Hannes Siebenhandl pushed to branch wip/fendor/T27202 at Glasgow Haskell Compiler / GHC Commits: bab16673 by fendor at 2026-05-20T09:49:28+02:00 Fix regression T27202: `:load` and `:add` work in GHCi To fix the regression there are conceptually two major things that we fix: * We don't remove the `importDirs` from `interactive-session` * When `:add`ing a module, we don't try to find them via PackageImports * The PackageImport is wrong as we can't know the package-name at this stage in ghc/UI.hs What does it mean to not remove the `importDirs` from `interactive-session`? It means that, given some initial `DynFlags`, we will use those `importDirs` in `interactive-session`. The initial `DynFlags`, however, depend on how you initialise the GHC session. For a simple session, initialised by ghc -isrc -this-unit-id main It is simple, just use the `DynFlags` given on the cli. Thus, `main` and `interactive-session` will have the same `DynFlags`, except for the `homeUnitId` and `interactive-session` depends on `main` by construction of the GHCi session. What about a multiple home unit session, though? ghc -unit @unit1 -unit @unit2 What are the `DynFlags` in this cli invocation? It shouldn't be either `@unti1` nor `@unit2`, as the order shouldn't matter or any other implicit condition. For consistency, we decide that the initial `DynFlags` are the top `DynFlags` on the cli, ignoring `-unit` flags. Thus, in this example, there are no `importsDirs` regardless of what we might find in `@unit1` and `@unit2`. But in this invocation: ghc -isrc -unit @unit1 -unit @unit2 The `interactive-session` will have the `importsDirs` `src`. Note, `-isrc` will be inherited in `@unit1` and `@unit2`, so you need to explicitly use `-i` to clear the `importsDirs`, in order to avoid accidentally adding `src` as an import directory to all other home units. This fix has been made possible by the improvements introduced in !15888, which avoids ambiguity when a home unit shares the `importsDirs` with the `interactive-session`, on top of being much faster for multiple home units. Adds regression tests for T27202 for `:load`ing and `:add`ing modules that are located in import directories. - - - - - f5f19413 by fendor at 2026-05-20T09:49:28+02:00 Use home unit package db stacks in GHCi prompt and session unit In order to import modules from home unit dependencies (e.g., `Data.Map`), the ghci prompt unit needs to populate its `UnitState`. This is tricky to handle correctly, which `PackageDBFlag`s should we use to populate the `UnitState`? We decide, the most intuitive solution for users is to depend on all `PackageDBFlag`s, so that any dependency can be imported in GHCi. This assumes consistency in the `PackageDBFlag`s, so no two home units specify `PackageDBFlag`s that are inconsistent with each other. We could simply concat all the `PackageDBFlag`s of the existing home units, but later `PackageDBFlag`s shadow earlier ones, leading to the last processed home units' `PackageDBFlag`s to shadow the earlier ones. This is hard to fix, we need to give users the capability to provide ghc options for the ghci prompt home unit. However, as this is considerably more work, we decided on an approximation that should work out most of the time. Package Db stacks in cabal and stack follow a certain structure: -no-user-package-db > -package-db $cabal-store > -package-db $local-db The first two arguments are always the same, namely the `-no-user-package-db` and `-package-db`. We compute the longest common prefix over all home units, and use that as the start of the package db stack. Then, over the rest of the `PackageDBFlag`s, we simply take the union and append them to our initial stack. We assume, that the rest of package dbs only defines very few, "local" units that are usually not shadowing each other. This allows us to get a relatively consistent