Vladislav Zavialov pushed to branch wip/int-index/imp-exp-whole-namespace at Glasgow Haskell Compiler / GHC

Commits:

• 37c94802
  by Vladislav Zavialov at 2025-11-19T23:47:32+03:00

  Namespace-specified wildcards in import/export lists (#25901)
  
  This change adds support for top-level namespace-specified wildcards
  `type ..` and `data ..` to import and export lists.
  
  Examples:
    import M (type ..) -- imports all type and class constructors from M
    import M (data ..) -- imports all data constructors and terms from M
    module M (type .., f) where
      -- exports all type and class constructors defined in M,
      -- plus the function 'f'
  
  The primary intended usage of this feature is in combination with module
  aliases, allowing namespace disambiguation:
    import Data.Proxy as T (type ..)  -- T.Proxy is unambiguously the type constructor
    import Data.Proxy as D (data ..)  -- D.Proxy is unambiguously the data constructor
  
  The patch accounts for the interactions of wildcards with:
  * Imports with `hiding` clauses
  * Import warnings -Wunused-imports, -Wdodgy-imports
  * Export warnings -Wduplicate-exports, -Wdodgy-exports
  
  Summary of the changes:
  
  1. Move the NamespaceSpecifier type from GHC.Hs.Binds to GHC.Hs.Basic,
     making it possible to use it in more places in the AST.
  
  2. Extend the AST (type: IE) with a representation of `..`, `type ..`,
     and `data ..` (constructor: IEWholeNamespace). Per the proposal, the
     plain `..` is always rejected with a dedicated error message.
  
  3. Extend the grammar in Parser.y with productions for `..`, `type ..`,
     and `data ..` in both import and export lists.
  
  4. Implement wildcard imports by updating the `filterImports` function
     in GHC.Rename.Names; the logic for IEWholeNamespace is roughly
     modeled after the Nothing (no explicit import list) case.
  
  5. Implement wildcard exports by updating the `exports_from_avail`
     function in GHC.Tc.Gen.Export; the logic for IEWholeNamespace is
     closely modeled after the IEModuleContents case.
  
  6. Refactor and extend diagnostics to report the new warnings and
     errors. See PsErrPlainWildcardImport, DodgyImportsWildcard,
                 PsErrPlainWildcardExport, DodgyExportsWildcard,
                 TcRnDupeWildcardExport.
  
  Note that this patch is specifically about top-level import/export
  items. Subordinate import/export items are left unchanged.
  

79 changed files:

