Improve driver diagnostic messages by including UnitId in message

Currently the driver diagnostics don't give any indication about which unit they correspond to.

For example `-Wmissing-home-modules` can fire multiple times for each different home unit and gives no indication about which unit it's actually reporting about.

Perhaps a longer term fix is to generalise the providence information away from a SrcSpan so that these kind of whole project errors can be reported with an accurate provenance. For now we can just include the `UnitId` in the error message.

Fixes #22678

14 files changed, 61 insertions, 49 deletions

diff --git a/compiler/GHC/Driver/Errors/Ppr.hs b/compiler/GHC/Driver/Errors/Ppr.hs
index 9ba53902bc..9e3822e460 100644
--- a/compiler/GHC/Driver/Errors/Ppr.hs
+++ b/compiler/GHC/Driver/Errors/Ppr.hs
@@ -92,28 +92,29 @@ instance Diagnostic DriverMessage where
       -> diagnosticMessage (defaultDiagnosticOpts @e) m
     DriverPsHeaderMessage m
       -> diagnosticMessage (psDiagnosticOpts opts) m
-    DriverMissingHomeModules missing buildingCabalPackage
+    DriverMissingHomeModules uid missing buildingCabalPackage
       -> let msg | buildingCabalPackage == YesBuildingCabalPackage
                  = hang
-                     (text "These modules are needed for compilation but not listed in your .cabal file's other-modules: ")
+                     (text "These modules are needed for compilation but not listed in your .cabal file's other-modules for" <+> quotes (ppr uid) <+> text ":")
                      4
                      (sep (map ppr missing))
                  | otherwise
                  =
                    hang
-                     (text "Modules are not listed in command line but needed for compilation: ")
+                     (text "Modules are not listed in options for"
+                        <+> quotes (ppr uid) <+> text "but needed for compilation:")
                      4
                      (sep (map ppr missing))
          in mkSimpleDecorated msg
-    DriverUnknownHiddenModules missing
+    DriverUnknownHiddenModules uid missing
       -> let msg = hang
-                     (text "Modules are listened as hidden but not part of the unit: ")
+                     (text "Modules are listed as hidden in options for" <+> quotes (ppr uid) <+> text "but not part of the unit:")
                      4
                      (sep (map ppr missing))
          in mkSimpleDecorated msg
-    DriverUnknownReexportedModules missing
+    DriverUnknownReexportedModules uid missing
       -> let msg = hang
-                     (text "Modules are listened as reexported but can't be found in any dependency: ")
+                     (text "Modules are listed as reexported in options for" <+> quotes (ppr uid) <+> text "but can't be found in any dependency:")
                      4
                      (sep (map ppr missing))
          in mkSimpleDecorated msg
diff --git a/compiler/GHC/Driver/Errors/Types.hs b/compiler/GHC/Driver/Errors/Types.hs
index cb7625ca09..10127a8d6c 100644
--- a/compiler/GHC/Driver/Errors/Types.hs
+++ b/compiler/GHC/Driver/Errors/Types.hs
@@ -143,17 +143,17 @@ data DriverMessage where
       Test case: warnings/should_compile/MissingMod
 
   -}
-  DriverMissingHomeModules :: [ModuleName] -> !BuildingCabalPackage -> DriverMessage
+  DriverMissingHomeModules :: UnitId -> [ModuleName] -> !BuildingCabalPackage -> DriverMessage
 
   {-| DriverUnknown is a warning that arises when a user tries to
       reexport a module which isn't part of that unit.
   -}
-  DriverUnknownReexportedModules :: [ModuleName] -> DriverMessage
+  DriverUnknownReexportedModules :: UnitId -> [ModuleName] -> DriverMessage
 
   {-| DriverUnknownHiddenModules is a warning that arises when a user tries to
       hide a module which isn't part of that unit.
   -}
-  DriverUnknownHiddenModules :: [ModuleName] -> DriverMessage
+  DriverUnknownHiddenModules :: UnitId -> [ModuleName] -> DriverMessage
 
   {-| DriverUnusedPackages occurs when when package is requested on command line,
       but was never needed during compilation. Activated by -Wunused-packages.
diff --git a/compiler/GHC/Driver/Make.hs b/compiler/GHC/Driver/Make.hs
index 5f48beeb40..eee37601f1 100644
--- a/compiler/GHC/Driver/Make.hs
+++ b/compiler/GHC/Driver/Make.hs
@@ -365,7 +365,7 @@ warnMissingHomeModules dflags targets mod_graph =
                 (mgModSummaries mod_graph))
 
     warn = singleMessage $ mkPlainMsgEnvelope diag_opts noSrcSpan
-                         $ DriverMissingHomeModules missing (checkBuildingCabalPackage dflags)
+                         $ DriverMissingHomeModules (homeUnitId_ dflags) missing (checkBuildingCabalPackage dflags)
 
