Bug in pattern synonyms with template haskell
#8761 (closed) added template haskell support for pattern synonyms, but I believe the implementation has a bug. If I create the following template Haskell syntax trees:
PatSynD AST_sin (RecordPatSyn [a0]) Unidir (ConP HomFree [ViewP (VarE embedSig) (ConP HomSig_sin [VarP a0])])
PatSynD AST_cos (RecordPatSyn [a0]) Unidir (ConP HomFree [ViewP (VarE embedSig) (ConP HomSig_cos [VarP a0])])the compiler complains that a0 is being redefined. Of course, this should be allowed because a0 is local to each pattern synonym.
A temporary workaround is to rename each variable to be unique to the pattern. The following template haskell compiles just fine.
PatSynD AST_sin (RecordPatSyn [a0_sin]) Unidir (ConP HomFree [ViewP (VarE embedSig) (ConP HomSig_sin [VarP a0_sin])])
PatSynD AST_cos (RecordPatSyn [a0_cos]) Unidir (ConP HomFree [ViewP (VarE embedSig) (ConP HomSig_cos [VarP a0_cos])])This is with GHC 8.1.20160518
Trac metadata
| Trac field | Value |
|---|---|
| Version | 8.1 |
| Type | Bug |
| TypeOfFailure | OtherFailure |
| Priority | normal |
| Resolution | Unresolved |
| Component | Compiler |
| Test case | |
| Differential revisions | |
| BlockedBy | |
| Related | |
| Blocking | |
| CC | |
| Operating system | |
| Architecture |