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authorJohn Ericson <John.Ericson@Obsidian.Systems>2020-04-30 11:09:24 -0400
committerCale Gibbard <cgibbard@gmail.com>2020-12-28 12:28:35 -0500
commit2113a1d600e579bb0f54a0526a03626f105c0365 (patch)
tree746a62bb019f399f3921fdfb1f1f15ae521f6c90 /utils
parentcbc7c3dda6bdf4acb760ca9eb545faeb98ab0dbe (diff)
downloadhaskell-2113a1d600e579bb0f54a0526a03626f105c0365.tar.gz
Put hole instantiation typechecking in the module graph and fix driver batch mode backpack edges
Backpack instantiations need to be typechecked to make sure that the arguments fit the parameters. `tcRnInstantiateSignature` checks instantiations with concrete modules, while `tcRnCheckUnit` checks instantiations with free holes (signatures in the current modules). Before this change, it worked that `tcRnInstantiateSignature` was called after typechecking the argument module, see `HscMain.hsc_typecheck`, while `tcRnCheckUnit` was called in `unsweep'` where-bound in `GhcMake.upsweep`. `tcRnCheckUnit` was called once per each instantiation once all the argument sigs were processed. This was done with simple "to do" and "already done" accumulators in the fold. `parUpsweep` did not implement the change. With this change, `tcRnCheckUnit` instead is associated with its own node in the `ModuleGraph`. Nodes are now: ```haskell data ModuleGraphNode -- | Instantiation nodes track the instantiation of other units -- (backpack dependencies) with the holes (signatures) of the current package. = InstantiationNode InstantiatedUnit -- | There is a module summary node for each module, signature, and boot module being built. | ModuleNode ExtendedModSummary ``` instead of just `ModSummary`; the `InstantiationNode` case is the instantiation of a unit to be checked. The dependencies of such nodes are the same "free holes" as was checked with the accumulator before. Both versions of upsweep on such a node call `tcRnCheckUnit`. There previously was an `implicitRequirements` function which would crawl through every non-current-unit module dep to look for all free holes (signatures) to add as dependencies in `GHC.Driver.Make`. But this is no good: we shouldn't be looking for transitive anything when building the graph: the graph should only have immediate edges and the scheduler takes care that all transitive requirements are met. So `GHC.Driver.Make` stopped using `implicitRequirements`, and instead uses a new `implicitRequirementsShallow`, which just returns the outermost instantiation node (or module name if the immediate dependency is itself a signature). The signature dependencies are just treated like any other imported module, but the module ones then go in a list stored in the `ModuleNode` next to the `ModSummary` as the "extra backpack dependencies". When `downsweep` creates the mod summaries, it adds this information too. ------ There is one code quality, and possible correctness thing left: In addition to `implicitRequirements` there is `findExtraSigImports`, which says something like "if you are an instantiation argument (you are substituted or a signature), you need to import its things too". This is a little non-local so I am not quite sure how to get rid of it in `GHC.Driver.Make`, but we probably should eventually. First though, let's try to make a test case that observes that we don't do this, lest it actually be unneeded. Until then, I'm happy to leave it as is. ------ Beside the ability to use `-j`, the other major user-visibile side effect of this change is that that the --make progress log now includes "Instantiating" messages for these new nodes. Those also are numbered like module nodes and count towards the total. ------ Fixes #17188 Updates hackage submomdule Metric Increase: T12425 T13035
Diffstat (limited to 'utils')
m---------utils/haddock0
1 files changed, 0 insertions, 0 deletions
diff --git a/utils/haddock b/utils/haddock
-Subproject 8a5ccf93c53a40abe42134c2282ac9b9d653224
+Subproject e7ee7957a7ac746cfa05d7218fe0c2d1fd27f56