 -- Check that any modules we want to reexport or hide are actually in the package.
 warnUnknownModules :: HscEnv -> DynFlags -> ModuleGraph -> IO DriverMessages
@@ -393,14 +393,14 @@ warnUnknownModules hsc_env dflags mod_graph = do
         _ -> return True
 
 
-    warn flag mod = singleMessage $ mkPlainMsgEnvelope diag_opts noSrcSpan
-                         $ flag mod
+    warn diagnostic = singleMessage $ mkPlainMsgEnvelope diag_opts noSrcSpan
+                         $ diagnostic
 
     final_msgs hidden_warns reexported_warns
           =
         unionManyMessages $
-          [warn DriverUnknownHiddenModules (Set.toList hidden_warns) | not (Set.null hidden_warns)]
-          ++ [warn DriverUnknownReexportedModules reexported_warns | not (null reexported_warns)]
+          [warn (DriverUnknownHiddenModules (homeUnitId_ dflags) (Set.toList hidden_warns)) | not (Set.null hidden_warns)]
+          ++ [warn (DriverUnknownReexportedModules (homeUnitId_ dflags) reexported_warns) | not (null reexported_warns)]
 
 -- | Describes which modules of the module graph need to be loaded.
 data LoadHowMuch
diff --git a/testsuite/tests/driver/multipleHomeUnits/all.T b/testsuite/tests/driver/multipleHomeUnits/all.T
index a21459d74f..ebee7b9f5d 100644
--- a/testsuite/tests/driver/multipleHomeUnits/all.T
+++ b/testsuite/tests/driver/multipleHomeUnits/all.T
@@ -7,6 +7,8 @@ test('multipleHomeUnits_cpp', [extra_files([ 'cpp-includes/', 'unitCPPIncludes']
 test('multipleHomeUnits_cfile', [extra_files([ 'c-file/', 'unitCFile'])], multiunit_compile, [['unitCFile'], '-fhide-source-paths'])
 test('multipleHomeUnits_callstack', [extra_files([ 'callstack/', 'unitCallstack'])], makefile_test, [])
 
+test('multipleHomeUnits_warnings', [extra_files([ 'unitWarnings', 'A.hs'])], multiunit_compile_fail, [['unitWarnings'], '-fhide-source-paths'])
+
 test('multipleHomeUnits_cpp2', [extra_files([ 'cpp-includes/', 'cpp-import/', 'unitCPPImport', 'unitCPPIncludes'])], multiunit_compile, [['unitCPPImport', 'unitCPPIncludes'], '-fhide-source-paths'])
 
 test('multiGHCi', [extra_files(['a/', 'b/', 'unitA', 'unitB', 'multiGHCi.script'])
diff --git a/testsuite/tests/driver/multipleHomeUnits/multipleHomeUnits_warnings.stderr b/testsuite/tests/driver/multipleHomeUnits/multipleHomeUnits_warnings.stderr
new file mode 100644
index 0000000000..64d1f6da40
--- /dev/null
+++ b/testsuite/tests/driver/multipleHomeUnits/multipleHomeUnits_warnings.stderr
@@ -0,0 +1,8 @@
+
+<no location info>: error: [GHC-38189]
+    Modules are listed as hidden in options for ‘unit-warnings’ but not part of the unit:
+        C
+
+<no location info>: error: [GHC-68286]
+    Modules are listed as reexported in options for ‘unit-warnings’ but can't be found in any dependency:
+        B
diff --git a/testsuite/tests/driver/multipleHomeUnits/unitWarnings b/testsuite/tests/driver/multipleHomeUnits/unitWarnings
new file mode 100644
index 0000000000..c2fff2cb2c
--- /dev/null
+++ b/testsuite/tests/driver/multipleHomeUnits/unitWarnings
@@ -0,0 +1 @@
+-i -i. A -reexported-module B -hidden-module C -this-unit-id unit-warnings
diff --git a/testsuite/tests/warnings/should_compile/MissingMod.stderr b/testsuite/tests/warnings/should_compile/MissingMod.stderr
index 92ada51d60..b36fe1437f 100644
--- a/testsuite/tests/warnings/should_compile/MissingMod.stderr
+++ b/testsuite/tests/warnings/should_compile/MissingMod.stderr
@@ -1,6 +1,6 @@
 
