Fix #6905 Clear call stack in addFinal

ChangeLog.md

@@ -51,6 +51,10 @@ Bug fixes:
 * After March 2026, Hackage requires Stack's user agent to be set when applying
   digest authentication to a request. Stack's `upload` command now does that,
   re-establishing authentication by Hackage username and password.
+* Stack 3.9.3 and earlier fail to construct a build plan if project package A
+  depends on project package B and package B's executables (only) depend on
+  package A and the name of A is before that of B, alphabetically. That bug is
+  fixed.
 
 ## v3.9.3 - 2026-02-19
 

src/Stack/Build/ConstructPlan.hs

@@ -483,7 +483,9 @@ addFinal ::
   -> M ()
 addFinal lp package allInOne buildHaddocks = do
   let name = package.name
-  res <- addPackageDeps package >>= \case
+  logDebugPlanS "addFinal" "Clearing the call stack."
+  res <- local (\ctx' -> ctx' { callStack = [] }) $
+           addPackageDeps package >>= \case
     Left e -> pure $ Left e
     Right (MissingPresentDeps missing present _minLoc) -> do
       let pkgConfigOpts = packageConfigureOptsFromPackage package
@@ -505,6 +507,10 @@ addFinal lp package allInOne buildHaddocks = do
         , cachePkgSrc = CacheSrcLocal (toFilePath (parent lp.cabalFP))
         , buildTypeConfig = packageBuildTypeConfig package
         }
+  ctx <- ask
+  logDebugPlanS "addFinal" $
+       "Restoring the call stack: "
+    <> fromString (show $ map packageNameString ctx.callStack)
   logDebugPlanS "addFinal" $
        "Adding to construction output "
     <> fromPackageName name

tests/integration/tests/6905-cyclic-plan/Main.hs

@@ -0,0 +1,27 @@
+-- | The test's project has project packages A and B.
+--
+-- In terms of main libraries, the dependencies are (->- is 'depends on'):
+--
+--     A ->- B
+--
+-- In terms of executables (a test suite):
+--
+--     B ->- A
+--
+-- As, overall, A ->- B and B ->- A, packages A and B cannot be built
+-- 'all-in-one'.
+--
+-- This integration test tests:
+--
+-- * when A is named myPackageA and B is named myPackageB; and
+--
+-- * when A is named myPackageD and B is named myPackageC.
+--
+-- See: https://github.com/commercialhaskell/stack/issues/6905
+
+import           StackTest
+
+main :: IO ()
+main = do
+  stack ["--stack-yaml", "stack1.yaml", "test"]
+  stack ["--stack-yaml", "stack2.yaml", "test"]

tests/integration/tests/multi-test/files/.gitignore → tests/integration/tests/6905-cyclic-plan/files/.gitignore

@@ -1,3 +1,4 @@
 myPackageA.cabal
+myPackageB.cabal
 myPackageC.cabal
-0myPackageB.cabal
+myPackageD.cabal

tests/integration/tests/6905-cyclic-plan/files/myPackageA/package.yaml

@@ -0,0 +1,11 @@
+spec-version: 0.36.0
+
+name: myPackageA
+
+dependencies:
+- base
+
+library:
+  source-dirs: src
+  dependencies:
+  - myPackageB

tests/integration/tests/6905-cyclic-plan/files/myPackageA/src/LibA.hs

@@ -0,0 +1,5 @@
+module LibA
+  ( funcB
+  ) where
+
+import LibB ( funcB )

tests/integration/tests/multi-test/files/myPackageB/package.yaml → tests/integration/tests/6905-cyclic-plan/files/myPackageB/package.yaml

