[Git][ghc/ghc][master] driver: Don't lose track of nodes when we fail to resolve cycles

[Marge Bot (@marge-bot)]

Marge Bot pushed to branch master at Glasgow Haskell Compiler / GHC


Commits:
8db8d2fd by Zubin Duggal at 2023-12-08T05:47:54-05:00
driver: Don't lose track of nodes when we fail to resolve cycles

The nodes that take part in a cycle should include both hs-boot and hs files,
but when we fail to resolve a cycle, we were only counting the nodes from the
graph without boot files.

Fixes #24196

- - - - -


6 changed files:

- compiler/GHC/Driver/Make.hs
- + testsuite/tests/driver/T24196/T24196.stderr
- + testsuite/tests/driver/T24196/T24196A.hs
- + testsuite/tests/driver/T24196/T24196A.hs-boot
- + testsuite/tests/driver/T24196/T24196B.hs
- + testsuite/tests/driver/T24196/all.T


Changes:

=====================================
compiler/GHC/Driver/Make.hs
=====================================
@@ -608,7 +608,7 @@ createBuildPlan mod_graph maybe_top_mod =
               -- Now perform another toposort but just with these nodes and relevant hs-boot files.
               -- The result should be acyclic, if it's not, then there's an unresolved cycle in the graph.
               mresolved_cycle = collapseSCC (topSortWithBoot nodes)
-          in acyclic ++ [maybe (UnresolvedCycle nodes) ResolvedCycle mresolved_cycle] ++ toBuildPlan sccs []
+          in acyclic ++ [either UnresolvedCycle ResolvedCycle mresolved_cycle] ++ toBuildPlan sccs []
 
         (mg, lookup_node) = moduleGraphNodes False (mgModSummaries' mod_graph)
         trans_deps_map = allReachable mg (mkNodeKey . node_payload)
@@ -639,12 +639,12 @@ createBuildPlan mod_graph maybe_top_mod =
         get_boot_module m = case m of ModuleNode _ ms | HsSrcFile <- ms_hsc_src ms -> lookupModuleEnv boot_modules (ms_mod ms); _ -> Nothing
 
         -- Any cycles should be resolved now
-        collapseSCC :: [SCC ModuleGraphNode] -> Maybe [(Either ModuleGraphNode ModuleGraphNodeWithBootFile)]
+        collapseSCC :: [SCC ModuleGraphNode] -> Either [ModuleGraphNode] [(Either ModuleGraphNode ModuleGraphNodeWithBootFile)]
         -- Must be at least two nodes, as we were in a cycle
-        collapseSCC [AcyclicSCC node1, AcyclicSCC node2] = Just [toNodeWithBoot node1, toNodeWithBoot node2]
+        collapseSCC [AcyclicSCC node1, AcyclicSCC node2] = Right [toNodeWithBoot node1, toNodeWithBoot node2]
         collapseSCC (AcyclicSCC node : nodes) = (toNodeWithBoot node :) <$> collapseSCC nodes
         -- Cyclic
-        collapseSCC _ = Nothing
+        collapseSCC nodes = Left (flattenSCCs nodes)
 
         toNodeWithBoot :: ModuleGraphNode -> Either ModuleGraphNode ModuleGraphNodeWithBootFile
         toNodeWithBoot mn =


=====================================
testsuite/tests/driver/T24196/T24196.stderr
=====================================
@@ -0,0 +1,4 @@
+Module graph contains a cycle:
+        module ‘T24196A’ (./T24196A.hs-boot)
+        imports module ‘T24196B’ (T24196B.hs)
+  which imports module ‘T24196A’ (./T24196A.hs-boot)


=====================================
testsuite/tests/driver/T24196/T24196A.hs
=====================================
@@ -0,0 +1 @@
+module T24196A where


=====================================
testsuite/tests/driver/T24196/T24196A.hs-boot
=====================================
@@ -0,0 +1,3 @@
+module T24196A where
+
+import T24196B


=====================================
testsuite/tests/driver/T24196/T24196B.hs
=====================================
@@ -0,0 +1,3 @@
+module T24196B where
+
+import {-# SOURCE #-} T24196A


=====================================
testsuite/tests/driver/T24196/all.T
=====================================
@@ -0,0 +1 @@
+test('T24196', extra_files(['T24196A.hs','T24196A.hs-boot','T24196B.hs']), multimod_compile_fail, ['T24196B',''])



View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/8db8d2fd1c881032b1b360c032b6d9d072c11723

-- 
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/8db8d2fd1c881032b1b360c032b6d9d072c11723
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