 <no location info>: warning: [GHC-32850] [-Wmissing-home-modules]
-    Modules are not listed in command line but needed for compilation: 
+    Modules are not listed in options for ‘main’ but needed for compilation:
         MissingMod1
 [1 of 2] Compiling MissingMod1      ( MissingMod1.hs, MissingMod1.o )
 [2 of 2] Compiling MissingMod       ( MissingMod.hs, MissingMod.o )
diff --git a/testsuite/tests/warnings/should_compile/T13727/T13727a.stderr b/testsuite/tests/warnings/should_compile/T13727/T13727a.stderr
index d34450454a..8df11b7d80 100644
--- a/testsuite/tests/warnings/should_compile/T13727/T13727a.stderr
+++ b/testsuite/tests/warnings/should_compile/T13727/T13727a.stderr
@@ -1,7 +1,7 @@
 
 <no location info>: warning: [GHC-32850] [-Wmissing-home-modules]
-    Modules are not listed in command line but needed for compilation: 
+    Modules are not listed in options for ‘main’ but needed for compilation:
         M1
-[1 of 3] Compiling M1               ( src-lib\M1.hs, src-lib\M1.o )
-[2 of 3] Compiling Main             ( src-exe\Main.hs, src-exe\Main.o )
-[3 of 3] Linking src-exe\Main.exe
+[1 of 3] Compiling M1               ( src-lib/M1.hs, src-lib/M1.o )
+[2 of 3] Compiling Main             ( src-exe/Main.hs, src-exe/Main.o )
+[3 of 3] Linking src-exe/Main
diff --git a/testsuite/tests/warnings/should_compile/T13727/T13727b.stderr b/testsuite/tests/warnings/should_compile/T13727/T13727b.stderr
index d34450454a..8df11b7d80 100644
--- a/testsuite/tests/warnings/should_compile/T13727/T13727b.stderr
+++ b/testsuite/tests/warnings/should_compile/T13727/T13727b.stderr
@@ -1,7 +1,7 @@
 
 <no location info>: warning: [GHC-32850] [-Wmissing-home-modules]
-    Modules are not listed in command line but needed for compilation: 
+    Modules are not listed in options for ‘main’ but needed for compilation:
         M1
-[1 of 3] Compiling M1               ( src-lib\M1.hs, src-lib\M1.o )
-[2 of 3] Compiling Main             ( src-exe\Main.hs, src-exe\Main.o )
-[3 of 3] Linking src-exe\Main.exe
+[1 of 3] Compiling M1               ( src-lib/M1.hs, src-lib/M1.o )
+[2 of 3] Compiling Main             ( src-exe/Main.hs, src-exe/Main.o )
+[3 of 3] Linking src-exe/Main
diff --git a/testsuite/tests/warnings/should_compile/T13727/T13727f.stderr b/testsuite/tests/warnings/should_compile/T13727/T13727f.stderr
index 165cd8100b..a7811c3c00 100644
--- a/testsuite/tests/warnings/should_compile/T13727/T13727f.stderr
+++ b/testsuite/tests/warnings/should_compile/T13727/T13727f.stderr
@@ -1,8 +1,8 @@
 
 <no location info>: warning: [GHC-32850] [-Wmissing-home-modules]
-    Modules are not listed in command line but needed for compilation: 
+    Modules are not listed in options for ‘main’ but needed for compilation:
         M1 Main
-[1 of 4] Compiling M1               ( src-lib\M1.hs, src-lib\M1.o )
-[2 of 4] Compiling Main             ( src-exe\Main.hs, src-exe\Main.o )
-[3 of 4] Compiling AltMain          ( src-exe\AltMain.hs, src-exe\AltMain.o )
-[4 of 4] Linking src-exe\AltMain.exe
+[1 of 4] Compiling M1               ( src-lib/M1.hs, src-lib/M1.o )
+[2 of 4] Compiling Main             ( src-exe/Main.hs, src-exe/Main.o )
+[3 of 4] Compiling AltMain          ( src-exe/AltMain.hs, src-exe/AltMain.o )
+[4 of 4] Linking src-exe/AltMain
diff --git a/testsuite/tests/warnings/should_compile/T13727/T13727g.stderr b/testsuite/tests/warnings/should_compile/T13727/T13727g.stderr
index 165cd8100b..a7811c3c00 100644
--- a/testsuite/tests/warnings/should_compile/T13727/T13727g.stderr
+++ b/testsuite/tests/warnings/should_compile/T13727/T13727g.stderr
@@ -1,8 +1,8 @@
 