package database stack for the ghci prompt home unit. Similar reasoning applies to the session unit in order to add modules to the session and have dependencies available in the module. We do something similar for `-package` flags, to make sure only the correct units are actually visible in the ghci session. This time, we simply take the union of all `PackageFlag`s, allowing us to import modules from the home unit dependencies. In the future, it would be beneficial to allow the user to provide the exact ghc options to control the visibilities. For now, this will have to do. - - - - - 66 changed files: - + changelog.d/T27202 - compiler/GHC/Driver/DynFlags.hs - compiler/GHC/Unit/State.hs - ghc/GHCi/UI.hs - ghc/Main.hs - testsuite/tests/driver/fat-iface/fat014.stdout - + testsuite/tests/ghci/prog-mhu006/Makefile - + testsuite/tests/ghci/prog-mhu006/a/A.hs - + testsuite/tests/ghci/prog-mhu006/all.T - + testsuite/tests/ghci/prog-mhu006/b/B.hs - + testsuite/tests/ghci/prog-mhu006/prog-mhu006a.script - + testsuite/tests/ghci/prog-mhu006/prog-mhu006a.stdout - + testsuite/tests/ghci/prog-mhu006/unitA - + testsuite/tests/ghci/prog-mhu006/unitB - testsuite/tests/ghci/prog003/prog003.T - testsuite/tests/ghci/prog018/prog018.stdout - testsuite/tests/ghci/prog020/Makefile - testsuite/tests/ghci/prog020/all.T - testsuite/tests/ghci/prog020/ghci.prog020.script → testsuite/tests/ghci/prog020/ghci.prog020a.script - testsuite/tests/ghci/prog020/ghci.prog020.stderr → testsuite/tests/ghci/prog020/ghci.prog020a.stderr - testsuite/tests/ghci/prog020/ghci.prog020.stdout → testsuite/tests/ghci/prog020/ghci.prog020a.stdout - + testsuite/tests/ghci/prog020/ghci.prog020b.script - + testsuite/tests/ghci/prog020/ghci.prog020b.stderr - + testsuite/tests/ghci/prog020/ghci.prog020b.stdout - + testsuite/tests/ghci/prog023/Makefile - + testsuite/tests/ghci/prog023/all.T - + testsuite/tests/ghci/prog023/prog023a.script - + testsuite/tests/ghci/prog023/prog023a.stdout - + testsuite/tests/ghci/prog023/prog023b.script - + testsuite/tests/ghci/prog023/prog023b.stdout - + testsuite/tests/ghci/prog023/src/A.hs - + testsuite/tests/ghci/prog024/Makefile - + testsuite/tests/ghci/prog024/all.T - + testsuite/tests/ghci/prog024/prog024a.script - + testsuite/tests/ghci/prog024/prog024a.stdout - + testsuite/tests/ghci/prog024/prog024b.script - + testsuite/tests/ghci/prog024/prog024b.stdout - + testsuite/tests/ghci/prog024/prog024c.script - + testsuite/tests/ghci/prog024/prog024c.stderr - + testsuite/tests/ghci/prog024/prog024c.stdout - + testsuite/tests/ghci/prog024/prog024d.script - + testsuite/tests/ghci/prog024/prog024d.stderr - + testsuite/tests/ghci/prog024/prog024d.stdout - + testsuite/tests/ghci/prog024/prog024e.script - + testsuite/tests/ghci/prog024/prog024e.stdout - + testsuite/tests/ghci/prog024/prog024f.script - + testsuite/tests/ghci/prog024/prog024f.stdout - + testsuite/tests/ghci/prog024/src/A.hs - + testsuite/tests/ghci/prog024/src/B.hs - + testsuite/tests/ghci/prog025/Makefile - + testsuite/tests/ghci/prog025/a/A.hs - + testsuite/tests/ghci/prog025/all.T - + testsuite/tests/ghci/prog025/prog025a.script - + testsuite/tests/ghci/prog025/prog025a.stdout - + testsuite/tests/ghci/prog025/prog025b.script - + testsuite/tests/ghci/prog025/prog025b.stdout - + testsuite/tests/ghci/prog025/testpkg/Test.hs - + testsuite/tests/ghci/prog025/testpkg/testpkg-0.1.0.0.pkg - + testsuite/tests/ghci/prog025/testpkg/testpkg-0.2.0.0.pkg - + testsuite/tests/ghci/prog025/unitA - testsuite/tests/ghci/scripts/T13997.stdout - testsuite/tests/ghci/scripts/T1914.stdout - testsuite/tests/ghci/scripts/T20217.stdout - testsuite/tests/ghci/scripts/T8042.stdout - testsuite/tests/ghci/scripts/T8042recomp.stdout - testsuite/tests/ghci/should_run/T10920.stderr The diff was not included because it is too large. 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