• compiler/GHC/Hs/Basic.hs
• compiler/GHC/Hs/Binds.hs
• compiler/GHC/Hs/ImpExp.hs
• compiler/GHC/Hs/Instances.hs
• compiler/GHC/HsToCore/Docs.hs
• compiler/GHC/Iface/Ext/Ast.hs
• compiler/GHC/Parser.y
• compiler/GHC/Parser/Errors/Ppr.hs
• compiler/GHC/Parser/Errors/Types.hs
• compiler/GHC/Parser/PostProcess.hs
• compiler/GHC/Rename/Names.hs
• compiler/GHC/Tc/Errors/Ppr.hs
• compiler/GHC/Tc/Errors/Types.hs
• compiler/GHC/Tc/Gen/Export.hs
• compiler/GHC/Types/Error/Codes.hs
• compiler/GHC/Types/Hint.hs
• compiler/GHC/Types/Hint/Ppr.hs
• compiler/Language/Haskell/Syntax/Extension.hs
• compiler/Language/Haskell/Syntax/ImpExp.hs
• docs/users_guide/9.16.1-notes.rst
• docs/users_guide/exts/explicit_namespaces.rst
• + testsuite/tests/module/T25901_exp_plain_wc.hs
• + testsuite/tests/module/T25901_exp_plain_wc.stderr
• + testsuite/tests/module/T25901_imp_plain_wc.hs
• + testsuite/tests/module/T25901_imp_plain_wc.stderr
• testsuite/tests/module/all.T
• + testsuite/tests/rename/should_compile/T25901_exp_1.hs
• + testsuite/tests/rename/should_compile/T25901_exp_1_helper.hs
• + testsuite/tests/rename/should_compile/T25901_exp_2.hs
• + testsuite/tests/rename/should_compile/T25901_exp_2_helper.hs
• + testsuite/tests/rename/should_compile/T25901_imp_hq.hs
• + testsuite/tests/rename/should_compile/T25901_imp_hu.hs
• + testsuite/tests/rename/should_compile/T25901_imp_sq.hs
• + testsuite/tests/rename/should_compile/T25901_imp_su.hs
• testsuite/tests/rename/should_compile/all.T
• + testsuite/tests/rename/should_fail/T25901_exp_fail_1.hs
• + testsuite/tests/rename/should_fail/T25901_exp_fail_1.stderr
• + testsuite/tests/rename/should_fail/T25901_exp_fail_1_helper.hs
• + testsuite/tests/rename/should_fail/T25901_exp_fail_2.hs
• + testsuite/tests/rename/should_fail/T25901_exp_fail_2.stderr
• + testsuite/tests/rename/should_fail/T25901_exp_fail_2_helper.hs
• + testsuite/tests/rename/should_fail/T25901_imp_hq_fail_5.hs
• + testsuite/tests/rename/should_fail/T25901_imp_hq_fail_5.stderr
• + testsuite/tests/rename/should_fail/T25901_imp_hq_fail_6.hs
• + testsuite/tests/rename/should_fail/T25901_imp_hq_fail_6.stderr
• + testsuite/tests/rename/should_fail/T25901_imp_hu_fail_4.hs
• + testsuite/tests/rename/should_fail/T25901_imp_hu_fail_4.stderr
• + testsuite/tests/rename/should_fail/T25901_imp_sq_fail_2.hs
• + testsuite/tests/rename/should_fail/T25901_imp_sq_fail_2.stderr
• + testsuite/tests/rename/should_fail/T25901_imp_sq_fail_3.hs
• + testsuite/tests/rename/should_fail/T25901_imp_sq_fail_3.stderr
• + testsuite/tests/rename/should_fail/T25901_imp_su_fail_1.hs
• + testsuite/tests/rename/should_fail/T25901_imp_su_fail_1.stderr
• testsuite/tests/rename/should_fail/all.T
• + testsuite/tests/warnings/should_compile/T25901_exp_dodgy.hs
• + testsuite/tests/warnings/should_compile/T25901_exp_dodgy.stderr
• + testsuite/tests/warnings/should_compile/T25901_exp_dup_wc_1.hs
• + testsuite/tests/warnings/should_compile/T25901_exp_dup_wc_1.stderr
• + testsuite/tests/warnings/should_compile/T25901_exp_dup_wc_2.hs
• + testsuite/tests/warnings/should_compile/T25901_exp_dup_wc_2.stderr
• + testsuite/tests/warnings/should_compile/T25901_exp_dup_wc_3.hs
• + testsuite/tests/warnings/should_compile/T25901_exp_dup_wc_3.stderr
• + testsuite/tests/warnings/should_compile/T25901_exp_dup_wc_4.hs
• + testsuite/tests/warnings/should_compile/T25901_exp_dup_wc_4.stderr
• + testsuite/tests/warnings/should_compile/T25901_helper_1.hs
• + testsuite/tests/warnings/should_compile/T25901_helper_2.hs
• + testsuite/tests/warnings/should_compile/T25901_helper_3.hs
• + testsuite/tests/warnings/should_compile/T25901_imp_dodgy_1.hs
• + testsuite/tests/warnings/should_compile/T25901_imp_dodgy_1.stderr
• + testsuite/tests/warnings/should_compile/T25901_imp_dodgy_2.hs
• + testsuite/tests/warnings/should_compile/T25901_imp_dodgy_2.stderr
• + testsuite/tests/warnings/should_compile/T25901_imp_unused_1.hs
• + testsuite/tests/warnings/should_compile/T25901_imp_unused_1.stderr
• + testsuite/tests/warnings/should_compile/T25901_imp_unused_2.hs
• + testsuite/tests/warnings/should_compile/T25901_imp_unused_2.stderr
• + testsuite/tests/warnings/should_compile/T25901_imp_unused_3.hs
• + testsuite/tests/warnings/should_compile/T25901_imp_unused_3.stderr
• testsuite/tests/warnings/should_compile/all.T
• utils/check-exact/ExactPrint.hs

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