 <no location info>: warning: [GHC-32850] [-Wmissing-home-modules]
-    Modules are not listed in command line but needed for compilation: 
+    Modules are not listed in options for ‘main’ but needed for compilation:
         M1 Main
-[1 of 4] Compiling M1               ( src-lib\M1.hs, src-lib\M1.o )
-[2 of 4] Compiling Main             ( src-exe\Main.hs, src-exe\Main.o )
-[3 of 4] Compiling AltMain          ( src-exe\AltMain.hs, src-exe\AltMain.o )
-[4 of 4] Linking src-exe\AltMain.exe
+[1 of 4] Compiling M1               ( src-lib/M1.hs, src-lib/M1.o )
+[2 of 4] Compiling Main             ( src-exe/Main.hs, src-exe/Main.o )
+[3 of 4] Compiling AltMain          ( src-exe/AltMain.hs, src-exe/AltMain.o )
+[4 of 4] Linking src-exe/AltMain
diff --git a/testsuite/tests/warnings/should_compile/T13727/T13727h.stderr b/testsuite/tests/warnings/should_compile/T13727/T13727h.stderr
index 3cbbcc1b9f..1ba4d56f24 100644
--- a/testsuite/tests/warnings/should_compile/T13727/T13727h.stderr
+++ b/testsuite/tests/warnings/should_compile/T13727/T13727h.stderr
@@ -1,8 +1,8 @@
 
 <no location info>: warning: [GHC-32850] [-Wmissing-home-modules]
-    Modules are not listed in command line but needed for compilation: 
+    Modules are not listed in options for ‘main’ but needed for compilation:
         M1
-[1 of 4] Compiling M1               ( src-lib\M1.hs, src-lib\M1.o )
-[2 of 4] Compiling Main             ( src-exe\Main.hs, src-exe\Main.o )
-[3 of 4] Compiling AltMain          ( src-exe\AltMain.hs, src-exe\AltMain.o )
-[4 of 4] Linking src-exe\AltMain.exe
+[1 of 4] Compiling M1               ( src-lib/M1.hs, src-lib/M1.o )
+[2 of 4] Compiling Main             ( src-exe/Main.hs, src-exe/Main.o )
+[3 of 4] Compiling AltMain          ( src-exe/AltMain.hs, src-exe/AltMain.o )
+[4 of 4] Linking src-exe/AltMain
diff --git a/testsuite/tests/warnings/should_compile/T13727/T13727i.stderr b/testsuite/tests/warnings/should_compile/T13727/T13727i.stderr
index 3cbbcc1b9f..1ba4d56f24 100644
--- a/testsuite/tests/warnings/should_compile/T13727/T13727i.stderr
+++ b/testsuite/tests/warnings/should_compile/T13727/T13727i.stderr
@@ -1,8 +1,8 @@
 
 <no location info>: warning: [GHC-32850] [-Wmissing-home-modules]
-    Modules are not listed in command line but needed for compilation: 
+    Modules are not listed in options for ‘main’ but needed for compilation:
         M1
-[1 of 4] Compiling M1               ( src-lib\M1.hs, src-lib\M1.o )
-[2 of 4] Compiling Main             ( src-exe\Main.hs, src-exe\Main.o )
-[3 of 4] Compiling AltMain          ( src-exe\AltMain.hs, src-exe\AltMain.o )
-[4 of 4] Linking src-exe\AltMain.exe
+[1 of 4] Compiling M1               ( src-lib/M1.hs, src-lib/M1.o )
+[2 of 4] Compiling Main             ( src-exe/Main.hs, src-exe/Main.o )
+[3 of 4] Compiling AltMain          ( src-exe/AltMain.hs, src-exe/AltMain.o )
+[4 of 4] Linking src-exe/AltMain
diff --git a/testsuite/tests/warnings/should_compile/T13727/T13727j.stderr b/testsuite/tests/warnings/should_compile/T13727/T13727j.stderr
index bf4f360054..a7f7dc7c5c 100644
--- a/testsuite/tests/warnings/should_compile/T13727/T13727j.stderr
+++ b/testsuite/tests/warnings/should_compile/T13727/T13727j.stderr
@@ -1,8 +1,8 @@
 
 <no location info>: warning: [GHC-32850] [-Wmissing-home-modules]
-    Modules are not listed in command line but needed for compilation: 
+    Modules are not listed in options for ‘main’ but needed for compilation:
         Main
-[1 of 4] Compiling M1               ( src-lib\M1.hs, src-lib\M1.o )
-[2 of 4] Compiling Main             ( src-exe\Main.hs, src-exe\Main.o )
-[3 of 4] Compiling AltMain          ( src-exe\AltMain.hs, src-exe\AltMain.o )
-[4 of 4] Linking src-exe\AltMain.exe
+[1 of 4] Compiling M1               ( src-lib/M1.hs, src-lib/M1.o )
+[2 of 4] Compiling Main             ( src-exe/Main.hs, src-exe/Main.o )
+[3 of 4] Compiling AltMain          ( src-exe/AltMain.hs, src-exe/AltMain.o )
+[4 of 4] Linking src-exe/AltMain