From 1d2acbbe88ec777e3b2bebf2157fa57a58f9bc57 Mon Sep 17 00:00:00 2001
From: Oleg Grenrus <oleg.grenrus@iki.fi>
Date: Tue, 14 Jul 2020 21:26:31 +0300
Subject: [PATCH 1/2] Add tests for #6961

---
 .../Regression/T6961/DepExternal/cabal.out    |  7 +++++++
 .../T6961/DepExternal/cabal.project           |  1 +
 .../T6961/DepExternal/cabal.test.hs           |  3 +++
 .../T6961/DepExternal/pkg-bar/exe/Main.hs     |  6 ++++++
 .../T6961/DepExternal/pkg-bar/pkg-bar.cabal   | 13 ++++++++++++
 .../pkg-foo/internal/InternalLib.hs           |  4 ++++
 .../T6961/DepExternal/pkg-foo/pkg-foo.cabal   | 19 ++++++++++++++++++
 .../T6961/DepExternal/pkg-foo/src/Lib.hs      |  3 +++
 .../Regression/T6961/DepInternal/cabal.out    |  8 ++++++++
 .../T6961/DepInternal/cabal.project           |  1 +
 .../T6961/DepInternal/cabal.test.hs           |  5 +++++
 .../T6961/DepInternal/pkg-bar/exe/Main.hs     |  6 ++++++
 .../T6961/DepInternal/pkg-bar/pkg-bar.cabal   | 13 ++++++++++++
 .../pkg-foo/internal/InternalLib.hs           |  4 ++++
 .../T6961/DepInternal/pkg-foo/pkg-foo.cabal   | 19 ++++++++++++++++++
 .../T6961/DepInternal/pkg-foo/src/Lib.hs      |  3 +++
 .../Regression/T6961/Exe/cabal.out            |  6 ++++++
 .../Regression/T6961/Exe/cabal.project        |  1 +
 .../Regression/T6961/Exe/cabal.test.hs        |  3 +++
 .../Regression/T6961/Exe/exe/Main.hs          |  6 ++++++
 .../Regression/T6961/Exe/issue6961.cabal      | 19 ++++++++++++++++++
 .../Regression/T6961/Exe/src/Lib.hs           |  4 ++++
 .../Regression/T6961/Test/cabal.out           |  8 ++++++++
 .../Regression/T6961/Test/cabal.project       |  1 +
 .../Regression/T6961/Test/cabal.test.hs       |  5 +++++
 .../Regression/T6961/Test/issue6961.cabal     | 20 +++++++++++++++++++
 .../Regression/T6961/Test/src/Lib.hs          |  4 ++++
 .../Regression/T6961/Test/tests/Main.hs       |  6 ++++++
 28 files changed, 198 insertions(+)
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/DepExternal/cabal.out
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/DepExternal/cabal.project
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/DepExternal/cabal.test.hs
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-bar/exe/Main.hs
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-bar/pkg-bar.cabal
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-foo/internal/InternalLib.hs
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-foo/pkg-foo.cabal
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-foo/src/Lib.hs
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/DepInternal/cabal.out
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/DepInternal/cabal.project
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/DepInternal/cabal.test.hs
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-bar/exe/Main.hs
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-bar/pkg-bar.cabal
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-foo/internal/InternalLib.hs
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-foo/pkg-foo.cabal
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-foo/src/Lib.hs
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/Exe/cabal.out
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/Exe/cabal.project
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/Exe/cabal.test.hs
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/Exe/exe/Main.hs
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/Exe/issue6961.cabal
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/Exe/src/Lib.hs
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.out
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.project
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.test.hs
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/Test/issue6961.cabal
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/Test/src/Lib.hs
 create mode 100644 cabal-testsuite/PackageTests/Regression/T6961/Test/tests/Main.hs

diff --git a/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/cabal.out b/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/cabal.out
new file mode 100644
index 00000000000..a063ee92cb8
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/cabal.out
@@ -0,0 +1,7 @@
+# cabal v2-build
+Resolving dependencies...
