Migrate errors to diagnostics in GHC.Tc.Module

This commit migrates the errors in GHC.Tc.Module to use the new
diagnostic infrastructure.

It required a significant overhaul of the compatibility checks between
an hs-boot or signature module and its implementation; we now use
a Writer monad to accumulate errors; see the BootMismatch datatype
in GHC.Tc.Errors.Types, with its panoply of subtypes.
For the sake of readability, several local functions inside the
'checkBootTyCon' function were split off into top-level functions.

We split off GHC.Types.HscSource into a "boot or sig" vs "normal hs file"
datatype, as this mirrors the logic in several other places where we
want to treat hs-boot and hsig files in a similar fashion.

This commit also refactors the Backpack checks for type synonyms
implementing abstract data, to correctly reject implementations that
contain qualified or quantified types (this fixes #23342 and #23344).

1 files changed, 10 insertions, 10 deletions

diff --git a/testsuite/tests/backpack/should_fail/bkpfail27.stderr b/testsuite/tests/backpack/should_fail/bkpfail27.stderr
index bc5a8c6bd5..d4ae895626 100644
--- a/testsuite/tests/backpack/should_fail/bkpfail27.stderr
+++ b/testsuite/tests/backpack/should_fail/bkpfail27.stderr
@@ -1,21 +1,21 @@
 [1 of 3] Processing p
-  [1 of 2] Compiling H[sig]           ( p/H.hsig, nothing )
-  [2 of 2] Compiling M                ( p/M.hs, nothing )
+  [1 of 2] Compiling H[sig]           ( p\H.hsig, nothing )
+  [2 of 2] Compiling M                ( p\M.hs, nothing )
 [2 of 3] Processing q
   Instantiating q
-  [1 of 1] Compiling H                ( q/H.hs, bkpfail27.out/q/H.o )
+  [1 of 1] Compiling H                ( q\H.hs, bkpfail27.out\q\H.o )
 [3 of 3] Processing r
   Instantiating r
   [1 of 1] Including p[H=q:H]
     Instantiating p[H=q:H]
-    [1 of 2] Compiling H[sig]           ( p/H.hsig, bkpfail27.out/p/p-D5Mg3foBSCrDbQDKH4WGSG/H.o )
+    [1 of 2] Compiling H[sig]           ( p\H.hsig, bkpfail27.out\p\p-D5Mg3foBSCrDbQDKH4WGSG\H.o )
 
-bkpfail27.bkp:15:9: error:
+bkpfail27.bkp:15:9: error: [GHC-15843]
     • Type constructor ‘T’ has conflicting definitions in the module
-      and its hsig file
+      and its hsig file.
       Main module: type T :: *
                    type T = F
-      Hsig file:  type T :: *
-                  data T
-      Illegal type family application in implementation of abstract data.
-    • while checking that q:H implements signature H in p[H=q:H]
+        Hsig file: type T :: *
+                   data T
+      Illegal implementation of abstract data: Invalid type family ‘F’.
+    • While checking that ‘q:H’ implements signature ‘H’ in ‘p[H=q:H]’.