ISSUE 352: Fix extra initial LR(0) seed in genLR0items#353
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marco-comini wants to merge 1 commit intohaskell:masterfrom
Closed
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
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Thanks! I merged this change manually without the test because our test suite isn't currently set up such that the test reproduces the issue, but it was helpful for me to verify locally. Now moving for the annoying CI upgrade that appears to strike every 3 months... Edit: Actually the pipeline on master appears to be alright. Strange. |
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@andreasabel and @marco-comini if you have the time, give https://hackage.haskell.org/package/happy-lib-2.2.1/candidate and https://hackage.haskell.org/package/happy-2.2.1/candidate a short glance to see if everything looks correct. Will release tomorrow |
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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).