ISSUE 352: Fix extra initial LR(0) seed in genLR0items#353
Open
marco-comini wants to merge 1 commit intohaskell:masterfrom
Open
ISSUE 352: Fix extra initial LR(0) seed in genLR0items#353marco-comini wants to merge 1 commit intohaskell:masterfrom
marco-comini wants to merge 1 commit intohaskell:masterfrom
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Fixes #352.
This patch fixes an off-by-one bug in
genLR0items.Previously, the initial LR(0) kernels were seeded with:
where
n_starts = length (starts g).This caused one extra initial seeded component to be generated. Consequently, Happy could introduce many additional states coming from the first ordinary grammar production, even when that production was unrelated to the declared entry point.
This patch changes the seed range so that only the intended start rules are used.
I also added a regression test (
tests/issue352.y).