes follow the existing coding style (use dune @fmt
to check). -
Tests for the changes have been added (for bug fixes / feature). -
Documentation has been updated. -
Changelog description has been added (if appropriate). -
Start titles under ## Changelog
section with #### (if appropriate). -
There is no image or uploaded file in changelog -
Examples in changed behaviour have been added to the changelog (for breaking change / feature).