+Build profile: -w ghc-<GHCVER> -O1
+In order, the following would be built:
+ - pkg-foo-0 (lib:internal-lib) (first run)
+ - pkg-foo-0 (lib) (first run)
+ - pkg-bar-0 (exe:example) (first run)
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/cabal.project b/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/cabal.project
new file mode 100644
index 00000000000..56221084a1f
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/cabal.project
@@ -0,0 +1 @@
+packages: pkg-foo pkg-bar
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/cabal.test.hs b/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/cabal.test.hs
new file mode 100644
index 00000000000..915337859f5
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/cabal.test.hs
@@ -0,0 +1,3 @@
+import Test.Cabal.Prelude
+main = cabalTest $
+  cabal "v2-build" ["all", "--dry-run", "--enable-tests"]
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-bar/exe/Main.hs b/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-bar/exe/Main.hs
new file mode 100644
index 00000000000..5edf24437d0
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-bar/exe/Main.hs
@@ -0,0 +1,6 @@
+module Main where
+
+import Lib
+
+main :: IO ()
+main = print value
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-bar/pkg-bar.cabal b/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-bar/pkg-bar.cabal
new file mode 100644
index 00000000000..a8c855e8fbc
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-bar/pkg-bar.cabal
@@ -0,0 +1,13 @@
+cabal-version: 2.0
+name: pkg-bar
+version: 0
+build-type: Simple
+
+synopsis: This should work
+category: Test
+
+executable example
+  default-language: Haskell2010
+  hs-source-dirs: exe
+  main-is: Main.hs
+  build-depends: base, pkg-foo
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-foo/internal/InternalLib.hs b/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-foo/internal/InternalLib.hs
new file mode 100644
index 00000000000..b925bcad362
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-foo/internal/InternalLib.hs
@@ -0,0 +1,4 @@
+module InternalLib where
+
+value :: Int
+value = 42
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-foo/pkg-foo.cabal b/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-foo/pkg-foo.cabal
new file mode 100644
index 00000000000..d22f7a32a6b
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-foo/pkg-foo.cabal
@@ -0,0 +1,19 @@
+cabal-version: 2.0
+name: pkg-foo
+version: 0
+build-type: Simple
+
+synopsis: This should work
+category: Test
+
+library
+  default-language: Haskell2010
+  hs-source-dirs: src
+  build-depends: base <5, internal-lib
+  exposed-modules: Lib
+
+library internal-lib
+  default-language: Haskell2010
+  hs-source-dirs: internal
+  build-depends: base <5
+  exposed-modules: InternalLib
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-foo/src/Lib.hs b/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-foo/src/Lib.hs
new file mode 100644
index 00000000000..c7683f97b49
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/DepExternal/pkg-foo/src/Lib.hs
@@ -0,0 +1,3 @@
+module Lib (value) where
+
+import InternalLib (value)
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/cabal.out b/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/cabal.out
new file mode 100644
index 00000000000..aa10de2a405
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/cabal.out
@@ -0,0 +1,8 @@
+# cabal v2-build
+Resolving dependencies...
+cabal: Could not resolve dependencies:
+[__0] trying: pkg-bar-0 (user goal)
+[__1] next goal: pkg-foo (user goal)
+[__1] rejecting: pkg-foo-0 (library 'internal-lib' is private, but it is required by pkg-bar)
+[__1] fail (backjumping, conflict set: pkg-bar, pkg-foo)
+After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: pkg-bar (2), pkg-foo (2)
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/cabal.project b/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/cabal.project
new file mode 100644
index 00000000000..56221084a1f
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/cabal.project
@@ -0,0 +1 @@
+packages: pkg-foo pkg-bar
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/cabal.test.hs b/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/cabal.test.hs
new file mode 100644
index 00000000000..6b4ad601b07
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/cabal.test.hs
@@ -0,0 +1,5 @@
+import Test.Cabal.Prelude
+main = cabalTest $
+  -- we try to depend on private component from outside,
+  -- so this should fail.