@@ -1,7 +1,6 @@
 spec-version: 0.36.0
 
-# Only builds if this package name comes before myPackageA, alphabetically!
-name: 0myPackageB
+name: myPackageB
 
 dependencies:
 - base

tests/integration/tests/6905-cyclic-plan/files/myPackageC/package.yaml

@@ -0,0 +1,16 @@
+spec-version: 0.36.0
+
+name: myPackageC
+
+dependencies:
+- base
+
+library:
+  source-dirs: src
+
+tests:
+  test:
+    source-dirs: test
+    main: Main.hs
+    dependencies:
+    - myPackageD

tests/integration/tests/6905-cyclic-plan/files/myPackageC/src/LibC.hs

@@ -0,0 +1,6 @@
+module LibC
+ ( funcC
+ ) where
+
+funcC :: IO ()
+funcC = pure ()

tests/integration/tests/6905-cyclic-plan/files/myPackageC/test/Main.hs

@@ -0,0 +1,4 @@
+import LibD ( funcC )
+
+main :: IO ()
+main = funcC

tests/integration/tests/6905-cyclic-plan/files/myPackageD/package.yaml

@@ -0,0 +1,11 @@
+spec-version: 0.36.0
+
+name: myPackageD
+
+dependencies:
+- base
+
+library:
+  source-dirs: src
+  dependencies:
+  - myPackageC

tests/integration/tests/6905-cyclic-plan/files/myPackageD/src/LibD.hs

@@ -0,0 +1,5 @@
+module LibD
+  ( funcC
+  ) where
+
+import LibC ( funcC )

tests/integration/tests/6905-cyclic-plan/files/stack1.yaml

@@ -0,0 +1,5 @@
+snapshot: ghc-9.10.3
+
+packages:
+- myPackageA
+- myPackageB

tests/integration/tests/6905-cyclic-plan/files/stack2.yaml

@@ -0,0 +1,5 @@
+snapshot: ghc-9.10.3
+
+packages:
+- myPackageC
+- myPackageD

tests/integration/tests/multi-test/Main.hs → tests/integration/tests/6905-multi-test/Main.hs

@@ -11,24 +11,18 @@
 -- As, overall, A ->- B and B ->- A, packages A and B cannot be built
 -- 'all-in-one'.
 --
--- This integration test passes when A is named myPackageA and B is named
--- 0myPackageB, but it fails when B is renamed myPackageB. That must be a bug in
--- Stack.
+-- A, B and C are named myPackageA, myPackageB and myPackageC respectively.
+--
+-- See:  https://github.com/commercialhaskell/stack/issues/6905
 
 import           Control.Monad ( unless )
 import           Data.List ( isInfixOf )
 import           StackTest
 
 main :: IO ()
 main = do
-  -- FIXME: Make 'clean' unnecessary (see #1411)
-  stack ["clean"]
   stackCheckStderr ["test", "--coverage"] $ \out -> do
     unless ("The coverage report for myPackageA's test-suite test1 is available at" `isInfixOf` out) $
       fail "Didn't get expected report for test1"
     unless ("[S-6829]" `isInfixOf` out) $
       fail "Didn't get expected empty report for test2"
-  -- Test then build works too.
-  stack ["clean"]
-  stack ["test"]
-  stack ["build"]

tests/integration/tests/6905-multi-test/files/.gitignore

@@ -0,0 +1,6 @@
+myPackageA.cabal
+myPackageB.cabal
+myPackageC.cabal
+myPackageD.cabal
+myPackageE.cabal
+myPackageF.cabal

tests/integration/tests/multi-test/files/myPackageA/package.yaml → tests/integration/tests/6905-multi-test/files/myPackageA/package.yaml

@@ -8,8 +8,7 @@ dependencies:
 library:
   source-dirs: src
   dependencies:
-  # Only builds if this package name comes before myPackageA, alphabetically!
-  - 0myPackageB
+  - myPackageB
 
 executables:
   myExeA:

tests/integration/tests/6905-multi-test/files/myPackageB/package.yaml

@@ -0,0 +1,16 @@
+spec-version: 0.36.0
+
+name: myPackageB
+
+dependencies:
+- base
+
+library:
+  source-dirs: src
+
+tests:
+  test:
+    source-dirs: test
+    main: Main.hs
+    dependencies:
+    - myPackageA

tests/integration/tests/6905-multi-test/files/myPackageB/src/LibB.hs

@@ -0,0 +1,6 @@
+module LibB
+ ( funcB
+ ) where
+
+funcB :: IO ()
+funcB = pure ()

tests/integration/tests/6905-multi-test/files/myPackageB/test/Main.hs

@@ -0,0 +1,4 @@
+import LibA ( funcB )
+
+main :: IO ()
+main = funcB