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| author | Krzysztof Gogolewski <krzysztof.gogolewski@tweag.io> | 2021-02-14 15:34:56 +0100 |
|---|---|---|
| committer | Marge Bot <ben+marge-bot@smart-cactus.org> | 2021-03-04 23:14:01 -0500 |
| commit | db898c8a33813f4bdfbd38fe7595fbdd819c172a (patch) | |
| tree | bd6a3a1c90a0af3d6cee1b80c44b5c367692ca74 /docs | |
| parent | f943edb0c40d20e1330450c3e148b8d0c877eded (diff) | |
| download | haskell-db898c8a33813f4bdfbd38fe7595fbdd819c172a.tar.gz | |
Add a Template Haskell warning flag -Wimplicit-lift
Part of #17804.
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/users_guide/9.2.1-notes.rst | 3 | ||||
| -rw-r--r-- | docs/users_guide/using-warnings.rst | 17 |
2 files changed, 20 insertions, 0 deletions
diff --git a/docs/users_guide/9.2.1-notes.rst b/docs/users_guide/9.2.1-notes.rst index c590a89d31..5e0bf1c317 100644 --- a/docs/users_guide/9.2.1-notes.rst +++ b/docs/users_guide/9.2.1-notes.rst @@ -79,6 +79,9 @@ Compiler since the argument was already forced in the first equation. For more details see :ghc-flag:`-Wredundant-bang-patterns`. +- New :ghc-flag:`-Wimplicit-lift` flag which warns when a Template Haskell quote + implicitly uses ``lift``. + - New :ghc-flag:`-finline-generics` and :ghc-flag:`-finline-generics-aggressively` flags for improving performance of generics-based algorithms. diff --git a/docs/users_guide/using-warnings.rst b/docs/users_guide/using-warnings.rst index c0345fb958..9771837b93 100644 --- a/docs/users_guide/using-warnings.rst +++ b/docs/users_guide/using-warnings.rst @@ -113,6 +113,7 @@ The following flags are simple ways to select standard "packages" of warnings: * :ghc-flag:`-Wunused-packages` * :ghc-flag:`-Wunused-type-patterns` * :ghc-flag:`-Wsafe` + * :ghc-flag:`-Wimplicit-lift` .. ghc-flag:: -Weverything :shortdesc: enable all warnings supported by GHC @@ -856,6 +857,22 @@ of ``-W(no-)*``. f :: forall k (a :: k). Proxy a +.. ghc-flag:: -Wimplicit-lift + :shortdesc: warn about implicit ``lift`` in Template Haskell quotes + :type: dynamic + :reverse: -Wno-implicit-lift + :category: warnings + + :since: 9.2 + + Template Haskell quotes referring to local variables bound outside + of the quote are implicitly converted to use ``lift`. For example, + ``f x = [| reverse x |]`` becomes ``f x = [| reverse $(lift x) |])``. + This flag issues a warning for every such implicit addition of ``lift``. + This can be useful when debugging more complex staged programs, + where an implicit `lift`` can accidentally conceal a variable + used at a wrong stage. + .. ghc-flag:: -Wimplicit-prelude :shortdesc: warn when the Prelude is implicitly imported :type: dynamic |