+  fails $ cabal "v2-build" ["all", "--dry-run", "--enable-tests"]
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-bar/exe/Main.hs b/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-bar/exe/Main.hs
new file mode 100644
index 00000000000..cfae2b73f2a
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-bar/exe/Main.hs
@@ -0,0 +1,6 @@
+module Main where
+
+import InternalLib
+
+main :: IO ()
+main = print value
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-bar/pkg-bar.cabal b/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-bar/pkg-bar.cabal
new file mode 100644
index 00000000000..2895fd54b2c
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-bar/pkg-bar.cabal
@@ -0,0 +1,13 @@
+cabal-version: 3.0
+name: pkg-bar
+version: 0
+build-type: Simple
+
+synopsis: This should work
+category: Test
+
+executable example
+  default-language: Haskell2010
+  hs-source-dirs: exe
+  main-is: Main.hs
+  build-depends: base, pkg-foo:internal-lib
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-foo/internal/InternalLib.hs b/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-foo/internal/InternalLib.hs
new file mode 100644
index 00000000000..b925bcad362
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-foo/internal/InternalLib.hs
@@ -0,0 +1,4 @@
+module InternalLib where
+
+value :: Int
+value = 42
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-foo/pkg-foo.cabal b/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-foo/pkg-foo.cabal
new file mode 100644
index 00000000000..d22f7a32a6b
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-foo/pkg-foo.cabal
@@ -0,0 +1,19 @@
+cabal-version: 2.0
+name: pkg-foo
+version: 0
+build-type: Simple
+
+synopsis: This should work
+category: Test
+
+library
+  default-language: Haskell2010
+  hs-source-dirs: src
+  build-depends: base <5, internal-lib
+  exposed-modules: Lib
+
+library internal-lib
+  default-language: Haskell2010
+  hs-source-dirs: internal
+  build-depends: base <5
+  exposed-modules: InternalLib
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-foo/src/Lib.hs b/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-foo/src/Lib.hs
new file mode 100644
index 00000000000..c7683f97b49
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/DepInternal/pkg-foo/src/Lib.hs
@@ -0,0 +1,3 @@
+module Lib (value) where
+
+import InternalLib (value)
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/Exe/cabal.out b/cabal-testsuite/PackageTests/Regression/T6961/Exe/cabal.out
new file mode 100644
index 00000000000..bde31817cf4
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/Exe/cabal.out
@@ -0,0 +1,6 @@
+# cabal v2-build
+Resolving dependencies...
+Build profile: -w ghc-<GHCVER> -O1
+In order, the following would be built:
+ - issue6961-0 (lib:internal-lib) (first run)
+ - issue6961-0 (exe:example) (first run)
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/Exe/cabal.project b/cabal-testsuite/PackageTests/Regression/T6961/Exe/cabal.project
new file mode 100644
index 00000000000..e6fdbadb439
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/Exe/cabal.project
@@ -0,0 +1 @@
+packages: .
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/Exe/cabal.test.hs b/cabal-testsuite/PackageTests/Regression/T6961/Exe/cabal.test.hs
new file mode 100644
index 00000000000..915337859f5
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/Exe/cabal.test.hs
@@ -0,0 +1,3 @@
+import Test.Cabal.Prelude
+main = cabalTest $
+  cabal "v2-build" ["all", "--dry-run", "--enable-tests"]
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/Exe/exe/Main.hs b/cabal-testsuite/PackageTests/Regression/T6961/Exe/exe/Main.hs
new file mode 100644
index 00000000000..5edf24437d0
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/Exe/exe/Main.hs
@@ -0,0 +1,6 @@
+module Main where
+
+import Lib
+
+main :: IO ()
+main = print value
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/Exe/issue6961.cabal b/cabal-testsuite/PackageTests/Regression/T6961/Exe/issue6961.cabal
new file mode 100644
index 00000000000..c2e3faf69f1
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/Exe/issue6961.cabal
@@ -0,0 +1,19 @@
+cabal-version: 2.0
+name: issue6961
+version: 0
+build-type: Simple
+
+synopsis: This should work
+category: Test
+
+library internal-lib
+  default-language: Haskell2010
+  hs-source-dirs: src
+  build-depends: base <5
+  exposed-modules: Lib
+
+executable example
+  default-language: Haskell2010
+  hs-source-dirs: exe
+  main-is: Main.hs
+  build-depends: base, internal-lib
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/Exe/src/Lib.hs b/cabal-testsuite/PackageTests/Regression/T6961/Exe/src/Lib.hs
new file mode 100644
index 00000000000..e4dce2beed1
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/Exe/src/Lib.hs
@@ -0,0 +1,4 @@
+module Lib where
+
+value :: Int
+value = 42
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.out b/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.out
new file mode 100644
index 00000000000..96820cffdc9
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.out
@@ -0,0 +1,8 @@
+# cabal v2-build
+Resolving dependencies...
+cabal: Could not resolve dependencies:
+[__0] trying: issue6961-0 (user goal)
+[__1] rejecting: issue6961:!test (constraint from config file, command line flag, or user target requires opposite flag selection)
+[__1] rejecting: issue6961:*test (requires library 'internal-lib' from issue6961, but the component is private)
+[__1] fail (backjumping, conflict set: issue6961, issue6961:test)
+After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: issue6961 (3), issue6961:test (3)
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.project b/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.project
new file mode 100644
index 00000000000..e6fdbadb439
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.project
@@ -0,0 +1 @@
+packages: .
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.test.hs b/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.test.hs
new file mode 100644
index 00000000000..a0c89658e3a
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.test.hs
@@ -0,0 +1,5 @@
+import Test.Cabal.Prelude
+main = cabalTest $
+  -- fails, but it shouldn't.
