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| author | Sebastian Graf <sebastian.graf@kit.edu> | 2019-11-25 15:51:40 +0100 |
|---|---|---|
| committer | Sebastian Graf <sebastian.graf@kit.edu> | 2019-11-26 15:52:00 +0100 |
| commit | c2ffcd476161a572ed0672b929ea59b8b97a231a (patch) | |
| tree | d1f0ab12ae58a10541768d8b89cd57becfa9c49c /compiler/main | |
| parent | b694b5662f8c9915b1a9d072cd530cd29124194a (diff) | |
| download | haskell-wip/T17270.tar.gz | |
Make warnings for TH splices opt-inwip/T17270
In #17270 we have the pattern-match checker emit incorrect warnings. The
reason for that behavior is ultimately an inconsistency in whether we
treat TH splices as written by the user (`FromSource :: Origin`) or as
generated code (`Generated`). This was first reported in #14838.
The current solution is to TH splices as `Generated` by default and only
treat them as `FromSource` when the user requests so
(-fenable-th-splice-warnings). There are multiple reasons for opt-in
rather than opt-out:
* It's not clear that the user that compiles a splice is the author of the code
that produces the warning. Think of the situation where she just splices in
code from a third-party library that produces incomplete pattern matches.
In this scenario, the user isn't even able to fix that warning.
* Gathering information for producing the warnings (pattern-match check
warnings in particular) is costly. There's no point in doing so if the user
is not interested in those warnings.
Fixes #17270, but not #14838, because the proper solution needs a GHC
proposal extending the TH AST syntax.
Diffstat (limited to 'compiler/main')
| -rw-r--r-- | compiler/main/DynFlags.hs | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/compiler/main/DynFlags.hs b/compiler/main/DynFlags.hs index 70f50f2a8b..d86c064ba8 100644 --- a/compiler/main/DynFlags.hs +++ b/compiler/main/DynFlags.hs @@ -557,6 +557,7 @@ data GeneralFlag | Opt_UnboxSmallStrictFields | Opt_DictsCheap | Opt_EnableRewriteRules -- Apply rewrite rules during simplification + | Opt_EnableThSpliceWarnings -- Enable warnings for TH splices | Opt_RegsGraph -- do graph coloring register allocation | Opt_RegsIterative -- do iterative coalescing graph coloring register allocation | Opt_PedanticBottoms -- Be picky about how we treat bottom @@ -4208,6 +4209,7 @@ fFlagsDeps = [ flagSpec "eager-blackholing" Opt_EagerBlackHoling, flagSpec "embed-manifest" Opt_EmbedManifest, flagSpec "enable-rewrite-rules" Opt_EnableRewriteRules, + flagSpec "enable-th-splice-warnings" Opt_EnableThSpliceWarnings, flagSpec "error-spans" Opt_ErrorSpans, flagSpec "excess-precision" Opt_ExcessPrecision, flagSpec "expose-all-unfoldings" Opt_ExposeAllUnfoldings, |