From 4aa5f88618a29cb53b988a8ae859caa2c70a6e62 Mon Sep 17 00:00:00 2001
From: Francesco Gazzetta <fgaz@fgaz.me>
Date: Mon, 24 Jul 2023 17:28:36 +0200
Subject: [PATCH] PD check: do not treat library names as package names (#9132)

Fixes #9122
---
 Cabal/src/Distribution/PackageDescription/Check.hs    |  7 +------
 .../PackageTests/Regression/T9122/p/p.cabal           |  6 ++++++
 .../PackageTests/Regression/T9122/q/q.cabal           | 10 ++++++++++
 .../PackageTests/Regression/T9122/setup.cabal.out     | 11 +++++++++++
 .../PackageTests/Regression/T9122/setup.out           | 11 +++++++++++
 .../PackageTests/Regression/T9122/setup.test.hs       |  5 +++++
 changelog.d/issue-9122                                |  4 ++++
 7 files changed, 48 insertions(+), 6 deletions(-)
 create mode 100644 cabal-testsuite/PackageTests/Regression/T9122/p/p.cabal
 create mode 100644 cabal-testsuite/PackageTests/Regression/T9122/q/q.cabal
 create mode 100644 cabal-testsuite/PackageTests/Regression/T9122/setup.cabal.out
 create mode 100644 cabal-testsuite/PackageTests/Regression/T9122/setup.out
 create mode 100644 cabal-testsuite/PackageTests/Regression/T9122/setup.test.hs
 create mode 100644 changelog.d/issue-9122

diff --git a/Cabal/src/Distribution/PackageDescription/Check.hs b/Cabal/src/Distribution/PackageDescription/Check.hs
index e8be60fcbc5..4c2701d95c3 100644
--- a/Cabal/src/Distribution/PackageDescription/Check.hs
+++ b/Cabal/src/Distribution/PackageDescription/Check.hs
@@ -1352,18 +1352,13 @@ checkFields pkg =
       , isNoVersion vr
       ]
 
-    internalLibraries =
-      map
-        (maybe (packageName pkg) unqualComponentNameToPackageName . libraryNameString . libName)
-        (allLibraries pkg)
-
     internalExecutables = map exeName $ executables pkg
 
     internalLibDeps =
       [ dep
       | bi <- allBuildInfo pkg
       , dep@(Dependency name _ _) <- targetBuildDepends bi
-      , name `elem` internalLibraries
+      , name == packageName pkg
       ]
 
     internalExeDeps =
diff --git a/cabal-testsuite/PackageTests/Regression/T9122/p/p.cabal b/cabal-testsuite/PackageTests/Regression/T9122/p/p.cabal
new file mode 100644
index 00000000000..1100690129a
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T9122/p/p.cabal
@@ -0,0 +1,6 @@
+cabal-version:      3.4
+name:               p
+Version:            2
+Build-Type:         Simple
+
+library
diff --git a/cabal-testsuite/PackageTests/Regression/T9122/q/q.cabal b/cabal-testsuite/PackageTests/Regression/T9122/q/q.cabal
new file mode 100644
index 00000000000..d9bd9b331e5
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T9122/q/q.cabal
@@ -0,0 +1,10 @@
+cabal-version:      3.4
+name:               q
+Version:            1
+Build-Type:         Simple
+
+library
+  build-depends:        q:p
+
+library p
+  build-depends:        p:p == 2
diff --git a/cabal-testsuite/PackageTests/Regression/T9122/setup.cabal.out b/cabal-testsuite/PackageTests/Regression/T9122/setup.cabal.out
new file mode 100644
index 00000000000..1367a55a1a0
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T9122/setup.cabal.out
@@ -0,0 +1,11 @@
+# Setup configure
+Configuring p-2...
+# Setup build
+Preprocessing library for p-2...
+Building library for p-2...
+# Setup copy
+Installing library in <PATH>
+# Setup register
+Registering library for p-2...
+# Setup configure
+Configuring q-1...
diff --git a/cabal-testsuite/PackageTests/Regression/T9122/setup.out b/cabal-testsuite/PackageTests/Regression/T9122/setup.out
new file mode 100644
index 00000000000..1367a55a1a0
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T9122/setup.out
@@ -0,0 +1,11 @@
+# Setup configure
+Configuring p-2...
+# Setup build
+Preprocessing library for p-2...
+Building library for p-2...
+# Setup copy
+Installing library in <PATH>
+# Setup register
+Registering library for p-2...
+# Setup configure
+Configuring q-1...
diff --git a/cabal-testsuite/PackageTests/Regression/T9122/setup.test.hs b/cabal-testsuite/PackageTests/Regression/T9122/setup.test.hs
new file mode 100644
index 00000000000..93a4a976b3b
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T9122/setup.test.hs
@@ -0,0 +1,5 @@
+import Test.Cabal.Prelude
+
+main = setupAndCabalTest $ withPackageDb $ do
+  withDirectory "p" $ setup_install []
+  withDirectory "q" $ setup "configure" []
diff --git a/changelog.d/issue-9122 b/changelog.d/issue-9122
new file mode 100644
index 00000000000..c8d82af1d86
--- /dev/null
+++ b/changelog.d/issue-9122
@@ -0,0 +1,4 @@
+synopsis: Fix dependency on an external package when an internal library with the same name exists
+packages: Cabal
+issues: #9122
+prs: #9132