+  -- https://github.com/haskell/cabal/issues/6961
+  fails $ cabal "v2-build" ["all", "--dry-run", "--enable-tests"]
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/Test/issue6961.cabal b/cabal-testsuite/PackageTests/Regression/T6961/Test/issue6961.cabal
new file mode 100644
index 00000000000..f2fff29c5e5
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/Test/issue6961.cabal
@@ -0,0 +1,20 @@
+cabal-version: 2.0
+name: issue6961
+version: 0
+build-type: Simple
+
+synopsis: This should work
+category: Test
+
+library internal-lib
+  default-language: Haskell2010
+  hs-source-dirs: src
+  build-depends: base <5
+  exposed-modules: Lib
+
+test-suite example
+  type: exitcode-stdio-1.0
+  default-language: Haskell2010
+  hs-source-dirs: exe
+  main-is: Main.hs
+  build-depends: base, internal-lib
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/Test/src/Lib.hs b/cabal-testsuite/PackageTests/Regression/T6961/Test/src/Lib.hs
new file mode 100644
index 00000000000..e4dce2beed1
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/Test/src/Lib.hs
@@ -0,0 +1,4 @@
+module Lib where
+
+value :: Int
+value = 42
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/Test/tests/Main.hs b/cabal-testsuite/PackageTests/Regression/T6961/Test/tests/Main.hs
new file mode 100644
index 00000000000..5edf24437d0
--- /dev/null
+++ b/cabal-testsuite/PackageTests/Regression/T6961/Test/tests/Main.hs
@@ -0,0 +1,6 @@
+module Main where
+
+import Lib
+
+main :: IO ()
+main = print value

From f374a1e90053534c769c9af69ccf6202fe390cbb Mon Sep 17 00:00:00 2001
From: Oleg Grenrus <oleg.grenrus@iki.fi>
Date: Tue, 14 Jul 2020 22:16:08 +0300
Subject: [PATCH 2/2] Fix #6961. Depending on a private component from the same
 package is fine.

---
 .../Distribution/Solver/Modular/Index.hs          |  5 +++--
 .../Distribution/Solver/Modular/Validate.hs       | 15 +++++++++------
 .../PackageTests/Regression/T6961/Test/cabal.out  | 10 ++++------
 .../Regression/T6961/Test/cabal.test.hs           |  4 +---
 .../Regression/T6961/Test/issue6961.cabal         |  2 +-
 5 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/cabal-install/Distribution/Solver/Modular/Index.hs b/cabal-install/Distribution/Solver/Modular/Index.hs
index c1a8c0be412..2f28d12de85 100644
--- a/cabal-install/Distribution/Solver/Modular/Index.hs
+++ b/cabal-install/Distribution/Solver/Modular/Index.hs
@@ -42,14 +42,15 @@ data ComponentInfo = ComponentInfo {
     compIsVisible   :: IsVisible
   , compIsBuildable :: IsBuildable
   }
+  deriving Show
 
 -- | Whether a component is visible in the current environment.
 newtype IsVisible = IsVisible Bool
-  deriving Eq
+  deriving (Eq, Show)
 
 -- | Whether a component is made unbuildable by a "buildable: False" field.
 newtype IsBuildable = IsBuildable Bool
-  deriving Eq
+  deriving (Eq, Show)
 
 mkIndex :: [(PN, I, PInfo)] -> Index
 mkIndex xs = M.map M.fromList (groupMap (L.map (\ (pn, i, pi) -> (pn, (i, pi))) xs))
diff --git a/cabal-install/Distribution/Solver/Modular/Validate.hs b/cabal-install/Distribution/Solver/Modular/Validate.hs
index 9c20c9bc321..b809e4fbbda 100644
--- a/cabal-install/Distribution/Solver/Modular/Validate.hs
+++ b/cabal-install/Distribution/Solver/Modular/Validate.hs
@@ -230,7 +230,7 @@ validate = cata go
           let newDeps :: Either Conflict (PPreAssignment, Map QPN ComponentDependencyReasons)
               newDeps = do
                 nppa <- mnppa
-                rComps' <- extendRequiredComponents aComps rComps newactives
+                rComps' <- extendRequiredComponents qpn aComps rComps newactives
                 checkComponentsInNewPackage (M.findWithDefault M.empty qpn rComps) qpn comps
                 return (nppa, rComps')
           in case newDeps of
@@ -265,7 +265,7 @@ validate = cata go
       -- We now try to get the new active dependencies we might learn about because
       -- we have chosen a new flag.
