#15279: CPP #includes may result in nonsensical SrcSpans -------------------------------------+------------------------------------- Reporter: wz1000 | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.4.3 Keywords: | Operating System: Unknown/Multiple Architecture: | Type of failure: Other Unknown/Multiple | Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- Consider the following code in `compiler/prelude/PrimOp.hs` {{{#!hs primOpInfo :: PrimOp -> PrimOpInfo #include "primop-primop-info.hs-incl" primOpInfo _ = error "primOpInfo: unknown primop" -- line 175 in PrimOp.hs }}} The MatchGroup for primOpInfo includes the `SrcSpan` `compiler/stage2/build/primop-primop-info.hs-incl:(1,1)-(175,49)` Here is line 175 in `primop-primop-info.hs-incl` {{{#!hs primOpInfo IndexSmallArrayOp = mkGenPrimOp (fsLit "indexSmallArray#") [alphaTyVar] [mkSmallArrayPrimTy alphaTy, intPrimTy] ((mkTupleTy Unboxed [alphaTy])) }}} The `SrcSpan`s end is somewhere in the middle of that line. I guess this occurs because `combineSrcSpans` doesn't take the file into account. I can think of multiple ways to fix this: 1. Make `combineSrcSpans` output an `UnhelpfulSrcSpan` if the files don't match(quick and easy) 2. Extend SrcSpan to properly support things spanning multiple files 3. Don't fix: People who use CPP get what they deserve. Option 3 is not unreasonable as options 1 and 2 will incur some performance penalty. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15279 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler