GHC HEAD panics on out-of-scope record pattern synonym (but not 9.10)

When attempting to make GHC HEAD build with ghcide-2.9.0.0 (see head.hackage!375 (merged)), it was discovered that GHC HEAD panics on invalid code that GHC 9.10 will reject with a proper error message. Here is a minimized version of the code that it panics on:

-- A.hs
{-# LANGUAGE PatternSynonyms #-}
module A
  ( T
  , T_(unT)
  , pattern T
  ) where

type T = T_ ()

data T_ a = PrivateT { unT_ :: a }

pattern T :: a -> T_ a
pattern T { unT } <- PrivateT { unT_ = unT }

-- B.hs
module B (T, T_(..)) where

import A (T, T_(..))

-- C.hs
{-# LANGUAGE RecordWildCards #-}
module C where

import B

foo :: T -> ()
foo (T { unT = x }) = x

Note that the T pattern synonym is not in scope in C, and GHC 9.10.1 correctly reports this:

$ ghc-9.10.1 C.hs
[1 of 3] Compiling A                ( A.hs, A.o )
[2 of 3] Compiling B                ( B.hs, B.o )
[3 of 3] Compiling C                ( C.hs, C.o )
C.hs:8:6: error: [GHC-76037]
    Not in scope: data constructor ‘T’
  |
8 | foo (T { unT = x }) = x
  |      ^

GHC HEAD (as of commit bc1d435e), on the other hand, will panic:

$ ~/Software/ghc-9.11.20240630/bin/ghc C.hs
[1 of 3] Compiling A                ( A.hs, A.o )
[2 of 3] Compiling B                ( B.hs, B.o )
[3 of 3] Compiling C                ( C.hs, C.o )
<no location info>: error:
    panic! (the 'impossible' happened)
  GHC version 9.11.20240630:
        lookupConstructorInfo: not a ConLike
  name: T
  Call stack:
      CallStack (from HasCallStack):
        callStackDoc, called at compiler/GHC/Utils/Panic.hs:190:37 in ghc-9.11-inplace:GHC.Utils.Panic
        pprPanic, called at compiler/GHC/Rename/Env.hs:439:18 in ghc-9.11-inplace:GHC.Rename.Env
  CallStack (from HasCallStack):
    panic, called at compiler/GHC/Utils/Error.hs:507:29 in ghc-9.11-inplace:GHC.Utils.Error


Please report this as a GHC bug:  https://www.haskell.org/ghc/reportabug

Note that:

• Re-exporting pattern T from B will cause GHC to accept the program (as expected) on both GHC 9.10.1 and HEAD.

• For some reason, enabling the RecordWildCards extension is essential to triggering the panic. If you remove this extension, then GHC HEAD will give a proper error message:

  $ ~/Software/ghc-9.11.20240630/bin/ghc C.hs
  [1 of 3] Compiling A                ( A.hs, A.o )
  [2 of 3] Compiling B                ( B.hs, B.o )
  [3 of 3] Compiling C                ( C.hs, C.o )
  C.hs:8:6: error: [GHC-01928]
      • Illegal term-level use of the type constructor ‘T’
      • imported from ‘B’ at C.hs:5:1-8
        (and originally defined in ‘A’ at A.hs:9:1-14)
      • In the pattern: T {unT = x}
        In an equation for ‘foo’: foo (T {unT = x}) = x
    |
  8 | foo (T { unT = x }) = x
    |      ^^^^^^^^^^^^^