Vladislav Zavialov pushed to branch wip/int-index/enforce-namespaces at Glasgow Haskell Compiler / GHC Commits: 161b1465 by Vladislav Zavialov at 2025-05-08T18:53:08+03:00 Take subordinate 'type' specifiers into account This patch fixes multiple bugs (#22581, #25983, #25984, #25991) in name resolution of subordinate import lists. Bug #22581 ---------- In subordinate import lists, the use of the `type` namespace specifier used to be ignored. For example, this import statement was incorrectly accepted: import Prelude (Bool(type True)) Now it results in an error message: <interactive>:2:17: error: [GHC-51433] In the import of ‘Prelude’: a data type called ‘Bool’ is exported, but its subordinate item ‘True’ is not in the type namespace. Bug #25983 ---------- In subordinate import lists within a `hiding` clause, non-existent items led to a poor warning message with -Wdodgy-imports. Consider: import Prelude hiding (Bool(X)) The warning message for this import statement used to misreport the cause of the problem: <interactive>:3:24: warning: [GHC-56449] [-Wdodgy-imports] In the import of ‘Prelude’: an item called ‘Bool’ is exported, but it is a type. Now the warning message is correct: <interactive>:2:24: warning: [GHC-10237] [-Wdodgy-imports] In the import of ‘Prelude’: a data type called ‘Bool’ is exported, but it does not export any constructors or record fields called ‘X’. Bug #25984 ---------- In subordinate import lists within a `hiding` clause, non-existent items resulted in the entire import declaration being discarded. For example, this program was incorrectly accepted: import Prelude hiding (Bool(True,X)) t = True Now it results in an error message: <interactive>:2:5: error: [GHC-88464] Data constructor not in scope: True Bug #25991 ---------- In subordinate import lists, it was not possible to refer to a class method if there was an associated type of the same name: module M_helper where class C a b where type a # b (#) :: a -> b -> () module M where import M_helper (C((#))) This import declaration failed with: M.hs:2:28: error: [GHC-10237] In the import of ‘M_helper’: an item called ‘C’ is exported, but it does not export any children (constructors, class methods or field names) called ‘#’. Now it is accepted. Summary ------- The changes required to fix these bugs are almost entirely confined to GHC.Rename.Names. Other than that, there is a new error constructor BadImportNonTypeSubordinates with error code [GHC-51433]. Test cases: T22581a T22581b T22581c T22581d T25983 T25984a T25984b T25991a T25991b1 T25991b2 - - - - - 50 changed files: - compiler/GHC/Rename/Names.hs - compiler/GHC/Tc/Errors/Ppr.hs - compiler/GHC/Tc/Errors/Types.hs - compiler/GHC/Types/Error/Codes.hs - docs/users_guide/9.14.1-notes.rst - docs/users_guide/exts/explicit_namespaces.rst - testsuite/tests/driver/RecompExports/RecompExports1.stderr - testsuite/tests/driver/RecompExports/RecompExports4.stderr - testsuite/tests/module/T21826.stderr - testsuite/tests/module/mod81.stderr - testsuite/tests/module/mod91.stderr - + testsuite/tests/rename/should_compile/T22581c.hs - + testsuite/tests/rename/should_compile/T22581c_helper.hs - + testsuite/tests/rename/should_compile/T22581d.script - + testsuite/tests/rename/should_compile/T22581d.stdout - + testsuite/tests/rename/should_compile/T25983a.hs - + testsuite/tests/rename/should_compile/T25983a.stderr - + testsuite/tests/rename/should_compile/T25983b.hs - + testsuite/tests/rename/should_compile/T25983b.stderr - + testsuite/tests/rename/should_compile/T25983c.hs - + testsuite/tests/rename/should_compile/T25983c.stderr - + testsuite/tests/rename/should_compile/T25983d.hs - + testsuite/tests/rename/should_compile/T25983d.stderr - + testsuite/tests/rename/should_compile/T25983e.hs - + testsuite/tests/rename/should_compile/T25983e.stderr - + testsuite/tests/rename/should_compile/T25983f.hs - + testsuite/tests/rename/should_compile/T25983f.stderr - + testsuite/tests/rename/should_compile/T25983g.hs - + testsuite/tests/rename/should_compile/T25983g.stderr - + testsuite/tests/rename/should_compile/T25984a.hs - + testsuite/tests/rename/should_compile/T25984a.stderr - + testsuite/tests/rename/should_compile/T25984a_helper.hs - + testsuite/tests/rename/should_compile/T25991a.hs - + testsuite/tests/rename/should_compile/T25991a_helper.hs - testsuite/tests/rename/should_compile/all.T - + testsuite/tests/rename/should_fail/T22581a.hs - + testsuite/tests/rename/should_fail/T22581a.stderr - + testsuite/tests/rename/should_fail/T22581a_helper.hs - + testsuite/tests/rename/should_fail/T22581b.hs - + testsuite/tests/rename/should_fail/T22581b.stderr - + testsuite/tests/rename/should_fail/T22581b_helper.hs - + testsuite/tests/rename/should_fail/T25984b.hs - + testsuite/tests/rename/should_fail/T25984b.stderr - + testsuite/tests/rename/should_fail/T25991b1.hs - + testsuite/tests/rename/should_fail/T25991b1.stderr - + testsuite/tests/rename/should_fail/T25991b2.hs - + testsuite/tests/rename/should_fail/T25991b2.stderr - + testsuite/tests/rename/should_fail/T25991b_helper.hs - testsuite/tests/rename/should_fail/T9006.stderr - testsuite/tests/rename/should_fail/all.T The diff was not included because it is too large. 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