The impossible happened with TH + -fno-omit-interface-pragmas (#8333) · Issues · Glasgow Haskell Compiler / GHC

The impossible happened with TH + -fno-omit-interface-pragmas

$ ./ghc-stage2 --interactive Test.hs
GHCi, version 7.7.20130919: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
[1 of 1] Compiling Main             ( /home/errge/tmp/Test.hs, interpreted )
ghc-stage2: panic! (the 'impossible' happened)
  (GHC version 7.7.20130919 for i386-unknown-linux):
	toIfaceTickish

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

> 
Leaving GHCi.

With Test.hs being:

{-# LANGUAGE TemplateHaskell #-}
{-# OPTIONS_GHC -fno-omit-interface-pragmas #-}

main :: IO ()
main = return ()

I want to make TemplateHaskell generated non-essential info visible even with -O0. Compilation works, everything is fine. But I can't load source code like this with GHCi, which is annoying.

Setting priority to high, since this is a crash.

Trac metadata

Trac field	Value
Version	7.7
Type	Bug
TypeOfFailure	OtherFailure
Priority	high
Resolution	Unresolved
Component	Compiler
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture

```
$ ./ghc-stage2 --interactive Test.hs
GHCi, version 7.7.20130919: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
[1 of 1] Compiling Main             ( /home/errge/tmp/Test.hs, interpreted )
ghc-stage2: panic! (the 'impossible' happened)
  (GHC version 7.7.20130919 for i386-unknown-linux):
	toIfaceTickish

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

> 
Leaving GHCi.
```

With Test.hs being:

```
{-# LANGUAGE TemplateHaskell #-}
{-# OPTIONS_GHC -fno-omit-interface-pragmas #-}

main :: IO ()
main = return ()
```

I want to make TemplateHaskell generated non-essential info visible even with -O0. Compilation works, everything is fine. But I can't load source code like this with GHCi, which is annoying.

Setting priority to high, since this is a crash.

<details><summary>Trac metadata</summary>

| Trac field             | Value        |
| ---------------------- | ------------ |
| Version                | 7.7          |
| Type                   | Bug          |
| TypeOfFailure          | OtherFailure |
| Priority               | high         |
| Resolution             | Unresolved   |
| Component              | Compiler     |
| Test case              |              |
| Differential revisions |              |
| BlockedBy              |              |
| Related                |              |
| Blocking               |              |
| CC                     |              |
| Operating system       |              |
| Architecture           |              |

</details>