       let newactives = extractNewDeps (F qfn) b npfa psa qdeps
-          mNewRequiredComps = extendRequiredComponents aComps rComps newactives
+          mNewRequiredComps = extendRequiredComponents qpn aComps rComps newactives
       -- As in the package case, we try to extend the partial assignment.
       let mnppa = extend extSupported langSupported pkgPresent newactives ppa
       case liftM2 (,) mnppa mNewRequiredComps of
@@ -295,7 +295,7 @@ validate = cata go
       -- We now try to get the new active dependencies we might learn about because
       -- we have chosen a new flag.
       let newactives = extractNewDeps (S qsn) b pfa npsa qdeps
-          mNewRequiredComps = extendRequiredComponents aComps rComps newactives
+          mNewRequiredComps = extendRequiredComponents qpn aComps rComps newactives
       -- As in the package case, we try to extend the partial assignment.
       let mnppa = extend extSupported langSupported pkgPresent newactives ppa
       case liftM2 (,) mnppa mNewRequiredComps of
@@ -534,11 +534,12 @@ createConflictSetForVersionConflict pkg
 -- known component dependencies. It returns a failure when a new dependency
 -- requires a component that is missing, private, or unbuildable in a previously
 -- chosen package.
-extendRequiredComponents :: Map QPN (Map ExposedComponent ComponentInfo)
+extendRequiredComponents :: QPN -- ^ package we extend
+                         -> Map QPN (Map ExposedComponent ComponentInfo)
                          -> Map QPN ComponentDependencyReasons
                          -> [LDep QPN]
                          -> Either Conflict (Map QPN ComponentDependencyReasons)
-extendRequiredComponents available = foldM extendSingle
+extendRequiredComponents eqpn available = foldM extendSingle
   where
     extendSingle :: Map QPN ComponentDependencyReasons
                  -> LDep QPN
@@ -554,7 +555,9 @@ extendRequiredComponents available = foldM extendSingle
                  Nothing ->
                      Left $ mkConflict qpn comp dr PackageRequiresMissingComponent
                  Just compInfo
-                   | compIsVisible compInfo == IsVisible False ->
+                   | compIsVisible compInfo == IsVisible False
+                   , eqpn /= qpn -- package components can depend on other components
+                   ->
                      Left $ mkConflict qpn comp dr PackageRequiresPrivateComponent
                    | compIsBuildable compInfo == IsBuildable False ->
                      Left $ mkConflict qpn comp dr PackageRequiresUnbuildableComponent
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.out b/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.out
index 96820cffdc9..8f28d66058a 100644
--- a/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.out
+++ b/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.out
@@ -1,8 +1,6 @@
 # cabal v2-build
 Resolving dependencies...
-cabal: Could not resolve dependencies:
-[__0] trying: issue6961-0 (user goal)
-[__1] rejecting: issue6961:!test (constraint from config file, command line flag, or user target requires opposite flag selection)
-[__1] rejecting: issue6961:*test (requires library 'internal-lib' from issue6961, but the component is private)
-[__1] fail (backjumping, conflict set: issue6961, issue6961:test)
-After searching the rest of the dependency tree exhaustively, these were the goals I've had most trouble fulfilling: issue6961 (3), issue6961:test (3)
+Build profile: -w ghc-<GHCVER> -O1
+In order, the following would be built:
+ - issue6961-0 (lib:internal-lib) (first run)
+ - issue6961-0 (test:example) (first run)
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.test.hs b/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.test.hs
index a0c89658e3a..915337859f5 100644
--- a/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.test.hs
+++ b/cabal-testsuite/PackageTests/Regression/T6961/Test/cabal.test.hs
@@ -1,5 +1,3 @@
 import Test.Cabal.Prelude
 main = cabalTest $
-  -- fails, but it shouldn't.
-  -- https://github.com/haskell/cabal/issues/6961
-  fails $ cabal "v2-build" ["all", "--dry-run", "--enable-tests"]
+  cabal "v2-build" ["all", "--dry-run", "--enable-tests"]
diff --git a/cabal-testsuite/PackageTests/Regression/T6961/Test/issue6961.cabal b/cabal-testsuite/PackageTests/Regression/T6961/Test/issue6961.cabal
index f2fff29c5e5..490ec5f55f9 100644
--- a/cabal-testsuite/PackageTests/Regression/T6961/Test/issue6961.cabal
+++ b/cabal-testsuite/PackageTests/Regression/T6961/Test/issue6961.cabal
@@ -15,6 +15,6 @@ library internal-lib
 test-suite example
   type: exitcode-stdio-1.0
   default-language: Haskell2010
-  hs-source-dirs: exe
+  hs-source-dirs: tests
   main-is: Main.hs
   build-depends: base, internal-lib