ghc 7.6.3 and 7.4.2 hang on -O2
I haven't had any luck finding a minimal test case for this, but the following replicates the issue on my two Linux machines running ghc 7.6.3:
git clone https://github.com/tsuraan/optimal-blocks cd optimal-blocks git checkout bceee69f9f03d2e559f96cdf58412ada09c96a8c cabal sandbox init cabal install --only-dependencies cabal configure cabal build
Cabal build will successfully build Algorithm.OptimalBlocks.SipHash and Algorithm.OptimalBlocks.BuzzHash, and it will attempt to build Algorithm.OptimalBlocks, but it will hang forever, using 100% of a single core. I have no idea how to debug this, but in src/Algorithm/OptimalBlocks.hs, if you replace the "in Blocks (reverse rlist) end" with "in Blocks [] bs", it will compile. Also, if that same file starts with the line "{-# OPTIONS_GHC -O1 #-}" it will compile.
This also happens on my Mac running OSX 10.8.5 and ghc 7.4.2 without llvm; I have to tweak the .cabal file a little to drop the lower bound on base and to get rid of the "-fllvm" flag, but if I do that I see the exact same behaviour.
Trac metadata
| Trac field | Value |
|---|---|
| Version | 7.6.3 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
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| Blocking | |
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