driver: Only check for unused package warning in after succesful downsweep

Before we would check for the unused package warning even if the module
graph was compromised due to an error in downsweep. This is easily
fixed by pushing warmUnusedPackages into depanalE, and then returning
the errors like the other downsweep errors.

Fixes #20242

8 files changed, 56 insertions, 0 deletions

diff --git a/testsuite/tests/cabal/t20242/BootNoHeader.cabal b/testsuite/tests/cabal/t20242/BootNoHeader.cabal
new file mode 100644
index 0000000000..1a20184494
--- /dev/null
+++ b/testsuite/tests/cabal/t20242/BootNoHeader.cabal
@@ -0,0 +1,12 @@
+cabal-version:      2.4
+name:               BootNoHeader
+version:            0.1.0.0
+
+executable BootNoHeader
+    main-is:          Main.hs
+    other-modules:    Foo
+    build-depends:    base
+    hs-source-dirs:   .
+    default-language: Haskell2010
+
+    ghc-options:      -Werror=unused-packages
diff --git a/testsuite/tests/cabal/t20242/Foo.hs b/testsuite/tests/cabal/t20242/Foo.hs
new file mode 100644
index 0000000000..c3707c7a24
--- /dev/null
+++ b/testsuite/tests/cabal/t20242/Foo.hs
@@ -0,0 +1,4 @@
+module Foo where
+
+a :: Int
+a = 5
diff --git a/testsuite/tests/cabal/t20242/Foo.hs-boot b/testsuite/tests/cabal/t20242/Foo.hs-boot
new file mode 100644
index 0000000000..9aa298fba9
--- /dev/null
+++ b/testsuite/tests/cabal/t20242/Foo.hs-boot
@@ -0,0 +1 @@
+a :: Int
diff --git a/testsuite/tests/cabal/t20242/Main.hs b/testsuite/tests/cabal/t20242/Main.hs
new file mode 100644
index 0000000000..de3cdee837
--- /dev/null
+++ b/testsuite/tests/cabal/t20242/Main.hs
@@ -0,0 +1,5 @@
+module Main where
+
+import {-# SOURCE #-} Foo
+
+main = putStrLn "Hello, world!"
diff --git a/testsuite/tests/cabal/t20242/Makefile b/testsuite/tests/cabal/t20242/Makefile
new file mode 100644
index 0000000000..1eab3808e6
--- /dev/null
+++ b/testsuite/tests/cabal/t20242/Makefile
@@ -0,0 +1,18 @@
+TOP=../../..
+include $(TOP)/mk/boilerplate.mk
+include $(TOP)/mk/test.mk
+
+SETUP = ./Setup -v0
+
+T20242: clean
+	$(MAKE) clean
+	'$(TEST_HC)' $(TEST_HC_OPTS) -v0 --make Setup
+	$(SETUP) clean
+	$(SETUP) configure $(CABAL_MINIMAL_BUILD) --with-ghc='$(TEST_HC)' --ghc-options='$(TEST_HC_OPTS)'
+	$(SETUP) build || true
+ifneq "$(CLEANUP)" ""
+	$(MAKE) clean
+endif
+
+clean :
+	$(RM) -r */dist Setup$(exeext) *.o *.hi
diff --git a/testsuite/tests/cabal/t20242/Setup.hs b/testsuite/tests/cabal/t20242/Setup.hs
new file mode 100644
index 0000000000..9a994af677
--- /dev/null
+++ b/testsuite/tests/cabal/t20242/Setup.hs
@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain
diff --git a/testsuite/tests/cabal/t20242/T20242.stderr b/testsuite/tests/cabal/t20242/T20242.stderr
new file mode 100644
index 0000000000..73c50e8c51
--- /dev/null
+++ b/testsuite/tests/cabal/t20242/T20242.stderr
@@ -0,0 +1,5 @@
+
+Foo.hs-boot:1:1: error:
+    File name does not match module name:
+    Saw     : ‘Main’
+    Expected: ‘Foo’
diff --git a/testsuite/tests/cabal/t20242/all.T b/testsuite/tests/cabal/t20242/all.T
new file mode 100644
index 0000000000..4e1c0387ee
--- /dev/null
+++ b/testsuite/tests/cabal/t20242/all.T
@@ -0,0 +1,9 @@
+if config.cleanup:
+   cleanup = 'CLEANUP=1'
+else:
+   cleanup = 'CLEANUP=0'
+
+test('T20242',
+     [extra_files(['Setup.hs', 'BootNoHeader.cabal','Foo.hs', 'Foo.hs-boot', 'Main.hs'])],
+     run_command,
+     ['$MAKE -s --no-print-directory T20242 ' + cleanup])